[PATCH] Move the -Wnonnull compare against NULL warning from FEs to early uninit under -Wnonnull-compare (PR c/69835)
Jakub Jelinek
jakub@redhat.com
Tue Feb 16 18:22:00 GMT 2016
On Tue, Feb 16, 2016 at 11:12:27AM -0700, Jeff Law wrote:
> >Not sure if it matters but wouldn't walking over function parameters
> >and their default def SSA names immediate uses be cheaper than
> >matching all conditions? Esp. as nonnull_arg_p walks over all
> >DECL_ARGUMENTS (up to the searched index) over and over again?
> >[we should simply set a flag on the PARM_DECL!]
> Seems like a waste to burn a flag bit for something like this.
>
> We're already walking all the statements in this code so it's really just
> the cost of testing if the existing statement is "interesting" for this
> warning. I guess you're suggesting jakub walk the arguments and if one is a
> marked as non-null, then walk the immediate uses. Yea, that's probably
> faster than doing the test for every statement.
I'm already bootstrapping/regtesting following variant.
> Swapping the nonnull_arg_p and the test for whether or not op1 is 0 would be
> a slight help as well, particularly if there was machine generated code with
> oodles of arguments.
>
> I'm not sure why we're testing OFFSET_TYPE against -1.
That is because NULL pointers to member are represented as -1 in the middle
end.
2016-02-16 Jakub Jelinek <jakub@redhat.com>
PR c/69835
* common.opt (Wnonnull-compare): New warning.
* doc/invoke.texi (-Wnonnull): Remove text about comparison
of arguments against NULL.
(-Wnonnull-compare): Document.
* Makefile.in (OBJS): Add gimple-ssa-nonnull-compare.o.
* tree-pass.h (make_pass_warn_nonnull_compare): Declare.
* passes.def (pass_warn_nonnull_compare): Add.
* gimple-ssa-nonnull-compare.c: New file.
c-family/
* c.opt (Wnonnull-compare): Enable for -Wall.
c/
* c-typeck.c (build_binary_op): Revert 2015-09-09 change.
cp/
* typeck.c (cp_build_binary_op): Revert 2015-09-09 change.
testsuite/
* c-c++-common/nonnull-1.c: Use -Wnonnull-compare instead of
-Wnonnull in dg-options.
* c-c++-common/nonnull-2.c: New test.
--- gcc/common.opt.jj 2016-02-16 16:14:40.787071893 +0100
+++ gcc/common.opt 2016-02-16 17:34:12.850648209 +0100
@@ -616,6 +616,10 @@ Wlarger-than=
Common RejectNegative Joined UInteger Warning
-Wlarger-than=<number> Warn if an object is larger than <number> bytes.
+Wnonnull-compare
+Var(warn_nonnull_compare) Warning
+Warn if comparing pointer parameter with nonnull attribute with NULL.
+
Wnull-dereference
Common Var(warn_null_dereference) Warning
Warn if dereferencing a NULL pointer may lead to erroneous or undefined behavior.
--- gcc/doc/invoke.texi.jj 2016-02-16 16:14:41.692059415 +0100
+++ gcc/doc/invoke.texi 2016-02-16 17:26:55.346587296 +0100
@@ -276,7 +276,8 @@ Objective-C and Objective-C++ Dialects}.
-Wmain -Wmaybe-uninitialized -Wmemset-transposed-args @gol
-Wmisleading-indentation -Wmissing-braces @gol
-Wmissing-field-initializers -Wmissing-include-dirs @gol
--Wno-multichar -Wnonnull -Wnormalized=@r{[}none@r{|}id@r{|}nfc@r{|}nfkc@r{]} @gol
+-Wno-multichar -Wnonnull -Wnonnull-compare @gol
+-Wnormalized=@r{[}none@r{|}id@r{|}nfc@r{|}nfkc@r{]} @gol
-Wnull-dereference -Wodr -Wno-overflow -Wopenmp-simd @gol
-Woverride-init-side-effects -Woverlength-strings @gol
-Wpacked -Wpacked-bitfield-compat -Wpadded @gol
@@ -3537,6 +3538,7 @@ Options} and @ref{Objective-C and Object
-Wmissing-braces @r{(only for C/ObjC)} @gol
-Wnarrowing @r{(only for C++)} @gol
-Wnonnull @gol
+-Wnonnull-compare @gol
-Wopenmp-simd @gol
-Wparentheses @gol
-Wpointer-sign @gol
@@ -3795,12 +3797,18 @@ formats that may yield only a two-digit
Warn about passing a null pointer for arguments marked as
requiring a non-null value by the @code{nonnull} function attribute.
