https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114277
--- Comment #11 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Hmm, I think we got side-tracked on the conditional move representation. For
this BZ I think a simple match.pd pattern may be sufficient.
x * ((x || y) != 0) -> x
x * ((x || y) == 0) -> 0
There's simplifications for the "&&" case as well, though they don't show up in
gimple as we've missed the necessary if-conversions.
(simplify
(mult:c (convert? (ne (bit_ior:c @0 @1) integer_zerop@2)) @0)
@0)
(simplify
(mult:c (convert? (eq (bit_ior:c @0 @1) integer_zerop@2)) @0)
{ build_zero_cst (type); })
So given this source:
int a,b;
void func_0(int x){
a=x*(x||b);
}
void func_1(int x){
a=x*!(x||b);
}
We can compile that down to this code on riscv:
func_0:
lui a5,%hi(a)
sw a0,%lo(a)(a5)
ret
func_1:
lui a5,%hi(a)
sw zero,%lo(a)(a5)
ret
Am I missing something here?
