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Re: [PATCH] Some -Walloc-size-larger-than= warning fixes (PR driver/81650)


On Thu, 3 Aug 2017, Jakub Jelinek wrote:

> Hi!
> 
> This patch attempts to fix some overflows during computation of the size
> and then effectively uses MIN (SSIZE_MAX, user_specified_value) as the
> bound.
> 
> Not really sure what exact behavior we want, whether that, or default
> to SSIZE_MAX (note the documentation mistakenly talks about SIZE_MAX / 2
> instead) and use MIN (SIZE_MAX, user_specified_value) for user specified
> value, or error out if user_specified_value is larger than
> SSIZE_MAX or larger than SIZE_MAX.  Also the else unit = 0; case
> probably should get diagnostics.  Another issue is if we want to diagnose,
> that right now it will be diagnosed only if some allocation routine is seen,
> diagnosing stuff during option processing is unfortunately too early because
> we don't have sizetype/ssizetype built yet.
> 
> Anyway, the following has been bootstrapped/regtested on x86_64-linux and
> i686-linux.

Ok.

Richard.

> 2017-08-03  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR driver/81650
> 	* calls.c (alloc_max_size): Use HOST_WIDE_INT_UC (10??)
> 	instead of 10??LU, perform unit multiplication in wide_int,
> 	don't change alloc_object_size_limit if the limit is larger
> 	than SSIZE_MAX.
> 
> 	* gcc.dg/pr81650.c: New test.
> 
> --- gcc/calls.c.jj	2017-06-12 12:42:01.000000000 +0200
> +++ gcc/calls.c	2017-08-02 13:41:00.887324420 +0200
> @@ -1222,32 +1222,38 @@ alloc_max_size (void)
>  		  else if (!strcasecmp (end, "KiB") || strcmp (end, "KB"))
>  		    unit = 1024;
>  		  else if (!strcmp (end, "MB"))
> -		    unit = 1000LU * 1000;
> +		    unit = HOST_WIDE_INT_UC (1000) * 1000;
>  		  else if (!strcasecmp (end, "MiB"))
> -		    unit = 1024LU * 1024;
> +		    unit = HOST_WIDE_INT_UC (1024) * 1024;
>  		  else if (!strcasecmp (end, "GB"))
> -		    unit = 1000LU * 1000 * 1000;
> +		    unit = HOST_WIDE_INT_UC (1000) * 1000 * 1000;
>  		  else if (!strcasecmp (end, "GiB"))
> -		    unit = 1024LU * 1024 * 1024;
> +		    unit = HOST_WIDE_INT_UC (1024) * 1024 * 1024;
>  		  else if (!strcasecmp (end, "TB"))
> -		    unit = 1000LU * 1000 * 1000 * 1000;
> +		    unit = HOST_WIDE_INT_UC (1000) * 1000 * 1000 * 1000;
>  		  else if (!strcasecmp (end, "TiB"))
> -		    unit = 1024LU * 1024 * 1024 * 1024;
> +		    unit = HOST_WIDE_INT_UC (1024) * 1024 * 1024 * 1024;
>  		  else if (!strcasecmp (end, "PB"))
> -		    unit = 1000LU * 1000 * 1000 * 1000 * 1000;
> +		    unit = HOST_WIDE_INT_UC (1000) * 1000 * 1000 * 1000 * 1000;
>  		  else if (!strcasecmp (end, "PiB"))
> -		    unit = 1024LU * 1024 * 1024 * 1024 * 1024;
> +		    unit = HOST_WIDE_INT_UC (1024) * 1024 * 1024 * 1024 * 1024;
>  		  else if (!strcasecmp (end, "EB"))
> -		    unit = 1000LU * 1000 * 1000 * 1000 * 1000 * 1000;
> +		    unit = HOST_WIDE_INT_UC (1000) * 1000 * 1000 * 1000 * 1000
> +			   * 1000;
>  		  else if (!strcasecmp (end, "EiB"))
> -		    unit = 1024LU * 1024 * 1024 * 1024 * 1024 * 1024;
> +		    unit = HOST_WIDE_INT_UC (1024) * 1024 * 1024 * 1024 * 1024
> +			   * 1024;
>  		  else
>  		    unit = 0;
>  		}
>  
>  	      if (unit)
> -		alloc_object_size_limit
> -		  = build_int_cst (ssizetype, limit * unit);
> +		{
> +		  wide_int w = wi::uhwi (limit, HOST_BITS_PER_WIDE_INT + 64);
> +		  w *= unit;
> +		  if (wi::ltu_p (w, alloc_object_size_limit))
> +		    alloc_object_size_limit = wide_int_to_tree (ssizetype, w);
> +		}
>  	    }
>  	}
>      }
> --- gcc/testsuite/gcc.dg/pr81650.c.jj	2017-08-02 14:52:22.864787221 +0200
> +++ gcc/testsuite/gcc.dg/pr81650.c	2017-08-02 14:21:11.000000000 +0200
> @@ -0,0 +1,9 @@
> +/* PR driver/81650 */
> +/* { dg-do compile } */
> +/* { dg-options "-Walloc-size-larger-than=9223372036854775807" } */
> +
> +void *
> +foo (void)
> +{
> +  return __builtin_malloc (5);
> +}
> 
> 	Jakub
> 
> 

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


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