Re: [PATCH] loop-invariant: JUMP_INSNs aren't loop invariant [PR97954]

[Richard Biener <rguenther@suse.de>]

On Tue, 1 Dec 2020, Jakub Jelinek wrote:

> Hi!
> 
> The following testcase ICEs because loop invariant motion moves asm goto
> with a single output as invariant.
> Normally, jumps aren't really moved, because if they are single set,
> they have their SET_DEST (pc) and pc_rtx has VOIDmode on which one of the
> functions find_invariant_insn calls bails out.  The code already punts on
> insns that can throw or trap.  And for asm goto without outputs, it isn't
> single set, or asm goto with two or more outputs it isn't single set either.
> 
> Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> trunk?

OK.

Thanks,
Richard.

> 2020-12-01  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR rtl-optimization/97954
> 	* loop-invariant.c (find_invariant_insn): Punt on JUMP_P insns.
> 
> 	* gcc.dg/pr97954.c: New test.
> 
> --- gcc/loop-invariant.c.jj	2020-01-12 11:54:36.000000000 +0100
> +++ gcc/loop-invariant.c	2020-11-30 09:56:37.022696142 +0100
> @@ -1099,6 +1099,10 @@ find_invariant_insn (rtx_insn *insn, boo
>    if (HAVE_cc0 && sets_cc0_p (insn))
>      return;
>  
> +  /* Jumps have control flow side-effects.  */
> +  if (JUMP_P (insn))
> +    return;
> +
>    set = single_set (insn);
>    if (!set)
>      return;
> --- gcc/testsuite/gcc.dg/pr97954.c.jj	2020-11-30 10:31:54.870891248 +0100
> +++ gcc/testsuite/gcc.dg/pr97954.c	2020-11-30 10:31:08.875407984 +0100
> @@ -0,0 +1,12 @@
> +/* PR rtl-optimization/97954 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +
> +int
> +foo (void)
> +{
> +  int x;
> + lab:
> +  asm goto ("": "=r" (x) : : : lab);
> +  return x;
> +}
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)