[Bug rtl-optimization/47138] New: backport r158175: replace dominated uses in loop-invariant

[Bug rtl-optimization/47138] New: backport r158175: replace dominated uses in loop-invariant

[bigotp at acm dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47138

           Summary: backport r158175: replace dominated uses in
                    loop-invariant
           Product: gcc
           Version: 4.4.5
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: bigotp@acm.org


While updating the msp430 back-end, I've discovered that the problem fixed in
trunk in revision 158175 bites me as well in 4.4.x and 4.5.x.  This is a
request to back-port the corresponding fix to gcc-4_4-branch and
gcc-4_5-branch.

[Bug rtl-optimization/47138] backport r158175: replace dominated uses in loop-invariant

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47138

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ebotcazou at gcc dot
                   |                            |gnu.org, jakub at gcc dot
                   |                            |gnu.org

--- Comment #1 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-01-01 08:47:45 UTC ---
This is

2010-04-09  Eric Botcazou  <ebotcazou@adacore.com>
        Bernd Schmidt  <bernds@codesourcery.com>

    * loop-invariant.c (replace_uses): New static function.
    (move_invariant_reg): Use it to ensure we can replace the uses.

We would need a testcase though.

RMs, what do you think?

[Bug rtl-optimization/47138] backport r158175: replace dominated uses in loop-invariant

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47138

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.01.01 08:48:35
                 CC|                            |rguenth at gcc dot gnu.org
     Ever Confirmed|0                           |1

[Bug rtl-optimization/47138] backport r158175: replace dominated uses in loop-invariant

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47138

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-02 17:50:02 UTC ---
The rev. doesn't have a testcase (and it didn't fix a bug?).

If you have a testcase that shows this patch fixes a regression it is ok
to backport.  If it fixes a wrong-code bug then it is also ok to backport
if you have a testcase.

[Bug rtl-optimization/47138] backport r158175: replace dominated uses in loop-invariant

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47138

--- Comment #3 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-01-02 18:18:23 UTC ---
> The rev. doesn't have a testcase (and it didn't fix a bug?).

See http://gcc.gnu.org/ml/gcc-patches/2010-04/msg00056.html

[Bug rtl-optimization/47138] backport r158175: replace dominated uses in loop-invariant

[bigotp at acm dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47138

--- Comment #4 from Peter A. Bigot <bigotp at acm dot org> 2011-01-02 18:33:21 UTC ---
Exactly: this problem also occurs with the TI msp430 target machine
description, currently maintained as a fork on the mspgcc project on
sourceforge.  I don't know how to provide a test case other than a tar file and
patch that adds that target, and a demonstration that without the referenced
change build of libgcc fails with unrecognized instruction patterns (a parallel
clobber didn't get updated, and the assert at the bottom of
cfgrtl.c:patch_jump_insn gets hit when redirect_jump fails on a target that
isn't an exit block).

On further reflection, since this is fixed in trunk and the msp430 target
wouldn't be back-ported into your repository for an existing release series,
I'm ok with closing this as not-worth-fixing.  I did, however, want an upstream
problem report on which to hang the patches that I'll be maintaining.

[Bug rtl-optimization/47138] backport r158175: replace dominated uses in loop-invariant

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47138

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

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

--- Comment #5 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-01-03 08:05:07 UTC ---
Let's be conservative.