[PATCH] Fix nonoverlapping_memrefs_p ICE (PR target/77834, take 2)

[Jakub Jelinek]

Hi!

On Wed, Nov 02, 2016 at 10:46:40AM +0100, Richard Biener wrote:
> Yeah, plus if a followup test would have disambiguated things (the
> dispatch to the tree oracle for example).

After discussing this on IRC that the dse.c and sched-deps.c (call (mem ...) )
changes are probably not safe, I'm proposing following patch which should be
safe to backport to release branches too, the only occurrences of
!DECL_RTL_SET_P where DECL_RTL worked fine in my bootstraps/regtests were
FUNCTION_DECLs, so the patch should only turn ICEs into returning the safe
return value that the expressions might overlap.

If/once this is in, I'm planning to test/submit a patch adding
  /* If one decl is known to be a function or label in a function and
     the other is some kind of data, they can't overlap.  */
  if ((TREE_CODE (exprx) == FUNCTION_DECL
       || TREE_CODE (exprx) == LABEL_DECL)
      != (TREE_CODE (expry) == FUNCTION_DECL
          || TREE_CODE (expry) == LABEL_DECL))
    return 1;
before that.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-11-04  Jakub Jelinek  <ja...@redhat.com>

        PR target/77834
        * alias.c (nonoverlapping_memrefs_p): Return 0 if exprx or expry
        doesn't have rtl set.

        * gcc.dg/pr77834.c: New test.

--- gcc/alias.c.jj      2016-10-21 17:06:27.000000000 +0200
+++ gcc/alias.c 2016-10-31 11:38:29.448031590 +0100
@@ -2755,6 +2755,13 @@ nonoverlapping_memrefs_p (const_rtx x, c
       || TREE_CODE (expry) == CONST_DECL)
     return 1;
 
+  /* If either of the decls doesn't have DECL_RTL set (e.g. marked as
+     living in multiple places), we can't tell anything.  Exception
+     are FUNCTION_DECLs for which we can create DECL_RTL on demand.  */
+  if ((!DECL_RTL_SET_P (exprx) && TREE_CODE (exprx) != FUNCTION_DECL)
+      || (!DECL_RTL_SET_P (expry) && TREE_CODE (expry) != FUNCTION_DECL))
+    return 0;
+
   rtlx = DECL_RTL (exprx);
   rtly = DECL_RTL (expry);
 
--- gcc/testsuite/gcc.dg/pr77834.c.jj   2016-10-31 11:41:46.290521464 +0100
+++ gcc/testsuite/gcc.dg/pr77834.c      2016-10-31 11:41:24.000000000 +0100
@@ -0,0 +1,18 @@
+/* PR target/77834 */
+/* { dg-do compile } */
+/* { dg-options "-O -ftree-pre -Wno-psabi" } */
+/* { dg-additional-options "-mstringop-strategy=libcall" { target i?86-*-* 
x86_64-*-* } } */
+
+typedef int V __attribute__ ((vector_size (64)));
+
+V
+foo (V u, V v, int w)
+{
+  do
+    {
+      if (u[0]) v ^= u[w];
+    }
+  while ((V) { 0, u[w] }[1]);
+  u = (V) { v[v[0]], u[u[0]] };
+  return v + u;
+}


        Jakub