On Tue, 8 Mar 2022, Jakub Jelinek wrote:
> Hi!
>
> The following testcase is miscompiled on powerpc64le-linux at -O1 and higher
> (except for -Og). The bug was introduced in r12-3252-gcad36f38576a6a7
> which for SIGN_EXTEND from SUBREG_PROMOTED_SIGNED_P SUBREG used
> SUBREG_PROMOTED_SET (temp, 1) (but that makes temp
> SUBREG_PROMOTED_UNSIGNED_P because SRP_UNSIGNED is 1) and similarly the
> ZERO_EXTEND from SUBREG_PROMOTED_UNSIGNED_P SUBREG used
> SUBREG_PROMOTED_SET (temp, 0) (but that makes temp
> SUBREG_PROMOTED_SIGNED_P because SRP_SIGNED is 0).
> The following patch fixes that (swaps the 0s and 1s), but for better
> readability uses the SRP_* constants.
> rtl.h has:
> /* Valid for subregs which are SUBREG_PROMOTED_VAR_P(). In that case
> this gives the necessary extensions:
> 0 - signed (SPR_SIGNED)
> 1 - normal unsigned (SPR_UNSIGNED)
> 2 - value is both sign and unsign extended for mode
> (SPR_SIGNED_AND_UNSIGNED).
> -1 - pointer unsigned, which most often can be handled like unsigned
> extension, except for generating instructions where we need to
> emit special code (ptr_extend insns) on some architectures
> (SPR_POINTER). */
> The expr.c change in the same commit looks ok to me (passes unsignedp
> to SUBREG_PROMOTED_SET, so 0 for signed, 1 for unsigned).
>
> Starting bootstrap/regtest on powerpc64{,le}-linux now, ok for trunk?
OK.
> 2022-03-08 Jakub Jelinek <ja...@redhat.com>
>
> PR rtl-optimization/104839
> * simplify-rtx.cc (simplify_unary_operation_1) <case SIGN_EXTEND>:
> Use SRP_SIGNED instead of incorrect 1 in SUBREG_PROMOTED_SET.
> (simplify_unary_operation_1) <case ZERO_EXTEND>: Use SRP_UNSIGNED
> instead of incorrect 0 in SUBREG_PROMOTED_SET.
>
> * gcc.c-torture/execute/pr104839.c: New test.
>
> --- gcc/simplify-rtx.cc.jj 2022-02-23 09:17:04.000000000 +0100
> +++ gcc/simplify-rtx.cc 2022-03-08 16:31:20.823246404 +0100
> @@ -1527,7 +1527,7 @@ simplify_context::simplify_unary_operati
> if (partial_subreg_p (temp))
> {
> SUBREG_PROMOTED_VAR_P (temp) = 1;
> - SUBREG_PROMOTED_SET (temp, 1);
> + SUBREG_PROMOTED_SET (temp, SRP_SIGNED);
> }
> return temp;
> }
> @@ -1662,7 +1662,7 @@ simplify_context::simplify_unary_operati
> if (partial_subreg_p (temp))
> {
> SUBREG_PROMOTED_VAR_P (temp) = 1;
> - SUBREG_PROMOTED_SET (temp, 0);
> + SUBREG_PROMOTED_SET (temp, SRP_UNSIGNED);
> }
> return temp;
> }
> --- gcc/testsuite/gcc.c-torture/execute/pr104839.c.jj 2022-03-08
> 16:46:51.418440078 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr104839.c 2022-03-08
> 16:46:27.044774203 +0100
> @@ -0,0 +1,37 @@
> +/* PR rtl-optimization/104839 */
> +
> +__attribute__((noipa)) short
> +foo (void)
> +{
> + return -1;
> +}
> +
> +__attribute__((noipa)) int
> +bar (void)
> +{
> + short i = foo ();
> + if (i == -2)
> + return 2;
> + long k = i;
> + int j = -1;
> + volatile long s = 300;
> + if (k < 0)
> + {
> + k += s;
> + if (k < 0)
> + j = 0;
> + }
> + else if (k >= s)
> + j = 0;
> + if (j != -1)
> + return 1;
> + return 0;
> +}
> +
> +int
> +main ()
> +{
> + if (bar () != 0)
> + __builtin_abort ();
> + return 0;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
