On Thu, 17 Feb 2022, Jakub Jelinek wrote:
> Hi!
>
> After the recent r12-7240 simplify_immed_subreg changes, we bail on more
> simplify_subreg calls than before, e.g. apparently for decimal modes
> in the NaN representations we almost never preserve anything except the
> canonical {q,s}NaNs.
> simplify_gen_subreg will punt in such cases because a SUBREG with VOIDmode
> is not valid, but debug_lowpart_subreg wants to attempt even harder, even
> if e.g. target indicates certain mode combinations aren't valid for the
> backend, dwarf2out can still handle them. But a SUBREG from a VOIDmode
> operand is just too much, the inner mode is lost there. We'd need some
> new rtx that would be able to represent those cases.
> For now, just punt in those cases.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
> 2022-02-17 Jakub Jelinek <ja...@redhat.com>
>
> PR debug/104557
> * valtrack.cc (debug_lowpart_subreg): Don't call gen_rtx_raw_SUBREG
> if expr has VOIDmode.
>
> * gcc.dg/dfp/pr104557.c: New test.
>
> --- gcc/valtrack.cc.jj 2022-01-18 11:59:00.252972485 +0100
> +++ gcc/valtrack.cc 2022-02-16 11:29:28.234826860 +0100
> @@ -558,7 +558,9 @@ debug_lowpart_subreg (machine_mode outer
> rtx ret = simplify_gen_subreg (outer_mode, expr, inner_mode, offset);
> if (ret)
> return ret;
> - return gen_rtx_raw_SUBREG (outer_mode, expr, offset);
> + if (GET_MODE (expr) != VOIDmode)
> + return gen_rtx_raw_SUBREG (outer_mode, expr, offset);
> + return NULL_RTX;
> }
>
> /* If UREGNO is referenced by any entry in DEBUG, emit a debug insn
> --- gcc/testsuite/gcc.dg/dfp/pr104557.c.jj 2022-02-16 11:36:03.733329235
> +0100
> +++ gcc/testsuite/gcc.dg/dfp/pr104557.c 2022-02-16 11:35:27.599831513
> +0100
> @@ -0,0 +1,22 @@
> +/* PR debug/104557 */
> +/* { dg-do compile } */
> +/* { dg-options "-O -g -Wno-psabi" } */
> +
> +typedef int __attribute__((__vector_size__ (32))) U;
> +typedef double __attribute__((__vector_size__ (32))) F;
> +typedef _Decimal64 __attribute__((__vector_size__ (32))) D;
> +
> +F
> +bar (void)
> +{
> + F f = __builtin_convertvector ((D) (-10.d < (D) ((D) (U) { 0, 0, 0, 0, 0,
> 0, 0, -0xe0 }
> + >= (D) { 80000000 })), F);
> + return f;
> +}
> +
> +F
> +foo ()
> +{
> + F x = bar ();
> + return x;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
