gcse.c (store_killed_in_insn): Consider pure calls as potential store killers in…

gcse.c (store_killed_in_insn): Consider pure calls as potential store killers in addition to normal calls.

	* gcse.c (store_killed_in_insn): Consider pure calls
	as potential store killers in addition to normal calls.

	* gcc.c-torture/execute/20011024-1.c: New test.

From-SVN: r47675

gcc/ChangeLog

 2001-12-05  Jakub Jelinek  <jakub@redhat.com>
 
+	* gcse.c (store_killed_in_insn): Consider pure calls
+	as potential store killers in addition to normal calls.
+
+2001-12-05  Jakub Jelinek  <jakub@redhat.com>
+
 	* expr.c (expand_expr): When checking promoted value, use
 	DECL_MODE (exp) and not mode.
 

gcc/gcse.c

@@ -6498,8 +6498,21 @@ store_killed_in_insn (x, insn)
   
   if (GET_CODE (insn) == CALL_INSN)
     {
+      /* A normal or pure call might read from pattern,
+	 but a const call will not.  */
       if (CONST_OR_PURE_CALL_P (insn))
-	return 0;
+	{
+	  rtx link;
+
+	  for (link = CALL_INSN_FUNCTION_USAGE (insn);
+	       link;
+	       link = XEXP (link, 1))
+	    if (GET_CODE (XEXP (link, 0)) == USE
+		&& GET_CODE (XEXP (XEXP (link, 0), 0)) == MEM
+		&& GET_CODE (XEXP (XEXP (XEXP (link, 0), 0), 0)) == SCRATCH)
+	      return 1;
+	  return 0;
+	}
       else
 	return 1;
     }

gcc/testsuite/ChangeLog

@@ -6,6 +6,8 @@
 
 	* g++.dg/other/anon-union.C: New test.
 
+	* gcc.c-torture/execute/20011024-1.c: New test.
+
 2001-12-04  Joseph S. Myers  <jsm28@cam.ac.uk>
 
 	* gcc.c-torture/execute/20000722-1.x,

gcc/testsuite/gcc.c-torture/execute/20011024-1.c

+/* Test whether store motion recognizes pure functions as potentially reading
+   any memory.  */
+
+typedef __SIZE_TYPE__ size_t;
+extern void *memcpy (void *dest, const void *src, size_t n);
+extern size_t strlen (const char *s);
+extern int strcmp (const char *s1, const char *s2) __attribute__((pure));
+
+char buf[50];
+
+static void foo (void)
+{
+  if (memcpy (buf, "abc", 4) != buf) abort ();
+  if (strcmp (buf, "abc")) abort ();
+  memcpy (buf, "abcdefgh", strlen ("abcdefgh") + 1);
+}
+
+int main (void)
+{
+  foo ();
+  return 0;
+}