Re: [PR67891] drop is_gimple_reg test from set_parm_rtl

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

On Wed, Oct 14, 2015 at 5:25 AM, Alexandre Oliva <aoliva@redhat.com> wrote:
> On Oct 12, 2015, Richard Biener <richard.guenther@gmail.com> wrote:
>
>> On Sat, Oct 10, 2015 at 3:16 PM, Alexandre Oliva <aoliva@redhat.com> wrote:
>>> On Oct  9, 2015, Richard Biener <richard.guenther@gmail.com> wrote:
>>>
>>>> Ok.  Note that I think emit_block_move shouldn't mess with the addressable flag.
>>>
>>> I have successfully tested a patch that stops it from doing so,
>>> reverting https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49429#c11 but
>>> according to bugs 49429 and 49454, it looks like removing it would mess
>>> with escape analysis introduced in r175063 for bug 44194.  The thread
>>> that introduces the mark_addressable calls suggests some discomfort with
>>> this solution, and even a suggestion that the markings should be
>>> deferred past the end of expand, but in the end there was agreement to
>>> go with it.  https://gcc.gnu.org/ml/gcc-patches/2011-06/msg01746.html
>
>> Aww, indeed.  Of course the issue is that we don't track pointers to the
>> stack introduced during RTL properly.
>
>> Thanks for checking.  Might want to add a comment before that
>> addressable setting now that you've done the archeology.
>
> I decided to give the following approach a try instead.  The following
> patch was regstrapped on x86_64-linux-gnu and i686-linux-gnu.
> Ok to install?

It looks ok to me but lacks a comment in mark_addressable_1 why we
do this queueing when currently expanding to RTL.

Richard.

> Would anyone with access to hpux (pa and ia64 are both affected) give it
> a spin?
>
>
> defer mark_addressable calls during expand till the end of expand
>
> From: Alexandre Oliva <aoliva@redhat.com>
>
> for  gcc/ChangeLog
>
>         * gimple-expr.c: Include hash-set.h and rtl.h.
>         (mark_addressable_queue): New var.
>         (mark_addressable): Factor actual marking into...
>         (mark_addressable_1): ... this.  Queue it up during expand.
>         (mark_addressable_2): New.
>         (flush_mark_addressable_queue): New.
>         * gimple-expr.h (flush_mark_addressable_queue): Declare.
>         * cfgexpand.c: Include gimple-expr.h.
>         (pass_expand::execute): Flush mark_addressable queue.
> ---
>  gcc/cfgexpand.c   |    3 +++
>  gcc/gimple-expr.c |   50 ++++++++++++++++++++++++++++++++++++++++++++++++--
>  gcc/gimple-expr.h |    1 +
>  3 files changed, 52 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
> index eaad859..a362e17 100644
> --- a/gcc/cfgexpand.c
> +++ b/gcc/cfgexpand.c
> @@ -51,6 +51,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "internal-fn.h"
>  #include "tree-eh.h"
>  #include "gimple-iterator.h"
> +#include "gimple-expr.h"
>  #include "gimple-walk.h"
>  #include "cgraph.h"
>  #include "tree-cfg.h"
> @@ -6373,6 +6374,8 @@ pass_expand::execute (function *fun)
>    /* We're done expanding trees to RTL.  */
>    currently_expanding_to_rtl = 0;
>
> +  flush_mark_addressable_queue ();
> +
>    FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (fun)->next_bb,
>                   EXIT_BLOCK_PTR_FOR_FN (fun), next_bb)
>      {
> diff --git a/gcc/gimple-expr.c b/gcc/gimple-expr.c
> index 2a6ba1a..db249a3 100644
> --- a/gcc/gimple-expr.c
> +++ b/gcc/gimple-expr.c
> @@ -35,6 +35,8 @@ along with GCC; see the file COPYING3.  If not see
>  #include "gimplify.h"
>  #include "stor-layout.h"
>  #include "demangle.h"
> +#include "hash-set.h"
> +#include "rtl.h"
>
>  /* ----- Type related -----  */
>
> @@ -823,6 +825,50 @@ is_gimple_mem_ref_addr (tree t)
>                   || decl_address_invariant_p (TREE_OPERAND (t, 0)))));
>  }
>
> +/* Hold trees marked addressable during expand.  */
> +
> +static hash_set<tree> *mark_addressable_queue;
> +
> +/* Mark X as addressable or queue it up if called during expand.  */
> +
> +static void
> +mark_addressable_1 (tree x)
> +{
> +  if (!currently_expanding_to_rtl)
> +    {
> +      TREE_ADDRESSABLE (x) = 1;
> +      return;
> +    }
> +
> +  if (!mark_addressable_queue)
> +    mark_addressable_queue = new hash_set<tree>();
> +  mark_addressable_queue->add (x);
> +}
> +
> +/* Adaptor for mark_addressable_1 for use in hash_set traversal.  */
> +
> +bool
> +mark_addressable_2 (tree const &x, void * ATTRIBUTE_UNUSED = NULL)
> +{
> +  mark_addressable_1 (x);
> +  return false;
> +}
> +
> +/* Mark all queued trees as addressable, and empty the queue.  To be
> +   called right after clearing CURRENTLY_EXPANDING_TO_RTL.  */
> +
> +void
> +flush_mark_addressable_queue ()
> +{
> +  gcc_assert (!currently_expanding_to_rtl);
> +  if (mark_addressable_queue)
> +    {
> +      mark_addressable_queue->traverse<void*, mark_addressable_2> (NULL);
> +      delete mark_addressable_queue;
> +      mark_addressable_queue = NULL;
> +    }
> +}
> +
>  /* Mark X addressable.  Unlike the langhook we expect X to be in gimple
>     form and we don't do any syntax checking.  */
>
> @@ -838,7 +884,7 @@ mark_addressable (tree x)
>        && TREE_CODE (x) != PARM_DECL
>        && TREE_CODE (x) != RESULT_DECL)
>      return;
> -  TREE_ADDRESSABLE (x) = 1;
> +  mark_addressable_1 (x);
>
>    /* Also mark the artificial SSA_NAME that points to the partition of X.  */
>    if (TREE_CODE (x) == VAR_DECL
> @@ -849,7 +895,7 @@ mark_addressable (tree x)
>      {
>        tree *namep = cfun->gimple_df->decls_to_pointers->get (x);
>        if (namep)
> -       TREE_ADDRESSABLE (*namep) = 1;
> +       mark_addressable_1 (*namep);
>      }
>  }
>
> diff --git a/gcc/gimple-expr.h b/gcc/gimple-expr.h
> index 3d1c89f..2917d2752c 100644
> --- a/gcc/gimple-expr.h
> +++ b/gcc/gimple-expr.h
> @@ -52,6 +52,7 @@ extern bool is_gimple_asm_val (tree);
>  extern bool is_gimple_min_lval (tree);
>  extern bool is_gimple_call_addr (tree);
>  extern bool is_gimple_mem_ref_addr (tree);
> +extern void flush_mark_addressable_queue (void);
>  extern void mark_addressable (tree);
>  extern bool is_gimple_reg_rhs (tree);
>
>
>
> --
> Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
> You must be the change you wish to see in the world. -- Gandhi
> Be Free! -- http://FSFLA.org/   FSF Latin America board member
> Free Software Evangelist|Red Hat Brasil GNU Toolchain Engineer