This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Implement -Wimplicit-fallthrough: the rest


...and the boring part.  It found a few bugs, e.g. in jcf-dump.c
and rs6000.c - I fixed those.

I think generally it's better to use the attribute rather than a falls
through comment, because the latter can't be followed by other comment
or a macro to work.

This patch has been tested on powerpc64le-unknown-linux-gnu, aarch64-linux-gnu,
and x86_64-redhat-linux.

2016-07-22  Marek Polacek  <polacek@redhat.com>

	PR c/7652
gcc/
	* Makefile.in (insn-attrtab.o-warn, insn-dfatab.o-warn,
	insn-latencytab.o-warn, insn-output.o-warn, insn-emit.o-warn): Add
	-Wno-switch-fallthrough.
	* alias.c (find_base_value): Adjust falls through comment.
	* builtins.c (expand_builtin_int_roundingfn_2): Add gcc_fallthrough.
	(expand_builtin): Likewise.
	* cfgexpand.c (expand_debug_expr): Adjust falls through comment.
	* combine.c (find_split_point): Likewise.
	(expand_compound_operation): Likewise.  Add gcc_fallthrough.
	(make_compound_operation): Adjust falls through comment.
	(canon_reg_for_combine): Add gcc_fallthrough.
	(force_to_mode): Adjust falls through comment.  Add gcc_fallthrough.
	(simplify_shift_const_1): Adjust falls through comment.
	(simplify_comparison): Likewise.
	* config/aarch64/aarch64-builtins.c (aarch64_simd_expand_args): Add
	gcc_fallthrough.
	* config/aarch64/predicates.md: Likewise.
	* config/i386/i386.c (ix86_gimplify_va_arg): Add gcc_fallthrough.
	(ix86_legitimate_constant_p): Likewise.
	(print_reg): Likewise.
	(ix86_print_operand): Likewise.
	(ix86_build_const_vector): Likewise.
	(ix86_expand_branch): Likewise.
	(ix86_sched_init_global): Adjust falls through comment.
	(ix86_expand_multi_arg_builtin): Add gcc_fallthrough.
	(ix86_expand_args_builtin): Add break.
	(ix86_expand_round_builtin): Likewise.
	(ix86_expand_builtin): Add gcc_fallthrough.
	(ix86_expand_vector_init_one_var): Likewise.
	* config/rs6000/rs6000.c (rs6000_builtin_vectorized_libmass): Likewise.
	(altivec_expand_ld_builtin): Add break.
	(altivec_expand_st_builtin): Likewise.
	(rs6000_emit_vector_compare_inner): Add gcc_fallthrough.
	(rs6000_adjust_cost): Likewise.
	(insn_must_be_first_in_group): Likewise.
	(rs6000_handle_altivec_attribute): Likewise.
	* config/rs6000/rs6000.md: Likewise.  Adjust falls through comment.
	* convert.c (convert_to_real_1): Add gcc_fallthrough.
	(convert_to_integer_1): Likewise.
	* cselib.c (cselib_expand_value_rtx_1): Add gcc_fallthrough.
	* dbxout.c (dbxout_symbol): Adjust falls through comment.
	* gcc/df-scan.c (df_uses_record): Likewise.
	* dojump.c (do_jump): Add gcc_fallthrough.
	* dwarf2out.c (mem_loc_descriptor): Likewise.  Adjust falls through
	comment.
	(resolve_args_picking_1): Likewise.
	(loc_list_from_tree_1): Likewise.
	(gen_formal_parameter_die): Likewise.
	* expmed.c (expand_divmod): Add gcc_fallthrough.
	(make_tree): Adjust falls through comment.
	* expr.c (expand_expr_real_2): Add gcc_fallthrough.
	(expand_expr_real_1): Likewise.  Adjust falls through comment.
	* final.c (output_alternate_entry_point): Add gcc_fallthrough.
	* fold-const.c (const_binop): Adjust falls through comment.
	(fold_truth_not_expr): Likewise.
	(make_range_step): Add gcc_fallthrough.
	(fold_cond_expr_with_comparison): Likewise.
	(fold_binary_loc): Likewise.
	(contains_label_1): Adjust falls through comment.
	(multiple_of_p): Likewise.
	* gcc.c (driver_handle_option): Add gcc_fallthrough.
	* gcov-tool.c (process_args): Likewise.
	* genattrtab.c (check_attr_test): Likewise.
	(make_canonical): Likewise.
	(write_test_expr): Likewise.
	* genconfig.c (walk_insn_part): Likewise.
	* gengtype.c (dbgprint_count_type_at): Add break.
	* genpreds.c (validate_exp): Adjust falls through comment.  Add
	gcc_fallthrough.
	(needs_variable): Adjust falls through comment.
	* gensupport.c (get_alternatives_number): Add gcc_fallthrough.
	(subst_dup): Likewise.
	* gimple-pretty-print.c (dump_gimple_assign): Likewise.
	* gimple-ssa-strength-reduction.c
	(find_candidates_dom_walker::before_dom_children): Likewise.
	* gimplify.c (gimplify_addr_expr): Adjust falls through comment.
	(omp_default_clause): Add gcc_fallthrough.
	(gimplify_scan_omp_clauses): Likewise.
	(goa_stabilize_expr): Likewise.
	* godump.c (go_format_type): Add gcc_fallthrough.
	* graphite-isl-ast-to-gimple.c (substitute_ssa_name): Adjust falls
	through comment.
	* hsa-gen.c (get_address_from_value): Likewise.
	(gen_hsa_insn_for_internal_fn_call): Add gcc_fallthrough.
	* ipa-icf.c (sem_function::hash_stmt): Adjust falls through comment.
	* ira.c (ira_setup_alts): Add gcc_fallthrough.
	* lra-eliminations.c (lra_eliminate_regs_1): Adjust falls through
	comment.
	* lto-streamer-out.c (lto_output_tree_ref): Add gcc_fallthrough.
	* omp-low.c (scan_sharing_clauses): Add gcc_fallthrough.
	(lower_rec_input_clauses): Likewise.
	* opts.c (common_handle_option): Likewise.
	* print-rtl.c (print_rtx): Likewise.
	* read-rtl.c (read_rtx_code): Likewise.
	* real.c (round_for_format): Likewise.
	* recog.c (asm_operand_ok): Likewise.
	* reg-stack.c (get_true_reg): Likewise.
	* reginfo.c (reg_scan_mark_refs): Adjust falls through comment.
	* reload1.c (set_label_offsets): Likewise.
	(eliminate_regs_1): Likewise.
	(elimination_effects): Add gcc_fallthrough.
	(reload_reg_reaches_end_p): Adjust falls through comment.
	* gcc/resource.c (mark_referenced_resources): Add gcc_fallthrough.
	(mark_set_resources): Likewise.
	* rtlanal.c (reg_overlap_mentioned_p): Likewise.
	(commutative_operand_precedence): Likewise.
	(rtx_cost): Likewise.
	* sched-rgn.c (is_exception_free): Likewise.
	* simplify-rtx.c (simplify_binary_operation_1): Likewise.
	(simplify_rtx): Adjust falls through comment.
	* stor-layout.c (int_mode_for_mode): Likewise.
	* toplev.c (print_to_asm_out_file): Add gcc_fallthrough.
	(print_to_stderr): Add gcc_fallthrough.
	* tree-cfg.c (gimple_verify_flow_info): Adjust falls through comment.
	* tree-chrec.c (chrec_fold_plus_1): Add gcc_fallthrough.
	(chrec_fold_multiply): Likewise.
	(evolution_function_is_invariant_rec_p): Likewise.
	(for_each_scev_op): Likewise.
	* tree-complex.c (expand_complex_division): Likewise.
	* tree-data-ref.c (siv_subscript_p): Add gcc_fallthrough.
	(get_references_in_stmt): Likewise.
	* tree-pretty-print.c (dump_omp_clause): Likewise.
	(dump_generic_node): Likewise.
	* tree-ssa-loop-ivopts.c (find_deriving_biv_for_expr): Likewise.
	* tree-vect-patterns.c (adjust_bool_pattern): Likewise.
	* tree.c (find_placeholder_in_expr): Adjust falls through comment.
	(substitute_in_expr): Likewise.
	(type_cache_hasher::equal): Likewise.
	(walk_type_fields): Likewise.
	* tree-chrec.c (chrec_fold_plus_1): Add gcc_fallthrough.
	* tree-eh.c (lower_eh_constructs_2): Likewise.
	* var-tracking.c (adjust_mems): Likewise.
	(set_dv_changed): Adjust falls through comment.
	* varasm.c (default_function_section): Add gcc_fallthrough.
	(const_rtx_hash_1): Likewise.
	(output_addressed_constants): Adjust falls through comment.
	* include/libiberty.h (D_FALLTHRU): Define.
gcc/c-family/
	* c-ada-spec.c (dump_generic_ada_node): Add gcc_fallthrough.
	* c-common.c (warn_if_unused_value): Likewise.
	(resolve_overloaded_builtin): Add gcc_fallthrough.
	(scalar_to_vector): Adjust falls through comment.
	* c-lex.c (lex_string): Add gcc_fallthrough.
	* c-opts.c (c_common_handle_option): Adjust falls through comment.
	* c-pragma.c (handle_pragma_pack): Add gcc_fallthrough.
	* c-pretty-print.c (c_pretty_printer::postfix_expression): Adjust
	falls through comment.
	* cilk.c (extract_free_variables): Add gcc_fallthrough.
gcc/c/
	* c-decl.c (pop_scope): Add gcc_fallthrough.
	* c-parser.c (c_parser_external_declaration): Add gcc_fallthrough.
	(c_parser_statement_after_labels): Add gcc_fallthrough.
	(c_parser_postfix_expression): Add gcc_fallthrough.
	* c-typeck.c (composite_type): Adjust falls through comment.
	(build_unary_op): Likewise.
	(c_mark_addressable): Add gcc_fallthrough.
	(c_finish_omp_clauses): Likewise.
gcc/cp/
	* call.c (add_builtin_candidate): Add gcc_fallthrough.
	(build_integral_nontype_arg_conv): Adjust falls through comment.
	(build_new_op_1):  Add gcc_fallthrough.
	(convert_like_real): Adjust falls through comment.
	* class.c (fixed_type_or_null): Likewise.
	* constexpr.c (cxx_eval_constant_expression): Adjust falls through
	comment.
	(potential_constant_expression_1): Likewise.  Add gcc_fallthrough.
	* cp-gimplify.c (cp_gimplify_expr): Adjust falls through comment.
	(cp_fold): Add gcc_fallthrough.
	* cvt.c (build_expr_type_conversion): Adjust falls through comment.
	* cxx-pretty-print.c (pp_cxx_unqualified_id): Add gcc_fallthrough.
	(pp_cxx_qualified_id): Likewise.
	(cxx_pretty_printer::constant): Adjust falls through comment.
	(cxx_pretty_printer::primary_expression): Add gcc_fallthrough.
	(pp_cxx_pm_expression): Adjust falls through comment.
	(cxx_pretty_printer::expression): Add gcc_fallthrough.
	(cxx_pretty_printer::declaration_specifiers): Reformat code.
	(pp_cxx_type_specifier_seq): Adjust falls through comment.
	(pp_cxx_ptr_operator): Likewise.  Add gcc_fallthrough.
	* error.c (dump_type): Likewise.
	(dump_decl): Likewise.
	(dump_expr): Add gcc_fallthrough.
	* mangle.c (write_type): Adjust falls through comment.
	* method.c (synthesized_method_walk): Add gcc_fallthrough.
	* name-lookup.c (arg_assoc_type): Likewise.
	* parser.c (cp_lexer_print_token): Adjust falls through comment.
	(cp_parser_skip_to_end_of_statement): Add gcc_fallthrough.
	(cp_parser_primary_expression): Likewise.
	(cp_parser_statement): Handle fallthrough attribute.
	(cp_parser_label_for_labeled_statement): Set FALLTHROUGH_LABEL_P on
	labels.
	(cp_parser_storage_class_specifier_opt): Add gcc_fallthrough.
	(cp_parser_operator): Likewise.
	(cp_parser_std_attribute): Handle fallthrough attribute.
	(cp_parser_check_std_attribute): Detect duplicated fallthrough
	attribute.
	(cp_parser_skip_to_end_of_template_parameter_list): Add
	gcc_fallthrough.
	(cp_parser_cache_defarg): Likewise.
	(cp_parser_omp_for_cond): Likewise.
	* pt.c (find_parameter_packs_r): Add gcc_fallthrough.
	(tsubst_aggr_type): Adjust falls through comment.
	(unify): Add gcc_fallthrough.
	* semantics.c (finish_omp_clauses): Likewise.
	(finish_decltype_type): Likewise.
	* tree.c (lvalue_kind): Likewise.
	* typeck.c (structural_comptypes): Likewise.
	(cp_build_binary_op): Likewise.
	(cp_build_modify_expr): Likewise.
gcc/fortran/
	* arith.c (eval_intrinsic): Add gcc_fallthrough.
	* array.c (gfc_ref_dimen_size): Likewise.
	* decl.c (match_attr_spec): Likewise.
	* dependency.c (dep_ref): Likewise.
	* dump-parse-tree.c (show_code_node): Likewise.
	* frontend-passes.c (optimize_op): Likewise.
	(gfc_expr_walker): Likewise.
	* parse.c (next_fixed): Likewise.
	* primary.c (match_arg_list_function): Likewise.
	(gfc_match_rvalue): Likewise.
	(match_variable): Likewise.
	* resolve.c (resolve_operator): Adjust falls through comment.
	(fixup_charlen): Add gcc_fallthrough.
	(resolve_allocate_expr): Adjust falls through comment.
	* trans-array.c (gfc_conv_ss_startstride): Add gcc_fallthrough.
	* trans-expr.c (flatten_array_ctors_without_strlen): Likewise.
	* trans-intrinsic.c (conv_intrinsic_cobound): Likewise.
	(gfc_conv_intrinsic_len): Adjust falls through comment.
	* trans-stmt.c (gfc_trans_where_2): Add gcc_fallthrough.
gcc/go/
	* go-system.h (go_fallthrough): Define.
	* gofrontend/escape.cc (Escape_analysis_assign::assign): Add
	go_fallthrough.
	* gofrontend/expressions.cc (Binary_expression::do_get_backend):
	Likewise.
gcc/java/
	* expr.c (java_truthvalue_conversion): Adjust falls through comment.
	* jcf-io.c (verify_constant_pool): Likewise.
	* typeck.c (promote_type): Likewise.  Add gcc_fallthrough.
	* jcf-dump.c (print_constant): Add break.
gcc/objc/
	* objc-encoding.c (encode_type): Add gcc_fallthrough.
libcpp/
	* lex.c (search_line_fast): Add CPP_FALLTHRU.
	(lex_raw_string): Likewise.
	(_cpp_lex_direct): Add CPP_FALLTHRU.
	(cpp_token_val_index): Adjust falls through comment.
	* macro.c (parse_params): Add CPP_FALLTHRU.
	* pch.c (write_macdef): Add CPP_FALLTHRU.
	(count_defs): Adjust falls through comment.
	(write_defs): Likewise.
libgcc/
	* soft-fp/op-common.h: Add _FP_FALLTHRU.
	* soft-fp/soft-fp.h (_FP_FALLTHRU): Define.
libgo/
	* runtime/heapdump.c (dumpefacetypes): Add break.
libiberty/
	* cp-demangle.c (d_print_mod): Add D_FALLTHRU.
libstdc++-v3/
	* libsupc++/hash_bytes.cc: Add [[gnu::fallthrough]].

diff --git gcc/gcc/Makefile.in gcc/gcc/Makefile.in
index 7a0160f..1f6cb7d 100644
--- gcc/gcc/Makefile.in
+++ gcc/gcc/Makefile.in
@@ -218,6 +218,11 @@ libgcov-merge-tool.o-warn = -Wno-error
 gimple-match.o-warn = -Wno-unused
 generic-match.o-warn = -Wno-unused
 dfp.o-warn = -Wno-strict-aliasing
+insn-attrtab.o-warn = -Wno-implicit-fallthrough
+insn-dfatab.o-warn = -Wno-implicit-fallthrough
+insn-latencytab.o-warn = -Wno-implicit-fallthrough
+insn-output.o-warn = -Wno-implicit-fallthrough
+insn-emit.o-warn = -Wno-implicit-fallthrough
 
 # All warnings have to be shut off in stage1 if the compiler used then
 # isn't gcc; configure determines that.  WARN_CFLAGS will be either
diff --git gcc/gcc/alias.c gcc/gcc/alias.c
index dd1dfd3..f4b5a92 100644
--- gcc/gcc/alias.c
+++ gcc/gcc/alias.c
@@ -1398,7 +1398,7 @@ find_base_value (rtx src)
       if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS)
 	break;
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case PLUS:
     case MINUS:
diff --git gcc/gcc/builtins.c gcc/gcc/builtins.c
index 03a0dc8..703219f 100644
--- gcc/gcc/builtins.c
+++ gcc/gcc/builtins.c
@@ -2587,7 +2587,7 @@ expand_builtin_int_roundingfn_2 (tree exp, rtx target)
     {
     CASE_FLT_FN (BUILT_IN_IRINT):
       fallback_fn = BUILT_IN_LRINT;
-      /* FALLTHRU */
+      gcc_fallthrough ();
     CASE_FLT_FN (BUILT_IN_LRINT):
     CASE_FLT_FN (BUILT_IN_LLRINT):
       builtin_optab = lrint_optab;
@@ -2595,7 +2595,7 @@ expand_builtin_int_roundingfn_2 (tree exp, rtx target)
 
