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Re: [PATCH] Fix do_jump (PR middle-end/40057)


On Thu, May 7, 2009 at 4:52 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> Hi!
>
> The following testcase is miscompiled with i?86-linux 32-bit HWI cc1, but
> not with 64-bit HWI x86_64-linux cc1 with -m32.
> The problem is that do_jump creates the (supposed to be 1 bit) mask with
> build_int_cst_type, if shift is HOST_BITS_PER_WIDE_INT - 1, then mask
> is a negative HOST_WIDE_INT number and so for long long has 33 bits set, not
> just 1. ?Fixed by using build_int_cst_wide_type instead.
> Also, prefer_and_bit_test has a similar bug, for 32-bit HWI and bitnum 31
> we want to create CONST_DOUBLE 2147483648, not CONST_INT -2147483648.
>
> Bootstrapped/regtested on i686-linux and x86_64-linux, ok for trunk/4.4?

Ok for all open branches (the patch should apply as-is to 4.3).

Thanks,
Richard.

> 2009-05-07 ?Jakub Jelinek ?<jakub@redhat.com>
>
> ? ? ? ?PR middle-end/40057
> ? ? ? ?* dojump.c (prefer_and_bit_test): Use immed_double_const instead of
> ? ? ? ?GEN_INT for 1 << bitnum.
> ? ? ? ?(do_jump) <case BIT_AND_EXPR>: Use build_int_cst_wide_type instead of
> ? ? ? ?build_int_cst_type.
>
> ? ? ? ?* gcc.c-torture/execute/pr40057.c: New test.
>
> --- gcc/dojump.c.jj ? ? 2009-04-24 21:41:28.000000000 +0200
> +++ gcc/dojump.c ? ? ? ?2009-05-07 14:54:05.000000000 +0200
> @@ -141,7 +141,8 @@ prefer_and_bit_test (enum machine_mode m
> ? ? }
>
> ? /* Fill in the integers. ?*/
> - ?XEXP (and_test, 1) = GEN_INT ((unsigned HOST_WIDE_INT) 1 << bitnum);
> + ?XEXP (and_test, 1)
> + ? ?= immed_double_const ((unsigned HOST_WIDE_INT) 1 << bitnum, 0, mode);
> ? XEXP (XEXP (shift_test, 0), 1) = GEN_INT (bitnum);
>
> ? return (rtx_cost (and_test, IF_THEN_ELSE, optimize_insn_for_speed_p ())
> @@ -475,10 +476,10 @@ do_jump (tree exp, rtx if_false_label, r
> ? ? ? ? ? ? ? ? ?&& prefer_and_bit_test (TYPE_MODE (argtype),
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?TREE_INT_CST_LOW (shift)))
> ? ? ? ? ? ? ? ?{
> - ? ? ? ? ? ? ? ? HOST_WIDE_INT mask = (HOST_WIDE_INT) 1
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?<< TREE_INT_CST_LOW (shift);
> + ? ? ? ? ? ? ? ? unsigned HOST_WIDE_INT mask
> + ? ? ? ? ? ? ? ? ? = (unsigned HOST_WIDE_INT) 1 << TREE_INT_CST_LOW (shift);
> ? ? ? ? ? ? ? ? ?do_jump (build2 (BIT_AND_EXPR, argtype, arg,
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?build_int_cst_type (argtype, mask)),
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?build_int_cst_wide_type (argtype, mask, 0)),
> ? ? ? ? ? ? ? ? ? ? ? ? ? clr_label, set_label);
> ? ? ? ? ? ? ? ? ?break;
> ? ? ? ? ? ? ? ?}
> --- gcc/testsuite/gcc.c-torture/execute/pr40057.c.jj ? ?2009-05-07 15:07:59.000000000 +0200
> +++ gcc/testsuite/gcc.c-torture/execute/pr40057.c ? ? ? 2009-05-07 15:05:54.000000000 +0200
> @@ -0,0 +1,37 @@
> +/* PR middle-end/40057 */
> +
> +extern void abort (void);
> +
> +__attribute__((noinline)) int
> +foo (unsigned long long x)
> +{
> + ?unsigned long long y = (x >> 31ULL) & 1ULL;
> + ?if (y == 0ULL)
> + ? ?return 0;
> + ?return -1;
> +}
> +
> +__attribute__((noinline)) int
> +bar (long long x)
> +{
> + ?long long y = (x >> 31LL) & 1LL;
> + ?if (y == 0LL)
> + ? ?return 0;
> + ?return -1;
> +}
> +
> +int
> +main (void)
> +{
> + ?if (sizeof (long long) != 8)
> + ? ?return 0;
> + ?if (foo (0x1682a9aaaULL))
> + ? ?abort ();
> + ?if (!foo (0x1882a9aaaULL))
> + ? ?abort ();
> + ?if (bar (0x1682a9aaaLL))
> + ? ?abort ();
> + ?if (!bar (0x1882a9aaaLL))
> + ? ?abort ();
> + ?return 0;
> +}
>
> ? ? ? ?Jakub
>


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