[Bug c++/30252] [4.2 regression] miscompilation of sigc++-2.0 based code with -fstrict-aliasing

[rguenth at gcc dot gnu dot org]

------- Comment #29 from rguenth at gcc dot gnu dot org  2007-06-04 15:45 -------
We can make it safe if we only really handle + in pointer arithmetic.  Like
with

@@ -3258,7 +3255,7 @@ handle_ptr_arith (VEC (ce_s, heap) *lhsc
   unsigned int i = 0;
   unsigned int j = 0;
   VEC (ce_s, heap) *temp = NULL;
-  unsigned int rhsoffset = 0;
+  unsigned HOST_WIDE_INT rhsoffset = 0;

   if (TREE_CODE (expr) != PLUS_EXPR
       && TREE_CODE (expr) != MINUS_EXPR)
@@ -3269,9 +3266,12 @@ handle_ptr_arith (VEC (ce_s, heap) *lhsc

   get_constraint_for (op0, &temp);
   if (POINTER_TYPE_P (TREE_TYPE (op0))
-      && TREE_CODE (op1) == INTEGER_CST
+      && host_integerp (op1, 1)
       && TREE_CODE (expr) == PLUS_EXPR)
     {
+      if ((TREE_INT_CST_LOW (op1) * BITS_PER_UNIT) / BITS_PER_UNIT
+         != TREE_INT_CST_LOW (op1))
+       return false;
       rhsoffset = TREE_INT_CST_LOW (op1) * BITS_PER_UNIT;
     }
   else


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30252