[Bug target/41081] New: redundant ZERO_EXTENDs

[Bug target/41081] New: redundant ZERO_EXTENDs

[amodra at bigpond dot net dot au]

Linux kernel block sha1 code on powerpc64 has many redundant clrldi
instructions, significantly slowing execution time.  Current gcc seems to
generate more of these than 3.4.5 which is in turn worse than 3.3.

Breakdown of clrldi insns
- 140 redundant clrldi on rotate insn output
- 79 other redundant clrldi
- 11 useful


-- 
           Summary: redundant ZERO_EXTENDs
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: amodra at bigpond dot net dot au
GCC target triplet: powerpc64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at bigpond dot net dot au]

------- Comment #1 from amodra at bigpond dot net dot au  2009-08-16 02:41 -------
Created an attachment (id=18372)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18372&action=view)
block sha1 source

blk_SHA1Block takes all its input from unsigned ints and only writes to
unsigned ints, thus all zero_extends in the body of this function are redundant


-- 

amodra at bigpond dot net dot au changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |amodra at bigpond dot net
                   |dot org                     |dot au
             Status|UNCONFIRMED                 |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at bigpond dot net dot au]

------- Comment #2 from amodra at bigpond dot net dot au  2009-08-16 02:45 -------
Created an attachment (id=18373)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18373&action=view)
Cure the zero_extends on rotate output

This patch teaches gcc that the powerpc rotate/shift unit appropriately zero or
sign extends to the full register width, at least for the most common case of
SImode operations.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at bigpond dot net dot au]

------- Comment #3 from amodra at bigpond dot net dot au  2009-08-16 03:05 -------
Created an attachment (id=18374)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18374&action=view)
aims to teach gcc that rotate/shift insn input register's high bits are ignored

This patch is aimed at the "79 other redundant clrldi", removing 59 cases on
rotate/shift input.  I'm not particularly happy with it due to hack for
LOAD_EXTEND_OP zero_extends.  Before I discovered that particular problem,
fwprop seemed a natural place to teach gcc about insn inputs.  If we don't
leave those zero_extends alone, some rotate insns will take their input
directly from the load, while other insns still need the zero_extend.  This
prevents combine from removing the zero_extend on loads.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at bigpond dot net dot au]

------- Comment #4 from amodra at bigpond dot net dot au  2009-08-16 03:07 -------
Please ignore the RS6000_ALT_REG_ALLOC_ORDER hunk in rs6000-2.diff.  I forgot
to edit that out..


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[steven at gcc dot gnu dot org]

------- Comment #5 from steven at gcc dot gnu dot org  2009-08-16 09:50 -------
If you are going to submit these patches, can you please make
EXTEND_INPUT_REG_OP a target hook instead of a macro?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at gcc dot gnu dot org]

------- Comment #6 from amodra at gcc dot gnu dot org  2009-08-23 02:57 -------
Subject: Bug 41081

Author: amodra
Date: Sun Aug 23 02:57:26 2009
New Revision: 151022

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=151022
Log:
        PR target/41081
        * fwprop.c (try_fwprop_subst): Allow multiple sets.
        (get_reg_use_in): New function.
        (forward_propagate_subreg): Propagate through subreg of zero_extend
        or sign_extend.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fwprop.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at bigpond dot net dot au]

------- Comment #7 from amodra at bigpond dot net dot au  2009-08-23 03:49 -------
.


-- 

amodra at bigpond dot net dot au changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at gcc dot gnu dot org]

------- Comment #8 from amodra at gcc dot gnu dot org  2009-08-23 03:53 -------
Subject: Bug 41081

Author: amodra
Date: Sun Aug 23 03:53:02 2009
New Revision: 151025

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=151025
Log:
        PR target/41081
        * config/rs6000/rs6000.md (rotlsi3_64, ashlsi3_64, lshrsi3_64,
        ashrsi3_64): New.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/rs6000/rs6000.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[hjl dot tools at gmail dot com]

------- Comment #9 from hjl dot tools at gmail dot com  2009-08-23 19:55 -------
Is it possible to extend this to address another zero extend bug, PR 17387?


