Re: [PATCH] Avoid duplicate -Warray-bounds warnings (PR tree-optimization/86614)

[Richard Biener <rguenther at suse dot de>]

On Thu, 22 Nov 2018, Jakub Jelinek wrote:

> Hi!
> 
> On the following testcases, we warn twice, once in the FE array bounds
> warning code and once later on.
> The FE array bounds warning code sets TREE_NO_WARNING on the corresponding
> MEM_REF, so it is easy to avoid the duplicate warning later.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

OK.

Richard.

> 2018-11-22  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR tree-optimization/86614
> 	* gimple-ssa-warn-restrict.c (maybe_diag_offset_bounds): Return early
> 	if TREE_NO_WARNING is set on ref.ref.
> 
> 	* c-c++-common/Warray-bounds-2.c (wrap_strncpy_dstarray_diff_neg,
> 	call_strncpy_dstarray_diff_neg): Don't expect late -Warray-bounds
> 	warnings, just early ones from FE.  Remove dg-prune-output.
> 	* c-c++-common/Warray-bounds-6.c: New test.
> 
> --- gcc/gimple-ssa-warn-restrict.c.jj	2018-10-19 10:59:08.279393367 +0200
> +++ gcc/gimple-ssa-warn-restrict.c	2018-11-22 18:13:33.813739648 +0100
> @@ -1582,6 +1582,9 @@ maybe_diag_offset_bounds (location_t loc
>    if (!warn_array_bounds)
>      return false;
>  
> +  if (ref.ref && TREE_NO_WARNING (ref.ref))
> +    return false;
> +
>    offset_int ooboff[] = { ref.offrange[0], ref.offrange[1] };
>    tree oobref = ref.offset_out_of_bounds (strict, ooboff);
>    if (!oobref)
> --- gcc/testsuite/c-c++-common/Warray-bounds-2.c.jj	2018-07-23 09:46:57.352997850 +0200
> +++ gcc/testsuite/c-c++-common/Warray-bounds-2.c	2018-11-22 18:29:49.911602501 +0100
> @@ -201,18 +201,16 @@ void call_strncpy_dst_diff_max (const ch
>  static void
>  wrap_strncpy_dstarray_diff_neg (char *d, const char *s, ptrdiff_t i, size_t n)
>  {
> -  strncpy (d + i, s, n);   /* { dg-warning "offset -\[0-9\]+ is out of the bounds \\\[0, 90] of object .ar10. with type .(struct )?Array ?\\\[2]." "strncpy" } */
> -}
> +  strncpy (d + i, s, n);   /* { dg-bogus "offset -\[0-9\]+ is out of the bounds \\\[0, 90] of object .ar10. with type .(struct )?Array ?\\\[2]." "strncpy" } */
> +}			   /* { dg-warning "array subscript -1 is outside array bounds" "" { target *-*-* } .-1 } */
>  
>  void call_strncpy_dstarray_diff_neg (const char *s, size_t n)
>  {
> -  struct Array ar10[2];    /* { dg-message ".ar10. declared here" } */
> -  sink (&ar10);
> +  struct Array ar10[2];    /* { dg-bogus ".ar10. declared here" } */
> +  sink (&ar10);		   /* { dg-message "while referencing" "" { target *-*-* } .-1 } */
>  
>    int off = (char*)ar10[1].a17 - (char*)ar10 + 1;
>    wrap_strncpy_dstarray_diff_neg (ar10[1].a17, s, -off, n);
>  
>    sink (&ar10);
>  }
> -
> -/* { dg-prune-output "outside array bounds" } */
> --- gcc/testsuite/c-c++-common/Warray-bounds-6.c.jj	2018-11-22 18:26:00.286397043 +0100
> +++ gcc/testsuite/c-c++-common/Warray-bounds-6.c	2018-11-22 18:31:55.479527492 +0100
> @@ -0,0 +1,18 @@
> +/* PR tree-optimization/86614 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -Warray-bounds" } */
> +
> +extern char *strncpy (char *, const char *, __SIZE_TYPE__);
> +
> +void sink (void *);
> +
> +struct A { char b[17]; } a[2];
> +
> +void g (const char *s, unsigned n)
> +{
> +  int i = (char *)a[1].b - (char *)a + 1;
> +  char *d = a[1].b;
> +  /* Ensure the same bug is not diagnosed more than once.  */
> +  strncpy (d + i, s, n);	/* { dg-warning "array subscript \[0-9]+ is outside array bounds of" } */
> +				/* { dg-bogus "offset \[0-9]+ is out of the bounds \\\[0, \[0-9]+\\\] of object 'a' with type" "" { target *-*-* } .-1 } */
> +}
> 
> 	Jakub
> 
> 

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