[Bug tree-optimization/47179] New: [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[Bug tree-optimization/47179] New: [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47179

           Summary: [4.5/4.6 Regression] SPU: errno misoptimization around
                    malloc call
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: uweigand@gcc.gnu.org
                CC: rguenther@suse.de
            Target: spu-elf


The problem described in PR 42944 is still present on SPU.

This is because the SPU system library (newlib) uses:

  extern struct _reent _impure_data;
  #define errno (_impure_data._errno)

in its version of errno.h, but GCC's call_may_clobber_ref_p_1 routine assumes
errno is always either a global or else accessed via a pointer.  It does not
handle component references.

(Note that the problem seems to be specific to the SPU, because of an
optimization that makes use of the fact that SPU code is always
single-threaded.  On other platforms, newlib accesses errno via a pointer as
well.)

[Bug tree-optimization/47179] [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47179

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011.01.11 12:14:27
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
   Target Milestone|---                         |4.5.3
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-11 12:14:27 UTC ---
Mine.

[Bug tree-optimization/47179] [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47179

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-14 15:02:27 UTC ---
Author: rguenth
Date: Fri Jan 14 15:02:20 2011
New Revision: 168788

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=168788
Log:
2011-01-14  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/47179
    * target.def (ref_may_alias_errno): New target hook.
    * targhooks.h (default_ref_may_alias_errno): Declare.
    * targhooks.c: Include tree-ssa-alias.h and tree-flow.h.
    (default_ref_may_alias_errno): New function.
    * target.h (struct ao_ref_s): Declare.
    * tree-ssa-alias.c: Include target.h.
    (call_may_clobber_ref_p_1): Use the ref_may_alias_errno target hook.
    * Makefile.in (tree-ssa-alias.o): Adjust dependencies.
    (targhooks.o): Likewise.
    * doc/tm.texi.in (TARGET_REF_MAY_ALIAS_ERRNO): Document.
    * doc/tm.texi (TARGET_REF_MAY_ALIAS_ERRNO): Copy documentation.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/Makefile.in
    trunk/gcc/doc/tm.texi
    trunk/gcc/doc/tm.texi.in
    trunk/gcc/target.def
    trunk/gcc/target.h
    trunk/gcc/targhooks.c
    trunk/gcc/targhooks.h
    trunk/gcc/tree-ssa-alias.c

[Bug tree-optimization/47179] [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47179

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|rguenth at gcc dot gnu.org  |uweigand at gcc dot gnu.org

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-14 15:04:16 UTC ---
Re-assigning to Uli for the SPU part.  I suggest not fixing this for 4.5
(it's a pretty arcane corner case anyway, esp. on SPU I guess).

[Bug tree-optimization/47179] [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47179

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4
                 CC|                            |jakub at gcc dot gnu.org

[Bug tree-optimization/47179] [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47179

--- Comment #4 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2011-01-18 20:13:59 UTC ---
Author: uweigand
Date: Tue Jan 18 20:13:56 2011
New Revision: 168961

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=168961
Log:
    PR tree-optimization/47179
    * config/spu/spu.c (spu_ref_may_alias_errno): New function.
    (TARGET_REF_MAY_ALIAS_ERRNO): Define.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/spu/spu.c

[Bug tree-optimization/47179] [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47179

Ulrich Weigand <uweigand at gcc dot gnu.org> changed:

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

--- Comment #5 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2011-01-18 20:16:10 UTC ---
Fixed.

[Bug tree-optimization/47179] [4.5/4.6 Regression] SPU: errno misoptimization around malloc call

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47179

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.5.3                       |4.6.0