[Bug rtl-optimization/44374] New: Hoist same instructions in different branches

[Bug rtl-optimization/44374] New: Hoist same instructions in different branches

[carrot at google dot com]

Compile the attached test case with options -march=armv7-a -mthumb -Os, 
this code snippet 

  if (native)
    dlmalloc_walk_heap(heap_chunk_callback, (void *)&ctx);
  else
    dvmHeapSourceWalk(heap_chunk_callback, (void *)&ctx);

is compiled to:

        cbz     r5, .L2
        ldr     r0, .L4            // A
        mov     r1, sp             // B
        bl      dlmalloc_walk_heap
        b       .L1
.L2:
        ldr     r0, .L4            // C
        mov     r1, sp             // D
        bl      dvmHeapSourceWalk
.L1:
        add     sp, sp, #44
        pop     {r4, r5, pc}
.L5:
        .align  2
.L4:
        .word   heap_chunk_callback

Note that instructions AB are equal to instructions CD, if we move the previous
conditional branch after B, then CD can be removed.

Option -O2 and target arm have the same problem.

Which pass should do this optimization? pass_rtl_hoist?


-- 
           Summary: Hoist same instructions in different branches
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: carrot at google dot com
 GCC build triplet: i686-linux
  GCC host triplet: i686-linux
GCC target triplet: arm-eabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

[Bug rtl-optimization/44374] Hoist same instructions in different branches

[carrot at google dot com]

------- Comment #1 from carrot at google dot com  2010-06-02 08:20 -------
Created an attachment (id=20805)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20805&action=view)
test case


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

[Bug rtl-optimization/44374] Hoist same instructions in different branches

[steven at gcc dot gnu dot org]

------- Comment #2 from steven at gcc dot gnu dot org  2010-06-02 08:54 -------
HOIST should do this.  You will have to check in the RTL dumps that the code is
exposed properly to this optimization.


-- 

steven at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2010-06-02 08:54:40
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

[Bug rtl-optimization/44374] Hoist same instructions in different branches

[bernds at gcc dot gnu dot org]

------- Comment #3 from bernds at gcc dot gnu dot org  2010-09-23 10:04 -------
Subject: Bug 44374

Author: bernds
Date: Thu Sep 23 10:04:33 2010
New Revision: 164552

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164552
Log:
        PR rtl-optimization/44374
        * basic-block.h (enum bb_flags): Add BB_MODIFIED.
        * df-core.c (df_set_bb_dirty): Set it.
        * ifcvt.c (find_memory): Remove function.
        (dead_or_predicable): Use can_move_insns_across.
        * df.h (can_move_insns_across): Declare function.
        * cfgcleanup.c (block_was_dirty): New static variable.
        (try_crossjump_bb, try_forward_edges): Test BB_MODIFIED flag rather
        than df_get_bb_dirty.
        (try_head_merge_bb): New static function.
        (try_optimize_cfg): Call it.  Call df_analyze if block_was_dirty
        is set.
        * df-problems.c: Include "target.h"
        (df_simulate_find_uses): New static function.
        (MEMREF_NORMAL, MEMREF_VOLATILE): New macros.
        (find_memory, find_memory_store): New static functions.
        (can_move_insns_across): New function.
        * Makefile.in (df-problems.o): Update dependencies.

testsuite/
        PR rtl-optimization/44374
        * gcc.target/arm/headmerge-1.c: New test.
        * gcc.target/arm/headmerge-2.c: New test.
        * gcc.target/i386/headmerge-1.c: New test.
        * gcc.target/i386/headmerge-2.c: New test.

