be more aggressive about transforming add -> or when the operands have no
intersecting bits. This triggers all over the place, for example in lencode,
with adds of stuff like:
%tmp580 = mul i32 %tmp579, 2
%tmp582 = and i32 %b8, 1
and
%tmp28 = shl i32 %abs.i, 1
%sign.0 = select i1 %tmp23, i32 1, i32 0
and
%tmp344 = shl i32 %tmp343, 2
%tmp346 = and i32 %tmp96, 3
etc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51263 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 8c5e136..3b34124 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2503,6 +2503,25 @@
if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
return R;
+
+ // A+B --> A|B iff A and B have no bits set in common.
+ if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
+ APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
+ APInt LHSKnownOne(IT->getBitWidth(), 0);
+ APInt LHSKnownZero(IT->getBitWidth(), 0);
+ ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
+ if (LHSKnownZero != 0) {
+ APInt RHSKnownOne(IT->getBitWidth(), 0);
+ APInt RHSKnownZero(IT->getBitWidth(), 0);
+ ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
+
+ // No bits in common -> bitwise or.
+ if ((LHSKnownZero|RHSKnownZero).isAllOnesValue()) {
+ cerr << "HACK\n" << *LHS << *RHS << "\n";
+ return BinaryOperator::CreateOr(LHS, RHS);
+ }
+ }
+ }
// W*X + Y*Z --> W * (X+Z) iff W == Y
if (I.getType()->isIntOrIntVector()) {