-Also warns when comparing an argument marked with the @code{nonnull}
-function attribute against null inside the function.
-
@option{-Wnonnull} is included in @option{-Wall} and @option{-Wformat}. It
can be disabled with the @option{-Wno-nonnull} option.
+@item -Wnonnull-compare
+@opindex Wnonnull-compare
+@opindex Wno-nonnull-compare
+Warn when comparing an argument marked with the @code{nonnull}
+function attribute against null inside the function.
+
+@option{-Wnonnull-compare} is included in @option{-Wall}. It
+can be disabled with the @option{-Wno-nonnull-compare} option.
+
@item -Wnull-dereference
@opindex Wnull-dereference
@opindex Wno-null-dereference
--- gcc/Makefile.in.jj 2016-02-11 20:28:54.000000000 +0100
+++ gcc/Makefile.in 2016-02-16 17:32:26.919086223 +0100
@@ -1278,6 +1278,7 @@ OBJS = \
gimple-pretty-print.o \
gimple-ssa-backprop.o \
gimple-ssa-isolate-paths.o \
+ gimple-ssa-nonnull-compare.o \
gimple-ssa-split-paths.o \
gimple-ssa-strength-reduction.o \
gimple-streamer-in.o \
--- gcc/tree-pass.h.jj 2016-01-19 13:31:07.000000000 +0100
+++ gcc/tree-pass.h 2016-02-16 17:28:39.155178102 +0100
@@ -472,6 +472,7 @@ extern gimple_opt_pass *make_pass_oacc_k
extern simple_ipa_opt_pass *make_pass_ipa_oacc (gcc::context *ctxt);
extern simple_ipa_opt_pass *make_pass_ipa_oacc_kernels (gcc::context *ctxt);
extern gimple_opt_pass *make_pass_gen_hsail (gcc::context *ctxt);
+extern gimple_opt_pass *make_pass_warn_nonnull_compare (gcc::context *ctxt);
/* IPA Passes */
extern simple_ipa_opt_pass *make_pass_ipa_lower_emutls (gcc::context *ctxt);
--- gcc/passes.def.jj 2016-02-10 16:01:57.000000000 +0100
+++ gcc/passes.def 2016-02-16 17:27:46.515892676 +0100
@@ -56,6 +56,7 @@ along with GCC; see the file COPYING3.
NEXT_PASS (pass_fixup_cfg);
NEXT_PASS (pass_init_datastructures);
NEXT_PASS (pass_build_ssa);
+ NEXT_PASS (pass_warn_nonnull_compare);
NEXT_PASS (pass_ubsan);
NEXT_PASS (pass_early_warn_uninitialized);
NEXT_PASS (pass_nothrow);
--- gcc/gimple-ssa-nonnull-compare.c.jj 2016-02-16 16:58:10.676272364 +0100
+++ gcc/gimple-ssa-nonnull-compare.c 2016-02-16 17:46:19.788692474 +0100
@@ -0,0 +1,150 @@
+/* -Wnonnull-compare warning support.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "backend.h"
+#include "tree.h"
+#include "gimple.h"
+#include "tree-pass.h"
+#include "ssa.h"
+#include "diagnostic-core.h"
+#include "tree-dfa.h"
+
+/* Warn about comparison of nonnull_arg_p argument initial values
+ with NULL. */
+
+static void
+do_warn_nonnull_compare (function *fun, tree arg)
+{
+ if (!POINTER_TYPE_P (TREE_TYPE (arg))
+ && TREE_CODE (TREE_TYPE (arg)) != OFFSET_TYPE)
+ return;
+
+ if (!nonnull_arg_p (arg))
+ return;
+
+ tree d = ssa_default_def (fun, arg);
+ if (d == NULL_TREE)
+ return;
+
+ use_operand_p use_p;
+ imm_use_iterator iter;
+
+ FOR_EACH_IMM_USE_FAST (use_p, iter, d)
