[Bug c++/38455] New: aligned struct members in heap-allocated code
tim at klingt dot org
gcc-bugzilla@gcc.gnu.org
Tue Dec 9 17:02:00 GMT 2008
the following code works on x86_64 as 64-bit binary, but the alignment
constraints of heap-allocated structs are not matched, when compiling 32-bit
code:
#include <assert.h>
template <int size = 4>
struct aligned_buffer
{
char padding;
float data[size] __attribute__((aligned((16))));
};
struct my_struct
{
aligned_buffer<> buf1;
char padding;
aligned_buffer<> buf2;
};
int main()
{
{
aligned_buffer<> ab;
assert((long)&ab.data % 16 == 0);
}
{
my_struct m;
assert((long)&m.buf1.data % 16 == 0);
assert((long)&m.buf2.data % 16 == 0);
}
{
aligned_buffer<> * ab = new aligned_buffer<>();
assert((long)&ab->data % 16 == 0); /* fails */
}
{
my_struct * m = new my_struct();
assert((long)&m->buf1.data % 16 == 0); /* fails */
assert((long)&m->buf2.data % 16 == 0); /* fails */
delete m;
}
}
g++ -m32: int main(): Assertion `(long)&ab->data % 16 == 0' failed.
g++ -m64: works fine
when changing the alignment from 16 to 64, the alignment constraints for
heap-allocated structs fail with both -m32 and -m64.
--
Summary: aligned struct members in heap-allocated code
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tim at klingt dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38455
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