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Require type compatible bases in DDR initialization (PR tree-optimization/70127)

Message ID 20160309201049.GS3017@tucnak.redhat.com
State New
Headers show

Commit Message

Jakub Jelinek March 9, 2016, 8:10 p.m. UTC 
On Tue, Mar 08, 2016 at 07:11:45PM +0100, Richard Biener wrote:
> I believe the safest fix is to re-instantiate the compatibility check by refactoring operand_equal_p to perform it on the full ref (but not recursions where it would be redundant and maybe too conservative).
> I've noticed this as well when doing the last operand_equal_p surgery, esp. The incomplete and bogus half-way type checking done at its top.

I've tried to add types_compatible_p check to operand_equal_p for all
toplevel expressions, but that affected 25x more operand_equal_p calls
during x86_64 and i686-linux bootstrap/regtest than just doing it
for *MEM_REF only - details in the PR; after discussions on IRC with Richard
and Honza I've committed reversion of the October change, and we'll need to
start with operand_equal_p changes early during stage1 next time, rather
than at the end of stage1.

Bootstrapped/regtested on x86_64-linux and i686-linux, committed to trunk.

2016-03-09  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/70127
	* fold-const.c (operand_equal_p): Revert the 2015-10-28 change.

	* gcc.c-torture/execute/pr70127.c: New test.



	Jakub
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Patch

--- gcc/fold-const.c.jj	2016-03-09 15:06:21.000000000 +0100
+++ gcc/fold-const.c	2016-03-09 18:25:07.429926750 +0100
@@ -3032,6 +3032,9 @@  operand_equal_p (const_tree arg0, const_
 					   TYPE_SIZE (TREE_TYPE (arg1)),
 					   flags)))
 		return 0;
+	      /* Verify that access happens in similar types.  */
+	      if (!types_compatible_p (TREE_TYPE (arg0), TREE_TYPE (arg1)))
+		return 0;
 	      /* Verify that accesses are TBAA compatible.  */
 	      if (!alias_ptr_types_compatible_p
 		    (TREE_TYPE (TREE_OPERAND (arg0, 1)),
--- gcc/testsuite/gcc.c-torture/execute/pr70127.c.jj	2016-03-08 12:11:11.890835632 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr70127.c	2016-03-08 12:10:58.000000000 +0100
@@ -0,0 +1,23 @@ 
+/* PR tree-optimization/70127 */
+
+struct S { int f; signed int g : 2; } a[1], c = {5, 1}, d;
+short b;
+
+__attribute__((noinline, noclone)) void
+foo (int x)
+{
+  if (x != 1)
+    __builtin_abort ();
+}
+
+int
+main ()
+{
+  while (b++ <= 0)
+    {
+      struct S e = {1, 1};
+      d = e = a[0] = c;
+    }
+  foo (a[0].g);
+  return 0;
+}