[Bug middle-end/17036] [3.5 Regression] ICE: (A >> N) & 1 ? (1 << N) : 0 where A of type unsigned int

[Graham Stott]

pinskia at gcc dot gnu dot org wrote:
> ------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-15 17:05 -------
> Confirmed
> : Search converges between 2004-06-20-trunk (#469) and 2004-06-22-trunk (#470).
> Reduced to:
> int main( int argc, char **arg )
> {
>  int R , N = 4;
>  unsigned int A = 2;
>  signed int B = 2;
>  ((B >> N) & 1) ? 1 : 0;
>  ((A >> N) & 1) ? 1 : 0;
>  return 0;
> }
> 
> 
> Looks like someone forgets to check to make sure that the N is really a constant.
> 

This patch should fixit but I don't have time to do a full bootstrap and
regression test on the patch.

-------------------------------------------------------------------
Index: fold-const.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/fold-const.c,v
retrieving revision 1.435
diff -c -p -r1.435 fold-const.c
*** fold-const.c        12 Aug 2004 04:01:04 -0000      1.435
--- fold-const.c        15 Aug 2004 17:53:10 -0000
*************** fold (tree expr)
*** 8874,8879 ****
--- 8874,8880 ----
           tree tem = TREE_OPERAND (arg0, 0);
           STRIP_NOPS (tem);
           if (TREE_CODE (tem) == RSHIFT_EXPR
+             && TREE_CODE (TREE_OPERAND (tem, 1)) == INTEGER_CST
                 && (unsigned HOST_WIDE_INT) tree_log2 (arg1) ==
                  TREE_INT_CST_LOW (TREE_OPERAND (tem, 1)))
             return fold (build2 (BIT_AND_EXPR, type,
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