PR middle-end/38343

	* builtins.c (expand_builtin_mempcpy_args): Handle COMPOUND_EXPRs
	potentially returned from folding memcpy.
	(expand_builtin_stpcpy_args): Similarly for folding strcpy.
	(fold_builtin_2): Handle BUILT_IN_STPCPY if result is ignored.

	* gcc.c-torture/compile/pr38343.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@142348 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 31 insertions, 12 deletions

diff --git a/gcc/builtins.c b/gcc/builtins.c
index a6ee5a96729..34066675873 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -3406,7 +3406,7 @@ expand_builtin_memcpy (tree exp, rtx target, enum machine_mode mode)
    stpcpy.  */
 
 static rtx
-expand_builtin_mempcpy(tree exp, rtx target, enum machine_mode mode)
+expand_builtin_mempcpy (tree exp, rtx target, enum machine_mode mode)
 {
   if (!validate_arglist (exp,
  			 POINTER_TYPE, POINTER_TYPE, INTEGER_TYPE, VOID_TYPE))
@@ -3433,15 +3433,18 @@ expand_builtin_mempcpy_args (tree dest, tree src, tree len, tree type,
 			     rtx target, enum machine_mode mode, int endp)
 {
     /* If return value is ignored, transform mempcpy into memcpy.  */
-  if (target == const0_rtx)
+  if (target == const0_rtx && implicit_built_in_decls[BUILT_IN_MEMCPY])
     {
       tree fn = implicit_built_in_decls[BUILT_IN_MEMCPY];
+      tree result = build_call_expr (fn, 3, dest, src, len);
 
-      if (!fn)
-	return NULL_RTX;
-
-      return expand_expr (build_call_expr (fn, 3, dest, src, len),
-			  target, mode, EXPAND_NORMAL);
+      while (TREE_CODE (result) == COMPOUND_EXPR)
+	{
+	  expand_expr (TREE_OPERAND (result, 0), const0_rtx, VOIDmode,
+		       EXPAND_NORMAL);
+	  result = TREE_OPERAND (result, 1);
+	}
+      return expand_expr (result, target, mode, EXPAND_NORMAL);
     }
   else
     {
@@ -3707,14 +3710,19 @@ expand_builtin_stpcpy (tree exp, rtx target, enum machine_mode mode)
   src = CALL_EXPR_ARG (exp, 1);
 
   /* If return value is ignored, transform stpcpy into strcpy.  */
-  if (target == const0_rtx)
+  if (target == const0_rtx && implicit_built_in_decls[BUILT_IN_STRCPY])
     {
       tree fn = implicit_built_in_decls[BUILT_IN_STRCPY];
-      if (!fn)
-	return NULL_RTX;
+      tree result = build_call_expr (fn, 2, dst, src);
 
-      return expand_expr (build_call_expr (fn, 2, dst, src),
-  			  target, mode, EXPAND_NORMAL);
+      STRIP_NOPS (result);
+      while (TREE_CODE (result) == COMPOUND_EXPR)
+	{
+	  expand_expr (TREE_OPERAND (result, 0), const0_rtx, VOIDmode,
+		       EXPAND_NORMAL);
+	  result = TREE_OPERAND (result, 1);
+	}
+      return expand_expr (result, target, mode, EXPAND_NORMAL);
     }
   else
     {
@@ -10463,6 +10471,17 @@ fold_builtin_2 (tree fndecl, tree arg0, tree arg1, bool ignore)
     case BUILT_IN_STRCPY:
       return fold_builtin_strcpy (fndecl, arg0, arg1, NULL_TREE);
 
+    case BUILT_IN_STPCPY:
+      if (ignore)
+	{
+	  tree fn = implicit_built_in_decls[BUILT_IN_STRCPY];
+	  if (!fn)
+	    break;
+
+	  return build_call_expr (fn, 2, arg0, arg1);
+	}
+      break;
+
     case BUILT_IN_STRCMP:
       return fold_builtin_strcmp (arg0, arg1);