[Bug debug/42455] New: "-fcompare-debug failure" at -O2 in 'recent' builds

[Bug debug/42455] New: "-fcompare-debug failure" at -O2 in 'recent' builds

[zsojka at seznam dot cz]

Command line:
g++ -fcompare-debug -O2 testcase.ii

Tested revisions:
r155363 - crash
r155256 - crash
r155141 - crash
r154886 - crash
r154830 - OK
r153685 - OK
4.4 - doesn't know -fcompare-debug

Output:
$ /mnt/svn/gcc-trunk/binary-155363-lto/bin/g++ -fcompare-debug testcase.ii -O2
g++: testcase.ii: -fcompare-debug failure


-- 
           Summary: "-fcompare-debug failure" at -O2 in 'recent' builds
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zsojka at seznam dot cz
  GCC host triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42455

[Bug debug/42455] "-fcompare-debug failure" at -O2 in 'recent' builds

[zsojka at seznam dot cz]

------- Comment #1 from zsojka at seznam dot cz  2009-12-22 00:07 -------
Created an attachment (id=19364)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19364&action=view)
original testcase


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42455

[Bug debug/42455] "-fcompare-debug failure" at -O2 in 'recent' builds

[zsojka at seznam dot cz]

------- Comment #2 from zsojka at seznam dot cz  2009-12-22 00:10 -------
Created an attachment (id=19365)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19365&action=view)
somewhat reduced testcase

Reducing the testcase is quite complicated, removing seemingly irrelevant lines
causes the crash to disappear.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42455

[Bug debug/42455] "-fcompare-debug failure" at -O2 in 'recent' builds

[hjl dot tools at gmail dot com]

------- Comment #3 from hjl dot tools at gmail dot com  2009-12-22 01:52 -------
It is caused by revision 154869:

http://gcc.gnu.org/ml/gcc-cvs/2009-12/msg00013.html


-- 

hjl dot tools at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-12-22 01:52:36
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42455

[Bug debug/42455] [4.5 Regression] "-fcompare-debug failure" at -O2 in 'recent' builds

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2009-12-30 20:57 -------
I'll have a look.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2009-12-22 01:52:36         |2009-12-30 20:57:19
               date|                            |
            Summary|"-fcompare-debug failure" at|[4.5 Regression] "-fcompare-
                   |-O2 in 'recent' builds      |debug failure" at -O2 in
                   |                            |'recent' builds
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42455

[Bug debug/42455] [4.5 Regression] "-fcompare-debug failure" at -O2 in 'recent' builds

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2010-01-01 18:43 -------
It's a false positive, the difference is

--- t2.gkd      2010-01-01 19:05:33.000000000 +0100
+++ t2.gk.gkd   2010-01-01 19:05:33.000000000 +0100
@@ -45,22 +45,22 @@
         ])# {*movdi_xor_rex64} (expr_list:REG_UNUSED (reg:CC 17 flags)
         (nil)))
 (insn:TI# 0 0 t2.ii:793 (set (mem/s/c:DI (plus:DI (reg/f:DI 7 sp)
-                (const_int 64 [0x40])) [5 ISRA.15+0 S8 A128])
+                (const_int 64 [0x40])) [5 ISRA.16+0 S8 A128])
         (reg:DI 2 cx [orig:62 D.xxxx._M_t._M_impl._M_header ] [62]))#
{*movdi_1
_rex64} (nil))

and similar others.  Thus we create a temporary variable name which
includes a UID which comes from gimplify.c:create_tmp_var_name.

The extra temporary comes from extra early SRA we do when building
with -g:

-! Disqualifying iter - No scalar replacements to be created.
-Marking D.3480 offset: 0, size: 8:  to be replaced.
+Candidate (3488): D.3488
+Marking D.3477 offset: 0, size: 8:  to be replaced.

-Access trees for D.3480 (UID: 3480): 
-access { base = (3480)'D.3480', offset = 0, size = 8, expr = D.3480._M_node,
ty
pe = bool, grp_write = 1, grp_read = 1, grp_hint = 0, grp_covered = 1,
grp_unsca
larizable_region = 0, grp_unscalarized_data = 0, grp_partial_lhs = 0,
grp_differ
ent_types = 1, grp_to_be_replaced = 1, grp_maybe_modified = 0,
grp_not_necessari
lly_dereferenced = 0
+Access trees for D.3477 (UID: 3477): 
+access { base = (3477)'D.3477', offset = 0, size = 8, expr = D.3477._M_node,
ty
pe = bool, grp_write = 1, grp_read = 1, grp_hint = 0, grp_covered = 1,
grp_unsca
larizable_region = 0, grp_unscalarized_data = 0, grp_partial_lhs = 0,
grp_differ
ent_types = 0, grp_to_be_replaced = 1, grp_maybe_modified = 0,
grp_not_necessari
lly_dereferenced = 0
+
+Marking iter offset: 0, size: 8:  to be replaced.
+
+Access trees for iter (UID: 3262): 
+access { base = (3262)'iter', offset = 0, size = 8, expr = iter._M_node, type
=
 bool, grp_write = 1, grp_read = 1, grp_hint = 0, grp_covered = 1,
grp_unscalari
zable_region = 0, grp_unscalarized_data = 0, grp_partial_lhs = 0,
grp_different_
types = 0, grp_to_be_replaced = 1, grp_maybe_modified = 0,
grp_not_necessarilly_
dereferenced = 0


I am testing a patch.  But in reality it will paper over a problem in SRA
that causes code-generation differences dependent on oder of analyzing
accesses.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jamborm at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42455

[Bug debug/42455] [4.5 Regression] "-fcompare-debug failure" at -O2 in 'recent' builds

[rguenth at gcc dot gnu dot org]

------- Comment #6 from rguenth at gcc dot gnu dot org  2010-01-01 20:22 -------
Subject: Bug 42455

Author: rguenth
Date: Fri Jan  1 20:22:17 2010
New Revision: 155559

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=155559
Log:
2010-01-01  Richard Guenther  <rguenther@suse.de>

        PR debug/42455
        * tree-sra.c (analyze_all_variable_accesses): Work in DECL_UID
        order.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/tree-sra.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42455

[Bug debug/42455] [4.5 Regression] "-fcompare-debug failure" at -O2 in 'recent' builds

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2010-01-01 20:22 -------
Fixed.


-- 

rguenth at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42455