     CASE_FLT_FN (BUILT_IN_IROUND):
       fallback_fn = BUILT_IN_LROUND;
-      /* FALLTHRU */
+      gcc_fallthrough ();
     CASE_FLT_FN (BUILT_IN_LROUND):
     CASE_FLT_FN (BUILT_IN_LLROUND):
       builtin_optab = lround_optab;
@@ -5902,6 +5902,7 @@ expand_builtin (tree exp, rtx target, rtx subtarget, machine_mode mode,
     CASE_FLT_FN (BUILT_IN_ILOGB):
       if (! flag_unsafe_math_optimizations)
 	break;
+      gcc_fallthrough ();
     CASE_FLT_FN (BUILT_IN_ISINF):
     CASE_FLT_FN (BUILT_IN_FINITE):
     case BUILT_IN_ISFINITE:
diff --git gcc/gcc/c-family/c-ada-spec.c gcc/gcc/c-family/c-ada-spec.c
index e33fdff..659ffa0 100644
--- gcc/gcc/c-family/c-ada-spec.c
+++ gcc/gcc/c-family/c-ada-spec.c
@@ -1862,6 +1862,8 @@ dump_generic_ada_node (pretty_printer *buffer, tree node, tree type, int spc,
     case TREE_BINFO:
       dump_generic_ada_node
 	(buffer, BINFO_TYPE (node), type, spc, limited_access, name_only);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
 
     case TREE_VEC:
       pp_string (buffer, "--- unexpected node: TREE_VEC");
diff --git gcc/gcc/c-family/c-common.c gcc/gcc/c-family/c-common.c
index 9900e93..11adabb 100644
--- gcc/gcc/c-family/c-common.c
+++ gcc/gcc/c-family/c-common.c
@@ -1518,6 +1521,7 @@ warn_if_unused_value (const_tree exp, location_t locus)
 	 but front ends may define such.  */
       if (EXPRESSION_CLASS_P (exp) && TREE_OPERAND_LENGTH (exp) == 0)
 	return false;
+      gcc_fallthrough ();
 
     warn:
       return warning_at (locus, OPT_Wunused_value, "value computed is not used");
@@ -11443,6 +11460,7 @@ resolve_overloaded_builtin (location_t loc, tree function,
 	    gcc_unreachable ();
 	}
 	/* Fallthrough to the normal processing.  */
+	gcc_fallthrough ();
       }
     case BUILT_IN_ATOMIC_EXCHANGE_N:
     case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N:
@@ -11451,6 +11469,7 @@ resolve_overloaded_builtin (location_t loc, tree function,
       {
 	fetch_op = false;
 	/* Fallthrough to further processing.  */
+	gcc_fallthrough ();
       }
     case BUILT_IN_ATOMIC_ADD_FETCH_N:
     case BUILT_IN_ATOMIC_SUB_FETCH_N:
@@ -11467,6 +11486,7 @@ resolve_overloaded_builtin (location_t loc, tree function,
       {
         orig_format = false;
 	/* Fallthru for parameter processing.  */
+	gcc_fallthrough ();
       }
     case BUILT_IN_SYNC_FETCH_AND_ADD_N:
     case BUILT_IN_SYNC_FETCH_AND_SUB_N:
@@ -12623,7 +12643,7 @@ scalar_to_vector (location_t loc, enum tree_code code, tree op0, tree op1,
       case BIT_XOR_EXPR:
       case BIT_AND_EXPR:
 	integer_only_op = true;
-	/* ... fall through ...  */
+	/* fall through */
 
       case VEC_COND_EXPR:
 
diff --git gcc/gcc/c-family/c-lex.c gcc/gcc/c-family/c-lex.c
index 8f33d86..6ad529b 100644
--- gcc/gcc/c-family/c-lex.c
+++ gcc/gcc/c-family/c-lex.c
@@ -1142,6 +1142,7 @@ lex_string (const cpp_token *tok, tree *valp, bool objc_string, bool translate)
 	  else
 	    error ("unsupported non-standard concatenation of string literals");
 	}
+      gcc_fallthrough ();
 
     case CPP_STRING:
       if (!concats)
diff --git gcc/gcc/c-family/c-opts.c gcc/gcc/c-family/c-opts.c
index c11e7e7..6053c91 100644
--- gcc/gcc/c-family/c-opts.c
+++ gcc/gcc/c-family/c-opts.c
@@ -436,7 +436,7 @@ c_common_handle_option (size_t scode, const char *arg, int value,
 
     case OPT_ffreestanding:
       value = !value;
-      /* Fall through....  */
+      /* Fall through.  */
     case OPT_fhosted:
       flag_hosted = value;
       flag_no_builtin = !value;
diff --git gcc/gcc/c-family/c-pragma.c gcc/gcc/c-family/c-pragma.c
index 277bc56..b218337 100644
--- gcc/gcc/c-family/c-pragma.c
+++ gcc/gcc/c-family/c-pragma.c
@@ -214,6 +214,7 @@ handle_pragma_pack (cpp_reader * ARG_UNUSED (dummy))
 	    align = maximum_field_alignment;
 	    break;
 	  }
+	gcc_fallthrough ();
       default:
 	GCC_BAD2 ("alignment must be a small power of two, not %d", align);
       }
diff --git gcc/gcc/c-family/c-pretty-print.c gcc/gcc/c-family/c-pretty-print.c
index 704d21d..374bd1a 100644
--- gcc/gcc/c-family/c-pretty-print.c
+++ gcc/gcc/c-family/c-pretty-print.c
@@ -1662,7 +1662,7 @@ c_pretty_printer::postfix_expression (tree e)
           id_expression (TREE_OPERAND (e, 0));
 	  break;
 	}
-      /* else fall through.  */
+      /* fall through.  */
 
     default:
       primary_expression (e);
diff --git gcc/gcc/c-family/cilk.c gcc/gcc/c-family/cilk.c
index 8f34cd6..87ba9f6 100644
--- gcc/gcc/c-family/cilk.c
+++ gcc/gcc/c-family/cilk.c
@@ -1096,6 +1096,7 @@ extract_free_variables (tree t, struct wrapper_data *wd,
     case RESULT_DECL:
       if (wd->type != CILK_BLOCK_SPAWN)
 	TREE_ADDRESSABLE (t) = 1;
+      gcc_fallthrough ();
     case VAR_DECL:
     case PARM_DECL:
       if (!is_global_var (t))
diff --git gcc/gcc/c/c-decl.c gcc/gcc/c/c-decl.c
index 41aabeb..9ff35b2 100644
--- gcc/gcc/c/c-decl.c
+++ gcc/gcc/c/c-decl.c
@@ -1328,7 +1328,7 @@ pop_scope (void)
 		set_type_context (TREE_TYPE (p), context);
 	    }
 
-	  /* Fall through.  */
+	  gcc_fallthrough ();
 	  /* Parameters go in DECL_ARGUMENTS, not BLOCK_VARS, and have
 	     already been put there by store_parm_decls.  Unused-
 	     parameter warnings are handled by function.c.
diff --git gcc/gcc/c/c-parser.c gcc/gcc/c/c-parser.c
index 8952bca..ef99fbb 100644
--- gcc/gcc/c/c-parser.c
+++ gcc/gcc/c/c-parser.c
@@ -1549,6 +1552,7 @@ c_parser_external_declaration (c_parser *parser)
 	}
       /* Else fall through, and yield a syntax error trying to parse
 	 as a declaration or function definition.  */
+      gcc_fallthrough ();
     default:
     decl_or_fndef:
       /* A declaration or a function definition (or, in Objective-C,
@@ -5342,6 +5389,7 @@ c_parser_statement_after_labels (c_parser *parser, bool *if_p,
     default:
     expr_stmt:
       stmt = c_finish_expr_stmt (loc, c_parser_expression_conv (parser).value);
+      gcc_fallthrough ();
     expect_semicolon:
       c_parser_skip_until_found (parser, CPP_SEMICOLON, "expected %<;%>");
       break;
@@ -8171,6 +8219,7 @@ c_parser_postfix_expression (c_parser *parser)
 	  break;
 	}
       /* Else fall through to report error.  */
+      gcc_fallthrough ();
     default:
       c_parser_error (parser, "expected expression");
       expr.set_error ();
diff --git gcc/gcc/c/c-typeck.c gcc/gcc/c/c-typeck.c
index 0b5ab91..1d34971 100644
--- gcc/gcc/c/c-typeck.c
+++ gcc/gcc/c/c-typeck.c
@@ -605,7 +605,7 @@ composite_type (tree t1, tree t2)
 
 	t1 = build_function_type (valtype, newargs);
 	t1 = qualify_type (t1, t2);
-	/* ... falls through ...  */
+	gcc_fallthrough ();
       }
 
     default:
@@ -4493,7 +4493,7 @@ build_unary_op (location_t location,
 	      return error_mark_node;
 	    }
 
-	  /* ... fall through ...  */
+	  /* fall through */
 
 	case ARRAY_REF:
 	  if (TYPE_REVERSE_STORAGE_ORDER (TREE_TYPE (TREE_OPERAND (arg, 0))))
@@ -4695,10 +4695,10 @@ c_mark_addressable (tree exp)
 	    return false;
 	  }
 
-	/* drops in */
+	gcc_fallthrough ();
       case FUNCTION_DECL:
 	TREE_ADDRESSABLE (x) = 1;
-	/* drops out */
+	gcc_fallthrough ();
       default:
 	return true;
     }
@@ -12948,6 +12948,7 @@ c_finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 
 	check_dup_generic:
 	  t = OMP_CLAUSE_DECL (c);
+	  gcc_fallthrough ();
 	check_dup_generic_t:
 	  if (!VAR_P (t) && TREE_CODE (t) != PARM_DECL)
 	    {
diff --git gcc/gcc/cfgexpand.c gcc/gcc/cfgexpand.c
index 9a2837b..8482f55 100644
--- gcc/gcc/cfgexpand.c
+++ gcc/gcc/cfgexpand.c
@@ -4239,7 +4239,7 @@ expand_debug_expr (tree exp)
 	  set_mem_attributes (op0, exp, 0);
 	  return op0;
 	}
-      /* Fall through...  */
+      /* Fall through.  */
 
     case INTEGER_CST:
     case REAL_CST:
diff --git gcc/gcc/combine.c gcc/gcc/combine.c
index 1becc3c..0764711 100644
--- gcc/gcc/combine.c
+++ gcc/gcc/combine.c
@@ -5135,7 +5135,7 @@ find_split_point (rtx *loc, rtx_insn *insn, bool set_src)
       split = find_split_point (&XEXP (x, 2), insn, false);
       if (split)
 	return split;
-      /* ... fall through ...  */
+      /* fall through */
     case RTX_BIN_ARITH:
     case RTX_COMM_ARITH:
     case RTX_COMPARE:
@@ -5143,7 +5143,7 @@ find_split_point (rtx *loc, rtx_insn *insn, bool set_src)
       split = find_split_point (&XEXP (x, 1), insn, false);
       if (split)
 	return split;
-      /* ... fall through ...  */
+      /* fall through */
     case RTX_UNARY:
       /* Some machines have (and (shift ...) ...) insns.  If X is not
 	 an AND, but XEXP (X, 0) is, use it as our split point.  */
@@ -6955,6 +6955,7 @@ expand_compound_operation (rtx x)
     {
     case ZERO_EXTEND:
       unsignedp = 1;
+      gcc_fallthrough ();
     case SIGN_EXTEND:
       /* We can't necessarily use a const_int for a multiword mode;
 	 it depends on implicitly extending the value.
@@ -6997,7 +6998,7 @@ expand_compound_operation (rtx x)
     case ZERO_EXTRACT:
       unsignedp = 1;
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case SIGN_EXTRACT:
       /* If the operand is a CLOBBER, just return it.  */
@@ -8033,7 +8034,7 @@ make_compound_operation (rtx x, enum rtx_code in_code)
 	  break;
 	}
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case ASHIFTRT:
       lhs = XEXP (x, 0);
@@ -8261,6 +8262,7 @@ canon_reg_for_combine (rtx x, rtx reg)
       if (op0 != XEXP (x, 0) || op1 != XEXP (x, 1) || op2 != XEXP (x, 2))
 	return simplify_gen_ternary (GET_CODE (x), GET_MODE (x),
 				     GET_MODE (op0), op0, op1, op2);
+      gcc_fallthrough ();
 
     case RTX_OBJ:
       if (REG_P (x))
@@ -8527,7 +8529,7 @@ force_to_mode (rtx x, machine_mode mode, unsigned HOST_WIDE_INT mask,
 				mode, smask, next_select);
       }
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case MULT:
       /* Substituting into the operands of a widening MULT is not likely to
@@ -8598,6 +8600,7 @@ force_to_mode (rtx x, machine_mode mode, unsigned HOST_WIDE_INT mask,
 				   XEXP (XEXP (x, 0), 1));
 	  return force_to_mode (x, mode, mask, next_select);
 	}
+      gcc_fallthrough ();
 
     binop:
       /* For most binary operations, just propagate into the operation and
@@ -8776,6 +8779,7 @@ force_to_mode (rtx x, machine_mode mode, unsigned HOST_WIDE_INT mask,
       if (mask == 1)
 	x = simplify_gen_binary (LSHIFTRT, GET_MODE (x),
 				 XEXP (x, 0), XEXP (x, 1));
+      gcc_fallthrough ();
 
     shiftrt:
 
@@ -8853,6 +8857,7 @@ force_to_mode (rtx x, machine_mode mode, unsigned HOST_WIDE_INT mask,
       /* (and (not FOO) CONST) is (not (or FOO (not CONST))), so we must
 	 use the full mask inside the NOT.  */
       mask = fuller_mask;
+      gcc_fallthrough ();
 
     unop:
       op0 = gen_lowpart_or_truncate (op_mode,
@@ -10400,7 +10405,7 @@ simplify_shift_const_1 (enum rtx_code code, machine_mode result_mode,
 	      continue;
 	    }
 
-	  /* ... fall through ...  */
+	  /* fall through */
 
 	case LSHIFTRT:
 	case ASHIFT:
@@ -11726,7 +11731,7 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
 	      continue;
 	    }
 
-	  /* ... fall through ...  */
+	  /* fall through */
 
 	case SIGN_EXTRACT:
 	  tem = expand_compound_operation (op0);
diff --git gcc/gcc/config/aarch64/aarch64-builtins.c gcc/gcc/config/aarch64/aarch64-builtins.c
index 6b90b2a..fe37ea2 100644
--- gcc/gcc/config/aarch64/aarch64-builtins.c
+++ gcc/gcc/config/aarch64/aarch64-builtins.c
@@ -999,6 +999,7 @@ aarch64_simd_expand_args (rtx target, int icode, int have_retval,
 		}
 	      /* Fall through - if the lane index isn't a constant then
 		 the next case will error.  */
+	      gcc_fallthrough ();
 	    case SIMD_ARG_CONSTANT:
 constant_arg:
 	      if (!(*insn_data[icode].operand[opc].predicate)
diff --git gcc/gcc/config/aarch64/predicates.md gcc/gcc/config/aarch64/predicates.md
index 8f2726d..9a7b336 100644
--- gcc/gcc/config/aarch64/predicates.md
+++ gcc/gcc/config/aarch64/predicates.md
@@ -180,6 +180,7 @@
 	  || GET_CODE (XEXP (op, 1)) != CONST_INT)
 	return false;
       op = XEXP (op, 0);
+      gcc_fallthrough ();
 
     case SYMBOL_REF:
       return SYMBOL_REF_TLS_MODEL (op) == TLS_MODEL_INITIAL_EXEC;
@@ -201,6 +202,7 @@
 	  || GET_CODE (XEXP (op, 1)) != CONST_INT)
 	return false;
       op = XEXP (op, 0);
+      gcc_fallthrough ();
 
     case SYMBOL_REF:
       return SYMBOL_REF_TLS_MODEL (op) == TLS_MODEL_LOCAL_EXEC;
diff --git gcc/gcc/config/i386/i386.c gcc/gcc/config/i386/i386.c
index ba35dce..ed6a019 100644
--- gcc/gcc/config/i386/i386.c
+++ gcc/gcc/config/i386/i386.c
@@ -9315,6 +9315,7 @@ pass_in_reg:
 	error_p = 1;
       if (cum->float_in_sse < 2)
 	break;
+      gcc_fallthrough ();
     case SFmode:
       if (cum->float_in_sse == -1)
 	error_p = 1;
@@ -9582,6 +9583,7 @@ pass_in_reg:
 	error_p = 1;
       if (cum->float_in_sse < 2)
 	break;
+      gcc_fallthrough ();
     case SFmode:
       if (cum->float_in_sse == -1)
 	error_p = 1;
@@ -10987,6 +10989,7 @@ ix86_gimplify_va_arg (tree valist, tree type, gimple_seq *pre_p,
 	  container = NULL;
 	  break;
 	}
+      gcc_fallthrough ();
 
     default:
       container = construct_container (nat_mode, TYPE_MODE (type),
@@ -15224,6 +15227,7 @@ ix86_legitimate_constant_p (machine_mode mode, rtx x)
 	case XImode:
 	  if (!standard_sse_constant_p (x, mode))
 	    return false;
+	  gcc_fallthrough ();
 	default:
 	  break;
 	}
@@ -17295,6 +17299,7 @@ print_reg (rtx x, int code, FILE *file)
     case 4:
       if (LEGACY_INT_REGNO_P (regno))
 	putc (msize == 8 && TARGET_64BIT ? 'r' : 'e', file);
+      gcc_fallthrough ();
     case 16:
     case 12:
     case 2:
@@ -17704,6 +17709,7 @@ ix86_print_operand (FILE *file, rtx x, int code)
 		  fputs ("eq_us", file);
 		  break;
 		}
+	     gcc_fallthrough ();
 	    case EQ:
 	      fputs ("eq", file);
 	      break;
@@ -17713,6 +17719,7 @@ ix86_print_operand (FILE *file, rtx x, int code)
 		  fputs ("nge", file);
 		  break;
 		}
+	     gcc_fallthrough ();
 	    case LT:
 	      fputs ("lt", file);
 	      break;
@@ -17722,6 +17729,7 @@ ix86_print_operand (FILE *file, rtx x, int code)
 		  fputs ("ngt", file);
 		  break;
 		}
+	     gcc_fallthrough ();
 	    case LE:
 	      fputs ("le", file);
 	      break;
@@ -17734,6 +17742,7 @@ ix86_print_operand (FILE *file, rtx x, int code)
 		  fputs ("neq_oq", file);
 		  break;
 		}
+	     gcc_fallthrough ();
 	    case NE:
 	      fputs ("neq", file);
 	      break;
@@ -17743,6 +17752,7 @@ ix86_print_operand (FILE *file, rtx x, int code)
 		  fputs ("ge", file);
 		  break;
 		}
+	     gcc_fallthrough ();
 	    case UNGE:
 	      fputs ("nlt", file);
 	      break;
@@ -17752,6 +17762,7 @@ ix86_print_operand (FILE *file, rtx x, int code)
 		  fputs ("gt", file);
 		  break;
 		}
+	     gcc_fallthrough ();
 	    case UNGT:
 	      fputs ("nle", file);
 	      break;
@@ -21499,6 +21510,7 @@ ix86_build_const_vector (machine_mode mode, bool vect, rtx value)
     case V4DImode:
     case V2DImode:
       gcc_assert (vect);
+      gcc_fallthrough ();
     case V16SFmode:
     case V8SFmode:
     case V4SFmode:
@@ -22484,6 +22496,8 @@ ix86_expand_branch (enum rtx_code code, rtx op0, rtx op1, rtx label)
 	  op0 = force_reg (mode, gen_rtx_XOR (mode, op0, op1));
 	  op1 = const0_rtx;
 	}
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case TImode:
       /* Expand DImode branch into multiple compare+branch.  */
       {
@@ -29844,7 +29858,7 @@ ix86_sched_init_global (FILE *, int, int)
 	  core2i7_ifetch_block_max_insns = 6;
 	  break;
 	}
-      /* ... Fall through ...  */
+      /* Fall through.  */
     default:
       targetm.sched.dfa_post_advance_cycle = NULL;
       targetm.sched.first_cycle_multipass_init = NULL;
@@ -38728,6 +38742,7 @@ ix86_expand_multi_arg_builtin (enum insn_code icode, tree exp, rtx target,
 		  goto xop_rotl;
 		case CODE_FOR_xop_rotlv16qi3:
 		  new_icode = CODE_FOR_rotlv16qi3;
+		  gcc_fallthrough ();
 		xop_rotl:
 		  if (CONST_INT_P (op))
 		    {
@@ -40115,6 +40130,7 @@ ix86_expand_args_builtin (const struct builtin_description *d,
 			error ("the next to last argument must be an 8-bit immediate");
 			break;
 		      }
+		    gcc_fallthrough ();
 		  case 1:
 		    error ("the last argument must be an 8-bit immediate");
 		    break;
@@ -40171,6 +40187,7 @@ ix86_expand_args_builtin (const struct builtin_description *d,
     case 5:
       pat = GEN_FCN (icode) (real_target, args[0].op, args[1].op,
 			     args[2].op, args[3].op, args[4].op);
+      break;
     case 6:
       pat = GEN_FCN (icode) (real_target, args[0].op, args[1].op,
 			     args[2].op, args[3].op, args[4].op,
@@ -40545,6 +40562,7 @@ ix86_expand_round_builtin (const struct builtin_description *d,
     case 5:
       pat = GEN_FCN (icode) (target, args[0].op, args[1].op,
 			     args[2].op, args[3].op, args[4].op);
+      break;
     case 6:
       pat = GEN_FCN (icode) (target, args[0].op, args[1].op,
 			     args[2].op, args[3].op, args[4].op,
@@ -41962,6 +41980,7 @@ ix86_expand_builtin (tree exp, rtx target, rtx subtarget,
             emit_insn (pat);
           return target;
         }
+      gcc_fallthrough ();
 
