[Bug middle-end/90861] OpenACC 'declare' not cleaning up for VLAs

[Bug middle-end/90861] OpenACC 'declare' not cleaning up for VLAs

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90861

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vries at gcc dot gnu.org

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 49317
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49317&action=edit
Tentative patch

[Bug middle-end/90861] OpenACC 'declare' not cleaning up for VLAs

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90861

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
Patch submitted:
https://gcc.gnu.org/pipermail/gcc-patches/2020-October/555606.html

[Bug middle-end/90861] OpenACC 'declare' not cleaning up for VLAs

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90861

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@gcc.gnu.org>:

https://gcc.gnu.org/g:3f2e15c2e66af9cca1dfe24ad7e9692f511ebd06

commit r11-3680-g3f2e15c2e66af9cca1dfe24ad7e9692f511ebd06
Author: Tom de Vries <tdevries@suse.de>
Date:   Tue Oct 6 13:07:25 2020 +0200

    [openacc] Fix acc declare for VLAs

    Consider test-case test.c, with VLA A:
    ...
    int main (void) {
      int N = 1000;
      int A[N];
      #pragma acc declare copy(A)
      return 0;
    }
    ...
    compiled using:
    ...
    $ gcc test.c -fopenacc -S -fdump-tree-all
    ...

    At original, we have:
    ...
      #pragma acc declare map(tofrom:A);
    ...
    but at gimple, we have a map (to:A.1), but not a map (from:A.1):
    ...
      int[0:D.2074] * A.1;

      {
        int A[0:D.2074] [value-expr: *A.1];

        saved_stack.2 = __builtin_stack_save ();
        try
          {
            A.1 = __builtin_alloca_with_align (D.2078, 32);
            #pragma omp target oacc_declare map(to:(*A.1) [len: D.2076])
          }
        finally
          {
            __builtin_stack_restore (saved_stack.2);
          }
      }
    ...

    This is caused by the following incompatibility.  When storing the desired
    from clause in oacc_declare_returns, we use 'A.1' as the key:
    ...
    10898                 oacc_declare_returns->put (decl, c);
    (gdb) call debug_generic_expr (decl)
    A.1
    (gdb) call debug_generic_expr (c)
    map(from:(*A.1))
    ...
    but when looking it up, we use 'A' as the key:
    ...
    (gdb)
    1471                  tree *c = oacc_declare_returns->get (t);
    (gdb) call debug_generic_expr (t)
    A
    ...

    Fix this by extracing the 'A.1' lookup key from 'A' using the decl-expr.

    In addition, unshare the looked up value, to fix avoid running into
    an "incorrect sharing of tree nodes" error.

    Using these two fixes, we get our desired:
    ...
         finally
           {
    +        #pragma omp target oacc_declare map(from:(*A.1))
             __builtin_stack_restore (saved_stack.2);
           }
    ...

    Build on x86_64-linux with nvptx accelerator, tested libgomp.

    gcc/ChangeLog:

    2020-10-06  Tom de Vries  <tdevries@suse.de>

            PR middle-end/90861
            * gimplify.c (gimplify_bind_expr): Handle lookup in
            oacc_declare_returns using key with decl-expr.

    libgomp/ChangeLog:

    2020-10-06  Tom de Vries  <tdevries@suse.de>

            PR middle-end/90861
            * testsuite/libgomp.oacc-c-c++-common/declare-vla.c: Remove xfail.

[Bug middle-end/90861] OpenACC 'declare' not cleaning up for VLAs

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90861

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |11.0

--- Comment #7 from Tom de Vries <vries at gcc dot gnu.org> ---
Patch committed, marking resolved-fixed.

[Bug middle-end/90861] OpenACC 'declare' not cleaning up for VLAs

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90861

Thomas Schwinge <tschwinge at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |vries at gcc dot gnu.org
         Resolution|FIXED                       |---
             Status|RESOLVED                    |REOPENED
                 CC|                            |burnus at gcc dot gnu.org

--- Comment #8 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
Tom, thanks for resolving this!  Just one more item: let's please also update
'c-c++-common/goacc/declare-pr90861.c' (current XFAIL) to match reality.

[Bug middle-end/90861] OpenACC 'declare' not cleaning up for VLAs

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90861

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tobias Burnus <burnus@gcc.gnu.org>:

https://gcc.gnu.org/g:a9802204603616df14ed47d05f1b86f1bd08d8fb

commit r11-3687-ga9802204603616df14ed47d05f1b86f1bd08d8fb
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Tue Oct 6 23:34:21 2020 +0200

    c-c++-common/goacc/declare-pr90861.c: Remove xfail

    gcc/testsuite/ChangeLog
            PR middle-end/90861
            * c-c++-common/goacc/declare-pr90861.c: Remove xfail.

[Bug middle-end/90861] OpenACC 'declare' not cleaning up for VLAs

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90861

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #10 from Tobias Burnus <burnus at gcc dot gnu.org> ---
(In reply to Thomas Schwinge from comment #8)
> let's please also update 'c-c++-common/goacc/declare-pr90861.c'

Well spotted – now FIXED.

Thanks for spotting – and to Tom for fixing the actual issue.