Re: RFA: Replace LAST_INSN_CODE with NUM_INSN_CODES

[Richard Sandiford <richard dot sandiford at arm dot com>]

Richard Sandiford <richard.sandiford@arm.com> writes:
> Claudiu reported that I'd botched the definition of LAST_INSN_CODE
> in my recent patches to reduce the size of insn_data.  I'd defined
> it as the last valid insn code, whereas it's supposed to be the
> last valid code +1.
>
> This patch replaces LAST_INSN_CODE with a separate NUM_INSN_CODES
> count, outside the enum.
>
> Tested on x86_64-linux-gnu and aarch64-linux-gnu.  OK to install?

Sorry, I realised later that this patch triggers a warning with older
host compilers about a trailing "," on the last enum value.  This patch
updates the gencodes.c part to fix that.  The other parts are unchanged.

I think the #defines for removed codes are a hold-over from the days
when CODE_FOR_nothing was the final enum value rather than the first,
amd so was only defined later in the file.  These days we can make them
proper enum aliases instead.

Tested on x86_64-linux-gnu and aarch64-linux-gnu.  OK to install?

Thanks,
Richard

gcc/
	* gencodes.c (gencodes): Print the comma for the preceding
	enum value rather than the current one.  Use aliased enum values
	rather than #defines for compiled-out patterns.
	(main): Update accordingly.  Replace LAST_INSN_CODE with
	NUM_INSN_CODES.
	* lra.c (insn_code_data): Update accordingly.
	(finish_insn_code_data_once, get_static_insn_data): Likewise.
	* recog.h (target_recog): Likewise.
	(preprocess_insn_constraints): Change parameter to unsigned int.
	* recog.c (preprocess_insn_constraints): Likewise.
	(recog_init): Replace LAST_INSN_CODE with NUM_INSN_CODES.
	* tree-vect-stmts.c (vectorizable_operation): Simplify.

diff --git a/gcc/gencodes.c b/gcc/gencodes.c
index c747891..d4560b4 100644
--- a/gcc/gencodes.c
+++ b/gcc/gencodes.c
@@ -40,9 +40,9 @@ gen_insn (md_rtx_info *info)
   if (name[0] != 0 && name[0] != '*')
     {
       if (truth == 0)
-	printf ("#define CODE_FOR_%s CODE_FOR_nothing\n", name);
+	printf (",\n   CODE_FOR_%s = CODE_FOR_nothing", name);
       else
-	printf ("  CODE_FOR_%s = %d,\n", name, info->index);
+	printf (",\n  CODE_FOR_%s = %d", name, info->index);
     }
 }
 
@@ -58,7 +58,7 @@ main (int argc, char **argv)
   if (!init_rtx_reader_args (argc, argv))
     return (FATAL_EXIT_CODE);
 
-  puts ("\
+  printf ("\
 /* Generated automatically by the program `gencodes'\n\
    from the machine description file `md'.  */\n\
 \n\
@@ -66,7 +66,7 @@ main (int argc, char **argv)
 #define GCC_INSN_CODES_H\n\
 \n\
 enum insn_code {\n\
-  CODE_FOR_nothing = 0,\n");
+  CODE_FOR_nothing = 0");
 
   /* Read the machine description.  */
 
@@ -83,10 +83,10 @@ enum insn_code {\n\
 	break;
     }
 
-  printf ("  LAST_INSN_CODE = %d\n\
-};\n\
+  printf ("\n};\n\
 \n\
-#endif /* GCC_INSN_CODES_H */\n", get_num_insn_codes () - 1);
+const unsigned int NUM_INSN_CODES = %d;\n\
+#endif /* GCC_INSN_CODES_H */\n", get_num_insn_codes ());
 
   if (ferror (stdout) || fflush (stdout) || fclose (stdout))
     return FATAL_EXIT_CODE;
diff --git a/gcc/lra.c b/gcc/lra.c
index 8ced164..a836cab 100644
--- a/gcc/lra.c
+++ b/gcc/lra.c
@@ -585,7 +585,7 @@ finish_insn_regs (void)
 
 /* Map INSN_CODE -> the static insn data.  This info is valid during
    all translation unit.  */
-struct lra_static_insn_data *insn_code_data[LAST_INSN_CODE];
+struct lra_static_insn_data *insn_code_data[NUM_INSN_CODES];
 