+ {
+ gimple *stmt = USE_STMT (use_p);
+ tree op = NULL_TREE;
+ location_t loc = gimple_location (stmt);
+ if (gimple_code (stmt) == GIMPLE_COND)
+ switch (gimple_cond_code (stmt))
+ {
+ case EQ_EXPR:
+ case NE_EXPR:
+ if (gimple_cond_lhs (stmt) == d)
+ op = gimple_cond_rhs (stmt);
+ break;
+ default:
+ break;
+ }
+ else if (is_gimple_assign (stmt))
+ switch (gimple_assign_rhs_code (stmt))
+ {
+ case EQ_EXPR:
+ case NE_EXPR:
+ if (gimple_assign_rhs1 (stmt) == d)
+ op = gimple_assign_rhs2 (stmt);
+ break;
+ case COND_EXPR:
+ switch (TREE_CODE (gimple_assign_rhs1 (stmt)))
+ {
+ case EQ_EXPR:
+ case NE_EXPR:
+ op = gimple_assign_rhs1 (stmt);
+ if (TREE_OPERAND (op, 0) != d)
+ {
+ op = NULL_TREE;
+ break;
+ }
+ loc = EXPR_LOC_OR_LOC (op, loc);
+ op = TREE_OPERAND (op, 1);
+ break;
+ default:
+ break;
+ }
+ break;
+ default:
+ break;
+ }
+ if (op
+ && (POINTER_TYPE_P (TREE_TYPE (arg))
+ ? integer_zerop (op) : integer_minus_onep (op)))
+ warning_at (loc, OPT_Wnonnull_compare,
+ "nonnull argument %qD compared to NULL", arg);
+ }
+}
+
+namespace {
+
+const pass_data pass_data_warn_nonnull_compare =
+{
+ GIMPLE_PASS, /* type */
+ "*nonnullcmp", /* name */
+ OPTGROUP_NONE, /* optinfo_flags */
+ TV_NONE, /* tv_id */
+ PROP_ssa, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ 0, /* todo_flags_finish */
+};
+
+class pass_warn_nonnull_compare : public gimple_opt_pass
+{
+public:
+ pass_warn_nonnull_compare (gcc::context *ctxt)
+ : gimple_opt_pass (pass_data_warn_nonnull_compare, ctxt)
+ {}
+
+ /* opt_pass methods: */
+ virtual bool gate (function *) { return warn_nonnull_compare; }
+
+ virtual unsigned int execute (function *);
+
+}; // class pass_warn_nonnull_compare
+
+unsigned int
+pass_warn_nonnull_compare::execute (function *fun)
+{
+ if (fun->static_chain_decl)
+ do_warn_nonnull_compare (fun, fun->static_chain_decl);
+
+ for (tree arg = DECL_ARGUMENTS (cfun->decl); arg; arg = DECL_CHAIN (arg))
+ do_warn_nonnull_compare (fun, arg);
+ return 0;
+}
+
+} // anon namespace
+
+gimple_opt_pass *
+make_pass_warn_nonnull_compare (gcc::context *ctxt)
+{
+ return new pass_warn_nonnull_compare (ctxt);
+}
--- gcc/c-family/c.opt.jj 2016-02-16 16:14:40.895070404 +0100
+++ gcc/c-family/c.opt 2016-02-16 17:26:55.347587282 +0100
@@ -677,6 +677,10 @@ Wnonnull
C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall)
;
+Wnonnull-compare
+C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall)
+;
+
Wnormalized
C ObjC C++ ObjC++ Warning Alias(Wnormalized=,nfc,none)
;
--- gcc/c/c-typeck.c.jj 2016-02-16 16:14:40.636073975 +0100
+++ gcc/c/c-typeck.c 2016-02-16 17:26:55.350587242 +0100
@@ -11086,11 +11086,6 @@ build_binary_op (location_t location, en
short_compare = 1;
else if (code0 == POINTER_TYPE && null_pointer_constant_p (orig_op1))
{
- if (warn_nonnull