     case IX86_BUILTIN_RDRAND16_STEP:
       icode = CODE_FOR_rdrandhi_1;
@@ -41976,6 +41995,7 @@ ix86_expand_builtin (tree exp, rtx target, rtx subtarget,
     case IX86_BUILTIN_RDRAND64_STEP:
       icode = CODE_FOR_rdranddi_1;
       mode0 = DImode;
+      gcc_fallthrough ();
 
 rdrand_step:
       op0 = gen_reg_rtx (mode0);
@@ -42027,6 +42047,7 @@ rdrand_step:
     case IX86_BUILTIN_RDSEED64_STEP:
       icode = CODE_FOR_rdseeddi_1;
       mode0 = DImode;
+      gcc_fallthrough ();
 
 rdseed_step:
       op0 = gen_reg_rtx (mode0);
@@ -42072,6 +42093,7 @@ rdseed_step:
     case IX86_BUILTIN_ADDCARRYX64:
       icode = CODE_FOR_addcarrydi;
       mode0 = DImode;
+      gcc_fallthrough ();
 
     handlecarry:
       arg0 = CALL_EXPR_ARG (exp, 0); /* unsigned char c_in.  */
@@ -42152,6 +42174,7 @@ rdseed_step:
       icode = CODE_FOR_kortestzhi;
       mode0 = HImode;
       mode1 = CCZmode;
+      gcc_fallthrough ();
 
     kortest:
       arg0 = CALL_EXPR_ARG (exp, 0); /* Mask reg src1.  */
@@ -42844,6 +42867,7 @@ rdseed_step:
 	  if (!TARGET_SSE)
 	    /* Emit a normal call if SSE isn't available.  */
 	    return expand_call (exp, target, ignore);
+	  gcc_fallthrough ();
 	default:
 	  return ix86_expand_args_builtin (d, exp, target);
 	}
@@ -46997,6 +47021,7 @@ ix86_expand_vector_init_one_var (bool mmx_ok, machine_mode mode,
       /* Use ix86_expand_vector_set in 64bit mode only.  */
       if (!TARGET_64BIT)
 	return false;
+      gcc_fallthrough ();
     case V4DFmode:
     case V8SFmode:
     case V8SImode:
diff --git gcc/gcc/config/rs6000/rs6000.c gcc/gcc/config/rs6000/rs6000.c
index 6fe94d5..3e0a8a1 100644
--- gcc/gcc/config/rs6000/rs6000.c
+++ gcc/gcc/config/rs6000/rs6000.c
@@ -5461,7 +5461,7 @@ rs6000_builtin_vectorized_libmass (combined_fn fn, tree type_out,
     CASE_CFN_HYPOT:
     CASE_CFN_POW:
       n_args = 2;
-      /* fall through */
+      gcc_fallthrough ();
 
     CASE_CFN_ACOS:
     CASE_CFN_ACOSH:
@@ -14401,6 +14401,7 @@ altivec_expand_ld_builtin (tree exp, rtx target, bool *expandedp)
       break;
     case ALTIVEC_BUILTIN_LD_INTERNAL_2di:
       icode = CODE_FOR_vector_altivec_load_v2di;
+      break;
     case ALTIVEC_BUILTIN_LD_INTERNAL_1ti:
       icode = CODE_FOR_vector_altivec_load_v1ti;
       break;
@@ -14462,6 +14463,7 @@ altivec_expand_st_builtin (tree exp, rtx target ATTRIBUTE_UNUSED,
       break;
     case ALTIVEC_BUILTIN_ST_INTERNAL_2di:
       icode = CODE_FOR_vector_altivec_store_v2di;
+      break;
     case ALTIVEC_BUILTIN_ST_INTERNAL_1ti:
       icode = CODE_FOR_vector_altivec_store_v1ti;
       break;
@@ -22535,6 +22537,7 @@ rs6000_emit_vector_compare_inner (enum rtx_code code, rtx op0, rtx op1)
     case GE:
       if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
 	return NULL_RTX;
+      gcc_fallthrough ();
 
     case EQ:
     case GT:
@@ -30236,6 +30239,7 @@ rs6000_adjust_cost (rtx_insn *insn, rtx link, rtx_insn *dep_insn, int cost)
                 && (INSN_CODE (dep_insn) >= 0)
                 && (get_attr_type (dep_insn) == TYPE_MFFGPR))
               return 2;
+	    gcc_fallthrough ();
 
           default:
             break;
@@ -30272,6 +30276,7 @@ rs6000_adjust_cost (rtx_insn *insn, rtx link, rtx_insn *dep_insn, int cost)
             }
         }
       /* Fall through, no cost for output dependency.  */
+      gcc_fallthrough ();
 
     case REG_DEP_ANTI:
       /* Anti dependency; DEP_INSN reads a register that INSN writes some
@@ -31418,6 +31423,7 @@ insn_must_be_first_in_group (rtx_insn *insn)
     case PROCESSOR_POWER5:
       if (is_cracked_insn (insn))
         return true;
+      gcc_fallthrough ();
     case PROCESSOR_POWER4:
       if (is_microcoded_insn (insn))
         return true;
@@ -32335,6 +32341,7 @@ rs6000_handle_altivec_attribute (tree *node,
 	case V4SImode: case V8HImode: case V16QImode: case V4SFmode:
 	case V2DImode: case V2DFmode:
 	  result = type;
+	  gcc_fallthrough ();
 	default: break;
 	}
       break;
@@ -32345,6 +32352,7 @@ rs6000_handle_altivec_attribute (tree *node,
 	case SImode: case V4SImode: result = bool_V4SI_type_node; break;
 	case HImode: case V8HImode: result = bool_V8HI_type_node; break;
 	case QImode: case V16QImode: result = bool_V16QI_type_node;
+	  gcc_fallthrough ();
 	default: break;
 	}
       break;
@@ -32352,6 +32360,7 @@ rs6000_handle_altivec_attribute (tree *node,
       switch (mode)
 	{
 	case V8HImode: result = pixel_V8HI_type_node;
+	  gcc_fallthrough ();
 	default: break;
 	}
     default: break;
diff --git gcc/gcc/config/rs6000/rs6000.md gcc/gcc/config/rs6000/rs6000.md
index 5afae92..6e2b782 100644
--- gcc/gcc/config/rs6000/rs6000.md
+++ gcc/gcc/config/rs6000/rs6000.md
@@ -8148,6 +8148,7 @@
     case 0:
       if (TARGET_STRING)
         return \"stswi %1,%P0,16\";
+      gcc_fallthrough ();
     case 1:
       return \"#\";
     case 2:
@@ -8156,7 +8157,7 @@
       if (TARGET_STRING
           && ! reg_overlap_mentioned_p (operands[0], operands[1]))
 	return \"lswi %0,%P1,16\";
-      /* ... fall through ...  */
+      /* fall through */
     case 3:
     case 4:
     case 5:
diff --git gcc/gcc/convert.c gcc/gcc/convert.c
index e6b4d29..8f18ee4 100644
--- gcc/gcc/convert.c
+++ gcc/gcc/convert.c
@@ -164,6 +164,7 @@ convert_to_real_1 (tree type, tree expr, bool fold_p)
 	       -fmath-errno.  */
 	    if (flag_errno_math)
 	      break;
+	    gcc_fallthrough ();
 	  CASE_MATHFN (ACOS)
 	  CASE_MATHFN (ACOSH)
 	  CASE_MATHFN (ASIN)
@@ -184,6 +185,7 @@ convert_to_real_1 (tree type, tree expr, bool fold_p)
 	    /* The above functions are not safe to do this conversion.  */
 	    if (!flag_unsafe_math_optimizations)
 	      break;
+	    gcc_fallthrough ();
 	  CASE_MATHFN (SQRT)
 	  CASE_MATHFN (FABS)
 	  CASE_MATHFN (LOGB)
@@ -516,7 +518,7 @@ convert_to_integer_1 (tree type, tree expr, bool dofold)
 	  /* Only convert nearbyint* if we can ignore math exceptions.  */
 	  if (flag_trapping_math)
 	    break;
-	  /* ... Fall through ...  */
+	  gcc_fallthrough ();
 	CASE_FLT_FN (BUILT_IN_RINT):
 	  /* Only convert in ISO C99 mode and with -fno-math-errno.  */
 	  if (!targetm.libc_has_function (function_c99_misc) || flag_errno_math)
diff --git gcc/gcc/cp/call.c gcc/gcc/cp/call.c
index f929fb2..25f215f 100644
--- gcc/gcc/cp/call.c
+++ gcc/gcc/cp/call.c
@@ -2421,6 +2421,7 @@ add_builtin_candidate (struct z_candidate **candidates, enum tree_code code,
     case PREDECREMENT_EXPR:
       if (TREE_CODE (type1) == BOOLEAN_TYPE)
 	return;
+      gcc_fallthrough ();
     case POSTINCREMENT_EXPR:
     case PREINCREMENT_EXPR:
       if (ARITHMETIC_TYPE_P (type1) || TYPE_PTROB_P (type1))
@@ -2457,6 +2458,7 @@ add_builtin_candidate (struct z_candidate **candidates, enum tree_code code,
     case UNARY_PLUS_EXPR: /* unary + */
       if (TYPE_PTR_P (type1))
 	break;
+      gcc_fallthrough ();
     case NEGATE_EXPR:
       if (ARITHMETIC_TYPE_P (type1))
 	break;
@@ -2542,6 +2544,8 @@ add_builtin_candidate (struct z_candidate **candidates, enum tree_code code,
 	  type2 = ptrdiff_type_node;
 	  break;
 	}
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case MULT_EXPR:
     case TRUNC_DIV_EXPR:
       if (ARITHMETIC_TYPE_P (type1) && ARITHMETIC_TYPE_P (type2))
@@ -2594,6 +2598,7 @@ add_builtin_candidate (struct z_candidate **candidates, enum tree_code code,
     case PLUS_EXPR:
       if (ARITHMETIC_TYPE_P (type1) && ARITHMETIC_TYPE_P (type2))
 	break;
+      gcc_fallthrough ();
     case ARRAY_REF:
       if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && TYPE_PTROB_P (type2))
 	{
@@ -2674,6 +2679,8 @@ add_builtin_candidate (struct z_candidate **candidates, enum tree_code code,
 	      type2 = ptrdiff_type_node;
 	      break;
 	    }
+	  /* XXX Really fallthru?  */
+	  gcc_fallthrough ();
 	case MULT_EXPR:
 	case TRUNC_DIV_EXPR:
 	  if (ARITHMETIC_TYPE_P (type1) && ARITHMETIC_TYPE_P (type2))
@@ -3960,7 +3967,7 @@ build_integral_nontype_arg_conv (tree type, tree expr, tsubst_flags_t complain)
 	if (complain & tf_error)
 	  error_at (loc, "conversion from %qT to %qT not considered for "
 		    "non-type template argument", t, type);
-	/* and fall through.  */
+	/* fall through.  */
 
       default:
 	conv = NULL;
@@ -5487,6 +5494,7 @@ build_new_op_1 (location_t loc, enum tree_code code, int flags, tree arg1,
     case MODIFY_EXPR:
       if (code2 != NOP_EXPR)
 	break;
+      gcc_fallthrough ();
     case COMPONENT_REF:
     case ARRAY_REF:
       memonly = true;
@@ -6655,7 +6663,7 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
 
       if (! MAYBE_CLASS_TYPE_P (totype))
 	return expr;
-      /* Else fall through.  */
+      /* Fall through.  */
     case ck_base:
       if (convs->kind == ck_base && !convs->need_temporary_p)
 	{
diff --git gcc/gcc/cp/class.c gcc/gcc/cp/class.c
index b2db7f8..6cbd58b 100644
--- gcc/gcc/cp/class.c
+++ gcc/gcc/cp/class.c
@@ -7391,7 +7391,7 @@ fixed_type_or_null (tree instance, int *nonnull, int *cdtorp)
 	    *nonnull = 1;
 	  return TREE_TYPE (TREE_TYPE (instance));
 	}
-      /* fall through...  */
+      /* fall through.  */
     case TARGET_EXPR:
     case PARM_DECL:
     case RESULT_DECL:
diff --git gcc/gcc/cp/constexpr.c gcc/gcc/cp/constexpr.c
index 240c606..2ed90ee 100644
--- gcc/gcc/cp/constexpr.c
+++ gcc/gcc/cp/constexpr.c
@@ -3886,7 +3887,7 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
 					    overflow_p);
       if (r)
 	break;
-      /* else fall through */
+      /* fall through */
 
     case PLUS_EXPR:
     case MINUS_EXPR:
@@ -5020,7 +5022,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict,
       /* A destructor.  */
       if (TYPE_P (TREE_OPERAND (t, 0)))
 	return true;
-      /* else fall through.  */
+      /* fall through.  */
 
     case REALPART_EXPR:
     case IMAGPART_EXPR:
@@ -5095,6 +5097,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict,
 	    }
 	  return false;
 	}
+      gcc_fallthrough ();
     case INIT_EXPR:
       return RECUR (TREE_OPERAND (t, 1), rval);
 
@@ -5172,6 +5175,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict,
     case TRUTH_OR_EXPR:
     case TRUTH_ORIF_EXPR:
       tmp = boolean_false_node;
+      gcc_fallthrough ();
     truth:
       {
 	tree op = TREE_OPERAND (t, 0);
diff --git gcc/gcc/cp/cp-gimplify.c gcc/gcc/cp/cp-gimplify.c
index 59953a6..2b28d86 100644
--- gcc/gcc/cp/cp-gimplify.c
+++ gcc/gcc/cp/cp-gimplify.c
@@ -659,7 +659,7 @@ cp_gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
       cp_gimplify_init_expr (expr_p);
       if (TREE_CODE (*expr_p) != INIT_EXPR)
 	return GS_OK;
-      /* Otherwise fall through.  */
+      /* Fall through.  */
     case MODIFY_EXPR:
     modify_expr_case:
       {
@@ -2067,6 +2067,7 @@ cp_fold (tree x)
 
     case VIEW_CONVERT_EXPR:
       rval_ops = false;
+      gcc_fallthrough ();
     case CONVERT_EXPR:
     case NOP_EXPR:
     case NON_LVALUE_EXPR:
@@ -2115,6 +2116,7 @@ cp_fold (tree x)
     case REALPART_EXPR:
     case IMAGPART_EXPR:
       rval_ops = false;
+      gcc_fallthrough ();
     case CONJ_EXPR:
     case FIX_TRUNC_EXPR:
     case FLOAT_EXPR:
@@ -2167,6 +2169,7 @@ cp_fold (tree x)
     case COMPOUND_EXPR:
     case MODIFY_EXPR:
       rval_ops = false;
+      gcc_fallthrough ();
     case POINTER_PLUS_EXPR:
     case PLUS_EXPR:
     case MINUS_EXPR:
diff --git gcc/gcc/cp/cvt.c gcc/gcc/cp/cvt.c
index 85b3047..977c665 100644
--- gcc/gcc/cp/cvt.c
+++ gcc/gcc/cp/cvt.c
@@ -1663,7 +1663,7 @@ build_expr_type_conversion (int desires, tree expr, bool complain)
       case INTEGER_TYPE:
 	if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
 	  return expr;
-	/* else fall through...  */
+	/* fall through.  */
 
       case BOOLEAN_TYPE:
 	return (desires & WANT_INT) ? expr : NULL_TREE;
diff --git gcc/gcc/cp/cxx-pretty-print.c gcc/gcc/cp/cxx-pretty-print.c
index 192b26c..1fd42c7 100644
--- gcc/gcc/cp/cxx-pretty-print.c
+++ gcc/gcc/cp/cxx-pretty-print.c
@@ -142,6 +142,7 @@ pp_cxx_unqualified_id (cxx_pretty_printer *pp, tree t)
 
     case OVERLOAD:
       t = OVL_CURRENT (t);
+      gcc_fallthrough ();
     case VAR_DECL:
     case PARM_DECL:
     case CONST_DECL:
@@ -153,6 +154,7 @@ pp_cxx_unqualified_id (cxx_pretty_printer *pp, tree t)
     case USING_DECL:
     case TEMPLATE_DECL:
       t = DECL_NAME (t);
+      gcc_fallthrough ();
 
     case IDENTIFIER_NODE:
       if (t == NULL)
@@ -280,6 +282,7 @@ pp_cxx_qualified_id (cxx_pretty_printer *pp, tree t)
 	 functions and some function templates.  */
     case OVERLOAD:
       t = OVL_CURRENT (t);
+      gcc_fallthrough ();
     case FUNCTION_DECL:
       if (DECL_FUNCTION_MEMBER_P (t))
 	pp_cxx_nested_name_specifier (pp, DECL_CONTEXT (t));
@@ -331,7 +334,7 @@ cxx_pretty_printer::constant (tree t)
 	  pp_string (this, "nullptr");
 	  break;
 	}
-      /* else fall through.  */
+      /* fall through.  */
 
