[Bug tree-optimization/36373] New: [4.2/4.3/4.4 Regression] Wrong code with struct return

[Bug tree-optimization/36373] New: [4.2/4.3/4.4 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

extern void abort (void);
struct Foo {
    int *p;
    int *q;
};
struct Foo __attribute__((noinline))
bar(int *p)
{
  struct Foo f;
  f.p = p;
  return f;
}
void __attribute__((noinline))
foo(struct Foo f)
{
  *f.p = 0;
}
int main()
{
  int a, b;
  a = 0;
  b = 1;
  struct Foo f;
  f = bar (&b);
  f.q = &a;
  foo(f);
  if (b != 0)
    abort ();
  return 0;
}


-- 
           Summary: [4.2/4.3/4.4 Regression] Wrong code with struct return
           Product: gcc
           Version: 4.3.1
            Status: UNCONFIRMED
          Keywords: wrong-code, alias
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3/4.4 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2008-05-29 15:07 -------
Mine.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
      Known to work|                            |4.1.2
   Last reconfirmed|0000-00-00 00:00:00         |2008-05-29 15:07:30
               date|                            |
   Target Milestone|---                         |4.2.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3/4.4 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2008-05-29 15:23 -------
First we miss the constraint

  f = &ANYTHING

from

  f = bar (&b);

but then we also do not handle at all the case of escaping pointers through
by-value passed structures

  foo (f);

and thus we end up not clobbering b for that call.  The first part is easy
to fix.  I have to think about the second one ...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3/4.4 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2008-05-29 15:44 -------
I have a patch.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3/4.4 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2008-05-30 10:58 -------
Umm.  It's worse.

With -O2 -fno-tree-sra:

extern void abort (void);
struct Foo {
    int *p;
} x;
struct Foo __attribute__((noinline))
bar(int *p)
{
  struct Foo f;
  f.p = p;
  return f;
}
void __attribute__((noinline))
foo()
{
  *x.p = 0;
}
int main()
{
  int b;
  b = 1;
  struct Foo g = bar (&b);
  x = g;
  foo();
  if (b != 0)
    abort ();
  return 0;
}


the escape through the global x doesn't work either.  SRA "fixes" this by

  # g_7 = VDEF <g_6(D)>
  g = bar (&b);
  # VUSE <g_7>
  g$p_2 = g.p; 
  # x_9 = VDEF <x_8(D)>
  x.p = g$p_2;

where we (after partial fixes) compute the points-to set of g$p_2 correctly
and thus mark that pointer as escaping to a global in the next stmt.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3/4.4 Regression] Wrong code with struct return

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3/4.4 Regression] Wrong code with struct return

[cnstar9988 at gmail dot com]

------- Comment #5 from cnstar9988 at gmail dot com  2008-06-26 06:51 -------
ping...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3/4.4 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #6 from rguenth at gcc dot gnu dot org  2008-06-27 18:54 -------
Subject: Bug 36373

Author: rguenth
Date: Fri Jun 27 18:53:43 2008
New Revision: 137197

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=137197
Log:
2008-06-27  Richard Guenther  <rguenther@suse.de>

        PR tree-optimization/36400
        PR tree-optimization/36373
        PR tree-optimization/36344
        * tree-ssa-structalias.c (var_escaped, escaped_tree, escaped_id,
        var_nonlocal, nonlocal_tree, nonlocal_id): New globals
        (update_alias_info): Remove call clobbering code.
        (make_constraint_to): New helper function.
        (make_escape_constraint): Likewise.
        (handle_rhs_call): Use it on all pointer containing arguments.
        Also mark the static chain escaped.
        (handle_lhs_call): Make constraints from NONLOCAL and ESCAPED
        instead of ANYTHING.
        (make_constraint_from): New helper split out from ...
        (make_constraint_from_anything): ... here.
        (find_func_aliases): Add constraints for escape sites.
        (intra_create_variable_infos): Make constraints from NONLOCAL
        for parameters.
        (find_what_p_points_to): Interpret NONLOCAL and ESCAPED the same
        as ANYTHING.
        (clobber_what_p_points_to): Remove.
        (clobber_what_escaped): New function.
        (init_base_vars): Init NONLOCAL and ESCAPED.
        (do_sd_constraint): Do not propagate the solution from ESCAPED
        but use ESCAPED as a placeholder.
        (solve_graph): Likewise.
        * tree-flow.h (clobber_what_p_points_to): Remove.
        (clobber_what_escaped): Declare.
        * tree-ssa-alias.c (set_initial_properties): Call it.
        Remove code clobbering escaped pointers.

        * gcc.dg/torture/pr36373-1.c: New testcase.
        * gcc.dg/torture/pr36373-2.c: Likewise.
        * gcc.dg/torture/pr36373-3.c: Likewise.
        * gcc.dg/torture/pr36373-4.c: Likewise.
        * gcc.dg/torture/pr36373-5.c: Likewise.
        * gcc.dg/torture/pr36373-6.c: Likewise.
        * gcc.dg/torture/pr36373-7.c: Likewise.
        * gcc.dg/torture/pr36373-8.c: Likewise.
        * gcc.dg/torture/pr36373-9.c: Likewise.
        * gcc.dg/torture/pr36373-10.c: Likewise.
        * gcc.dg/torture/pr36400.c: Likewise.
        * gcc.c-torture/execute/pta-field-1.c: Likewise.
        * gcc.c-torture/execute/pta-field-2.c: Likewise.
        * gcc.dg/tree-ssa/loadpre8.c: Remove XFAIL.
        * gcc.dg/tree-ssa/pr24287.c: XFAIL.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/tree-ssa/loadpre8.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr24287.c
    trunk/gcc/tree-flow.h
    trunk/gcc/tree-ssa-alias.c
    trunk/gcc/tree-ssa-structalias.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3/4.4 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2008-06-27 21:55 -------
Subject: Bug 36373

