https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64822
Bug ID: 64822
Summary: tree-ssa-sccvn miscompile union containing bitfield
for big-endian targets
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jiwang at gcc dot gnu.org
given the following simple testcase,
union {
unsigned f0;
unsigned f1 : 24;
} const g_3983 = {1};
int main() {
printf("checksum = %08x\n", g_3983.f1);
}
on aarch64, or other target support big-endian, then
./cc1 -O2 -mbig-endian test.c
during tree-ssa-sccvn pass g_3983.f1 is evaluated into constant 1 while I think
it should be zero for big-endian.