     default:
       c_pretty_printer::constant (t);
@@ -417,6 +420,7 @@ cxx_pretty_printer::primary_expression (tree t)
 
     case BASELINK:
       t = BASELINK_FUNCTIONS (t);
+      gcc_fallthrough ();
     case VAR_DECL:
     case PARM_DECL:
     case FIELD_DECL:
@@ -872,7 +876,7 @@ pp_cxx_pm_expression (cxx_pretty_printer *pp, tree t)
 	  pp_cxx_qualified_id (pp, t);
 	  break;
 	}
-      /* Else fall through.  */
+      /* Fall through.  */
     case MEMBER_REF:
     case DOTSTAR_EXPR:
       pp_cxx_pm_expression (pp, TREE_OPERAND (t, 0));
@@ -1057,6 +1061,7 @@ cxx_pretty_printer::expression (tree t)
 
     case OVERLOAD:
       t = OVL_CURRENT (t);
+      gcc_fallthrough ();
     case VAR_DECL:
     case PARM_DECL:
     case FIELD_DECL:
@@ -1267,7 +1272,9 @@ cxx_pretty_printer::declaration_specifiers (tree t)
       else if (DECL_NONSTATIC_MEMBER_FUNCTION_P (t))
 	declaration_specifiers (TREE_TYPE (TREE_TYPE (t)));
       else
-	default:
+        c_pretty_printer::declaration_specifiers (t);
+      break;
+    default:
         c_pretty_printer::declaration_specifiers (t);
       break;
     }
@@ -1364,7 +1371,7 @@ pp_cxx_type_specifier_seq (cxx_pretty_printer *pp, tree t)
 	  pp_cxx_ptr_operator (pp, t);
 	  break;
 	}
-      /* else fall through */
+      /* fall through */
 
     default:
       if (!(TREE_CODE (t) == FUNCTION_DECL && DECL_CONSTRUCTOR_P (t)))
@@ -1406,6 +1413,7 @@ pp_cxx_ptr_operator (cxx_pretty_printer *pp, tree t)
 	  pp_star (pp);
 	  break;
 	}
+      gcc_fallthrough ();
     case OFFSET_TYPE:
       if (TYPE_PTRMEM_P (t))
 	{
@@ -1416,7 +1424,7 @@ pp_cxx_ptr_operator (cxx_pretty_printer *pp, tree t)
 	  pp_cxx_cv_qualifier_seq (pp, t);
 	  break;
 	}
-      /* else fall through.  */
+      /* fall through.  */
 
     default:
       pp_unsupported_tree (pp, t);
diff --git gcc/gcc/cp/error.c gcc/gcc/cp/error.c
index 69a40cc..637bce2 100644
--- gcc/gcc/cp/error.c
+++ gcc/gcc/cp/error.c
@@ -450,7 +450,7 @@ dump_type (cxx_pretty_printer *pp, tree t, int flags)
 		     ? DECL_ORIGINAL_TYPE (t) : TREE_TYPE (t), flags);
 	  break;
 	}
-      /* Else fall through.  */
+      /* Fall through.  */
 
     case TEMPLATE_DECL:
     case NAMESPACE_DECL:
@@ -576,6 +576,7 @@ dump_type (cxx_pretty_printer *pp, tree t, int flags)
     default:
       pp_unsupported_tree (pp, t);
       /* Fall through to error.  */
+      gcc_fallthrough ();
 
     case ERROR_MARK:
       pp_string (pp, M_("<type error>"));
@@ -1065,7 +1066,7 @@ dump_decl (cxx_pretty_printer *pp, tree t, int flags)
 	  dump_type (pp, DECL_CONTEXT (t), flags);
 	  break;
 	}
-      /* Else fall through.  */
+      /* Fall through.  */
     case FIELD_DECL:
     case PARM_DECL:
       dump_simple_decl (pp, t, TREE_TYPE (t), flags);
@@ -1277,6 +1278,7 @@ dump_decl (cxx_pretty_printer *pp, tree t, int flags)
     default:
       pp_unsupported_tree (pp, t);
       /* Fall through to error.  */
+      gcc_fallthrough ();
 
     case ERROR_MARK:
       pp_string (pp, M_("<declaration error>"));
@@ -2509,6 +2511,7 @@ dump_expr (cxx_pretty_printer *pp, tree t, int flags)
       goto cast;
     case DYNAMIC_CAST_EXPR:
       pp_cxx_ws_string (pp, "dynamic_cast");
+      gcc_fallthrough ();
     cast:
       pp_cxx_begin_template_argument_list (pp);
       dump_type (pp, TREE_TYPE (t), flags);
@@ -2776,6 +2779,7 @@ dump_expr (cxx_pretty_printer *pp, tree t, int flags)
     default:
       pp_unsupported_tree (pp, t);
       /* fall through to ERROR_MARK...  */
+      gcc_fallthrough ();
     case ERROR_MARK:
       pp_string (pp, M_("<expression error>"));
       break;
diff --git gcc/gcc/cp/mangle.c gcc/gcc/cp/mangle.c
index d5b26d6..eacc22a 100644
--- gcc/gcc/cp/mangle.c
+++ gcc/gcc/cp/mangle.c
@@ -2051,7 +2051,7 @@ write_type (tree type)
 		  ++is_builtin_type;
 		  break;
 		}
-	      /* else fall through.  */
+	      /* fall through.  */
 	    case TEMPLATE_PARM_INDEX:
 	      write_template_param (type);
 	      break;
diff --git gcc/gcc/cp/method.c gcc/gcc/cp/method.c
index cd8faaf..72c9717 100644
--- gcc/gcc/cp/method.c
+++ gcc/gcc/cp/method.c
@@ -1402,6 +1402,7 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
     case sfk_move_constructor:
     case sfk_move_assignment:
       move_p = true;
+      gcc_fallthrough ();
     case sfk_copy_constructor:
     case sfk_copy_assignment:
       copy_arg_p = true;
diff --git gcc/gcc/cp/name-lookup.c gcc/gcc/cp/name-lookup.c
index 7c3942a52..4694887 100644
--- gcc/gcc/cp/name-lookup.c
+++ gcc/gcc/cp/name-lookup.c
@@ -5659,6 +5659,7 @@ arg_assoc_type (struct arg_lookup *k, tree type)
     case RECORD_TYPE:
       if (TYPE_PTRMEMFUNC_P (type))
 	return arg_assoc_type (k, TYPE_PTRMEMFUNC_FN_TYPE (type));
+      gcc_fallthrough ();
     case UNION_TYPE:
       return arg_assoc_class (k, type);
     case POINTER_TYPE:
diff --git gcc/gcc/cp/parser.c gcc/gcc/cp/parser.c
index b71b9e5..1364f68 100644
--- gcc/gcc/cp/parser.c
+++ gcc/gcc/cp/parser.c
@@ -1266,7 +1266,7 @@ cp_lexer_print_token (FILE * stream, cp_token *token)
 	 For example, `struct' is mapped to an INTEGER_CST.  */
       if (!identifier_p (token->u.value))
 	break;
-      /* else fall through */
+      /* fall through */
     case CPP_NAME:
       fputs (IDENTIFIER_POINTER (token->u.value), stream);
       break;
@@ -3488,6 +3488,7 @@ cp_parser_skip_to_end_of_statement (cp_parser* parser)
 	      cp_lexer_consume_token (parser->lexer);
 	      return;
 	    }
+	  gcc_fallthrough ();
 
 	case CPP_OPEN_BRACE:
 	  ++nesting_depth;
@@ -5139,6 +5153,7 @@ cp_parser_primary_expression (cp_parser *parser,
 	      cp_parser_skip_to_end_of_block_or_statement (parser);
 	      return error_mark_node;
 	    }
+	  gcc_fallthrough ();
 	default:
 	  cp_parser_error (parser, "expected primary-expression");
 	  return error_mark_node;
@@ -12893,6 +12932,7 @@ cp_parser_storage_class_specifier_opt (cp_parser* parser)
       if (cxx_dialect != cxx98)
         return NULL_TREE;
       /* Fall through for C++98.  */
+      gcc_fallthrough ();
 
     case RID_REGISTER:
     case RID_STATIC:
@@ -14012,6 +14052,7 @@ cp_parser_operator (cp_parser* parser)
     case CPP_UTF8STRING:
     case CPP_UTF8STRING_USERDEF:
       utf8 = true;
+      gcc_fallthrough ();
     case CPP_STRING:
     case CPP_WSTRING:
     case CPP_STRING16:
@@ -27164,6 +27219,7 @@ cp_parser_skip_to_end_of_template_parameter_list (cp_parser* parser)
 	    }
           /* Fall through for C++0x, so we handle the second `>' in
              the `>>'.  */
+	  gcc_fallthrough ();
 
 	case CPP_GREATER:
 	  if (!nesting_depth && level-- == 0)
@@ -27581,6 +27637,7 @@ cp_parser_cache_defarg (cp_parser *parser, bool nsdmi)
 	      parser->in_template_argument_list_p = saved_italp;
 	      break;
 	    }
+	  gcc_fallthrough ();
 	case CPP_CLOSE_PAREN:
 	case CPP_ELLIPSIS:
 	  /* If we run into a non-nested `;', `}', or `]',
@@ -27619,6 +27676,7 @@ cp_parser_cache_defarg (cp_parser *parser, bool nsdmi)
 	  /* Fall through for C++0x, which treats the `>>'
 	     operator like two `>' tokens in certain
 	     cases.  */
+	  gcc_fallthrough ();
 
 	case CPP_GREATER:
 	  if (depth == 0)
@@ -33261,6 +33319,7 @@ cp_parser_omp_for_cond (cp_parser *parser, tree decl, enum tree_code code)
       if (code == CILK_SIMD || code == CILK_FOR)
 	break;
       /* Fall through: OpenMP disallows NE_EXPR.  */
+      gcc_fallthrough ();
     default:
       return error_mark_node;
     }
diff --git gcc/gcc/cp/pt.c gcc/gcc/cp/pt.c
index d7f3808..c92898e 100644
--- gcc/gcc/cp/pt.c
+++ gcc/gcc/cp/pt.c
@@ -3450,6 +3450,7 @@ find_parameter_packs_r (tree *tp, int *walk_subtrees, void* data)
 
     case TEMPLATE_TYPE_PARM:
       t = TYPE_MAIN_VARIANT (t);
+      gcc_fallthrough ();
     case TEMPLATE_TEMPLATE_PARM:
       /* If the placeholder appears in the decl-specifier-seq of a function
 	 parameter pack (14.6.3), or the type-specifier-seq of a type-id that
@@ -11454,7 +11455,7 @@ tsubst_aggr_type (tree t,
       if (TYPE_PTRMEMFUNC_P (t))
 	return tsubst (TYPE_PTRMEMFUNC_FN_TYPE (t), args, complain, in_decl);
 
-      /* Else fall through.  */
+      /* Fall through.  */
     case ENUMERAL_TYPE:
     case UNION_TYPE:
       if (TYPE_TEMPLATE_INFO (t) && uses_template_parms (t))
@@ -20233,6 +20234,7 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict,
       if (is_overloaded_fn (parm) || type_unknown_p (parm))
 	return unify_success (explain_p);
       gcc_assert (EXPR_P (parm));
+      gcc_fallthrough ();
     expr:
       /* We must be looking at an expression.  This can happen with
 	 something like:
diff --git gcc/gcc/cp/semantics.c gcc/gcc/cp/semantics.c
index 19daeff..74a3912 100644
--- gcc/gcc/cp/semantics.c
+++ gcc/gcc/cp/semantics.c
@@ -6011,6 +6011,7 @@ finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	    }
 	  else
 	    t = OMP_CLAUSE_DECL (c);
+	  gcc_fallthrough ();
 	check_dup_generic_t:
 	  if (t == current_class_ptr
 	      && (ort != C_ORT_OMP_DECLARE_SIMD
@@ -6066,6 +6067,7 @@ finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	    bitmap_set_bit (&generic_head, DECL_UID (t));
 	  if (!field_ok)
 	    break;
+	  gcc_fallthrough ();
 	handle_field_decl:
 	  if (!remove
 	      && TREE_CODE (t) == FIELD_DECL
@@ -6212,11 +6214,13 @@ finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	      OMP_CLAUSE_OPERAND (c, 1) = t;
 	    }
 	  /* Check operand 0, the num argument.  */
+	  gcc_fallthrough ();
 
 	case OMP_CLAUSE_WORKER:
 	case OMP_CLAUSE_VECTOR:
 	  if (OMP_CLAUSE_OPERAND (c, 0) == NULL_TREE)
 	    break;
+	  gcc_fallthrough ();
 
 	case OMP_CLAUSE_NUM_TASKS:
 	case OMP_CLAUSE_NUM_TEAMS:
@@ -6818,6 +6822,7 @@ finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 		  && TREE_CODE (OMP_CLAUSE_DECL (c)) == COMPONENT_REF)
 		bitmap_set_bit (&map_field_head, DECL_UID (t));
 	    }
+	  gcc_fallthrough ();
 	handle_map_references:
 	  if (!remove
 	      && !processing_template_decl
@@ -8879,6 +8884,7 @@ finish_decltype_type (tree expr, bool id_expression_or_member_access_p,
               break;
             }
           /* Fall through for fields that aren't bitfields.  */
+	  gcc_fallthrough ();
 
         case FUNCTION_DECL:
         case VAR_DECL:
diff --git gcc/gcc/cp/tree.c gcc/gcc/cp/tree.c
index 6adeb63..bd7393f 100644
--- gcc/gcc/cp/tree.c
+++ gcc/gcc/cp/tree.c
@@ -141,11 +141,13 @@ lvalue_kind (const_tree ref)
 	 lvalues.  */
       if (! TREE_STATIC (ref))
 	return clk_none;
+      gcc_fallthrough ();
     case VAR_DECL:
       if (TREE_READONLY (ref) && ! TREE_STATIC (ref)
 	  && DECL_LANG_SPECIFIC (ref)
 	  && DECL_IN_AGGR_P (ref))
 	return clk_none;
+      gcc_fallthrough ();
     case INDIRECT_REF:
     case ARROW_EXPR:
     case ARRAY_REF:
diff --git gcc/gcc/cp/typeck.c gcc/gcc/cp/typeck.c
index d4bfb11..3639c7a 100644
--- gcc/gcc/cp/typeck.c
+++ gcc/gcc/cp/typeck.c
@@ -1306,6 +1306,7 @@ structural_comptypes (tree t1, tree t2, int strict)
       if (TYPE_REF_IS_RVALUE (t1) != TYPE_REF_IS_RVALUE (t2))
 	return false;
       /* fall through to checks for pointer types */
+      gcc_fallthrough ();
 
     case POINTER_TYPE:
       if (TYPE_MODE (t1) != TYPE_MODE (t2)
@@ -4260,6 +4261,7 @@ cp_build_binary_op (location_t location,
 	}
       /* The pointer - int case is just like pointer + int; fall
 	 through.  */
+      gcc_fallthrough ();
     case PLUS_EXPR:
       if ((code0 == POINTER_TYPE || code1 == POINTER_TYPE)
 	  && (code0 == INTEGER_TYPE || code1 == INTEGER_TYPE))
@@ -7532,6 +7534,7 @@ cp_build_modify_expr (location_t loc, tree lhs, enum tree_code modifycode,
 		    TREE_OPERAND (lhs, 0),
 		    TREE_OPERAND (lhs, 1));
       /* Fall through.  */
+      gcc_fallthrough ();
 
       /* Handle (a ? b : c) used as an "lvalue".  */
     case COND_EXPR:
diff --git gcc/gcc/cselib.c gcc/gcc/cselib.c
index 14c7b32..24b1976 100644
--- gcc/gcc/cselib.c
+++ gcc/gcc/cselib.c
@@ -1619,6 +1619,8 @@ cselib_expand_value_rtx_1 (rtx orig, struct expand_value_data *evd,
 		return orig;
 	    }
       }
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
 
     CASE_CONST_ANY:
     case SYMBOL_REF:
diff --git gcc/gcc/dbxout.c gcc/gcc/dbxout.c
index da0987f..ad256c7 100644
--- gcc/gcc/dbxout.c
+++ gcc/gcc/dbxout.c
@@ -2867,7 +2867,7 @@ dbxout_symbol (tree decl, int local ATTRIBUTE_UNUSED)
 	 disguised VAR_DECLs like Out parameters in Ada.  */
       gcc_assert (TREE_CODE (decl) == VAR_DECL);
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case RESULT_DECL:
     case VAR_DECL:
diff --git gcc/gcc/df-scan.c gcc/gcc/df-scan.c
index 19d8e0f..9cd647a 100644
--- gcc/gcc/df-scan.c
+++ gcc/gcc/df-scan.c
@@ -2875,7 +2875,7 @@ df_uses_record (struct df_collection_rec *collection_rec,
 	  df_uses_record (collection_rec, loc, ref_type, bb, insn_info, flags);
 	  return;
 	}
-      /* ... Fall through ...  */
+      /* Fall through */
 
     case REG:
       df_ref_record (DF_REF_REGULAR, collection_rec,
diff --git gcc/gcc/dojump.c gcc/gcc/dojump.c
index 58f1e03..6e2435b 100644
--- gcc/gcc/dojump.c
+++ gcc/gcc/dojump.c
@@ -461,12 +461,14 @@ do_jump (tree exp, rtx_code_label *if_false_label,
           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF
           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_RANGE_REF)
         goto normal;
+      gcc_fallthrough ();
     case CONVERT_EXPR:
       /* If we are narrowing the operand, we have to do the compare in the
          narrower mode.  */
       if ((TYPE_PRECISION (TREE_TYPE (exp))
            < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
         goto normal;
+      gcc_fallthrough ();
     case NON_LVALUE_EXPR:
     case ABS_EXPR:
     case NEGATE_EXPR:
@@ -610,6 +612,7 @@ do_jump (tree exp, rtx_code_label *if_false_label,
 	goto normal;
 