Author: rguenth
Date: Fri Jun 27 21:54:42 2008
New Revision: 137204

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=137204
Log:
2008-06-27  Richard Guenther  <rguenther@suse.de>

        PR tree-optimization/36400
        PR tree-optimization/36373
        PR tree-optimization/36344
        * tree-ssa-structalias.c (var_escaped, escaped_tree, escaped_id,
        var_nonlocal, nonlocal_tree, nonlocal_id): New globals
        (update_alias_info): Remove call clobbering code.
        (make_constraint_to): New helper function.
        (make_escape_constraint): Likewise.
        (handle_rhs_call): Use it on all pointer containing arguments.
        Also mark the static chain escaped.
        (handle_lhs_call): Make constraints from NONLOCAL and ESCAPED
        instead of ANYTHING.
        (make_constraint_from): New helper split out from ...
        (make_constraint_from_anything): ... here.
        (find_func_aliases): Add constraints for escape sites.
        (intra_create_variable_infos): Make constraints from NONLOCAL
        for parameters.
        (find_what_p_points_to): Interpret NONLOCAL and ESCAPED the same
        as ANYTHING.
        (clobber_what_p_points_to): Remove.
        (clobber_what_escaped): New function.
        (init_base_vars): Init NONLOCAL and ESCAPED.
        (do_sd_constraint): Do not propagate the solution from ESCAPED
        but use ESCAPED as a placeholder.
        (solve_graph): Likewise.
        * tree-flow.h (clobber_what_p_points_to): Remove.
        (clobber_what_escaped): Declare.
        * tree-ssa-alias.c (set_initial_properties): Call it.
        Remove code clobbering escaped pointers.

        * gcc.dg/torture/pr36373-1.c: New testcase.
        * gcc.dg/torture/pr36373-2.c: Likewise.
        * gcc.dg/torture/pr36373-3.c: Likewise.
        * gcc.dg/torture/pr36373-4.c: Likewise.
        * gcc.dg/torture/pr36373-5.c: Likewise.
        * gcc.dg/torture/pr36373-6.c: Likewise.
        * gcc.dg/torture/pr36373-7.c: Likewise.
        * gcc.dg/torture/pr36373-8.c: Likewise.
        * gcc.dg/torture/pr36373-9.c: Likewise.
        * gcc.dg/torture/pr36373-10.c: Likewise.
        * gcc.dg/torture/pr36400.c: Likewise.
        * gcc.c-torture/execute/pta-field-1.c: Likewise.
        * gcc.c-torture/execute/pta-field-2.c: Likewise.
        * gcc.dg/tree-ssa/loadpre8.c: Remove XFAIL.
        * gcc.dg/tree-ssa/pr24287.c: XFAIL.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pta-field-1.c
    trunk/gcc/testsuite/gcc.c-torture/execute/pta-field-2.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-1.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-10.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-2.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-3.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-4.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-5.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-6.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-7.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-8.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36373-9.c
    trunk/gcc/testsuite/gcc.dg/torture/pr36400.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #8 from rguenth at gcc dot gnu dot org  2008-06-28 11:19 -------
Fixed for 4.4.0.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|4.1.2                       |4.1.2 4.4.0
            Summary|[4.2/4.3/4.4 Regression]    |[4.2/4.3 Regression] Wrong
                   |Wrong code with struct      |code with struct return
                   |return                      |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3 Regression] Wrong code with struct return

[jakub at gcc dot gnu dot org]

------- Comment #9 from jakub at gcc dot gnu dot org  2008-07-31 09:25 -------
Downgrading to P2, as the required changes are probably too big and risky for
the branches.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P1                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3 Regression] Wrong code with struct return

[ramana at icerasemi dot com]

------- Comment #10 from ramana at icerasemi dot com  2009-01-15 10:37 -------
Change CC addresses


-- 

ramana at icerasemi dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|ramana at icerasemi dot com |ramana dot r at gmail dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.2/4.3 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #11 from rguenth at gcc dot gnu dot org  2009-01-16 23:08 -------
I have no plans to fix this on the branches.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|rguenth at gcc dot gnu dot  |unassigned at gcc dot gnu
                   |org                         |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.3 Regression] Wrong code with struct return

[jsm28 at gcc dot gnu dot org]

------- Comment #12 from jsm28 at gcc dot gnu dot org  2009-03-31 20:51 -------
Closing 4.2 branch.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.2/4.3 Regression] Wrong  |[4.3 Regression] Wrong code
                   |code with struct return     |with struct return
   Target Milestone|4.2.5                       |4.3.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373

[Bug tree-optimization/36373] [4.3 Regression] Wrong code with struct return

[rguenth at gcc dot gnu dot org]

------- Comment #13 from rguenth at gcc dot gnu dot org  2009-06-17 12:37 -------
WONTFIX for 4.3.  Alias fixes are considered too risky at this stage.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
      Known to fail|                            |4.3.4
         Resolution|                            |FIXED
   Target Milestone|4.3.4                       |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36373