On Sat, Nov 25, 2023 at 8:19 AM Jakub Jelinek <ja...@redhat.com> wrote:
>
> Hi!
>
> The following testcase is miscompiled in GCC 14 because the
> *jcc_bt<mode>_mask and *jcc_bt<SWI48:mode>_mask_1 patterns have just
> one argument in (match_operator 0 "bt_comparison_operator" [...])
> but as bt_comparison_operator is eq,ne, we need two.
> The md readers don't warn about it, after all, some checks can
> be done in the predicate rather than specified explicitly, and the
> behavior is that anything is accepted as the second argument.
>
> I went through all other i386.md match_operator uses and all others
> looked right (extract_operator using 3 operands, all others 2).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> I think we'll want to fix this at different spots in older releases
> because I think the bug was introduced already in 2008, though most
> likely just latent.
>
> 2023-11-25 Jakub Jelinek <ja...@redhat.com>
>
> PR target/111408
> * config/i386/i386.md (*jcc_bt<mode>_mask,
> *jcc_bt<SWI48:mode>_mask_1): Add (const_int 0) as expected
> second operand of bt_comparison_operator.
>
> * gcc.c-torture/execute/pr111408.c: New test.
OK, also for backports.
Thanks,
Uros.
>
> --- gcc/config/i386/i386.md.jj 2023-11-24 08:43:31.892529819 +0100
> +++ gcc/config/i386/i386.md 2023-11-24 14:26:38.645009163 +0100
> @@ -16879,7 +16879,8 @@ (define_insn_and_split "*jcc_bt<mode>_ma
> (const_int 1)
> (and:QI
> (match_operand:QI 2 "register_operand")
> - (match_operand 3 "const_int_operand")))])
> + (match_operand 3 "const_int_operand")))
> + (const_int 0)])
> (label_ref (match_operand 4))
> (pc)))
> (clobber (reg:CC FLAGS_REG))]
> @@ -16915,7 +16916,8 @@ (define_insn_and_split "*jcc_bt<SWI48:mo
> (subreg:QI
> (and:SWI248
> (match_operand:SWI248 2 "register_operand")
> - (match_operand 3 "const_int_operand")) 0))])
> + (match_operand 3 "const_int_operand")) 0))
> + (const_int 0)])
> (label_ref (match_operand 4))
> (pc)))
> (clobber (reg:CC FLAGS_REG))]
> --- gcc/testsuite/gcc.c-torture/execute/pr111408.c.jj 2023-11-24
> 14:45:51.992871046 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr111408.c 2023-11-24
> 14:44:54.809671610 +0100
> @@ -0,0 +1,26 @@
> +/* PR target/111408 */
> +
> +int a, b, c, d;
> +short e;
> +
> +int
> +foo ()
> +{
> + c = a % (sizeof (int) * 8);
> + if (b & 1 << c)
> + return -1;
> + return 0;
> +}
> +
> +int
> +main ()
> +{
> + for (; e != 1; e++)
> + {
> + int g = foo ();
> + if (g + d - 9 + d)
> + continue;
> + for (;;)
> + __builtin_abort ();
> + }
> +}
>
> Jakub
>