       /* Boolean comparisons can be compiled as TRUTH_AND_EXPR.  */
+      gcc_fallthrough ();
 
     case TRUTH_AND_EXPR:
       /* High branch cost, expand as the bitwise AND of the conditions.
diff --git gcc/gcc/dwarf2out.c gcc/gcc/dwarf2out.c
index e3cb586..dc751bb 100644
--- gcc/gcc/dwarf2out.c
+++ gcc/gcc/dwarf2out.c
@@ -13334,6 +13334,8 @@ mem_loc_descriptor (rtx rtl, machine_mode mode,
       if (!subreg_lowpart_p (rtl))
 	break;
       inner = SUBREG_REG (rtl);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case TRUNCATE:
       if (inner == NULL_RTX)
         inner = XEXP (rtl, 0);
@@ -13602,6 +13604,8 @@ mem_loc_descriptor (rtx rtl, machine_mode mode,
 						 initialized);
 	  break;
 	}
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
 
     symref:
       mem_loc_result = new_addr_loc_descr (rtl, dtprel_false);
@@ -13671,7 +13675,7 @@ mem_loc_descriptor (rtx rtl, machine_mode mode,
 					: -GET_MODE_UNIT_SIZE (mem_mode),
 					mode));
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case PLUS:
     plus:
@@ -15597,7 +15601,7 @@ resolve_args_picking_1 (dw_loc_descr_ref loc, unsigned initial_frame_offset,
 	  if (!resolve_args_picking_1 (l->dw_loc_next, frame_offset_, dpi,
 				       frame_offsets))
 	    return false;
-	  /* Fall through... */
+	  /* Fall through. */
 
 	case DW_OP_skip:
 	  l = l->dw_loc_oprnd1.v.val_loc;
@@ -16350,7 +16354,7 @@ loc_list_from_tree_1 (tree loc, int want_address,
 		      TREE_OPERAND (loc, 1), TREE_OPERAND (loc, 0));
       }
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case COND_EXPR:
       {
@@ -19652,6 +19656,7 @@ gen_formal_parameter_die (tree node, tree origin, bool emit_name_p,
 	}
       if (origin == NULL && DECL_ARTIFICIAL (node))
 	add_AT_flag (parm_die, DW_AT_artificial, 1);
+      gcc_fallthrough ();
     add_location:
       if (node && node != origin)
         equate_decl_number_to_die (node, parm_die);
diff --git gcc/gcc/expmed.c gcc/gcc/expmed.c
index f776e54..c78ac91 100644
--- gcc/gcc/expmed.c
+++ gcc/gcc/expmed.c
@@ -4465,6 +4465,7 @@ expand_divmod (int rem_flag, enum tree_code code, machine_mode mode,
 	      }
 	    break;
 	  }
+	gcc_fallthrough ();
       fail1:
 	delete_insns_since (last);
 	break;
@@ -5172,7 +5173,7 @@ make_tree (tree type, rtx x)
       t = SYMBOL_REF_DECL (x);
       if (t)
 	return fold_convert (type, build_fold_addr_expr (t));
-      /* else fall through.  */
+      /* fall through.  */
 
     default:
       t = build_decl (RTL_LOCATION (x), VAR_DECL, NULL_TREE, type);
diff --git gcc/gcc/expr.c gcc/gcc/expr.c
index 1cb233c..e55fee2 100644
--- gcc/gcc/expr.c
+++ gcc/gcc/expr.c
@@ -8407,6 +8407,8 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
 	 offset to have matching modes.  */
       else if (TYPE_PRECISION (sizetype) > TYPE_PRECISION (type))
 	treeop1 = fold_convert_loc (loc, type, treeop1);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
 
     case PLUS_EXPR:
       /* If we are adding a constant, a VAR_DECL that is sp, fp, or ap, and
@@ -9575,9 +9577,9 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
     switch (TREE_CODE_LENGTH (code))
       {
 	default:
-	case 3: treeop2 = TREE_OPERAND (exp, 2);
-	case 2: treeop1 = TREE_OPERAND (exp, 1);
-	case 1: treeop0 = TREE_OPERAND (exp, 0);
+	case 3: treeop2 = TREE_OPERAND (exp, 2); gcc_fallthrough ();
+	case 2: treeop1 = TREE_OPERAND (exp, 1); gcc_fallthrough ();
+	case 1: treeop0 = TREE_OPERAND (exp, 0); gcc_fallthrough ();
 	case 0: break;
       }
   ops.code = code;
@@ -9749,11 +9751,12 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
 	  && (TREE_STATIC (exp) || DECL_EXTERNAL (exp)))
 	layout_decl (exp, 0);
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case FUNCTION_DECL:
     case RESULT_DECL:
       decl_rtl = DECL_RTL (exp);
+      gcc_fallthrough ();
     expand_decl_rtl:
       gcc_assert (decl_rtl);
 
@@ -9957,7 +9960,7 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
 	  return original_target;
 	}
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case STRING_CST:
       temp = expand_expr_constant (exp, 1, modifier);
diff --git gcc/gcc/final.c gcc/gcc/final.c
index 5b04311..1e99f74 100644
--- gcc/gcc/final.c
+++ gcc/gcc/final.c
@@ -2096,9 +2096,11 @@ output_alternate_entry_point (FILE *file, rtx_insn *insn)
     case LABEL_WEAK_ENTRY:
 #ifdef ASM_WEAKEN_LABEL
       ASM_WEAKEN_LABEL (file, name);
+      gcc_fallthrough ();
 #endif
     case LABEL_GLOBAL_ENTRY:
       targetm.asm_out.globalize_label (file, name);
+      gcc_fallthrough ();
     case LABEL_STATIC_ENTRY:
 #ifdef ASM_OUTPUT_TYPE_DIRECTIVE
       ASM_OUTPUT_TYPE_DIRECTIVE (file, name, "function");
diff --git gcc/gcc/fold-const.c gcc/gcc/fold-const.c
index c5d9a79..8b054a9 100644
--- gcc/gcc/fold-const.c
+++ gcc/gcc/fold-const.c
@@ -1300,7 +1300,7 @@ const_binop (enum tree_code code, tree arg1, tree arg2)
 	    return do_mpc_arg2 (arg1, arg2, type,
                                 /* do_nonfinite= */ folding_initializer,
 				mpc_div);
-	  /* Fallthru ... */
+	  /* Fallthru. */
 	case TRUNC_DIV_EXPR:
 	case CEIL_DIV_EXPR:
 	case FLOOR_DIV_EXPR:
@@ -3696,7 +3696,7 @@ fold_truth_not_expr (location_t loc, tree arg)
       if (TREE_CODE (TREE_TYPE (arg)) == BOOLEAN_TYPE)
 	return build1_loc (loc, TRUTH_NOT_EXPR, type, arg);
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case FLOAT_EXPR:
       loc1 = expr_location_or (TREE_OPERAND (arg, 0), loc);
@@ -4460,6 +4460,7 @@ make_range_step (location_t loc, enum tree_code code, tree arg0, tree arg1,
 
       if (TYPE_OVERFLOW_UNDEFINED (arg0_type))
 	*strict_overflow_p = true;
+      gcc_fallthrough ();
 
       normalize:
 	/* Check for an unsigned range which has wrapped around the maximum
@@ -5101,6 +5102,7 @@ fold_cond_expr_with_comparison (location_t loc, tree type,
       case UNLT_EXPR:
 	if (flag_trapping_math)
 	  break;
+	gcc_fallthrough ();
       case LE_EXPR:
       case LT_EXPR:
 	if (TYPE_UNSIGNED (TREE_TYPE (arg1)))
@@ -9452,6 +9454,7 @@ fold_binary_loc (location_t loc,
                 }
             }
 	}
+      gcc_fallthrough ();
 
      bit_rotate:
       /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
@@ -9541,6 +9544,7 @@ fold_binary_loc (location_t loc,
 	      }
 	  }
       }
+      gcc_fallthrough ();
 
     associate:
       /* In most languages, can't associate operations on floats through
@@ -10323,6 +10327,8 @@ fold_binary_loc (location_t loc,
       /* If first arg is constant zero, return it.  */
       if (integer_zerop (arg0))
 	return fold_convert_loc (loc, type, arg0);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case TRUTH_AND_EXPR:
       /* If either arg is constant true, drop it.  */
       if (TREE_CODE (arg0) == INTEGER_CST && ! integer_zerop (arg0))
@@ -10378,6 +10384,8 @@ fold_binary_loc (location_t loc,
       /* If first arg is constant true, return it.  */
       if (TREE_CODE (arg0) == INTEGER_CST && ! integer_zerop (arg0))
 	return fold_convert_loc (loc, type, arg0);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case TRUTH_OR_EXPR:
       /* If either arg is constant zero, drop it.  */
       if (TREE_CODE (arg0) == INTEGER_CST && integer_zerop (arg0))
@@ -11222,7 +11230,7 @@ contains_label_1 (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
     case GOTO_EXPR:
       *walk_subtrees = 0;
 
-      /* ... fall through ...  */
+      /* fall through */
 
     default:
       return NULL_TREE;
@@ -12587,7 +12595,7 @@ multiple_of_p (tree type, const_tree top, const_tree bottom)
 	      < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (top, 0)))))
 	return 0;
 
-      /* .. fall through ...  */
+      /* fall through */
 
     case SAVE_EXPR:
       return multiple_of_p (type, TREE_OPERAND (top, 0), bottom);
diff --git gcc/gcc/fortran/arith.c gcc/gcc/fortran/arith.c
index 47a5504..8af7540 100644
--- gcc/gcc/fortran/arith.c
+++ gcc/gcc/fortran/arith.c
@@ -1521,7 +1521,7 @@ eval_intrinsic (gfc_intrinsic_op op,
 	  break;
 	}
 
-    /* Fall through  */
+    gcc_fallthrough ();
     /* Numeric binary  */
     case INTRINSIC_PLUS:
     case INTRINSIC_MINUS:
diff --git gcc/gcc/fortran/array.c gcc/gcc/fortran/array.c
index 03c8b17..2330998 100644
--- gcc/gcc/fortran/array.c
+++ gcc/gcc/fortran/array.c
@@ -2323,6 +2323,7 @@ gfc_ref_dimen_size (gfc_array_ref *ar, int dimen, mpz_t *result, mpz_t *end)
 	  mpz_mul (*end, *end, stride);
 	  mpz_add (*end, *end, lower);
 	}
+      gcc_fallthrough ();
 
     cleanup:
       mpz_clear (upper);
diff --git gcc/gcc/fortran/decl.c gcc/gcc/fortran/decl.c
index 1b62833..6c6842f 100644
--- gcc/gcc/fortran/decl.c
+++ gcc/gcc/fortran/decl.c
@@ -3911,6 +3911,7 @@ match_attr_spec (void)
 		      d = DECL_CODIMENSION;
 		      break;
 		    }
+		  gcc_fallthrough ();
 		case 'n':
 		  if (match_string_p ("tiguous"))
 		    {
diff --git gcc/gcc/fortran/dependency.c gcc/gcc/fortran/dependency.c
index a873dbe..fd174d9 100644
--- gcc/gcc/fortran/dependency.c
+++ gcc/gcc/fortran/dependency.c
@@ -2250,6 +2250,7 @@ dep_ref (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 
 	      /* Overlap codes are in order of priority.  We only need to
 		 know the worst one.*/
+	      gcc_fallthrough ();
 
 	    update_fin_dep:
 	      if (this_dep > fin_dep)
diff --git gcc/gcc/fortran/dump-parse-tree.c gcc/gcc/fortran/dump-parse-tree.c
index f507434..1eb8777 100644
--- gcc/gcc/fortran/dump-parse-tree.c
+++ gcc/gcc/fortran/dump-parse-tree.c
@@ -2162,6 +2162,7 @@ show_code_node (int level, gfc_code *c)
 
     case EXEC_FLUSH:
       fputs ("FLUSH", dumpfile);
+      gcc_fallthrough ();
 
     show_filepos:
       fp = c->ext.filepos;
@@ -2378,6 +2379,7 @@ show_code_node (int level, gfc_code *c)
 
     case EXEC_WRITE:
       fputs ("WRITE", dumpfile);
+      gcc_fallthrough ();
 
     show_dt:
       dt = c->ext.dt;
@@ -2468,6 +2470,7 @@ show_code_node (int level, gfc_code *c)
 	  fputs (" SIGN=", dumpfile);
 	  show_expr (dt->sign);
 	}
+      gcc_fallthrough ();
 
     show_dt_code:
       for (c = c->block->next; c; c = c->next)
diff --git gcc/gcc/fortran/frontend-passes.c gcc/gcc/fortran/frontend-passes.c
index d4dee47..317283f 100644
--- gcc/gcc/fortran/frontend-passes.c
+++ gcc/gcc/fortran/frontend-passes.c
@@ -1442,7 +1442,7 @@ optimize_op (gfc_expr *e)
     case INTRINSIC_LT:
       changed = optimize_comparison (e, op);
 
-      /* Fall through */
+      gcc_fallthrough ();
       /* Look at array constructors.  */
     case INTRINSIC_PLUS:
     case INTRINSIC_MINUS:
@@ -3310,6 +3310,7 @@ gfc_expr_walker (gfc_expr **e, walk_expr_fn_t exprfn, void *data)
 
 	    /* Fall through to the variable case in order to walk the
 	       reference.  */
+	    gcc_fallthrough ();
 
 	  case EXPR_SUBSTRING:
 	  case EXPR_VARIABLE:
diff --git gcc/gcc/fortran/parse.c gcc/gcc/fortran/parse.c
index bd7b138..b9f6c8c 100644
--- gcc/gcc/fortran/parse.c
+++ gcc/gcc/fortran/parse.c
@@ -1262,7 +1262,7 @@ next_fixed (void)
 		  return decode_oacc_directive ();
 		}
 	    }
-	  /* FALLTHROUGH */
+	  gcc_fallthrough ();
 
 	  /* Comments have already been skipped by the time we get
 	     here so don't bother checking for them.  */
@@ -3699,6 +3699,7 @@ declSt:
 	      unexpected_statement (st);
 	      break;
 	    }
+	  gcc_fallthrough ();
 
 	default:
 	  break;
diff --git gcc/gcc/fortran/primary.c gcc/gcc/fortran/primary.c
index c2faa0f..799ebc9 100644
--- gcc/gcc/fortran/primary.c
+++ gcc/gcc/fortran/primary.c
@@ -1686,18 +1686,21 @@ match_arg_list_function (gfc_actual_arglist *result)
 	      result->name = "%LOC";
 	      break;
 	    }
+	  gcc_fallthrough ();
 	case 'r':
 	  if (strncmp (name, "ref", 3) == 0)
 	    {
 	      result->name = "%REF";
 	      break;
 	    }
+	  gcc_fallthrough ();
 	case 'v':
 	  if (strncmp (name, "val", 3) == 0)
 	    {
 	      result->name = "%VAL";
 	      break;
 	    }
+	  gcc_fallthrough ();
 	default:
 	  m = MATCH_ERROR;
 	  goto cleanup;
@@ -3007,6 +3010,7 @@ gfc_match_rvalue (gfc_expr **result)
 	  m = gfc_match_varspec (e, 0, false, true);
 	  break;
 	}
+     gcc_fallthrough ();
 
     /* Match a function reference.  */
     function0:
@@ -3412,6 +3416,7 @@ match_variable (gfc_expr **result, int equiv_flag, int host_flag)
 	break;
 
       /* Fall through to error */
+      gcc_fallthrough ();
 
     default:
       gfc_error ("%qs at %C is not a variable", sym->name);
diff --git gcc/gcc/fortran/resolve.c gcc/gcc/fortran/resolve.c
index 1fc540a..7340454 100644
--- gcc/gcc/fortran/resolve.c
+++ gcc/gcc/fortran/resolve.c
@@ -3542,7 +3542,7 @@ resolve_operator (gfc_expr *e)
       if (!gfc_resolve_expr (e->value.op.op2))
 	return false;
 
-    /* Fall through...  */
+    /* Fall through.  */
 
     case INTRINSIC_NOT:
     case INTRINSIC_UPLUS:
@@ -3660,7 +3660,7 @@ resolve_operator (gfc_expr *e)
 	  goto bad_op;
 	}
 
-      /* Fall through...  */
+      /* Fall through.  */
 
     case INTRINSIC_EQ:
     case INTRINSIC_EQ_OS:
@@ -5419,14 +5419,17 @@ fixup_charlen (gfc_expr *e)
     {
     case EXPR_OP:
       gfc_resolve_character_operator (e);
+      gcc_fallthrough ();
 
     case EXPR_ARRAY:
       if (e->expr_type == EXPR_ARRAY)
 	gfc_resolve_character_array_constructor (e);
+      gcc_fallthrough ();
 
     case EXPR_SUBSTRING:
       if (!e->ts.u.cl && e->ref)
 	gfc_resolve_substring_charlen (e);
+      gcc_fallthrough ();
 
     default:
       if (!e->ts.u.cl)
@@ -7301,7 +7304,7 @@ resolve_allocate_expr (gfc_expr *e, gfc_code *code, bool *array_alloc_wo_spec)
 	      && ar->stride[i] == NULL)
 	    break;
 
-	  /* Fall Through...  */
+	  /* Fall through.  */
 
 	case DIMEN_UNKNOWN:
 	case DIMEN_VECTOR:
diff --git gcc/gcc/fortran/trans-array.c gcc/gcc/fortran/trans-array.c
index e95c8dd..2ef6263 100644
--- gcc/gcc/fortran/trans-array.c
+++ gcc/gcc/fortran/trans-array.c
@@ -4031,6 +4031,7 @@ done:
 		    continue;
 		  }
 		  /* Otherwise fall through GFC_SS_FUNCTION.  */
+		  gcc_fallthrough ();
 	      }
 	    case GFC_ISYM_LCOBOUND:
 	    case GFC_ISYM_UCOBOUND:
@@ -4041,6 +4041,7 @@ done:
 	      continue;
 	    }
 
+	  gcc_fallthrough ();
 	case GFC_SS_CONSTRUCTOR:
 	case GFC_SS_FUNCTION:
 	  for (n = 0; n < ss->dimen; n++)
diff --git gcc/gcc/fortran/trans-expr.c gcc/gcc/fortran/trans-expr.c
index e3559f4..7e8dc6a 100644
--- gcc/gcc/fortran/trans-expr.c
+++ gcc/gcc/fortran/trans-expr.c
@@ -2102,6 +2102,7 @@ flatten_array_ctors_without_strlen (gfc_expr* e)
 	}
 
       /* Otherwise, fall through to handle constructor elements.  */
+      gcc_fallthrough ();
     case EXPR_STRUCTURE:
       for (c = gfc_constructor_first (e->value.constructor);
 	   c; c = gfc_constructor_next (c))
diff --git gcc/gcc/fortran/trans-intrinsic.c gcc/gcc/fortran/trans-intrinsic.c
index c655540..0623338 100644
--- gcc/gcc/fortran/trans-intrinsic.c
+++ gcc/gcc/fortran/trans-intrinsic.c
@@ -2136,6 +2136,7 @@ conv_intrinsic_cobound (gfc_se * se, gfc_expr * expr)
 	  bound = fold_build2_loc (input_location, MINUS_EXPR,
 				   gfc_array_index_type, bound,
 				   gfc_index_one_node);
+	  gcc_fallthrough ();
 	case 1:
 	  break;
 	default:
@@ -5329,7 +5330,7 @@ gfc_conv_intrinsic_len (gfc_se * se, gfc_expr * expr)
 	  break;
 	}
 