Added:
    trunk/gcc/config/i386/core2.md
    trunk/gcc/testsuite/gcc.target/arm/headmerge-1.c
    trunk/gcc/testsuite/gcc.target/arm/headmerge-2.c
    trunk/gcc/testsuite/gcc.target/i386/headmerge-1.c
    trunk/gcc/testsuite/gcc.target/i386/headmerge-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/Makefile.in
    trunk/gcc/basic-block.h
    trunk/gcc/cfgcleanup.c
    trunk/gcc/df-core.c
    trunk/gcc/df-problems.c
    trunk/gcc/df.h
    trunk/gcc/ifcvt.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

[Bug rtl-optimization/44374] Hoist same instructions in different branches

[bernds at gcc dot gnu dot org]

------- Comment #4 from bernds at gcc dot gnu dot org  2010-09-23 10:08 -------
Fixed.


-- 

bernds at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

[Bug rtl-optimization/44374] Hoist same instructions in different branches

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

H.J. Lu <hjl.tools at gmail dot com> changed:

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

--- Comment #5 from H.J. Lu <hjl.tools at gmail dot com> 2010-11-03 18:25:22 UTC ---
Patch was reverted:

http://gcc.gnu.org/ml/gcc-cvs/2010-11/msg00145.html

[Bug rtl-optimization/44374] Hoist same instructions in different branches

[bernds at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

--- Comment #6 from Bernd Schmidt <bernds at gcc dot gnu.org> 2010-12-14 00:23:48 UTC ---
Author: bernds
Date: Tue Dec 14 00:23:40 2010
New Revision: 167779

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=167779
Log:
gcc/
    PR rtl-optimization/44374
    Reapply patch with fixes.
    * basic-block.h (enum bb_flags): Add BB_MODIFIED.
    * df-core.c (df_set_bb_dirty): Set it.
    * ifcvt.c (find_memory): Remove function.
    (dead_or_predicable): Use can_move_insns_across.
    * df.h (can_move_insns_across): Declare function.
    * cfgcleanup.c (block_was_dirty): New static variable.
    (flow_find_head_matching_sequence): Test for epilogue notes.
    (try_crossjump_bb, try_forward_edges): Test BB_MODIFIED flag rather
    than df_get_bb_dirty.
    (try_head_merge_bb): New static function.
    (try_optimize_cfg): Call it.  Call df_analyze if block_was_dirty
    is set.
    * df-problems.c: Include "target.h"
    (df_simulate_find_uses): New static function.
    (MEMREF_NORMAL, MEMREF_VOLATILE): New macros.
    (find_memory, find_memory_store): New static functions.
    (can_move_insns_across): New function.
    * Makefile.in (df-problems.o): Update dependencies.

gcc/testsuite/
    PR rtl-optimization/44374
    Reapply patch with fixes.
    * gcc.target/arm/headmerge-1.c: New test.
    * gcc.target/arm/headmerge-2.c: New test.
    * gcc.target/i386/headmerge-1.c: New test.
    * gcc.target/i386/headmerge-2.c: New test.


Added:
    trunk/gcc/testsuite/gcc.target/arm/headmerge-1.c
    trunk/gcc/testsuite/gcc.target/arm/headmerge-2.c
    trunk/gcc/testsuite/gcc.target/i386/headmerge-1.c
    trunk/gcc/testsuite/gcc.target/i386/headmerge-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/Makefile.in
    trunk/gcc/basic-block.h
    trunk/gcc/cfgcleanup.c
    trunk/gcc/df-core.c
    trunk/gcc/df-problems.c
    trunk/gcc/df.h
    trunk/gcc/ifcvt.c
    trunk/gcc/testsuite/ChangeLog

[Bug rtl-optimization/44374] Hoist same instructions in different branches

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bernds at gcc dot gnu.org,
                   |                            |steven at gcc dot gnu.org

--- Comment #7 from Steven Bosscher <steven at gcc dot gnu.org> 2011-04-02 13:47:01 UTC ---
Is this now fixed, or are there reasons why the bug status is REOPENED?

[Bug rtl-optimization/44374] Hoist same instructions in different branches

[bernds at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44374

Bernd Schmidt <bernds at gcc dot gnu.org> changed:

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

--- Comment #8 from Bernd Schmidt <bernds at gcc dot gnu.org> 2011-04-02 13:51:21 UTC ---
Fixed again.