-- 

hjl dot tools at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl dot tools at gmail dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at bigpond dot net dot au]

------- Comment #10 from amodra at bigpond dot net dot au  2009-08-24 02:38 -------
No, that looks like a different problem.  It affects powerpc64 too.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[amodra at gcc dot gnu dot org]

------- Comment #11 from amodra at gcc dot gnu dot org  2009-08-30 06:09 -------
Subject: Bug 41081

Author: amodra
Date: Sun Aug 30 06:09:42 2009
New Revision: 151221

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=151221
Log:
        PR target/41081
        * fwprop.c (get_reg_use_in): Delete.
        (free_load_extend): New function.
        (forward_propagate_subreg): Use it.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fwprop.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[bergner at gcc dot gnu dot org]

------- Comment #12 from bergner at gcc dot gnu dot org  2009-10-02 17:12 -------
Subject: Bug 41081

Author: bergner
Date: Fri Oct  2 17:12:31 2009
New Revision: 152411

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=152411
Log:
        Backport from mainline:

        2009-08-23  Alan Modra  <amodra@bigpond.net.au>
        PR target/41081
        * config/rs6000/rs6000.md (rotlsi3_64, ashlsi3_64, lshrsi3_64,
        ashrsi3_64): New.


        Backport from 4.3 branch:

        2009-09-25  Alan Modra  <amodra@bigpond.net.au>
        * config/rs6000/rs6000.md (load_toc_v4_PIC_3c): Correct POWER
        form of instruction.

        2009-09-23  Alan Modra  <amodra@bigpond.net.au>
        PR target/40473
        * config/rs6000/rs6000.c (rs6000_output_function_prologue): Don't
        call final to emit non-scheduled prologue, instead insert at entry.

Modified:
    branches/ibm/gcc-4_3-branch/gcc/ChangeLog.ibm
    branches/ibm/gcc-4_3-branch/gcc/config/rs6000/rs6000.c
    branches/ibm/gcc-4_3-branch/gcc/config/rs6000/rs6000.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[bergner at gcc dot gnu dot org]

------- Comment #13 from bergner at gcc dot gnu dot org  2009-10-03 01:39 -------
Subject: Bug 41081

Author: bergner
Date: Sat Oct  3 01:39:14 2009
New Revision: 152430

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=152430
Log:
        Backport from mainline.

        2009-08-30  Alan Modra  <amodra@bigpond.net.au>

        PR target/41081
        * fwprop.c (get_reg_use_in): Delete.
        (free_load_extend): New function.
        (forward_propagate_subreg): Use it.

        2009-08-23  Alan Modra  <amodra@bigpond.net.au>

        PR target/41081
        * fwprop.c (try_fwprop_subst): Allow multiple sets.
        (get_reg_use_in): New function.
        (forward_propagate_subreg): Propagate through subreg of zero_extend
        or sign_extend.

        2009-05-08  Paolo Bonzini  <bonzini@gnu.org>

        PR rtl-optimization/33928
        PR 26854
        * fwprop.c (use_def_ref, get_def_for_use, bitmap_only_bit_bitween,
        process_uses, build_single_def_use_links): New.
        (update_df): Update use_def_ref.
        (forward_propagate_into): Use get_def_for_use instead of use-def
        chains.
        (fwprop_init): Call build_single_def_use_links and let it initialize
        dataflow.
        (fwprop_done): Free use_def_ref.
        (fwprop_addr): Eliminate duplicate call to df_set_flags.
        * df-problems.c (df_rd_simulate_artificial_defs_at_top,
        df_rd_simulate_one_insn): New.
        (df_rd_bb_local_compute_process_def): Update head comment.
        (df_chain_create_bb): Use the new RD simulation functions.
        * df.h (df_rd_simulate_artificial_defs_at_top,
        df_rd_simulate_one_insn): New.
        * opts.c (decode_options): Enable fwprop at -O1.
        * doc/invoke.texi (-fforward-propagate): Document this.

