[Bug c/51730] [4.7 Regression] autoconf 2.60 through 2.67 stdbool.h check fails with GCC 4.7

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51730

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-02 14:15:39 UTC ---
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Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    (revision 182784)
+++ gcc/fold-const.c    (working copy)
@@ -8886,6 +8886,13 @@ fold_comparison (location_t loc, enum tr
              indirect_base0 = true;
            }
          offset0 = TREE_OPERAND (arg0, 1);
+         if (host_integerp (offset0, 1)
+             && (TREE_INT_CST_LOW (offset0)
+                 & ((unsigned HOST_WIDE_INT)-1 << (HOST_BITS_PER_WIDE_INT -
exact_log2 (BITS_PER_UNIT)))) == 0)
+           {
+             bitpos0 = TREE_INT_CST_LOW (offset0) * BITS_PER_UNIT;
+             offset0 = NULL_TREE;
+           }
        }

       base1 = arg1;
@@ -8909,6 +8916,13 @@ fold_comparison (location_t loc, enum tr
              indirect_base1 = true;
            }
          offset1 = TREE_OPERAND (arg1, 1);
+         if (host_integerp (offset1, 1)
+             && (TREE_INT_CST_LOW (offset1)
+                 & ((unsigned HOST_WIDE_INT)-1 << (HOST_BITS_PER_WIDE_INT -
exact_log2 (BITS_PER_UNIT)))) == 0)
+           {
+             bitpos1 = TREE_INT_CST_LOW (offset1) * BITS_PER_UNIT;
+             offset1 = NULL_TREE;
+           }
        }

       /* A local variable can never be pointed to by

to be beautified ...