Re: [PATCH] emit-rtl: Fix -fcompare-debug bug with label references in debug insns [PR105203]

[Richard Biener via Gcc-patches]

> Am 20.04.2022 um 18:52 schrieb Jakub Jelinek via Gcc-patches 
> <gcc-patches@gcc.gnu.org>:
> 
> Hi!
> 
> When we compute LABEL_NUSES from scratch, mark_all_labels doesn't call
> mark_jump_label on DEBUG_INSNs:
>              if (NONDEBUG_INSN_P (insn))
>                mark_jump_label (PATTERN (insn), insn, 0);
> and so doesn't increment LABEL_NUSES from references in DEBUG_INSNs.
> But, when we call emit_copy_of_insn_after e.g. when duplicating some
> DEBUG_INSNs, we call it even on those, which then results in LABEL_NUSES
> differences and -fcompare-debug failures.
> 
> The following patch makes sure we don't call it on DEBUG_INSNs.
> 
> Bootstrapped/regtested on powerpc64le-linux, ok for trunk?

Ok

Richard 
> 
> 2022-04-20  Jakub Jelinek  <ja...@redhat.com>
> 
>    PR debug/105203
>    * emit-rtl.cc (emit_copy_of_insn_after): Don't call mark_jump_label
>    on DEBUG_INSNs.
> 
>    * gfortran.dg/g77/pr105203.f: New test.
> 
> --- gcc/emit-rtl.cc.jj    2022-02-23 09:17:04.805125253 +0100
> +++ gcc/emit-rtl.cc    2022-04-20 10:26:44.972198107 +0200
> @@ -6440,7 +6440,8 @@ emit_copy_of_insn_after (rtx_insn *insn,
>     }
> 
>   /* Update LABEL_NUSES.  */
> -  mark_jump_label (PATTERN (new_rtx), new_rtx, 0);
> +  if (NONDEBUG_INSN_P (insn))
> +    mark_jump_label (PATTERN (new_rtx), new_rtx, 0);
> 
>   INSN_LOCATION (new_rtx) = INSN_LOCATION (insn);
> 
> --- gcc/testsuite/gfortran.dg/g77/pr105203.f.jj    2022-04-20 
> 10:29:44.830696254 +0200
> +++ gcc/testsuite/gfortran.dg/g77/pr105203.f    2022-04-20 10:31:13.532463772 
> +0200
> @@ -0,0 +1,20 @@
> +C Test case for PR debug/105203
> +C Origin: kmcca...@princeton.edu
> +C
> +C { dg-do compile }
> +C { dg-options "-O2 -fcompare-debug -ftracer -w" }
> +C { dg-additional-options "-fPIC" { target fpic } }
> +      SUBROUTINE FOO (B)
> +
> +  10  CALL BAR (A)
> +      ASSIGN 20 TO M
> +      IF (100.LT.A) GOTO 10
> +      GOTO 40
> +C
> +  20  IF (B.LT.ABS(A)) GOTO 10
> +      ASSIGN 30 TO M
> +      GOTO 40
> +C
> +  30  ASSIGN 10 TO M
> +  40  GOTO M,(10,20,30)
> +      END
> 
>    Jakub
>