Fix x86 memset bug, reported by Karl Guenter Wuensch.

	* expr.c (expand_builtin, case BUILT_IN_MEMSET): Break if either
	val or len has TREE_SIDE_EFFECTS set.

From-SVN: r19471

2 files changed, 12 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2a77dca..ca79fe8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,8 @@
 Tue Apr 28 17:53:33 1998  Jim Wilson  <wilson@cygnus.com>
 
+	* expr.c (expand_builtin, case BUILT_IN_MEMSET): Break if either
+	val or len has TREE_SIDE_EFFECTS set.
+
 	* sparc.md (mulsidi3): Call const v8plus and v8plus routines.
 	(mulsidi3_v8plus, const_mulsidi3_v8plus): Delete asterisk from name.
 	(smuldi3_highpart): Call const v8plus routine.
diff --git a/gcc/expr.c b/gcc/expr.c
index 8473181..c094a0f 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -8609,6 +8609,15 @@ expand_builtin (exp, target, subtarget, mode, ignore)
 	  if (dest_align == 0)
 	    break;
 
+	  /* If the arguments have side-effects, then we can only evaluate
+	     them at most once.  The following code evaluates them twice if
+	     they are not constants because we break out to expand_call
+	     in that case.  They can't be constants if they have side-effects
+	     so we can check for that first.  Alternatively, we could call
+	     save_expr to make multiple evaluation safe.  */
+	  if (TREE_SIDE_EFFECTS (val) || TREE_SIDE_EFFECTS (len))
+	    break;
+
 	  /* If VAL is not 0, don't do this operation in-line. */
 	  if (expand_expr (val, NULL_RTX, VOIDmode, 0) != const0_rtx)
 	    break;