Modified:
    branches/ibm/gcc-4_3-branch/gcc/ChangeLog.ibm
    branches/ibm/gcc-4_3-branch/gcc/REVISION
    branches/ibm/gcc-4_3-branch/gcc/df-problems.c
    branches/ibm/gcc-4_3-branch/gcc/df.h
    branches/ibm/gcc-4_3-branch/gcc/doc/invoke.texi
    branches/ibm/gcc-4_3-branch/gcc/fwprop.c
    branches/ibm/gcc-4_3-branch/gcc/opts.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[bergner at gcc dot gnu dot org]

------- Comment #14 from bergner at gcc dot gnu dot org  2010-04-28 22:53 -------
Subject: Bug 41081

Author: bergner
Date: Wed Apr 28 22:52:57 2010
New Revision: 158846

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=158846
Log:
        Backport from mainline:
        2009-08-23  Alan Modra  <amodra@bigpond.net.au>

        PR target/41081
        * config/rs6000/rs6000.md (rotlsi3_64, ashlsi3_64, lshrsi3_64,
        ashrsi3_64): New.

Modified:
    branches/ibm/gcc-4_4-branch/gcc/ChangeLog.ibm
    branches/ibm/gcc-4_4-branch/gcc/config/rs6000/rs6000.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081

[Bug target/41081] redundant ZERO_EXTENDs

[bergner at gcc dot gnu dot org]

------- Comment #15 from bergner at gcc dot gnu dot org  2010-04-29 14:34 -------
Subject: Bug 41081

Author: bergner
Date: Thu Apr 29 14:34:35 2010
New Revision: 158902

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=158902
Log:
        Backport from mainline.

        2009-08-30  Alan Modra  <amodra@bigpond.net.au>

        PR target/41081
        * fwprop.c (get_reg_use_in): Delete.
        (free_load_extend): New function.
        (forward_propagate_subreg): Use it.

        2009-08-23  Alan Modra  <amodra@bigpond.net.au>

        PR target/41081
        * fwprop.c (try_fwprop_subst): Allow multiple sets.
        (get_reg_use_in): New function.
        (forward_propagate_subreg): Propagate through subreg of zero_extend
        or sign_extend.

        2009-05-08  Paolo Bonzini  <bonzini@gnu.org>

        PR rtl-optimization/33928
        PR 26854
        * fwprop.c (use_def_ref, get_def_for_use, bitmap_only_bit_bitween,
        process_uses, build_single_def_use_links): New.
        (update_df): Update use_def_ref.
        (forward_propagate_into): Use get_def_for_use instead of use-def
        chains.
        (fwprop_init): Call build_single_def_use_links and let it initialize
        dataflow.
        (fwprop_done): Free use_def_ref.
        (fwprop_addr): Eliminate duplicate call to df_set_flags.
        * df-problems.c (df_rd_simulate_artificial_defs_at_top,
        df_rd_simulate_one_insn): New.
        (df_rd_bb_local_compute_process_def): Update head comment.
        (df_chain_create_bb): Use the new RD simulation functions.
        * df.h (df_rd_simulate_artificial_defs_at_top,
        df_rd_simulate_one_insn): New.
        * opts.c (decode_options): Enable fwprop at -O1.
        * doc/invoke.texi (-fforward-propagate): Document this.

Modified:
    branches/ibm/gcc-4_4-branch/gcc/ChangeLog.ibm
    branches/ibm/gcc-4_4-branch/gcc/df-problems.c
    branches/ibm/gcc-4_4-branch/gcc/df.h
    branches/ibm/gcc-4_4-branch/gcc/doc/invoke.texi
    branches/ibm/gcc-4_4-branch/gcc/fwprop.c
    branches/ibm/gcc-4_4-branch/gcc/opts.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081