-      /* Otherwise fall through.  */
+      /* Fall through.  */
 
     default:
       /* Anybody stupid enough to do this deserves inefficient code.  */
diff --git gcc/gcc/fortran/trans-stmt.c gcc/gcc/fortran/trans-stmt.c
index 6e4e2a7..b3a4d86 100644
--- gcc/gcc/fortran/trans-stmt.c
+++ gcc/gcc/fortran/trans-stmt.c
@@ -4969,6 +4969,7 @@ gfc_trans_where_2 (gfc_code * code, tree mask, bool invert,
             case EXEC_ASSIGN:
               expr1 = cnext->expr1;
               expr2 = cnext->expr2;
+	      gcc_fallthrough ();
     evaluate:
               if (nested_forall_info != NULL)
                 {
diff --git gcc/gcc/gcc.c gcc/gcc/gcc.c
index 7460f6a..becd304 100644
--- gcc/gcc/gcc.c
+++ gcc/gcc/gcc.c
@@ -3857,6 +3857,7 @@ driver_handle_option (struct gcc_options *opts,
 
     case OPT_fcompare_debug_:
       compare_debug_replacement_opt = decoded->canonical_option[0];
+      gcc_fallthrough ();
     compare_debug_with_arg:
       gcc_assert (decoded->canonical_option_num_elements == 1);
       gcc_assert (arg != NULL);
diff --git gcc/gcc/gcov-tool.c gcc/gcc/gcov-tool.c
index f3da73c..28c9393 100644
--- gcc/gcc/gcov-tool.c
+++ gcc/gcc/gcov-tool.c
@@ -547,9 +547,11 @@ process_args (int argc, char **argv)
         case 'h':
           print_usage (false);
           /* Print_usage will exit.  */
+	  gcc_fallthrough ();
         case 'v':
           print_version ();
           /* Print_version will exit.  */
+	  gcc_fallthrough ();
         default:
           print_usage (true);
           /* Print_usage will exit.  */
diff --git gcc/gcc/genattrtab.c gcc/gcc/genattrtab.c
index d39d4a7..28795a6 100644
--- gcc/gcc/genattrtab.c
+++ gcc/gcc/genattrtab.c
@@ -888,6 +888,7 @@ check_attr_test (file_location loc, rtx exp, attr_desc *attr)
 	  ATTR_IND_SIMPLIFIED_P (exp) = 1;
 	  break;
 	}
+      gcc_fallthrough ();
     default:
       fatal_at (loc, "invalid operator `%s' in definition of attribute"
 		" `%s'", GET_RTX_NAME (GET_CODE (exp)), attr->name);
@@ -1218,6 +1219,7 @@ make_canonical (file_location loc, struct attr_desc *attr, rtx exp)
 
       exp = newexp;
       /* Fall through to COND case since this is now a COND.  */
+      gcc_fallthrough ();
 
     case COND:
       {
@@ -3458,6 +3460,7 @@ write_test_expr (FILE *outf, rtx exp, unsigned int attrs_cached, int flags,
     case GE: case GT:
     case LE: case LT:
       comparison_operator = FLG_BITWISE;
+      gcc_fallthrough ();
 
     case PLUS:   case MINUS:  case MULT:     case DIV:      case MOD:
     case AND:    case IOR:    case XOR:
@@ -3613,6 +3616,7 @@ write_test_expr (FILE *outf, rtx exp, unsigned int attrs_cached, int flags,
 	}
 
       /* Otherwise, fall through to normal unary operator.  */
+      gcc_fallthrough ();
 
     /* Unary operators.  */
     case ABS:  case NEG:
diff --git gcc/gcc/genconfig.c gcc/gcc/genconfig.c
index 815e30d..ac65338 100644
--- gcc/gcc/genconfig.c
+++ gcc/gcc/genconfig.c
@@ -83,6 +83,8 @@ walk_insn_part (rtx part, int recog_p, int non_pc_set_src)
     case MATCH_OP_DUP:
     case MATCH_PAR_DUP:
       ++dup_operands_seen_this_insn;
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case MATCH_SCRATCH:
     case MATCH_PARALLEL:
     case MATCH_OPERATOR:
diff --git gcc/gcc/gengtype.c gcc/gcc/gengtype.c
index 5479b8f..0518355 100644
--- gcc/gcc/gengtype.c
+++ gcc/gcc/gengtype.c
@@ -175,6 +175,7 @@ dbgprint_count_type_at (const char *fil, int lin, const char *msg, type_p t)
 	{
 	case TYPE_UNDEFINED:
 	  nb_undefined++;
+	  break;
 	case TYPE_SCALAR:
 	  nb_scalar++;
 	  break;
diff --git gcc/gcc/genpreds.c gcc/gcc/genpreds.c
index dd7dbbf..f2cedb5 100644
--- gcc/gcc/genpreds.c
+++ gcc/gcc/genpreds.c
@@ -51,12 +51,12 @@ validate_exp (rtx exp, const char *name, file_location loc)
     case IF_THEN_ELSE:
       if (validate_exp (XEXP (exp, 2), name, loc))
 	return true;
-      /* else fall through */
+      /* fall through */
     case AND:
     case IOR:
       if (validate_exp (XEXP (exp, 1), name, loc))
 	return true;
-      /* else fall through */
+      /* fall through */
     case NOT:
       return validate_exp (XEXP (exp, 0), name, loc);
 
@@ -74,7 +74,7 @@ validate_exp (rtx exp, const char *name, file_location loc)
 	      }
 	  }
       }
-      /* fall through */
+      gcc_fallthrough ();
 
       /* These need no special checking.  */
     case MATCH_OPERAND:
@@ -174,12 +174,12 @@ needs_variable (rtx exp, const char *var)
     case IF_THEN_ELSE:
       if (needs_variable (XEXP (exp, 2), var))
 	return true;
-      /* else fall through */
+      /* fall through */
     case AND:
     case IOR:
       if (needs_variable (XEXP (exp, 1), var))
 	return true;
-      /* else fall through */
+      /* fall through */
     case NOT:
       return needs_variable (XEXP (exp, 0), var);
 
diff --git gcc/gcc/gensupport.c gcc/gcc/gensupport.c
index 0eb4591..795f88c 100644
--- gcc/gcc/gensupport.c
+++ gcc/gcc/gensupport.c
@@ -1038,6 +1038,8 @@ get_alternatives_number (rtx pattern, int *n_alt, file_location loc)
 	case 'V':
 	  if (XVEC (pattern, i) == NULL)
 	    break;
+	  /* XXX Really fallthru?  */
+	  gcc_fallthrough ();
 
 	case 'E':
 	  for (j = XVECLEN (pattern, i) - 1; j >= 0; --j)
@@ -2156,6 +2158,8 @@ subst_dup (rtx pattern, int n_alt, int n_subst_alt)
 	case 'V':
 	  if (XVEC (pattern, i) == NULL)
 	    break;
+	  /* XXX Really fallthru?  */
+	  gcc_fallthrough ();
 	case 'E':
 	  if (code != MATCH_DUP && code != MATCH_OP_DUP)
 	    for (j = XVECLEN (pattern, i) - 1; j >= 0; --j)
diff --git gcc/gcc/gimple-pretty-print.c gcc/gcc/gimple-pretty-print.c
index 48edacc..7c12f84 100644
--- gcc/gcc/gimple-pretty-print.c
+++ gcc/gcc/gimple-pretty-print.c
@@ -517,8 +517,10 @@ dump_gimple_assign (pretty_printer *buffer, gassign *gs, int spc, int flags)
 	{
 	case 4:
 	  arg3 = gimple_assign_rhs3 (gs);
+	  gcc_fallthrough ();
 	case 3:
 	  arg2 = gimple_assign_rhs2 (gs);
+	  gcc_fallthrough ();
 	case 2:
 	  arg1 = gimple_assign_rhs1 (gs);
 	  break;
diff --git gcc/gcc/gimple-ssa-strength-reduction.c gcc/gcc/gimple-ssa-strength-reduction.c
index 6e277e7..0b759cd 100644
--- gcc/gcc/gimple-ssa-strength-reduction.c
+++ gcc/gcc/gimple-ssa-strength-reduction.c
@@ -1694,7 +1694,7 @@ find_candidates_dom_walker::before_dom_children (basic_block bb)
 	    case POINTER_PLUS_EXPR:
 	    case MINUS_EXPR:
 	      rhs2 = gimple_assign_rhs2 (gs);
-	      /* Fall-through.  */
+	      gcc_fallthrough ();
 
 	    CASE_CONVERT:
 	    case MODIFY_EXPR:
diff --git gcc/gcc/gimplify.c gcc/gcc/gimplify.c
index fb27dd0..0beb1ff 100644
--- gcc/gcc/gimplify.c
+++ gcc/gcc/gimplify.c
@@ -5190,7 +5553,7 @@ gimplify_addr_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
       if (integer_zerop (TREE_OPERAND (op0, 1)))
 	goto do_indirect_ref;
 
-      /* ... fall through ... */
+      /* fall through */
 
     default:
       /* If we see a call to a declared builtin or see its address
@@ -6155,6 +6518,7 @@ omp_default_clause (struct gimplify_omp_ctx *ctx, tree decl,
 	flags |= GOVD_FIRSTPRIVATE;
       else
 	flags |= GOVD_SHARED;
+      gcc_fallthrough ();
     found_outer:
       break;
 
@@ -6941,6 +7305,7 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 	    case OACC_DATA:
 	      if (TREE_CODE (TREE_TYPE (decl)) != ARRAY_TYPE)
 		break;
+	      gcc_fallthrough ();
 	    case OMP_TARGET_DATA:
 	    case OMP_TARGET_ENTER_DATA:
 	    case OMP_TARGET_EXIT_DATA:
@@ -7424,6 +7789,7 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 
 	do_add:
 	  decl = OMP_CLAUSE_DECL (c);
+	  gcc_fallthrough ();
 	do_add_decl:
 	  if (error_operand_p (decl))
 	    {
@@ -7557,6 +7923,7 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 			  "copyprivate variable %qE is not threadprivate"
 			  " or private in outer context", DECL_NAME (decl));
 	    }
+	  gcc_fallthrough ();
 	do_notice:
 	  if (outer_ctx)
 	    omp_notice_variable (outer_ctx, decl, true);
@@ -9964,6 +10331,8 @@ goa_stabilize_expr (tree *expr_p, gimple_seq *pre_p, tree lhs_addr,
     case tcc_comparison:
       saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 1), pre_p, lhs_addr,
 				     lhs_var);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case tcc_unary:
       saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p, lhs_addr,
 				     lhs_var);
@@ -9978,6 +10347,8 @@ goa_stabilize_expr (tree *expr_p, gimple_seq *pre_p, tree lhs_addr,
 	case TRUTH_XOR_EXPR:
 	  saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 1), pre_p,
 					 lhs_addr, lhs_var);
+	  /* XXX Really fallthru?  */
+	  gcc_fallthrough ();
 	case TRUTH_NOT_EXPR:
 	  saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p,
 					 lhs_addr, lhs_var);
diff --git gcc/gcc/go/go-system.h gcc/gcc/go/go-system.h
index cb7e745..e1b6a70 100644
--- gcc/gcc/go/go-system.h
+++ gcc/gcc/go/go-system.h
@@ -138,4 +138,7 @@ struct hash<T*>
 // When using gcc, go_unreachable is just gcc_unreachable.
 #define go_unreachable() gcc_unreachable()
 
+// When using gcc, go_fallthrough is just gcc_fallthrough.
+#define go_fallthrough() gcc_fallthrough()
+
 #endif // !defined(GO_SYSTEM_H)
diff --git gcc/gcc/go/gofrontend/escape.cc gcc/gcc/go/gofrontend/escape.cc
index af8f1e2..5b95d87 100644
--- gcc/gcc/go/gofrontend/escape.cc
+++ gcc/gcc/go/gofrontend/escape.cc
@@ -1484,6 +1484,7 @@ Escape_analysis_assign::assign(Node* dst, Node* src)
 	    if (!e->type()->has_pointer())
 	      break;
 	  }
+	  go_fallthrough ();
 
 	case Expression::EXPRESSION_CONVERSION:
 	case Expression::EXPRESSION_TYPE_GUARD:
diff --git gcc/gcc/go/gofrontend/expressions.cc gcc/gcc/go/gofrontend/expressions.cc
index 5f7e4c9..a13c997 100644
--- gcc/gcc/go/gofrontend/expressions.cc
+++ gcc/gcc/go/gofrontend/expressions.cc
@@ -5745,6 +5745,7 @@ Binary_expression::do_get_backend(Translate_context* context)
     case OPERATOR_DIV:
       if (left_type->float_type() != NULL || left_type->complex_type() != NULL)
         break;
+      go_fallthrough ();
     case OPERATOR_MOD:
       is_idiv_op = true;
       break;
@@ -5754,6 +5755,7 @@ Binary_expression::do_get_backend(Translate_context* context)
       break;
     case OPERATOR_BITCLEAR:
       this->right_ = Expression::make_unary(OPERATOR_XOR, this->right_, loc);
+      go_fallthrough ();
     case OPERATOR_AND:
       break;
     default:
diff --git gcc/gcc/godump.c gcc/gcc/godump.c
index e3448a1..608542c 100644
--- gcc/gcc/godump.c
+++ gcc/gcc/godump.c
@@ -893,6 +893,7 @@ go_format_type (struct godump_container *container, tree type,
     case UNION_TYPE:
       is_union = true;
       /* Fall through to RECORD_TYPE case.  */
+      gcc_fallthrough ();
     case RECORD_TYPE:
       {
 	unsigned int prev_field_end;
diff --git gcc/gcc/graphite-isl-ast-to-gimple.c gcc/gcc/graphite-isl-ast-to-gimple.c
index 07c88026..0eb564a 100644
--- gcc/gcc/graphite-isl-ast-to-gimple.c
+++ gcc/gcc/graphite-isl-ast-to-gimple.c
@@ -1496,7 +1496,7 @@ substitute_ssa_name (tree exp, tree f, tree r)
 	if (exp == f)
 	  return r;
 
-	/* Fall through...  */
+	/* Fall through.  */
 
       case tcc_exceptional:
       case tcc_unary:
diff --git gcc/gcc/hsa-gen.c gcc/gcc/hsa-gen.c
index 6cf1538..b4498e2 100644
--- gcc/gcc/hsa-gen.c
+++ gcc/gcc/hsa-gen.c
@@ -4519,7 +4519,7 @@ get_address_from_value (tree val, hsa_bb *hbb)
     case INTEGER_CST:
       if (tree_fits_shwi_p (val))
 	return new hsa_op_address (NULL, NULL, tree_to_shwi (val));
-      /* Otherwise fall-through */
+      /* fall-through */
 
     default:
       HSA_SORRY_ATV (EXPR_LOCATION (val),
@@ -5039,6 +5039,8 @@ gen_hsa_insn_for_internal_fn_call (gcall *stmt, hsa_bb *hbb)
     case IFN_FMIN:
     case IFN_FMAX:
       gen_hsa_insns_for_call_of_internal_fn (stmt, hbb);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
 
     default:
       HSA_SORRY_ATV (gimple_location (stmt),
diff --git gcc/gcc/ipa-icf.c gcc/gcc/ipa-icf.c
index 3c04b5a..f29d929 100644
--- gcc/gcc/ipa-icf.c
+++ gcc/gcc/ipa-icf.c
@@ -1643,7 +1643,7 @@ sem_function::hash_stmt (gimple *stmt, inchash::hash &hstate)
 	  add_type (TREE_TYPE (gimple_assign_lhs (stmt)), two);
 	  break;
 	}
-      /* ... fall through ... */
+      /* fall through */
     case GIMPLE_CALL:
     case GIMPLE_ASM:
     case GIMPLE_COND:
diff --git gcc/gcc/ira.c gcc/gcc/ira.c
index c66bb9e..f6eb7ca 100644
--- gcc/gcc/ira.c
+++ gcc/gcc/ira.c
@@ -1832,6 +1832,7 @@ ira_setup_alts (rtx_insn *insn, HARD_REG_SET &alts)
 		  case '#':
 		  case ',':
 		    c = '\0';
+		    gcc_fallthrough ();
 		  case '\0':
 		    len = 0;
 		    break;
diff --git gcc/gcc/java/expr.c gcc/gcc/java/expr.c
index 2b856e5..ca58d28 100644
--- gcc/gcc/java/expr.c
+++ gcc/gcc/java/expr.c
@@ -191,7 +191,7 @@ java_truthvalue_conversion (tree expr)
       if (TYPE_PRECISION (TREE_TYPE (expr))
           >= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (expr, 0))))
         return java_truthvalue_conversion (TREE_OPERAND (expr, 0));
-      /* fall through to default */
+      /* fall through */
 
