Platform:
Fedora release 8 (Werewolf)
Linux chevy.lbl.gov 2.6.23.15-137.fc8 #1 SMP Sun Feb 10 17:03:13 EST 2008
x86_64 x86_64 x86_64 GNU/Linux
% g++ -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /net/chevy/raid1/rwgk/gcc_trunk/configure
--prefix=/net/cci-filer1/vol1/tmp/rwgk/gcc_trunk_141361_fc8_x86_64
--enable-languages=c,c++,fortran
Thread model: posix
gcc version 4.4.0 20081025 (experimental) (GCC)
Problematic C++ code fragment:
rot_mx proper_r = r;
int proper_order = type_;
if (proper_order < 0) {
std::cout << "A branch" << std::endl;
proper_order *= -1;
proper_r = -proper_r;
}
if (proper_order > 1) {
std::cout << "B branch" << std::endl;
...
}
Compiled with (just to show optimization options; please ignore the rest):
g++ -o cctbx/sgtbx/rot_mx_info.o -c -fno-strict-aliasing -fPIC
-ftemplate-depth-120 -w -DNDEBUG -O3 -ffast-math -fno-associative-math
-ftrapping-math -DBOOST_DISABLE_THREADS -fopenmp -Iinclude
-I/net/chevy/raid1/rwgk/hot/include -I/net/chevy/raid1/rwgk/as_in_cvs/include
"-I/net/chevy/raid1/rwgk/hot/b u f/include" -I/net/chevy/raid1/rwgk/as_in_cvs
-I/net/chevy/raid1/rwgk/hot/boost
/net/chevy/raid1/rwgk/as_in_cvs/cctbx/sgtbx/rot_mx_info.cpp
Given type_ = -2, the print statements should show
A branch
B branch
but only "B branch" is actually shown.
I can work around this problem either by compiling without optimizations, or by
replacing the code above with:
rot_mx proper_r;
int proper_order;
if (type_ < 0) {
std::cout << "A branch" << std::endl;
proper_order = -type_;
proper_r = -r;
}
else {
std::cout << "A else branch" << std::endl;
proper_order = type_;
proper_r = r;
}
if (proper_order > 1) {
std::cout << "B branch" << std::endl;
...
}
I tried to reduce the problem, but it turns out to be tricky. The code above is
part of a shared library (.so). Simply moving it into the same translation unit
as the calling code makes the error go away.
Before I spend more time on this, does the problem look familiar? (I.e. could
it be that this bug was reported already?)
I could give you a self-contained but very large reproducer. This would enable
you to inspect the generated code, and maybe give us a clue how to construct a
minimal reproducer.
--
Summary: code generation error
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rwgk at yahoo dot com
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37922
