[InstCombine] Improve mul(x, pow2) -> shl combine for vector constants
Refactor getLogBase2Vector into getLogBase2 to accept all scalars/vectors. Generalize from ConstantDataVector to support all constant vectors.
llvm-svn: 324603
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 6e7e11a..9fd6500 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -132,18 +132,30 @@
/// \brief A helper routine of InstCombiner::visitMul().
///
-/// If C is a vector of known powers of 2, then this function returns
-/// a new vector obtained from C replacing each element with its logBase2.
+/// If C is a scalar/vector of known powers of 2, then this function returns
+/// a new scalar/vector obtained from logBase2 of C.
/// Return a null pointer otherwise.
-static Constant *getLogBase2Vector(ConstantDataVector *CV) {
+static Constant *getLogBase2(Type *Ty, Constant *C) {
const APInt *IVal;
- SmallVector<Constant *, 4> Elts;
+ if (const auto *CI = dyn_cast<ConstantInt>(C))
+ if (match(C, m_APInt(IVal)) && IVal->isPowerOf2())
+ return ConstantInt::get(Ty, IVal->logBase2());
- for (unsigned I = 0, E = CV->getNumElements(); I != E; ++I) {
- Constant *Elt = CV->getElementAsConstant(I);
+ if (!Ty->isVectorTy())
+ return nullptr;
+
+ SmallVector<Constant *, 4> Elts;
+ for (unsigned I = 0, E = Ty->getVectorNumElements(); I != E; ++I) {
+ Constant *Elt = C->getAggregateElement(I);
+ if (!Elt)
+ return nullptr;
+ if (isa<UndefValue>(Elt)) {
+ Elts.push_back(UndefValue::get(Ty->getScalarType()));
+ continue;
+ }
if (!match(Elt, m_APInt(IVal)) || !IVal->isPowerOf2())
return nullptr;
- Elts.push_back(ConstantInt::get(Elt->getType(), IVal->logBase2()));
+ Elts.push_back(ConstantInt::get(Ty->getScalarType(), IVal->logBase2()));
}
return ConstantVector::get(Elts);
@@ -232,16 +244,8 @@
}
if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) {
- Constant *NewCst = nullptr;
- if (match(C1, m_APInt(IVal)) && IVal->isPowerOf2())
- // Replace X*(2^C) with X << C, where C is either a scalar or a splat.
- NewCst = ConstantInt::get(NewOp->getType(), IVal->logBase2());
- else if (ConstantDataVector *CV = dyn_cast<ConstantDataVector>(C1))
- // Replace X*(2^C) with X << C, where C is a vector of known
- // constant powers of 2.
- NewCst = getLogBase2Vector(CV);
-
- if (NewCst) {
+ // Replace X*(2^C) with X << C, where C is either a scalar or a vector.
+ if (Constant *NewCst = getLogBase2(NewOp->getType(), C1)) {
unsigned Width = NewCst->getType()->getPrimitiveSizeInBits();
BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst);