On Tue, Mar 15, 2016 at 02:18:33PM +0100, Jakub Jelinek wrote:
> So do you prefer this instead?
>
> 2016-03-15 Jakub Jelinek <ja...@redhat.com>
>
> PR rtl-optimization/70222
> * combine.c (simplify_shift_const_1): For A >> B >> C LSHIFTRT
> optimization if mode is different from result_mode, queue up masking
> of the result in outer_op. Formatting fix.
>
> * gcc.c-torture/execute/pr70222-1.c: New test.
> * gcc.c-torture/execute/pr70222-2.c: New test.
This one looks fine, too (if it works ;-) )
Segher
> --- gcc/combine.c.jj 2016-03-14 23:18:37.958408627 +0100
> +++ gcc/combine.c 2016-03-15 14:08:34.754434506 +0100
> @@ -10524,9 +10524,19 @@ simplify_shift_const_1 (enum rtx_code co
> && CONST_INT_P (XEXP (varop, 0))
> && !CONST_INT_P (XEXP (varop, 1)))
> {
> + /* For ((unsigned) (cstULL >> count)) >> cst2 we have to make
> + sure the result will be masked. See PR70222. */
> + if (code == LSHIFTRT
> + && mode != result_mode
> + && !merge_outer_ops (&outer_op, &outer_const, AND,
> + GET_MODE_MASK (result_mode)
> + >> orig_count, result_mode,
> + &complement_p))
> + break;
> +
> rtx new_rtx = simplify_const_binary_operation (code, mode,
> - XEXP (varop, 0),
> - GEN_INT (count));
> + XEXP (varop, 0),
> + GEN_INT (count));
> varop = gen_rtx_fmt_ee (code, mode, new_rtx, XEXP (varop, 1));
> count = 0;
> continue;
> --- gcc/testsuite/gcc.c-torture/execute/pr70222-1.c.jj 2016-03-15
> 11:30:41.657000384 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr70222-1.c 2016-03-15
> 11:30:41.657000384 +0100
> @@ -0,0 +1,30 @@
> +/* PR rtl-optimization/70222 */
> +
> +int a = 1;
> +unsigned int b = 2;
> +int c = 0;
> +int d = 0;
> +
> +void
> +foo ()
> +{
> + int e = ((-(c >= c)) < b) > ((int) (-1ULL >> ((a / a) * 15)));
> + d = -e;
> +}
> +
> +__attribute__((noinline, noclone)) void
> +bar (int x)
> +{
> + if (x != -1)
> + __builtin_abort ();
> +}
> +
> +int
> +main ()
> +{
> +#if __CHAR_BIT__ == 8 && __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
> + foo ();
> + bar (d);
> +#endif
> + return 0;
> +}
> --- gcc/testsuite/gcc.c-torture/execute/pr70222-2.c.jj 2016-03-15
> 11:36:13.273366841 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr70222-2.c 2016-03-15
> 11:36:18.156298614 +0100
> @@ -0,0 +1,20 @@
> +/* PR rtl-optimization/70222 */
> +
> +#if __CHAR_BIT__ == 8 && __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
> +__attribute__((noinline, noclone)) unsigned int
> +foo (int x)
> +{
> + unsigned long long y = -1ULL >> x;
> + return (unsigned int) y >> 31;
> +}
> +#endif
> +
> +int
> +main ()
> +{
> +#if __CHAR_BIT__ == 8 && __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
> + if (foo (15) != 1 || foo (32) != 1 || foo (33) != 0)
> + __builtin_abort ();
> +#endif
> + return 0;
> +}
