[PATCH] Track VLA bounds in VTA (PR debug/43150)

[Richard Guenther]

On Tue, Feb 23, 2010 at 11:47 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> Hi!
>
> Now that we have VLA debuginfo at -O0 fixed again, I think
> it wouldn't hurt to have at least in most cases proper debug info
> also for VLAs at -O1 and above.  Thanks to VTA this is achievable,
> we just need to tell var-tracking that it should track such vars,
> and gimplifier to clear DECL_IGNORED_P on the artificial vars not
> just at -O0, but always.  It doesn't change generated optimized code,
> just allows debug info to be emitted.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

I suppose it might not work with -fno-var-tracking-assignments but
won't cause any problems there as well?

Ok.

Thanks,
Richard.

> 2010-02-23  Jakub Jelinek  <jakub@redhat.com>
>
>        PR debug/43150
>        * gimplify.c (gimplify_type_sizes): Clear DECL_IGNORED_P for VLA
>        bounds even for -O+.
>        * var-tracking.c (track_expr_p): If !need_rtl, don't mandate
>        expr needs to have DECL_NAME set.
>
>        * gcc.dg/guality/vla-1.c: New test.
>
> --- gcc/gimplify.c.jj   2010-02-23 12:15:50.000000000 +0100
> +++ gcc/gimplify.c      2010-02-23 14:00:53.000000000 +0100
> @@ -7367,9 +7367,10 @@ gimplify_type_sizes (tree type, gimple_s
>       /* These types may not have declarations, so handle them here.  */
>       gimplify_type_sizes (TREE_TYPE (type), list_p);
>       gimplify_type_sizes (TYPE_DOMAIN (type), list_p);
> -      /* When not optimizing, ensure VLA bounds aren't removed.  */
> -      if (!optimize
> -         && TYPE_DOMAIN (type)
> +      /* Ensure VLA bounds aren't removed, for -O0 they should be variables
> +        with assigned stack slots, for -O1+ -g they should be tracked
> +        by VTA.  */
> +      if (TYPE_DOMAIN (type)
>          && INTEGRAL_TYPE_P (TYPE_DOMAIN (type)))
>        {
>          t = TYPE_MIN_VALUE (TYPE_DOMAIN (type));
> --- gcc/var-tracking.c.jj       2010-02-23 12:15:38.000000000 +0100
> +++ gcc/var-tracking.c  2010-02-23 13:56:42.000000000 +0100
> @@ -4150,7 +4150,7 @@ track_expr_p (tree expr, bool need_rtl)
>     return 0;
>
>   /* It also must have a name...  */
> -  if (!DECL_NAME (expr))
> +  if (!DECL_NAME (expr) && need_rtl)
>     return 0;
>
>   /* ... and a RTL assigned to it.  */
> --- gcc/testsuite/gcc.dg/guality/vla-1.c.jj     2010-02-23 14:26:01.000000000 +0100
> +++ gcc/testsuite/gcc.dg/guality/vla-1.c        2010-02-23 14:16:47.000000000 +0100
> @@ -0,0 +1,36 @@
> +/* PR debug/43150 */
> +/* { dg-do run } */
> +/* { dg-options "-g" } */
> +
> +void __attribute__((noinline))
> +bar (short *p)
> +{
> +  __builtin_memset (p, '\0', 17 * sizeof (*p));
> +  asm volatile ("" : : "r" (p) : "memory");
> +}
> +
> +int __attribute__((noinline))
> +f1 (int i)
> +{
> +  char a[i + 1];
> +  a[0] = 5;            /* { dg-final { gdb-test 17 "i" "5" } } */
> +  return a[0];         /* { dg-final { gdb-test 17 "sizeof (a)" "6" } } */
> +}
> +
> +int __attribute__((noinline))
> +f2 (int i)
> +{
> +  short a[i * 2 + 7];  /* { dg-final { gdb-test 24 "i" "5" } } */
> +  bar (a);             /* { dg-final { gdb-test 24 "sizeof (a)" "17 * sizeof (short)" } } */
> +  return a[i + 4];
> +}
> +
> +int
> +main ()
> +{
> +  int i = 5;
> +  asm volatile ("" : "=r" (i) : "0" (i));
> +  f1 (i);
> +  f2 (i);
> +  return 0;
> +}
>
>        Jakub
>