 /* Debug insns are represented as a special insn with one input
    operand which is RTL expression in var_location.  */
@@ -631,9 +631,7 @@ init_insn_code_data_once (void)
 static void
 finish_insn_code_data_once (void)
 {
-  int i;
-
-  for (i = 0; i < LAST_INSN_CODE; i++)
+  for (unsigned int i = 0; i < NUM_INSN_CODES; i++)
     {
       if (insn_code_data[i] != NULL)
 	free (insn_code_data[i]);
@@ -650,7 +648,7 @@ get_static_insn_data (int icode, int nop, int ndup, int nalt)
   struct lra_static_insn_data *data;
   size_t n_bytes;
 
-  lra_assert (icode < LAST_INSN_CODE);
+  lra_assert (icode < (int) NUM_INSN_CODES);
   if (icode >= 0 && (data = insn_code_data[icode]) != NULL)
     return data;
   lra_assert (nop >= 0 && ndup >= 0 && nalt >= 0);
diff --git a/gcc/recog.c b/gcc/recog.c
index 352aec2..c032424 100644
--- a/gcc/recog.c
+++ b/gcc/recog.c
@@ -2441,9 +2441,9 @@ preprocess_constraints (int n_operands, int n_alternatives,
    instruction ICODE.  */
 
 const operand_alternative *
-preprocess_insn_constraints (int icode)
+preprocess_insn_constraints (unsigned int icode)
 {
-  gcc_checking_assert (IN_RANGE (icode, 0, LAST_INSN_CODE));
+  gcc_checking_assert (IN_RANGE (icode, 0, NUM_INSN_CODES - 1));
   if (this_target_recog->x_op_alt[icode])
     return this_target_recog->x_op_alt[icode];
 
@@ -4118,7 +4118,7 @@ recog_init ()
     }
   memset (this_target_recog->x_bool_attr_masks, 0,
 	  sizeof (this_target_recog->x_bool_attr_masks));
-  for (int i = 0; i < LAST_INSN_CODE; ++i)
+  for (unsigned int i = 0; i < NUM_INSN_CODES; ++i)
     if (this_target_recog->x_op_alt[i])
       {
 	free (this_target_recog->x_op_alt[i]);
diff --git a/gcc/recog.h b/gcc/recog.h
index ce931eb..327d6c0 100644
--- a/gcc/recog.h
+++ b/gcc/recog.h
@@ -137,7 +137,7 @@ extern void extract_constrain_insn_cached (rtx_insn *);
 extern void extract_insn_cached (rtx_insn *);
 extern void preprocess_constraints (int, int, const char **,
 				    operand_alternative *);
-extern const operand_alternative *preprocess_insn_constraints (int);
+extern const operand_alternative *preprocess_insn_constraints (unsigned int);
 extern void preprocess_constraints (rtx_insn *);
 extern rtx_insn *peep2_next_insn (int);
 extern int peep2_regno_dead_p (int, int);
@@ -393,8 +393,8 @@ enum bool_attr {
 /* Target-dependent globals.  */
 struct target_recog {
   bool x_initialized;
-  alternative_mask x_bool_attr_masks[LAST_INSN_CODE][BA_LAST + 1];
-  operand_alternative *x_op_alt[LAST_INSN_CODE];
+  alternative_mask x_bool_attr_masks[NUM_INSN_CODES][BA_LAST + 1];
+  operand_alternative *x_op_alt[NUM_INSN_CODES];
 };
 
 extern struct target_recog default_target_recog;
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 2ddd434..f87c066 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -4719,7 +4719,7 @@ vectorizable_operation (gimple stmt, gimple_stmt_iterator *gsi,
   tree new_temp;
   int op_type;
   optab optab;
-  int icode;
+  bool target_support_p;
   tree def;
   gimple def_stmt;
   enum vect_def_type dt[3]
@@ -4870,12 +4870,7 @@ vectorizable_operation (gimple stmt, gimple_stmt_iterator *gsi,
 
   vec_mode = TYPE_MODE (vectype);
   if (code == MULT_HIGHPART_EXPR)
-    {
-      if (can_mult_highpart_p (vec_mode, TYPE_UNSIGNED (vectype)))
-	icode = LAST_INSN_CODE;
-      else
-	icode = CODE_FOR_nothing;
-    }
+    target_support_p = can_mult_highpart_p (vec_mode, TYPE_UNSIGNED (vectype));
   else
     {
       optab = optab_for_tree_code (code, vectype, optab_default);
@@ -4886,10 +4881,11 @@ vectorizable_operation (gimple stmt, gimple_stmt_iterator *gsi,
                              "no optab.\n");
 	  return false;
 	}
-      icode = (int) optab_handler (optab, vec_mode);
+      target_support_p = (optab_handler (optab, vec_mode)
+			  != CODE_FOR_nothing);
     }
 
-  if (icode == CODE_FOR_nothing)
+  if (!target_support_p)
     {
       if (dump_enabled_p ())
 	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,