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[Bug c++/53505] New: bitfield with bool type generated broken object code
- From: "rockeet at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 28 May 2012 07:26:02 +0000
- Subject: [Bug c++/53505] New: bitfield with bool type generated broken object code
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53505
Bug #: 53505
Summary: bitfield with bool type generated broken object code
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: c++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: rockeet@gmail.com
compiler flag: -Wall -Wextra -O[0|1|2|3|fast]
All optimization levels: 1,2,3,fast reproduce the bug
-O0 is OK.
The expected output is 0
//================================================
$g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/opt/libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.7.0-RC-20120314/configure --prefix=/opt
--with-gmp=/opt --with-mpfr=/opt --with-mpc=/opt --with-ppl=/opt
--with-cloog=/opt --with-local-prefix=/opt --enable-languages=c,c++ :
(reconfigured) ../gcc-4.7.0-RC-20120314/configure --prefix=/opt --with-gmp=/opt
--with-mpfr=/opt --with-mpc=/opt --with-ppl=/opt --with-cloog=/opt
--with-local-prefix=/opt --enable-languages=c,c++,fortran
Thread model: posix
gcc version 4.7.0 20120314 (prerelease) (GCC)
//================================================
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <vector>
#if 1
#define BIT bool // reproduce the bug
#else
#define BIT unsigned // bug vanished
#endif
struct A {
unsigned int a;
unsigned char c1, c2;
BIT b1 : 1;
BIT b2 : 1;
BIT b3 : 1;
A() {
memset(this, -1, sizeof(A));
a = 0;
c1 = c2 = 0;
b1 = 0;
b2 = 0;
b3 = 0;
}
};
void f(const std::vector<A>& v) {
int s = 0;
for (int i = 0, n = v.size(); i < n; ++i) {
const A a = v[i]; // produce the bug
// const A&a = v[i]; // bug vanished if 'a' is a const reference
s += a.b1 ? 1 : 0;
}
printf("%d\n", s);
}
int main(int argc, char* argv[]) {
size_t size = argc < 2 ? 100 : atoi(argv[1]);
std::vector<A> v(size);
f(v);
return 0;
}