https://bugs.llvm.org/show_bug.cgi?id=40750
Bug ID: 40750
Summary: Better optimizations for logical ops with bit fields
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Tested on Intel Haswell 4720HQ
struct test {
int a : 1;
int b : 1; // if changed to 2, GCC and Clang produces same codegen
};
int get(struct test *s) {
return s->a || s->b;
}
GCC:
get:
xor eax, eax
test BYTE PTR [rdi], 3
setne al
ret
Clang:
get: # @get
movzx ecx, byte ptr [rdi]
mov eax, 1
test cl, 1
jne .LBB0_2
shr ecx
and ecx, 1
mov eax, ecx
.LBB0_2:
ret
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