[PATCH] refactor gimple asm memory clobber checking

[Nathan Froyd]

There are a couple places that check GIMPLE_ASMs for clobbering memory;
this patch centralizes the logic in gimple.c.

Tested on x86_64-unknown-linux-gnu.  OK to commit?

-Nathan

        * gimple.h (gimple_asm_clobbers_memory_p): Declare.
        * gimple.c (gimple_asm_clobbers_memory_p): Define.
        * ipa-pure-const.c (check_stmt): Call it.
        * tree-ssa-operands.c (get_asm_expr_operands): Likewise.

diff --git a/gcc/gimple.c b/gcc/gimple.c
index 090fc94..5dc62ea 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -5142,4 +5142,21 @@ gimple_call_builtin_p (gimple stmt, enum 
built_in_function code)
          && DECL_FUNCTION_CODE (fndecl) == code);
 }
 
+/* Return true if STMT clobbers memory.  STMT is required to be a
+   GIMPLE_ASM.  */
+
+bool
+gimple_asm_clobbers_memory_p (const_gimple stmt)
+{
+  unsigned i;
+
+  for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
+    {
+      tree op = gimple_asm_clobber_op (stmt, i);
+      if (strcmp (TREE_STRING_POINTER (TREE_VALUE (op)), "memory") == 0)
+       return true;
+    }
+
+  return false;
+}
 #include "gt-gimple.h"
diff --git a/gcc/gimple.h b/gcc/gimple.h
index 572cabc..840e149 100644
--- a/gcc/gimple.h
+++ b/gcc/gimple.h
@@ -973,6 +973,7 @@ extern bool walk_stmt_load_store_ops (gimple, void *,
                                      bool (*)(gimple, tree, void *));
 extern bool gimple_ior_addresses_taken (bitmap, gimple);
 extern bool gimple_call_builtin_p (gimple, enum built_in_function);
+extern bool gimple_asm_clobbers_memory_p (const_gimple);
 
 /* In gimplify.c  */
 extern tree create_tmp_var_raw (tree, const char *);
diff --git a/gcc/ipa-pure-const.c b/gcc/ipa-pure-const.c
index b7deb57..eb5b0f6 100644
--- a/gcc/ipa-pure-const.c
+++ b/gcc/ipa-pure-const.c
@@ -639,7 +639,6 @@ static void
 check_stmt (gimple_stmt_iterator *gsip, funct_state local, bool ipa)
 {
   gimple stmt = gsi_stmt (*gsip);
-  unsigned int i = 0;
 
   if (is_gimple_debug (stmt))
     return;
@@ -693,16 +692,12 @@ check_stmt (gimple_stmt_iterator *gsip, funct_state 
local, bool ipa)
        }
       break;
     case GIMPLE_ASM:
-      for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
+      if (gimple_asm_clobbers_memory_p (stmt))
        {
-         tree op = gimple_asm_clobber_op (stmt, i);
-         if (strcmp (TREE_STRING_POINTER (TREE_VALUE (op)), "memory") == 0)
-           {
-              if (dump_file)
-                fprintf (dump_file, "    memory asm clobber is not 
const/pure");
-             /* Abandon all hope, ye who enter here. */
-             local->pure_const_state = IPA_NEITHER;
-           }
+         if (dump_file)
+           fprintf (dump_file, "    memory asm clobber is not const/pure");
+         /* Abandon all hope, ye who enter here. */
+         local->pure_const_state = IPA_NEITHER;
        }
       if (gimple_asm_volatile_p (stmt))
        {
diff --git a/gcc/tree-ssa-operands.c b/gcc/tree-ssa-operands.c
index 57f443f..7f76cbf 100644
--- a/gcc/tree-ssa-operands.c
+++ b/gcc/tree-ssa-operands.c
@@ -832,15 +832,8 @@ get_asm_expr_operands (gimple stmt)
     }
 
   /* Clobber all memory and addressable symbols for asm ("" : : : "memory");  
*/
-  for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
-    {
-      tree link = gimple_asm_clobber_op (stmt, i);
-      if (strcmp (TREE_STRING_POINTER (TREE_VALUE (link)), "memory") == 0)
-       {
-         add_virtual_operand (stmt, opf_def);
-         break;
-       }
-    }
+  if (gimple_asm_clobbers_memory_p (stmt))
+    add_virtual_operand (stmt, opf_def);
 }