https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103514
Bug ID: 103514
Summary: Missing XOR-EQ-AND Optimization
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: navidrahimi at microsoft dot com
Target Milestone: ---
We are not optimizing &&-^-== combination, LLVM does it [1]:
// Proof of correctness https://alive2.llvm.org/ce/z/a4tuWF
bool
src (bool a, bool b)
{
return (a && b) == (a ^ b);
}
bool
tgt (bool a, bool b)
{
return !(a || b);
}
// Proof of correctness https://alive2.llvm.org/ce/z/w-iotd
bool
src (bool a, bool b)
{
return (a && b) ^ (a == b);
}
bool
tgt (bool a, bool b)
{
return !(a || b);
}
I will be sending a patch for this. This will solve it, I have to run the
testsuite and write a few tests:
/* (a && b) first_op (a second_op b) -> !(a || b) */
(for first_op (bit_xor eq)
(for second_op (bit_xor eq)
(simplify
(first_op:c (bit_and:c truth_valued_p@0 truth_valued_p@1) (second_op:c @0
@1))
(if (first_op != second_op)
(bit_not (bit_ior @0 @1))))))
1) https://compiler-explorer.com/z/WqTxYhG3s
