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[SelectionDAG] Expose the "getValidShiftAmount" helpers available. NFCI. 

These are going to be useful in TargetLowering::SimplifyDemandedBits, so expose these helpers outside of SelectionDAG.cpp

Also add an getValidShiftAmountConstant early-out to getValidMinimumShiftAmountConstant/getValidMaximumShiftAmountConstant so we can use them for scalar cases as well.
This commit is contained in:
Simon Pilgrim 2020-02-17 13:38:20 +00:00
parent 78d455adf0
commit a1585aec6f
2 changed files with 37 additions and 12 deletions
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17
llvm/include/llvm/CodeGen/SelectionDAG.h
View File

@ -1671,6 +1671,23 @@ public:
/// that element from the source vector.
SDValue getSplatValue(SDValue V);
/// If a SHL/SRA/SRL node \p V has a constant or splat constant shift amount
/// that is less than the element bit-width of the shift node, return it.
const APInt *getValidShiftAmountConstant(SDValue V,
const APInt &DemandedElts) const;
/// If a SHL/SRA/SRL node \p V has constant shift amounts that are all less
/// than the element bit-width of the shift node, return the minimum value.
const APInt *
getValidMinimumShiftAmountConstant(SDValue V,
const APInt &DemandedElts) const;
/// If a SHL/SRA/SRL node \p V has constant shift amounts that are all less
/// than the element bit-width of the shift node, return the maximum value.
const APInt *
getValidMaximumShiftAmountConstant(SDValue V,
const APInt &DemandedElts) const;
/// Match a binop + shuffle pyramid that represents a horizontal reduction
/// over the elements of a vector starting from the EXTRACT_VECTOR_ELT node /p
/// Extract. The reduction must use one of the opcodes listed in /p

32
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -2407,10 +2407,12 @@ SDValue SelectionDAG::getSplatValue(SDValue V) {
return SDValue();
}
/// If a SHL/SRA/SRL node has a constant or splat constant shift amount that
/// is less than the element bit-width of the shift node, return it.
static const APInt *getValidShiftAmountConstant(SDValue V,
const APInt &DemandedElts) {
const APInt *
SelectionDAG::getValidShiftAmountConstant(SDValue V,
const APInt &DemandedElts) const {
assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
V.getOpcode() == ISD::SRA) &&
"Unknown shift node");
unsigned BitWidth = V.getScalarValueSizeInBits();
if (ConstantSDNode *SA = isConstOrConstSplat(V.getOperand(1), DemandedElts)) {
// Shifting more than the bitwidth is not valid.
@ -2421,10 +2423,13 @@ static const APInt *getValidShiftAmountConstant(SDValue V,
return nullptr;
}
/// If a SHL/SRA/SRL node has constant vector shift amounts that are all less
/// than the element bit-width of the shift node, return the minimum value.
static const APInt *
getValidMinimumShiftAmountConstant(SDValue V, const APInt &DemandedElts) {
const APInt *SelectionDAG::getValidMinimumShiftAmountConstant(
SDValue V, const APInt &DemandedElts) const {
assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
V.getOpcode() == ISD::SRA) &&
"Unknown shift node");
if (const APInt *ValidAmt = getValidShiftAmountConstant(V, DemandedElts))
return ValidAmt;
unsigned BitWidth = V.getScalarValueSizeInBits();
auto *BV = dyn_cast<BuildVectorSDNode>(V.getOperand(1));
if (!BV)
@ -2447,10 +2452,13 @@ getValidMinimumShiftAmountConstant(SDValue V, const APInt &DemandedElts) {
return MinShAmt;
}
/// If a SHL/SRA/SRL node has constant vector shift amounts that are all less
/// than the element bit-width of the shift node, return the maximum value.
static const APInt *
getValidMaximumShiftAmountConstant(SDValue V, const APInt &DemandedElts) {
const APInt *SelectionDAG::getValidMaximumShiftAmountConstant(
SDValue V, const APInt &DemandedElts) const {
assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
V.getOpcode() == ISD::SRA) &&
"Unknown shift node");
if (const APInt *ValidAmt = getValidShiftAmountConstant(V, DemandedElts))
return ValidAmt;
unsigned BitWidth = V.getScalarValueSizeInBits();
auto *BV = dyn_cast<BuildVectorSDNode>(V.getOperand(1));
if (!BV)