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[Bug middle-end/42509] [4.5 Regression] bootstrap failure in stage3 (integer overflow in preprocessor expression)



------- Comment #22 from rguenth at gcc dot gnu dot org  2010-04-02 12:33 -------
Or a combination of both.  In particular the code doesn't account for
the negative offsets we offset the spill-slot decl with when trying to
handle a NULL MEM_OFFSET conservatively.

I wonder what sizex / sizey is for the spill-slot-decl, or rather what
mode or size it has ...

Least pessimizing patch follows, it looks like nobody else would
disambiguate spill slots otherwise (apart from the tree oracle calls).

Index: gcc/alias.c
===================================================================
--- gcc/alias.c (revision 157942)
+++ gcc/alias.c (working copy)
@@ -2147,6 +2147,13 @@ nonoverlapping_memrefs_p (const_rtx x, c
   if (exprx == 0 || expry == 0)
     return 0;

+  /* For spill-slot accesses make sure we have valid offsets.  */
+  if ((exprx == get_spill_slot_decl (false)
+       && ! MEM_OFFSET (x))
+      || (expry == get_spill_slot_decl (false)
+         && ! MEM_OFFSET (y)))
+    return 0;
+
   /* If both are field references, we may be able to determine something.  */
   if (TREE_CODE (exprx) == COMPONENT_REF
       && TREE_CODE (expry) == COMPONENT_REF


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42509


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