[Bug c++/47541] New: For integer pointers, the value of ++*p is not written back to memory
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47541 Summary: For integer pointers, the value of ++*p is not written back to memory Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: veks...@il.ibm.com The problem occurs in a copy constructor both for 386 and for X86-64. This is a copy constructor of a reference counting object which uses int* to keep track of the number of copies of an "A" object. The copy constructor messes up, it calculates the new count (in some cases), but forgets to write it back to the int*. The attached test case is a bit complicated, yet it is a simplification of real code. There are two options to see the issue: $ g++ -O2 -g refcount.cpp && ./a.out Segmentation fault (core dumped) $ g++ -O2 -DTRACE -g refcount.cpp && ./a.out A::A() RefCount() count=1 RefCount(const RefCount&) count=1 ~RefCount() A::~A count=0 Segmentation fault (core dumped) As you can see, the reference is not incremented when it should be. $ g++ -v Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.5.1/lto-wrapper Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --enable-languages=c,c++,objc,obj-c++,java,fortran,ada,lto --enable-plugin --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux Thread model: posix gcc version 4.5.1 20100924 (Red Hat 4.5.1-4) (GCC)
[Bug c++/47541] For integer pointers, the value of ++*p is not written back to memory
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47541 Michael Veksler changed: What|Removed |Added Version|4.5.1 |4.6.0 --- Comment #1 from Michael Veksler 2011-01-30 09:39:50 UTC --- I recreated this bug, with the same attachment, for 4.6.0 20110129 (experimental): Target: x86_64-unknown-linux-gnu Configured with: ../gcc-4.6-20110129/configure--enable-languages=c++ Thread model: posix gcc version 4.6.0 20110129 (experimental) (GCC) Updating the version accordingly. Also, it seems to me that this worked fine with the gcc-4.4 series (I was able to work with that code just fine with fc13 which, as far as I can remember, comes with gcc-4.4). In that case, this is a regression.
[Bug c++/47541] For integer pointers, the value of ++*p is not written back to memory
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47541 --- Comment #3 from Michael Veksler 2011-01-30 12:39:04 UTC --- Created attachment 23168 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23168 This is a minimal file to reproduce this error Strange, it got lost somehow. Here it is, again.
[Bug gcov-profile/51484] New: Can't create C++ executable with -profile-generate
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51484
Bug #: 51484
Summary: Can't create C++ executable with -profile-generate
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: gcov-profile
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: veks...@il.ibm.com
Hello,
How can I turn profile driven optimizations with gcc-4.7.0 development version?
It used to work with gcc-4.6.x and before. I am trying to use the latest GCC
trunk:
$ /opt/gcc47-20111207/bin/g++ -v
Using built-in specs.
COLLECT_GCC=/opt/gcc47-20111207/bin/g++
COLLECT_LTO_WRAPPER=/opt/gcc47-20111207/libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-source/configure --prefix=/opt/gcc47-20111207
--enable-languages='c++ c'
Thread model: posix
gcc version 4.7.0 20111206 (experimental) (GCC)
I have got two files:
// t.cpp
#include
void f() { std::cout<< "hello\n"; }
// t.cpp
void f();
int main() { f(); return 0; }
I compile them with:
$ rm -rf prof
$ /opt/gcc47-20111207/bin/g++ -c t.cpp -g -O2 -m32 -fprofile-generate=prof
$ /opt/gcc47-20111207/bin/g++ -c t2.cpp -g -O2 -m32 -fprofile-generate=prof
$ /opt/gcc47-20111207/bin/g++ -O2 t2.o t.o -g -m32 -fprofile-generate=prof
and I get:
= begin
/home/me/t2.cpp:3: undefined reference to
`__gcov0__ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc'
/home/me/t2.cpp:3: undefined reference to
`__gcov0__ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc'
t2.o: In function `operator<<>':
/opt/gcc47-20111207/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/../../../../include/c++/4.7.0/ostream:515:
undefined reference to
`__gcov0__ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc'
/opt/gcc47-20111207/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/../../../../include/c++/4.7.0/ostream:515:
undefined reference to
`__gcov0__ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc'
collect2: error: ld returned 1 exit status
== end
Neither adding -lgcov at the end nor adding
/opt/gcc47-20111207/lib/gcc/x86_64-unknown-linux-gnu/4.7.0/32/libgcov.a
helps.
[Bug c++/55639] Partial nested template specialization leads to segmentation fault of g++
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55639
Michael Veksler changed:
What|Removed |Added
CC||veksler at il dot ibm.com
--- Comment #2 from Michael Veksler 2012-12-10
14:18:07 UTC ---
I have a possibly similar test case (can someone confirm if my case is a DUP?).
--- t.cpp --
template
struct A {
template
struct B;
};
template
struct A::template B<0> {
int foo();
};
end --
$ /opt/gcc4.7.2/bin/g++ t.cpp
t.cpp:8:23: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
$/opt/gcc4.7.2/bin/g++ -v
Using built-in specs.
COLLECT_GCC=/opt/gcc4.7.2/bin/g++
COLLECT_LTO_WRAPPER=/opt/gcc4.7.2/libexec/gcc/x86_64-unknown-linux-gnu/4.7.2/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.7.2/configure --prefix=/opt/gcc4.7.2
Thread model: posix
gcc version 4.7.2 (GCC)
[Bug c++/49481] New: Warn about string literal + character
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49481
Summary: Warn about string literal + character
Product: gcc
Version: 4.5.1
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: veks...@il.ibm.com
Consider:
void f(const std::string &a, std::string & b)
{
b+= "_" + a[1];
}
Although syntactically correct, this code is most certainly buggy:
this is not Java and "_" is not a string object.
When compiling C++, and maybe C, and gcc encounteres
operator+
it should issue a warning.
