Re: [PATCH] cfgexpand: Yet another spot with debug insns references to global vars without varpool nodes [PR105630]

[Richard Biener <rguenther@suse.de>]

On Thu, 19 May 2022, Jakub Jelinek wrote:

> Hi!
> 
> This is similar to the earlier patch to avoid having MEM_EXPRs
> referencing global vars without varpool nodes, but this time
> the difference is that during gimplification some hashing
> actually created DECL_RTLs for the n VAR_DECL and the previous
> change was in the if above this when DECL_RTL is NULL and we are
> considering creating it.
> 
> The following patch drops on the floor references to vars where
> we've optimized away the varpool node even when it has DECL_RTL.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, plus
> bootstrapped on those without the cfgexpand.cc change, reapplied
> it and rebuilt stage3 cc1/cc1plus, the resulting cc1/cc1plus
> binaries on both targets were identical except for the 16-byte
> executable_checksum (I've done the second bootstraps in the same
> directory as the first one after moving the previous one elsewhere,
> so pathnames were the same, just checksum hasn't been regenerated).
> So, at least on those binaries this patch doesn't affect debug info
> at all.
> 
> Ok for trunk?

OK.

Thanks,
Richard.

> 2022-05-19  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR debug/105630
> 	* cfgexpand.cc (expand_debug_expr): For VAR_DECL, punt for
> 	global vars without symtab node even when they have DECL_RTL
> 	set.
> 
> 	* gcc.dg/pr105630.c: New test.
> 
> --- gcc/cfgexpand.cc.jj	2022-05-09 09:09:20.005477502 +0200
> +++ gcc/cfgexpand.cc	2022-05-18 13:53:49.622983222 +0200
> @@ -4575,6 +4575,10 @@ expand_debug_expr (tree exp)
>  	      || SYMBOL_REF_DECL (XEXP (op0, 0)) != exp)
>  	    return NULL;
>  	}
> +      else if (VAR_P (exp)
> +	       && is_global_var (exp)
> +	       && symtab_node::get (exp) == NULL)
> +	return NULL;
>        else
>  	op0 = copy_rtx (op0);
>  
> --- gcc/testsuite/gcc.dg/pr105630.c.jj	2022-05-18 14:02:18.426050242 +0200
> +++ gcc/testsuite/gcc.dg/pr105630.c	2022-05-18 14:02:07.103204525 +0200
> @@ -0,0 +1,22 @@
> +/* PR debug/105630 */
> +/* { dg-do compile { target pthread } } */
> +/* { dg-options "-O1 -ftree-parallelize-loops=2 -fcompare-debug" } */
> +
> +int m;
> +static int n;
> +
> +void
> +foo (void)
> +{
> +  int *arr[] = { &n, &n, &n };
> +  int unused = n;
> +
> +  m = 0;
> +}
> +
> +void
> +bar (int *arr, int i)
> +{
> +  while (i < 1)
> +    arr[i++] = 1;
> +}
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)