- && TREE_CODE (op0) == PARM_DECL && nonnull_arg_p (op0))
- warning_at (location, OPT_Wnonnull,
- "nonnull argument %qD compared to NULL", op0);
-
if (TREE_CODE (op0) == ADDR_EXPR
&& decl_with_nonnull_addr_p (TREE_OPERAND (op0, 0)))
{
@@ -11111,11 +11106,6 @@ build_binary_op (location_t location, en
}
else if (code1 == POINTER_TYPE && null_pointer_constant_p (orig_op0))
{
- if (warn_nonnull
- && TREE_CODE (op1) == PARM_DECL && nonnull_arg_p (op1))
- warning_at (location, OPT_Wnonnull,
- "nonnull argument %qD compared to NULL", op1);
-
if (TREE_CODE (op1) == ADDR_EXPR
&& decl_with_nonnull_addr_p (TREE_OPERAND (op1, 0)))
{
--- gcc/cp/typeck.c.jj 2016-02-16 16:14:40.657073685 +0100
+++ gcc/cp/typeck.c 2016-02-16 17:26:55.352587215 +0100
@@ -4514,11 +4514,6 @@ cp_build_binary_op (location_t location,
|| (code0 == POINTER_TYPE
&& TYPE_PTR_P (type1) && integer_zerop (op1)))
{
- if (warn_nonnull
- && TREE_CODE (op0) == PARM_DECL && nonnull_arg_p (op0))
- warning_at (location, OPT_Wnonnull,
- "nonnull argument %qD compared to NULL", op0);
-
if (TYPE_PTR_P (type1))
result_type = composite_pointer_type (type0, type1, op0, op1,
CPO_COMPARISON, complain);
@@ -4558,11 +4553,6 @@ cp_build_binary_op (location_t location,
|| (code1 == POINTER_TYPE
&& TYPE_PTR_P (type0) && integer_zerop (op0)))
{
- if (warn_nonnull
- && TREE_CODE (op1) == PARM_DECL && nonnull_arg_p (op1))
- warning_at (location, OPT_Wnonnull,
- "nonnull argument %qD compared to NULL", op1);
-
if (TYPE_PTR_P (type0))
result_type = composite_pointer_type (type0, type1, op0, op1,
CPO_COMPARISON, complain);
--- gcc/testsuite/c-c++-common/nonnull-1.c.jj 2016-02-16 16:14:40.310078470 +0100
+++ gcc/testsuite/c-c++-common/nonnull-1.c 2016-02-16 17:26:55.352587215 +0100
@@ -1,7 +1,7 @@
/* Test for the bad usage of "nonnull" function attribute parms. */
/* */
/* { dg-do compile } */
-/* { dg-options "-Wnonnull" } */
+/* { dg-options "-Wnonnull-compare" } */
#include <stddef.h>
#include <stdlib.h>
--- gcc/testsuite/c-c++-common/nonnull-2.c.jj 2016-02-16 17:26:55.353587201 +0100
+++ gcc/testsuite/c-c++-common/nonnull-2.c 2016-02-16 17:26:55.353587201 +0100
@@ -0,0 +1,26 @@
+/* Test for the bad usage of "nonnull" function attribute parms. */
+/* { dg-do compile } */
+/* { dg-options "-Wnonnull-compare" } */
+
+void bar (char **);
+
+__attribute__((nonnull (1, 3))) int
+foo (char *cp1, char *cp2, char *cp3, char *cp4)
+{
+ if (cp1 == (char *) 0) /* { dg-warning "nonnull argument" "cp1 compared to NULL" } */
+ return 1;
+
+ cp1 = cp2;
+ if (cp1 == (char *) 0) /* { dg-bogus "nonnull argument" } */
+ return 2;
+
+ if (!cp4) /* { dg-bogus "nonnull argument" } */
+ return 3;
+
+ char **p = &cp3;
+ bar (p);
+ if (cp3 == (char *) 0) /* { dg-bogus "nonnull argument" } */
+ return 4;
+
+ return 5;
+}
Jakub
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