[PATCH] Fix PR43661

[Richard Guenther]

This fixes an ICE when folding an unfolded tree by explicitly handling
the case we didn't expect to encounter.

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2010-04-06  Richard Guenther  <rguenther@suse.de>

	PR middle-end/43661
	* fold-const.c (fold_comparison): Handle X * 0 CMP 0.

	* gcc.c-torture/compile/pr43661.c: New testcase.

Index: gcc/fold-const.c
===================================================================
*** gcc/fold-const.c	(revision 157983)
--- gcc/fold-const.c	(working copy)
*************** fold_comparison (location_t loc, enum tr
*** 9576,9582 ****
        tree variable1 = TREE_OPERAND (arg0, 0);
        enum tree_code cmp_code = code;
  
!       gcc_assert (!integer_zerop (const1));
  
        fold_overflow_warning (("assuming signed overflow does not occur when "
  			      "eliminating multiplication in comparison "
--- 9576,9584 ----
        tree variable1 = TREE_OPERAND (arg0, 0);
        enum tree_code cmp_code = code;
  
!       /* Handle unfolded multiplication by zero.  */
!       if (integer_zerop (const1))
! 	return fold_build2_loc (loc, cmp_code, type, const1, const2);
  
        fold_overflow_warning (("assuming signed overflow does not occur when "
  			      "eliminating multiplication in comparison "
Index: gcc/testsuite/gcc.c-torture/compile/pr43661.c
===================================================================
*** gcc/testsuite/gcc.c-torture/compile/pr43661.c	(revision 0)
--- gcc/testsuite/gcc.c-torture/compile/pr43661.c	(revision 0)
***************
*** 0 ****
--- 1,5 ----
+ int
+ func (int x)
+ {
+   return 0 ? (unsigned short) (0 ? : 1 * (signed char) (x ^ x) >= 0) : 1;
+ }