https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98289
Bug ID: 98289
Summary: [x86] Suboptimal optimization of stack usage when
function call to cold function is not needed
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
void f(bool cond)
{
if (cond)
__builtin_abort();
}
On x86 with current trunk and -O3, this results in :
f(bool):
sub rsp, 8
test dil, dil
jne .L3
add rsp, 8
ret
f(bool) [clone .cold]:
.L3:
call abort
This seems like a regression over GCC 7.5, which outputs :
f(bool):
test dil, dil
jne .L7
rep ret
.L7:
sub rsp, 8
call abort
Along with LLVM, which has similar output. Only emitting the code to begin the
call upon being asked to do seems quicker in the case where the call doesn't
occur.