     default:
       return fold_build2 (NE_EXPR, boolean_type_node,
diff --git gcc/gcc/java/jcf-dump.c gcc/gcc/java/jcf-dump.c
index 1331b55..8b00e57 100644
--- gcc/gcc/java/jcf-dump.c
+++ gcc/gcc/java/jcf-dump.c
@@ -926,6 +926,7 @@ print_constant (FILE *out, JCF *jcf, int index, int verbosity)
 	  if (verbosity > 0)
 	    fprintf (out, "Fieldref: %ld=", (long) JPOOL_USHORT2 (jcf, index));
 	  print_constant (out, jcf, JPOOL_USHORT2 (jcf, index), 0);
+	  break;
 	case 5:
 	case 6:
 	case 7:
diff --git gcc/gcc/java/jcf-io.c gcc/gcc/java/jcf-io.c
index a560db7..cc8616b 100644
--- gcc/gcc/java/jcf-io.c
+++ gcc/gcc/java/jcf-io.c
@@ -471,7 +471,7 @@ verify_constant_pool (JCF *jcf)
 	  if (n <= 0 || n >= JPOOL_SIZE(jcf)
 	      || JPOOL_TAG (jcf, n) != CONSTANT_Utf8)
 	    return i;
-	  /* ... fall through ... */
+	  /* fall through */
 	case CONSTANT_Class:
 	case CONSTANT_String:
 	  n = JPOOL_USHORT1 (jcf, i);
diff --git gcc/gcc/java/typeck.c gcc/gcc/java/typeck.c
index d2e3db6..8e52daf 100644
--- gcc/gcc/java/typeck.c
+++ gcc/gcc/java/typeck.c
@@ -332,6 +332,7 @@ promote_type (tree type)
     case INTEGER_TYPE:
       if (type == char_type_node)
 	return promoted_char_type_node;
+      gcc_fallthrough ();
     handle_int:
       if (TYPE_PRECISION (type) < TYPE_PRECISION (int_type_node))
 	{
@@ -341,7 +342,7 @@ promote_type (tree type)
 	    return promoted_byte_type_node;
 	  return int_type_node;
 	}
-      /* ... else fall through ... */
+      /* fall through */
     default:
       return type;
     }
diff --git gcc/gcc/lra-eliminations.c gcc/gcc/lra-eliminations.c
index 9ae5cfe..08cc390 100644
--- gcc/gcc/lra-eliminations.c
+++ gcc/gcc/lra-eliminations.c
@@ -484,7 +484,7 @@ lra_eliminate_regs_1 (rtx_insn *insn, rtx x, machine_mode mem_mode,
 	    return gen_rtx_MULT (Pmode, to, XEXP (x, 1));
 	}
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case CALL:
     case COMPARE:
@@ -536,7 +536,7 @@ lra_eliminate_regs_1 (rtx_insn *insn, rtx x, machine_mode mem_mode,
 	    }
 	}
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case INSN_LIST:
     case INT_LIST:
diff --git gcc/gcc/lto-streamer-out.c gcc/gcc/lto-streamer-out.c
index e243337..572b53b 100644
--- gcc/gcc/lto-streamer-out.c
+++ gcc/gcc/lto-streamer-out.c
@@ -231,6 +231,7 @@ lto_output_tree_ref (struct output_block *ob, tree expr)
     case VAR_DECL:
     case DEBUG_EXPR_DECL:
       gcc_assert (decl_function_context (expr) == NULL || TREE_STATIC (expr));
+      gcc_fallthrough ();
     case PARM_DECL:
       streamer_write_record_start (ob, LTO_global_decl_ref);
       lto_output_var_decl_index (ob->decl_state, ob->main_stream, expr);
diff --git gcc/gcc/objc/objc-encoding.c gcc/gcc/objc/objc-encoding.c
index 41ac6a4..cc64e1b 100644
--- gcc/gcc/objc/objc-encoding.c
+++ gcc/gcc/objc/objc-encoding.c
@@ -622,6 +622,7 @@ encode_type (tree type, int curtype, int format)
 	}
       /* Else, they are encoded exactly like the integer type that is
 	 used by the compiler to store them.  */
+      gcc_fallthrough ();
     case INTEGER_TYPE:
       {
 	char c;
diff --git gcc/gcc/omp-low.c gcc/gcc/omp-low.c
index 04509f3..0490d55 100644
--- gcc/gcc/omp-low.c
+++ gcc/gcc/omp-low.c
@@ -1949,6 +1949,7 @@ scan_sharing_clauses (tree clauses, omp_context *ctx,
 	case OMP_CLAUSE_FIRSTPRIVATE:
 	case OMP_CLAUSE_LINEAR:
 	  decl = OMP_CLAUSE_DECL (c);
+	  gcc_fallthrough ();
 	do_private:
 	  if ((OMP_CLAUSE_CODE (c) == OMP_CLAUSE_FIRSTPRIVATE
 	       || OMP_CLAUSE_CODE (c) == OMP_CLAUSE_IS_DEVICE_PTR)
@@ -4432,6 +4433,7 @@ lower_rec_input_clauses (tree clauses, gimple_seq *ilist, gimple_seq *dlist,
 			      || is_global_var (OMP_CLAUSE_DECL (c)));
 		  continue;
 		}
+	      gcc_fallthrough ();
 	    case OMP_CLAUSE_FIRSTPRIVATE:
 	    case OMP_CLAUSE_COPYIN:
 	      break;
@@ -4943,6 +4945,7 @@ lower_rec_input_clauses (tree clauses, gimple_seq *ilist, gimple_seq *dlist,
 		}
 	      else
 		x = NULL;
+	      gcc_fallthrough ();
 	    do_private:
 	      tree nx;
 	      nx = lang_hooks.decls.omp_clause_default_ctor
@@ -5015,6 +5018,7 @@ lower_rec_input_clauses (tree clauses, gimple_seq *ilist, gimple_seq *dlist,
 		      goto do_dtor;
 		    }
 		}
+	      gcc_fallthrough ();
 	    do_firstprivate:
 	      x = build_outer_var_ref (var, ctx);
 	      if (is_simd)
diff --git gcc/gcc/opts.c gcc/gcc/opts.c
index 4053fb1..f6da14e 100644
--- gcc/gcc/opts.c
+++ gcc/gcc/opts.c
@@ -1980,6 +1980,7 @@ common_handle_option (struct gcc_options *opts,
       opts->x_flag_profile_use = true;
       value = true;
       /* No break here - do -fprofile-use processing. */
+      gcc_fallthrough ();
     case OPT_fprofile_use:
       enable_fdo_optimizations (opts, opts_set, value);
       if (!opts_set->x_flag_profile_reorder_functions)
@@ -1996,6 +1997,7 @@ common_handle_option (struct gcc_options *opts,
       opts->x_flag_auto_profile = true;
       value = true;
       /* No break here - do -fauto-profile processing. */
+      gcc_fallthrough ();
     case OPT_fauto_profile:
       enable_fdo_optimizations (opts, opts_set, value);
       if (!opts_set->x_flag_profile_correction)
@@ -2009,6 +2011,7 @@ common_handle_option (struct gcc_options *opts,
       opts->x_profile_data_prefix = xstrdup (arg);
       value = true;
       /* No break here - do -fprofile-generate processing. */
+      gcc_fallthrough ();
     case OPT_fprofile_generate:
       if (!opts_set->x_profile_arc_flag)
 	opts->x_profile_arc_flag = value;
diff --git gcc/gcc/print-rtl.c gcc/gcc/print-rtl.c
index a905127..b9d7cf4 100644
--- gcc/gcc/print-rtl.c
+++ gcc/gcc/print-rtl.c
@@ -217,6 +217,7 @@ print_rtx (const_rtx in_rtx)
       case 'S':
       case 's':
 	str = XSTR (in_rtx, i);
+	gcc_fallthrough ();
       string:
 
 	if (str == 0)
diff --git gcc/gcc/read-rtl.c gcc/gcc/read-rtl.c
index a705859..b8880b9 100644
--- gcc/gcc/read-rtl.c
+++ gcc/gcc/read-rtl.c
@@ -1163,6 +1163,7 @@ read_rtx_code (const char *code_name)
 	    break;
 	  }
 	/* Now process the vector.  */
+	gcc_fallthrough ();
 
       case 'E':
 	{
diff --git gcc/gcc/real.c gcc/gcc/real.c
index b009ed6..b472b05 100644
--- gcc/gcc/real.c
+++ gcc/gcc/real.c
@@ -2667,6 +2667,7 @@ round_for_format (const struct real_format *fmt, REAL_VALUE_TYPE *r)
     {
     underflow:
       get_zero (r, r->sign);
+      gcc_fallthrough ();
     case rvc_zero:
       if (!fmt->has_signed_zero)
 	r->sign = 0;
@@ -2674,6 +2675,7 @@ round_for_format (const struct real_format *fmt, REAL_VALUE_TYPE *r)
 
     overflow:
       get_inf (r, r->sign);
+      gcc_fallthrough ();
     case rvc_inf:
       return;
 
diff --git gcc/gcc/recog.c gcc/gcc/recog.c
index 80d1779..f400a6e 100644
--- gcc/gcc/recog.c
+++ gcc/gcc/recog.c
@@ -1792,6 +1792,7 @@ asm_operand_ok (rtx op, const char *constraint, const char **constraints)
 
 	     Match any memory and hope things are resolved after reload.  */
 	  incdec_ok = true;
+	  gcc_fallthrough ();
 	default:
 	  cn = lookup_constraint (constraint);
 	  switch (get_constraint_type (cn))
diff --git gcc/gcc/reg-stack.c gcc/gcc/reg-stack.c
index c931349..a4a3ac2 100644
--- gcc/gcc/reg-stack.c
+++ gcc/gcc/reg-stack.c
@@ -423,6 +423,8 @@ get_true_reg (rtx *pat)
 				  GET_MODE (subreg));
 	      return pat;
 	    }
+	  /* XXX Really fallthru?  */
+	  gcc_fallthrough ();
 	}
       case FLOAT:
       case FIX:
diff --git gcc/gcc/reginfo.c gcc/gcc/reginfo.c
index f4dac08..0cda6aa 100644
--- gcc/gcc/reginfo.c
+++ gcc/gcc/reginfo.c
@@ -1149,7 +1149,7 @@ reg_scan_mark_refs (rtx x, rtx_insn *insn)
       if (REG_P (dest) && !REG_ATTRS (dest))
 	set_reg_attrs_from_value (dest, SET_SRC (x));
 
-      /* ... fall through ...  */
+      /* fall through */
 
     default:
       {
diff --git gcc/gcc/reload1.c gcc/gcc/reload1.c
index 5622e89..8318b8a 100644
--- gcc/gcc/reload1.c
+++ gcc/gcc/reload1.c
@@ -2330,7 +2330,7 @@ set_label_offsets (rtx x, rtx_insn *insn, int initial_p)
 
       x = LABEL_REF_LABEL (x);
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case CODE_LABEL:
       /* If we know nothing about this label, set the desired offsets.  Note
@@ -2377,7 +2377,7 @@ set_label_offsets (rtx x, rtx_insn *insn, int initial_p)
     case JUMP_INSN:
       set_label_offsets (PATTERN (insn), insn, initial_p);
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case INSN:
     case CALL_INSN:
@@ -2692,7 +2692,7 @@ eliminate_regs_1 (rtx x, machine_mode mem_mode, rtx insn,
 			       ep->previous_offset * INTVAL (XEXP (x, 1)));
 	    }
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case CALL:
     case COMPARE:
@@ -2739,7 +2739,7 @@ eliminate_regs_1 (rtx x, machine_mode mem_mode, rtx insn,
 	    }
 	}
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case INSN_LIST:
     case INT_LIST:
@@ -3032,6 +3032,7 @@ elimination_effects (rtx x, machine_mode mem_mode)
 	break;
 
       /* Fall through to generic unary operation case.  */
+      gcc_fallthrough ();
     case STRICT_LOW_PART:
     case NEG:          case NOT:
     case SIGN_EXTEND:  case ZERO_EXTEND:
@@ -5501,7 +5502,7 @@ reload_reg_reaches_end_p (unsigned int regno, int reloadnum)
 
       opnum = reload_n_operands;
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case RELOAD_FOR_OUTPUT:
     case RELOAD_FOR_OUTPUT_ADDRESS:
diff --git gcc/gcc/resource.c gcc/gcc/resource.c
index ae2f5d8..6e58b3b 100644
--- gcc/gcc/resource.c
+++ gcc/gcc/resource.c
@@ -364,6 +364,7 @@ mark_referenced_resources (rtx x, struct resources *res,
 	}
 
       /* ... fall through to other INSN processing ...  */
+      gcc_fallthrough ();
 
     case INSN:
     case JUMP_INSN:
@@ -674,6 +675,7 @@ mark_set_resources (rtx x, struct resources *res, int in_dest,
 	}
 
       /* ... and also what its RTL says it modifies, if anything.  */
+      gcc_fallthrough ();
 
     case JUMP_INSN:
     case INSN:
diff --git gcc/gcc/rtlanal.c gcc/gcc/rtlanal.c
index 9445329..74eee1f 100644
--- gcc/gcc/rtlanal.c
+++ gcc/gcc/rtlanal.c
@@ -1765,6 +1765,7 @@ reg_overlap_mentioned_p (const_rtx x, const_rtx in)
     case REG:
       regno = REGNO (x);
       endregno = END_REGNO (x);
+      gcc_fallthrough ();
     do_reg:
       return refers_to_regno_p (regno, endregno, in, (rtx*) 0);
 
@@ -3421,6 +3422,7 @@ commutative_operand_precedence (rtx op)
       /* Then prefer NEG and NOT.  */
       if (code == NEG || code == NOT)
         return 1;
+      gcc_fallthrough ();
 
     default:
       return 0;
@@ -4095,7 +4097,7 @@ rtx_cost (rtx x, machine_mode mode, enum rtx_code outer_code,
       factor = GET_MODE_SIZE (mode) / UNITS_PER_WORD;
       if (factor == 0)
 	factor = 1;
-      /* Pass through.  */
+      gcc_fallthrough ();
     default:
       total = factor * COSTS_N_INSNS (1);
     }
diff --git gcc/gcc/sched-rgn.c gcc/gcc/sched-rgn.c
index fa662ff..03c0e13 100644
--- gcc/gcc/sched-rgn.c
+++ gcc/gcc/sched-rgn.c
@@ -2052,6 +2052,7 @@ is_exception_free (rtx_insn *insn, int bb_src, int bb_trg)
       if (is_pfree (insn, bb_src, bb_trg))
 	return 1;
       /* Don't 'break' here: PFREE-candidate is also PRISKY-candidate.  */
+      gcc_fallthrough ();
     case PRISKY_CANDIDATE:
       if (!flag_schedule_speculative_load_dangerous
 	  || is_prisky (insn, bb_src, bb_trg))
diff --git gcc/gcc/simplify-rtx.c gcc/gcc/simplify-rtx.c
index c34f2f5..df770da1 100644
--- gcc/gcc/simplify-rtx.c
+++ gcc/gcc/simplify-rtx.c
@@ -3308,6 +3308,7 @@ simplify_binary_operation_1 (enum rtx_code code, machine_mode mode,
 				     tmp);
 	  return lowpart_subreg (mode, tmp, inner_mode);
 	}
+      gcc_fallthrough ();
     canonicalize_shift:
       if (SHIFT_COUNT_TRUNCATED && CONST_INT_P (op1))
 	{
@@ -6253,7 +6254,7 @@ simplify_rtx (const_rtx x)
       if (swap_commutative_operands_p (XEXP (x, 0), XEXP (x, 1)))
 	return simplify_gen_binary (code, mode, XEXP (x, 1), XEXP (x, 0));
 
-      /* Fall through....  */
+      /* Fall through.  */
 
     case RTX_BIN_ARITH:
       return simplify_binary_operation (code, mode, XEXP (x, 0), XEXP (x, 1));
diff --git gcc/gcc/stor-layout.c gcc/gcc/stor-layout.c
index 4ada959..78a5f04 100644
--- gcc/gcc/stor-layout.c
+++ gcc/gcc/stor-layout.c
@@ -398,7 +398,7 @@ int_mode_for_mode (machine_mode mode)
       if (mode == BLKmode)
 	break;
 
-      /* ... fall through ...  */
+      /* fall through */
 
     case MODE_CC:
     default:
diff --git gcc/gcc/toplev.c gcc/gcc/toplev.c
index b0bb3ec..d593b92 100644
--- gcc/gcc/toplev.c
+++ gcc/gcc/toplev.c
@@ -731,7 +731,7 @@ print_to_asm_out_file (print_switch_type type, const char * text)
     case SWITCH_TYPE_DESCRIPTIVE:
       if (ASM_COMMENT_START[0] == 0)
 	prepend_sep = false;
-      /* Drop through.  */
+      gcc_fallthrough ();
     case SWITCH_TYPE_PASSED:
     case SWITCH_TYPE_ENABLED:
       if (prepend_sep)
@@ -761,7 +761,7 @@ print_to_stderr (print_switch_type type, const char * text)
     case SWITCH_TYPE_PASSED:
     case SWITCH_TYPE_ENABLED:
       fputc (' ', stderr);
-      /* Drop through.  */
+      gcc_fallthrough ();
 
     case SWITCH_TYPE_DESCRIPTIVE:
       fputs (text, stderr);
diff --git gcc/gcc/tree-cfg.c gcc/gcc/tree-cfg.c
index 0728020..4036223 100644
--- gcc/gcc/tree-cfg.c
+++ gcc/gcc/tree-cfg.c
@@ -5412,7 +5412,7 @@ gimple_verify_flow_info (void)
 	case GIMPLE_CALL:
 	  if (!gimple_call_builtin_p (stmt, BUILT_IN_RETURN))
 	    break;
-	  /* ... fallthru ... */
+	  /* fallthru */
 	case GIMPLE_RETURN:
 	  if (!single_succ_p (bb)
 	      || (single_succ_edge (bb)->flags
diff --git gcc/gcc/tree-chrec.c gcc/gcc/tree-chrec.c
index ee789a2..4507bf6 100644
--- gcc/gcc/tree-chrec.c
+++ gcc/gcc/tree-chrec.c
@@ -287,6 +287,7 @@ chrec_fold_plus_1 (enum tree_code code, tree type,
 	CASE_CONVERT:
 	  if (tree_contains_chrecs (op1, NULL))
 	    return chrec_dont_know;
+	  gcc_fallthrough ();
 
 	default:
 	  if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
@@ -304,6 +305,7 @@ chrec_fold_plus_1 (enum tree_code code, tree type,
     CASE_CONVERT:
       if (tree_contains_chrecs (op0, NULL))
 	return chrec_dont_know;
+      gcc_fallthrough ();
 
     default:
       switch (TREE_CODE (op1))
@@ -423,6 +425,7 @@ chrec_fold_multiply (tree type,
 	CASE_CONVERT:
 	  if (tree_contains_chrecs (op1, NULL))
 	    return chrec_dont_know;
+	  gcc_fallthrough ();
 
 	default:
 	  if (integer_onep (op1))
@@ -439,6 +442,7 @@ chrec_fold_multiply (tree type,
     CASE_CONVERT:
       if (tree_contains_chrecs (op0, NULL))
 	return chrec_dont_know;
+      gcc_fallthrough ();
 
     default:
       if (integer_onep (op0))
@@ -461,6 +465,7 @@ chrec_fold_multiply (tree type,
 	CASE_CONVERT:
 	  if (tree_contains_chrecs (op1, NULL))
 	    return chrec_dont_know;
+	  gcc_fallthrough ();
 
 	default:
 	  if (integer_onep (op1))
@@ -1026,6 +1031,7 @@ evolution_function_is_invariant_rec_p (tree chrec, int loopnum)
       if (!evolution_function_is_invariant_rec_p (TREE_OPERAND (chrec, 1),
 						  loopnum))
 	return false;
+      gcc_fallthrough ();
 
     case 1:
       if (!evolution_function_is_invariant_rec_p (TREE_OPERAND (chrec, 0),
@@ -1527,12 +1533,15 @@ for_each_scev_op (tree *scev, bool (*cbck) (tree *, void *), void *data)
     {
     case 3:
       for_each_scev_op (&TREE_OPERAND (*scev, 2), cbck, data);
+      gcc_fallthrough ();
 
     case 2:
       for_each_scev_op (&TREE_OPERAND (*scev, 1), cbck, data);
+      gcc_fallthrough ();
 
     case 1:
       for_each_scev_op (&TREE_OPERAND (*scev, 0), cbck, data);
+      gcc_fallthrough ();
 
     default:
       cbck (scev, data);
diff --git gcc/gcc/tree-complex.c gcc/gcc/tree-complex.c
index d7baf22..9cb8986 100644
--- gcc/gcc/tree-complex.c
+++ gcc/gcc/tree-complex.c
@@ -1336,6 +1336,8 @@ expand_complex_division (gimple_stmt_iterator *gsi, tree inner_type,
       rr = gimplify_build2 (gsi, code, inner_type, ai, bi);
       ri = gimplify_build2 (gsi, code, inner_type, ar, bi);
       ri = gimplify_build1 (gsi, NEGATE_EXPR, inner_type, ri);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
 
