Re: [PATCH, PR63995, CHKP] Use single static bounds var for varpool nodes sharing asm name

[Richard Biener <richard dot guenther at gmail dot com>]

On Tue, Nov 25, 2014 at 9:45 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
> Hi,
>
> This patch partly fixes PR bootstrap/63995 by avoiding duplicating static bounds vars.  With this fix bootstrap still fails at stage 2 and 3 comparison.
>
> Bootstrapped and checked on x86_64-unknown-linux-gnu.  OK for trunk?
>
> Thanks,
> Ilya
> --
> gcc/
>
> 2014-11-25  Ilya Enkovich  <ilya.enkovich@intel.com>
>
>         PR bootstrap/63995
>         * tree-chkp (chkp_make_static_bounds): Share bounds var
>         between nodes sharing assembler name.
>
> gcc/testsuite
>
> 2014-11-25  Ilya Enkovich  <ilya.enkovich@intel.com>
>
>         PR bootstrap/63995
>         * g++.dg/dg.exp: Add mpx-dg.exp.
>         * g++.dg/pr63995-1.C: New.
>
>
> diff --git a/gcc/testsuite/g++.dg/dg.exp b/gcc/testsuite/g++.dg/dg.exp
> index 14beae1..44eab0c 100644
> --- a/gcc/testsuite/g++.dg/dg.exp
> +++ b/gcc/testsuite/g++.dg/dg.exp
> @@ -18,6 +18,7 @@
>
>  # Load support procs.
>  load_lib g++-dg.exp
> +load_lib mpx-dg.exp
>
>  # If a testcase doesn't have special options, use these.
>  global DEFAULT_CXXFLAGS
> diff --git a/gcc/testsuite/g++.dg/pr63995-1.C b/gcc/testsuite/g++.dg/pr63995-1.C
> new file mode 100644
> index 0000000..82e7606
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr63995-1.C
> @@ -0,0 +1,16 @@
> +/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
> +/* { dg-require-effective-target mpx } */
> +/* { dg-options "-O2 -g -fcheck-pointer-bounds -mmpx" } */
> +
> +int test1 (int i)
> +{
> +  extern const int arr[10];
> +  return arr[i];
> +}
> +
> +extern const int arr[10];
> +
> +int test2 (int i)
> +{
> +  return arr[i];
> +}
> diff --git a/gcc/tree-chkp.c b/gcc/tree-chkp.c
> index 3e38691..d425084 100644
> --- a/gcc/tree-chkp.c
> +++ b/gcc/tree-chkp.c
> @@ -2727,9 +2727,29 @@ chkp_make_static_bounds (tree obj)
>    /* First check if we already have required var.  */
>    if (chkp_static_var_bounds)
>      {
> -      slot = chkp_static_var_bounds->get (obj);
> -      if (slot)
> -       return *slot;
> +      /* If there is a symbol sharing assembler name with obj,
> +        we may use its bounds.  */
> +      if (TREE_CODE (obj) == VAR_DECL)
> +       {
> +         varpool_node *node = varpool_node::get_create (obj);
> +
> +         while (node->previous_sharing_asm_name)
> +           node = (varpool_node *)node->previous_sharing_asm_name;
> +
> +         while (node)
> +           {
> +             slot = chkp_static_var_bounds->get (node->decl);
> +             if (slot)
> +               return *slot;
> +             node = (varpool_node *)node->next_sharing_asm_name;
> +           }

Hum.  varpool_node::get returns the ultimate alias target thus the
walking shouldn't be necessary.  Just

  node = varpool_node::get_create (obj);
  slot = chkp_static_var_bounds->get (node->decl);
  if (slot)
    return *slot;

and then making sure to set the decl also for node->decl.  I suppose
it really asks for making chkp_static_var_bounds->get based on
a varpool node and not a decl so you consistently use the ultimate
alias target.

Richard.

> +       }
> +      else
> +       {
> +         slot = chkp_static_var_bounds->get (obj);
> +         if (slot)
> +           return *slot;
> +       }
>      }
>
>    /* Build decl for bounds var.  */