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* [Bug c/28727] New: Wrong code generated (assignment incorrectly optimized out)
@ 2006-08-14 18:58 qrczak at knm dot org dot pl
2006-08-14 19:00 ` [Bug c/28727] " qrczak at knm dot org dot pl
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: qrczak at knm dot org dot pl @ 2006-08-14 18:58 UTC (permalink / raw)
To: gcc-bugs
The attached module, when compiled with -O2, has wrong code generated for the
last set_global_field call. The assembly shows:
leal 4(%edx), %eax
cmpl marked_limit, %eax
movl BadArguments, %ecx
movl $record_12420+4, (%edx)
movl %eax, marked_top
jbe .L28
movl %ecx, record_12420+4
call gc
.L28:
leave
xorl %eax, %eax
ret
while the assignment of BadArguments (from %ecx) to record_12420+4 should be
performed unconditionally, as can be easily deduced from the source.
This is gcc-4.2.0-0.20060806r115974. The bug doesn't manifest without -O2 or
when the number of set_global_field calls is reduced.
--
Summary: Wrong code generated (assignment incorrectly optimized
out)
Product: gcc
Version: 4.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: qrczak at knm dot org dot pl
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28727
^ permalink raw reply [flat|nested] 5+ messages in thread* [Bug c/28727] Wrong code generated (assignment incorrectly optimized out) 2006-08-14 18:58 [Bug c/28727] New: Wrong code generated (assignment incorrectly optimized out) qrczak at knm dot org dot pl @ 2006-08-14 19:00 ` qrczak at knm dot org dot pl 2006-08-14 19:11 ` [Bug middle-end/28727] " pinskia at gcc dot gnu dot org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: qrczak at knm dot org dot pl @ 2006-08-14 19:00 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from qrczak at knm dot org dot pl 2006-08-14 19:00 ------- Created an attachment (id=12075) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=12075&action=view) Test case -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28727 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/28727] Wrong code generated (assignment incorrectly optimized out) 2006-08-14 18:58 [Bug c/28727] New: Wrong code generated (assignment incorrectly optimized out) qrczak at knm dot org dot pl 2006-08-14 19:00 ` [Bug c/28727] " qrczak at knm dot org dot pl @ 2006-08-14 19:11 ` pinskia at gcc dot gnu dot org 2006-08-26 19:15 ` qrczak at knm dot org dot pl 2006-08-26 20:46 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2006-08-14 19:11 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from pinskia at gcc dot gnu dot org 2006-08-14 19:10 ------- Most likely related to PR 28003. -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- BugsThisDependsOn| |28003 Keywords| |alias http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28727 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/28727] Wrong code generated (assignment incorrectly optimized out) 2006-08-14 18:58 [Bug c/28727] New: Wrong code generated (assignment incorrectly optimized out) qrczak at knm dot org dot pl 2006-08-14 19:00 ` [Bug c/28727] " qrczak at knm dot org dot pl 2006-08-14 19:11 ` [Bug middle-end/28727] " pinskia at gcc dot gnu dot org @ 2006-08-26 19:15 ` qrczak at knm dot org dot pl 2006-08-26 20:46 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: qrczak at knm dot org dot pl @ 2006-08-26 19:15 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from qrczak at knm dot org dot pl 2006-08-26 19:15 ------- The problem seems to be caused by illegal type punning. Rewriting the code to avoid pointer casts cures the bug, and -fno-strict-aliasing cures it too, so gcc is probably correct. Thanks to Michael Veksler for pointing this out. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28727 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/28727] Wrong code generated (assignment incorrectly optimized out) 2006-08-14 18:58 [Bug c/28727] New: Wrong code generated (assignment incorrectly optimized out) qrczak at knm dot org dot pl ` (2 preceding siblings ...) 2006-08-26 19:15 ` qrczak at knm dot org dot pl @ 2006-08-26 20:46 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2006-08-26 20:46 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from pinskia at gcc dot gnu dot org 2006-08-26 20:46 ------- *** This bug has been marked as a duplicate of 21920 *** -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |DUPLICATE http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28727 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2006-08-26 20:46 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2006-08-14 18:58 [Bug c/28727] New: Wrong code generated (assignment incorrectly optimized out) qrczak at knm dot org dot pl 2006-08-14 19:00 ` [Bug c/28727] " qrczak at knm dot org dot pl 2006-08-14 19:11 ` [Bug middle-end/28727] " pinskia at gcc dot gnu dot org 2006-08-26 19:15 ` qrczak at knm dot org dot pl 2006-08-26 20:46 ` pinskia at gcc dot gnu dot org
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