middle-end/107115 - avoid bogus redundant store removal during RTL expansion

The following preserves the (premature) redundant store removal
done in store_expr by appropriately guarding it with
mems_same_for_tbaa_p.  The testcase added needs scheduling disabled
for now since there's a similar bug there still present.

	PR middle-end/107115
	* expr.cc (store_expr): Check mems_same_for_tbaa_p before
	eliding a seemingly redundant store.

	* gcc.dg/torture/pr107115.c: New testcase.

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 80bb1b8a4c5b8350fb1b8f57a99fd52e5882fcb6..ba627f176a784faf7caca94a61f49f5c6cbd315c 100644 (file)
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -6207,7 +6207,9 @@ store_expr (tree exp, rtx target, int call_param_p,
 
   if ((! rtx_equal_p (temp, target)
        || (temp != target && (side_effects_p (temp)
-                             || side_effects_p (target))))
+                             || side_effects_p (target)
+                             || (MEM_P (temp)
+                                 && !mems_same_for_tbaa_p (temp, target)))))
       && TREE_CODE (exp) != ERROR_MARK
       /* If store_expr stores a DECL whose DECL_RTL(exp) == TARGET,
         but TARGET is not valid memory reference, TEMP will differ

diff --git a/gcc/testsuite/gcc.dg/torture/pr107115.c b/gcc/testsuite/gcc.dg/torture/pr107115.c
new file mode 100644 (file)
index 0000000..5f7b6ff
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr107115.c
@@ -0,0 +1,37 @@
+/* { dg-do run } */
+/* PR/107115 */
+/* { dg-additional-options "-fno-schedule-insns -fno-schedule-insns2" } */
+
+#include <stdlib.h>
+
+void test1(long *p1)
+{
+  p1[0] = 1;
+}
+long test2(long long *p2, int index1, int index2)
+{
+  p2[index1] = 2;
+  return p2[index2];
+}
+long test3(long *p3, int index2, long value)
+{
+  p3[index2] = 3;
+  p3[index2] = value;
+  return p3[0];
+}
+long test4(void *p4, int index1, int index2)
+{
+  test1(p4);
+  long temp = test2(p4, index1, index2);
+  return test3(p4, index2, temp);
+}
+long (*volatile vtest)(void *, int, int) = test4;
+int main(void)
+{
+  void *pp = malloc(sizeof (long) + sizeof(long long));
+  if (!pp) abort();
+  long result = vtest(pp, 0, 0);
+  if (*(long *)pp != 2 || result != 2)
+    __builtin_abort ();
+  return 0;
+}