[PATCH] Fix GC ICE with optimize attribute (PR other/88007)

[Richard Biener]

On Wed, 14 Nov 2018, Jakub Jelinek wrote:

> Hi!
> 
> As mentioned in the PR, ggc_collect is ok with GTY char * fields to point
> outside of GC memory, or if it points at the start of a GC chunk, or
> to the start of the STRING_CST string, anything else is not allowed.
> 
> parse_optimize_options constructs the whole option like "-falign-jumps=16"
> into GC memory and then the option code puts into the arg pointer to
> that 16 within that string and if we get ggc_collect after that, we
> get ICE.
> 
> Fixed by using opts_obstack instead.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

Richard.

> 2018-11-14  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR other/88007
> 	* c-common.c (parse_optimize_options): Allocate option string from
> 	opts_obstack rather than as GC memory.  Move the allocation after
> 	warning for invalid option.
> 
> 	* gcc.dg/pr88007.c: New test.
> 
> --- gcc/c-family/c-common.c.jj	2018-11-14 00:55:39.359532382 +0100
> +++ gcc/c-family/c-common.c	2018-11-14 10:22:13.673689852 +0100
> @@ -5523,8 +5523,6 @@ parse_optimize_options (tree args, bool
>  		  next_p = NULL;
>  		}
>  
> -	      r = q = (char *) ggc_alloc_atomic (len2 + 3);
> -
>  	      /* If the user supplied -Oxxx or -fxxx, only allow -Oxxx or -fxxx
>  		 options.  */
>  	      if (*p == '-' && p[1] != 'O' && p[1] != 'f')
> @@ -5539,6 +5537,9 @@ parse_optimize_options (tree args, bool
>  		  continue;
>  		}
>  
> +	      /* Can't use GC memory here, see PR88007.  */
> +	      r = q = XOBNEWVEC (&opts_obstack, char, len2 + 3);
> +
>  	      if (*p != '-')
>  		{
>  		  *r++ = '-';
> --- gcc/testsuite/gcc.dg/pr88007.c.jj	2018-11-14 10:06:51.493890122 +0100
> +++ gcc/testsuite/gcc.dg/pr88007.c	2018-11-14 10:07:26.749309009 +0100
> @@ -0,0 +1,15 @@
> +/* PR other/88007 */
> +/* { dg-do compile } */
> +/* { dg-options "--param ggc-min-expand=3 --param ggc-min-heapsize=1024" } */
> +/* { dg-skip-if "no code alignment > 2" { "pdp11-*-*" } } */
> +
> +void bar (void);
> +
> +__attribute__((optimize ("align-loops=16", "align-jumps=16",
> +			 "align-labels=16", "align-functions=16")))
> +void
> +foo (void)
> +{
> +  for (int i = 0; i < 1024; ++i)
> +    bar ();
> +}
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)