     case PAIR (ONLY_REAL, VARYING):
     case PAIR (ONLY_IMAG, VARYING):
diff --git gcc/gcc/tree-data-ref.c gcc/gcc/tree-data-ref.c
index 081ee603..8b86f87 100644
--- gcc/gcc/tree-data-ref.c
+++ gcc/gcc/tree-data-ref.c
@@ -1685,6 +1685,7 @@ siv_subscript_p (const_tree chrec_a, const_tree chrec_b)
 	    case POLYNOMIAL_CHREC:
 	      if (CHREC_VARIABLE (chrec_a) != CHREC_VARIABLE (chrec_b))
 		return false;
+	      gcc_fallthrough ();
 
 	    default:
 	      return true;
@@ -3889,7 +3890,9 @@ get_references_in_stmt (gimple *stmt, vec<data_ref_loc, va_heap> *references)
 	  case IFN_MASK_LOAD:
 	    if (gimple_call_lhs (stmt) == NULL_TREE)
 	      break;
+	    /* XXX Really fallthru?  */
 	    ref.is_read = true;
+	    gcc_fallthrough ();
 	  case IFN_MASK_STORE:
 	    ptr = build_int_cst (TREE_TYPE (gimple_call_arg (stmt, 1)), 0);
 	    align = tree_to_shwi (gimple_call_arg (stmt, 1));
diff --git gcc/gcc/tree-pretty-print.c gcc/gcc/tree-pretty-print.c
index 734ecda..74cd9da 100644
--- gcc/gcc/tree-pretty-print.c
+++ gcc/gcc/tree-pretty-print.c
@@ -743,6 +743,7 @@ dump_omp_clause (pretty_printer *pp, tree clause, int spc, int flags)
       pp_colon (pp);
       dump_generic_node (pp, OMP_CLAUSE_DECL (clause),
 			 spc, flags, false);
+      gcc_fallthrough ();
      print_clause_size:
       if (OMP_CLAUSE_SIZE (clause))
 	{
@@ -2946,6 +2947,8 @@ dump_generic_node (pretty_printer *pp, tree node, int spc, int flags,
 
     dump_omp_loop:
       dump_omp_clauses (pp, OMP_FOR_CLAUSES (node), spc, flags);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
 
     dump_omp_loop_cilk_for:
       if (!(flags & TDF_SLIM))
diff --git gcc/gcc/tree-ssa-loop-ivopts.c gcc/gcc/tree-ssa-loop-ivopts.c
index 62ba71b..1f9eb8a 100644
--- gcc/gcc/tree-ssa-loop-ivopts.c
+++ gcc/gcc/tree-ssa-loop-ivopts.c
@@ -1885,8 +1885,8 @@ find_deriving_biv_for_expr (struct ivopts_data *data, tree expr)
       iv = find_deriving_biv_for_expr (data, e2);
       if (iv)
 	return iv;
+      gcc_fallthrough ();
 
-      /* Fallthru.  */
     CASE_CONVERT:
       /* Casts are simple.  */
       return find_deriving_biv_for_expr (data, e1);
diff --git gcc/gcc/tree-vect-patterns.c gcc/gcc/tree-vect-patterns.c
index 2457844..a95e8d9 100644
--- gcc/gcc/tree-vect-patterns.c
+++ gcc/gcc/tree-vect-patterns.c
@@ -3358,6 +3358,7 @@ adjust_bool_pattern (tree var, tree out_type,
     case BIT_XOR_EXPR:
       irhs1 = *defs.get (rhs1);
       irhs2 = *defs.get (rhs2);
+      gcc_fallthrough ();
     and_ior_xor:
       if (TYPE_PRECISION (TREE_TYPE (irhs1))
 	  != TYPE_PRECISION (TREE_TYPE (irhs2)))
diff --git gcc/gcc/tree-chrec.c gcc/gcc/tree-chrec.c
index 707a3aa..09ba618 100644
--- gcc/gcc/tree-chrec.c
+++ gcc/gcc/tree-chrec.c
@@ -329,6 +329,7 @@ chrec_fold_plus_1 (enum tree_code code, tree type,
 	CASE_CONVERT:
 	  if (tree_contains_chrecs (op1, NULL))
 	    return chrec_dont_know;
+	  gcc_fallthrough ();
 
 	default:
 	  {
diff --git gcc/gcc/tree-eh.c gcc/gcc/tree-eh.c
index db72156..3cc7899 100644
--- gcc/gcc/tree-eh.c
+++ gcc/gcc/tree-eh.c
@@ -2011,6 +2011,7 @@ lower_eh_constructs_2 (struct leh_state *state, gimple_stmt_iterator *gsi)
 		 is accessible to abuse by users.  Just remove it and
 		 replace the use with the arbitrary value zero.  */
 	      rhs = build_int_cst (TREE_TYPE (TREE_TYPE (fndecl)), 0);
+	      gcc_fallthrough ();
 	    do_replace:
 	      lhs = gimple_call_lhs (stmt);
 	      x = gimple_build_assign (lhs, rhs);
diff --git gcc/gcc/tree.c gcc/gcc/tree.c
index 661d385..72c8696 100644
--- gcc/gcc/tree.c
+++ gcc/gcc/tree.c
@@ -3727,7 +3727,7 @@ find_placeholder_in_expr (tree exp, vec<tree> *refs)
 	    break;
 	  }
 
-        /* Fall through...  */
+        /* Fall through.  */
 
       case tcc_exceptional:
       case tcc_unary:
@@ -3816,7 +3816,7 @@ substitute_in_expr (tree exp, tree f, tree r)
 	if (exp == f)
 	  return r;
 
-        /* Fall through...  */
+        /* Fall through.  */
 
       case tcc_exceptional:
       case tcc_unary:
@@ -7027,7 +7027,7 @@ type_cache_hasher::equal (type_hash *a, type_hash *b)
 				   TYPE_VALUES (b->type))))
 	return 0;
 
-      /* ... fall through ... */
+      /* fall through */
 
     case INTEGER_TYPE:
     case REAL_TYPE:
@@ -11564,7 +11564,7 @@ walk_type_fields (tree type, walk_tree_fn func, void *data,
 	  break;
 	}
 
-      /* ... fall through ... */
+      /* fall through */
 
     case COMPLEX_TYPE:
       WALK_SUBTREE (TREE_TYPE (type));
diff --git gcc/gcc/var-tracking.c gcc/gcc/var-tracking.c
index 5d09879..d01af62 100644
--- gcc/gcc/var-tracking.c
+++ gcc/gcc/var-tracking.c
@@ -1056,6 +1056,8 @@ adjust_mems (rtx loc, const_rtx old_rtx, void *data)
 					 ? GET_MODE_SIZE (amd->mem_mode)
 					 : -GET_MODE_SIZE (amd->mem_mode),
 					 GET_MODE (loc)));
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case POST_INC:
     case POST_DEC:
       if (addr == loc)
@@ -1076,6 +1078,8 @@ adjust_mems (rtx loc, const_rtx old_rtx, void *data)
       return addr;
     case PRE_MODIFY:
       addr = XEXP (loc, 1);
+      /* XXX Really fallthru?  */
+      gcc_fallthrough ();
     case POST_MODIFY:
       if (addr == loc)
 	addr = XEXP (loc, 0);
@@ -1112,6 +1116,7 @@ adjust_mems (rtx loc, const_rtx old_rtx, void *data)
 				 SUBREG_BYTE (loc));
       if (tem == NULL_RTX)
 	tem = gen_rtx_raw_SUBREG (GET_MODE (loc), addr, SUBREG_BYTE (loc));
+      gcc_fallthrough ();
     finish_subreg:
       if (MAY_HAVE_DEBUG_INSNS
 	  && GET_CODE (tem) == SUBREG
@@ -3148,7 +3153,7 @@ set_dv_changed (decl_or_value dv, bool newv)
     case ONEPART_DEXPR:
       if (newv)
 	NO_LOC_P (DECL_RTL_KNOWN_SET (dv_as_decl (dv))) = false;
-      /* Fall through...  */
+      /* Fall through.  */
 
     default:
       DECL_CHANGED (dv_as_decl (dv)) = newv;
diff --git gcc/gcc/varasm.c gcc/gcc/varasm.c
index 4ef6115..f656d81 100644
--- gcc/gcc/varasm.c
+++ gcc/gcc/varasm.c
@@ -589,6 +589,7 @@ default_function_section (tree decl, enum node_frequency freq,
            these ELF section.  */
         if (!in_lto_p || !flag_profile_values)
           return get_named_text_section (decl, ".text.hot", NULL);
+	gcc_fallthrough ();
       default:
 	return NULL;
     }
@@ -3568,6 +3569,7 @@ const_rtx_hash_1 (const_rtx x)
     {
     case CONST_INT:
       hwi = INTVAL (x);
+      gcc_fallthrough ();
 
     fold_hwi:
       {
@@ -4172,7 +4174,7 @@ output_addressed_constants (tree exp)
     case POINTER_PLUS_EXPR:
     case MINUS_EXPR:
       output_addressed_constants (TREE_OPERAND (exp, 1));
-      /* Fall through.  */
+      gcc_fallthrough ();
 
     CASE_CONVERT:
     case VIEW_CONVERT_EXPR:
diff --git gcc/include/libiberty.h gcc/include/libiberty.h
index a9c885f..89a9e6d 100644
--- gcc/include/libiberty.h
+++ gcc/include/libiberty.h
@@ -735,5 +735,10 @@ extern unsigned long libiberty_len;
 }
 #endif
 
+#if GCC_VERSION >= 7000
+# define D_FALLTHRU() __attribute__((fallthrough))
+#else
+# define D_FALLTHRU()
+#endif
 
 #endif /* ! defined (LIBIBERTY_H) */
diff --git gcc/libcpp/internal.h gcc/libcpp/internal.h
index ca2b498..de9cc25 100644
--- gcc/libcpp/internal.h
+++ gcc/libcpp/internal.h
@@ -78,6 +78,12 @@ struct cset_converter
    efficiency, and partly to limit runaway recursion.  */
 #define CPP_STACK_MAX 200
 
+#if __GNUC__ >= 7
+# define CPP_FALLTHRU __attribute__((fallthrough))
+#else
+# define CPP_FALLTHRU
+#endif
+
 /* Host alignment handling.  */
 struct dummy
 {
diff --git gcc/libcpp/lex.c gcc/libcpp/lex.c
index 236418d..e5184df 100644
--- gcc/libcpp/lex.c
+++ gcc/libcpp/lex.c
@@ -610,6 +610,7 @@ search_line_fast (const uchar *s, const uchar *end ATTRIBUTE_UNUSED)
 	if (l != 0)
 	  break;
 	s += sizeof(unsigned long);
+	CPP_FALLTHRU;
       case 2:
 	l = u.l[i++];
 	if (l != 0)
@@ -1574,6 +1575,7 @@ lex_raw_string (cpp_reader *pfile, cpp_token *token, const uchar *base,
 	      BUF_APPEND (base, cur - base);
 	      base = cur;
 	      BUF_APPEND ("\\", 1);
+	      CPP_FALLTHRU;
 	    after_backslash:
 	      if (note->type == ' ')
 		{
@@ -2717,6 +2817,8 @@ _cpp_lex_direct (cpp_reader *pfile)
 	  }
 	buffer->cur++;
       }
+      /* XXX Really fallthru?  */
+      CPP_FALLTHRU;
 
     default:
       create_literal (pfile, result, buffer->cur - 1, 1, CPP_OTHER);
@@ -3322,7 +3424,7 @@ cpp_token_val_index (const cpp_token *tok)
 	return CPP_TOKEN_FLD_SOURCE;
       else if (tok->type == CPP_PRAGMA)
 	return CPP_TOKEN_FLD_PRAGMA;
-      /* else fall through */
+      /* fall through */
     default:
       return CPP_TOKEN_FLD_NONE;
     }
diff --git gcc/libcpp/macro.c gcc/libcpp/macro.c
index a3b8348..d71e2cd 100644
--- gcc/libcpp/macro.c
+++ gcc/libcpp/macro.c
@@ -2886,6 +2886,7 @@ parse_params (cpp_reader *pfile, cpp_macro *macro)
 	    return true;
 
 	  /* Fall through to pick up the error.  */
+	  CPP_FALLTHRU;
 	case CPP_COMMA:
 	  if (!prev_ident)
 	    {
diff --git gcc/libcpp/pch.c gcc/libcpp/pch.c
index aa5ed6b..09f36d9 100644
--- gcc/libcpp/pch.c
+++ gcc/libcpp/pch.c
@@ -55,6 +55,8 @@ write_macdef (cpp_reader *pfile, cpp_hashnode *hn, void *file_p)
     case NT_VOID:
       if (! (hn->flags & NODE_POISONED))
 	return 1;
+      /* XXX Really fallthru?  */
+      CPP_FALLTHRU;
 
     case NT_MACRO:
       if ((hn->flags & NODE_BUILTIN)
@@ -230,7 +232,7 @@ count_defs (cpp_reader *pfile ATTRIBUTE_UNUSED, cpp_hashnode *hn, void *ss_p)
       if (hn->flags & NODE_BUILTIN)
 	return 1;
 
-      /* else fall through.  */
+      /* fall through.  */
 
     case NT_VOID:
       {
@@ -269,7 +271,7 @@ write_defs (cpp_reader *pfile ATTRIBUTE_UNUSED, cpp_hashnode *hn, void *ss_p)
       if (hn->flags & NODE_BUILTIN)
 	return 1;
 
-      /* else fall through.  */
+      /* fall through.  */
 
     case NT_VOID:
       {
diff --git gcc/libgcc/soft-fp/op-common.h gcc/libgcc/soft-fp/op-common.h
index 080ef0e..d3cb206 100644
--- gcc/libgcc/soft-fp/op-common.h
+++ gcc/libgcc/soft-fp/op-common.h
@@ -898,6 +898,7 @@
 	case _FP_CLS_COMBINE (FP_CLS_NAN, FP_CLS_INF):		\
 	case _FP_CLS_COMBINE (FP_CLS_NAN, FP_CLS_ZERO):		\
 	  R##_s = X##_s;					\
+	  _FP_FALLTHRU;						\
 								\
 	case _FP_CLS_COMBINE (FP_CLS_INF, FP_CLS_INF):		\
 	case _FP_CLS_COMBINE (FP_CLS_INF, FP_CLS_NORMAL):	\
@@ -911,6 +912,7 @@
 	case _FP_CLS_COMBINE (FP_CLS_INF, FP_CLS_NAN):		\
 	case _FP_CLS_COMBINE (FP_CLS_ZERO, FP_CLS_NAN):		\
 	  R##_s = Y##_s;					\
+	  _FP_FALLTHRU;						\
 								\
 	case _FP_CLS_COMBINE (FP_CLS_NORMAL, FP_CLS_INF):	\
 	case _FP_CLS_COMBINE (FP_CLS_NORMAL, FP_CLS_ZERO):	\
@@ -1198,6 +1200,7 @@
 								\
 	case _FP_CLS_COMBINE (FP_CLS_NORMAL, FP_CLS_ZERO):	\
 	  FP_SET_EXCEPTION (FP_EX_DIVZERO);			\
+	  _FP_FALLTHRU;						\
 	case _FP_CLS_COMBINE (FP_CLS_INF, FP_CLS_ZERO):		\
 	case _FP_CLS_COMBINE (FP_CLS_INF, FP_CLS_NORMAL):	\
 	  R##_c = FP_CLS_INF;					\
diff --git gcc/libgcc/soft-fp/soft-fp.h gcc/libgcc/soft-fp/soft-fp.h
index 3b39336..ee03fa2 100644
--- gcc/libgcc/soft-fp/soft-fp.h
+++ gcc/libgcc/soft-fp/soft-fp.h
@@ -71,6 +71,12 @@
     [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
 #endif
 
+#if (defined __GNUC__ && __GNUC__ >= 7)
+# define _FP_FALLTHRU __attribute__((fallthrough)) 
+#else
+# define _FP_FALLTHRU
+#endif
+
 /* In the Linux kernel, some architectures have a single function that
    uses different kinds of unpacking and packing depending on the
    instruction being emulated, meaning it is not readily visible to
diff --git gcc/libgo/runtime/heapdump.c gcc/libgo/runtime/heapdump.c
index d0cfb01..1ce8aa2 100644
--- gcc/libgo/runtime/heapdump.c
+++ gcc/libgo/runtime/heapdump.c
@@ -766,6 +766,7 @@ dumpefacetypes(void *obj __attribute__ ((unused)), uintptr size, const Type *typ
 		for(i = 0; i <= size - type->__size; i += type->__size)
 			//playgcprog(i, (uintptr*)type->gc + 1, dumpeface_callback, obj);
 		break;
+		break;
 	case TypeInfo_Chan:
 		if(type->__size == 0) // channels may have zero-sized objects in them
 			break;
diff --git gcc/libiberty/cp-demangle.c gcc/libiberty/cp-demangle.c
index 0c6d714..9ad787a 100644
--- gcc/libiberty/cp-demangle.c
+++ gcc/libiberty/cp-demangle.c
@@ -5777,11 +5777,13 @@ d_print_mod (struct d_print_info *dpi, int options,
     case DEMANGLE_COMPONENT_REFERENCE_THIS:
       /* For the ref-qualifier, put a space before the &.  */
       d_append_char (dpi, ' ');
+      D_FALLTHRU ();
     case DEMANGLE_COMPONENT_REFERENCE:
       d_append_char (dpi, '&');
       return;
     case DEMANGLE_COMPONENT_RVALUE_REFERENCE_THIS:
       d_append_char (dpi, ' ');
+      D_FALLTHRU ();
     case DEMANGLE_COMPONENT_RVALUE_REFERENCE:
       d_append_string (dpi, "&&");
       return;
diff --git gcc/libstdc++-v3/libsupc++/hash_bytes.cc gcc/libstdc++-v3/libsupc++/hash_bytes.cc
index 2e5bbfa..1042de6 100644
--- gcc/libstdc++-v3/libsupc++/hash_bytes.cc
+++ gcc/libstdc++-v3/libsupc++/hash_bytes.cc
@@ -95,8 +95,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
       case 3:
 	hash ^= static_cast<unsigned char>(buf[2]) << 16;
+	[[gnu::fallthrough]];
       case 2:
 	hash ^= static_cast<unsigned char>(buf[1]) << 8;
+	[[gnu::fallthrough]];
       case 1:
 	hash ^= static_cast<unsigned char>(buf[0]);
 	hash *= m;

	Marek


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]