[Bug debug/44901] New: [4.6 Regression] -fcompare-debug failure for C++ i386.c

[Bug debug/44901] New: [4.6 Regression] -fcompare-debug failure for C++ i386.c

[amylaar at gcc dot gnu dot org]

We currently have a bootstrap-lean failure on tree-predcom.c .
The preprocessed file shows a compare-debug failure for
gcc (GCC) 4.6.0 20100708 (experimental), but not for
gcc (GCC) 4.6.0 20100705 (experimental), gcc (GCC) 4.6.0 20100630
(experimental)
or gcc (GCC) 4.4.4 20100630 (Red Hat 4.4.4-10).


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           Summary: [4.6 Regression] -fcompare-debug failure for C++ i386.c
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Keywords: build
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: amylaar at gcc dot gnu dot org
  GCC host triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for C++ i386.c

[amylaar at gcc dot gnu dot org]

------- Comment #1 from amylaar at gcc dot gnu dot org  2010-07-10 10:53 -------
Created an attachment (id=21174)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21174&action=view)
test case - compressed with xz

$ ./bld-20100708/gcc/xgcc -B./bld-20100708/gcc -c -fpreprocessed  -g -O2
-fomit-frame-pointer -fcompare-debug -DIN_GCC   -W -Wall -Wwrite-strings
-Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wmissing-format-attribute
-pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -Werror
-Wold-style-definition -Wc++-compat -fno-common treepred.c
xgcc: error: treepred.c: -fcompare-debug failure


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for tree-predcom.c

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.6 Regression] -fcompare- |[4.6 Regression] -fcompare-
                   |debug failure for C++ i386.c|debug failure for tree-
                   |                            |predcom.c
   Target Milestone|---                         |4.6.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for tree-predcom.c

[hjl dot tools at gmail dot com]

------- Comment #2 from hjl dot tools at gmail dot com  2010-07-10 15:37 -------
It is caused by revision 161862:

http://gcc.gnu.org/ml/gcc-cvs/2010-07/msg00216.html


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hjl dot tools at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |froydnj at codesourcery dot
                   |                            |com
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2010-07-10 15:37:50
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for tree-predcom.c

[jakub at gcc dot gnu dot org]

------- Comment #3 from jakub at gcc dot gnu dot org  2010-07-12 10:19 -------
Fails even with -fno-var-tracking, so does not look VTA related.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for tree-predcom.c

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2010-07-12 14:26 -------
Created an attachment (id=21183)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21183&action=view)
pr44901.i

Reduced testcase:

./xgcc -B ./ -S -m32 -fcompare-debug -O2 -fno-var-tracking /tmp/pr44901.i -w
xgcc: error: /tmp/pr44901.i: -fcompare-debug failure


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for tree-predcom.c

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2010-07-12 14:50 -------
All the unordered removals for local_decls are obviously wrong.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for tree-predcom.c

[froydnj at codesourcery dot com]

------- Comment #6 from froydnj at codesourcery dot com  2010-07-12 14:56 -------
Subject: Re:  [4.6 Regression] -fcompare-debug failure for
        tree-predcom.c

Why are the unordered removals "obviously" wrong?  And why, if they're
"obviously" wrong, does this problem only turn up with a specific
bootstrap config?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for tree-predcom.c

[jakub at gcc dot gnu dot org]

------- Comment #7 from jakub at gcc dot gnu dot org  2010-07-12 15:23 -------
Created an attachment (id=21185)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21185&action=view)
gcc46-pr44901.patch

Untested fix.

Expansion depends on the order of vars in cfun->local_decls, see e.g.
expand_used_vars.  The removal of vars from local_decls sometimes depends on
whether compiling with -g or -g0, and the unordered removal changes the
relative ordering between vars that are going to get pseudos/memory assigned,
which means -g/-g0 affect (resp. might affect) code generation, which is
undesirable.


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jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901

[Bug debug/44901] [4.6 Regression] -fcompare-debug failure for tree-predcom.c

[jakub at gcc dot gnu dot org]

------- Comment #8 from jakub at gcc dot gnu dot org  2010-07-13 07:00 -------
Subject: Bug 44901

Author: jakub
Date: Tue Jul 13 06:59:56 2010
New Revision: 162126

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=162126
Log:
        PR debug/44901
        * vec.h (VEC_block_remove): Fix comment.
        * tree-ssa-live.c (remove_unused_locals): Don't use
        VEC_unordered_remove on local_decls, instead replace a single
        vector element in each iteration if at least one element had
        to be removed and VEC_truncate at the end.
        * omp-low.c (expand_omp_taskreg): Likewise.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/omp-low.c
    trunk/gcc/tree-ssa-live.c
    trunk/gcc/vec.h


------- Comment #9 from jakub at gcc dot gnu dot org  2010-07-13 11:40 -------
Fixed.


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jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44901