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[DAGCombiner] add enum for store source value; NFC 

This removes existing code duplication and allows us to
assert that we are handling the expected cases.

We have a list of outstanding bugs that could benefit by
handling truncated source values, so that's a possible
addition going forward.
This commit is contained in:
Sanjay Patel 2020-07-08 11:48:41 -04:00
parent 800fb68420
commit 39329d5724
1 changed files with 26 additions and 18 deletions
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44
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -638,6 +638,19 @@ namespace {
: MemNode(N), OffsetFromBase(Offset) {}
};
// Classify the origin of a stored value.
enum class StoreSource { Unknown, Constant, Extract, Load };
StoreSource getStoreSource(SDValue StoreVal) {
if (isa<ConstantSDNode>(StoreVal) || isa<ConstantFPSDNode>(StoreVal))
return StoreSource::Constant;
if (StoreVal.getOpcode() == ISD::EXTRACT_VECTOR_ELT ||
StoreVal.getOpcode() == ISD::EXTRACT_SUBVECTOR)
return StoreSource::Extract;
if (isa<LoadSDNode>(StoreVal))
return StoreSource::Load;
return StoreSource::Unknown;
}
/// This is a helper function for visitMUL to check the profitability
/// of folding (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2).
/// MulNode is the original multiply, AddNode is (add x, c1),
@ -16024,14 +16037,12 @@ void DAGCombiner::getStoreMergeCandidates(
if (BasePtr.getBase().isUndef())
return;
bool IsConstantSrc = isa<ConstantSDNode>(Val) || isa<ConstantFPSDNode>(Val);
bool IsExtractVecSrc = (Val.getOpcode() == ISD::EXTRACT_VECTOR_ELT ||
Val.getOpcode() == ISD::EXTRACT_SUBVECTOR);
bool IsLoadSrc = isa<LoadSDNode>(Val);
StoreSource StoreSrc = getStoreSource(Val);
assert(StoreSrc != StoreSource::Unknown && "Expected known source for store");
BaseIndexOffset LBasePtr;
// Match on loadbaseptr if relevant.
EVT LoadVT;
if (IsLoadSrc) {
if (StoreSrc == StoreSource::Load) {
auto *Ld = cast<LoadSDNode>(Val);
LBasePtr = BaseIndexOffset::match(Ld, DAG);
LoadVT = Ld->getMemoryVT();
@ -16059,7 +16070,7 @@ void DAGCombiner::getStoreMergeCandidates(
// Allow merging constants of different types as integers.
bool NoTypeMatch = (MemVT.isInteger()) ? !MemVT.bitsEq(Other->getMemoryVT())
: Other->getMemoryVT() != MemVT;
if (IsLoadSrc) {
if (StoreSrc == StoreSource::Load) {
if (NoTypeMatch)
return false;
// The Load's Base Ptr must also match
@ -16083,13 +16094,13 @@ void DAGCombiner::getStoreMergeCandidates(
} else
return false;
}
if (IsConstantSrc) {
if (StoreSrc == StoreSource::Constant) {
if (NoTypeMatch)
return false;
if (!(isa<ConstantSDNode>(OtherBC) || isa<ConstantFPSDNode>(OtherBC)))
return false;
}
if (IsExtractVecSrc) {
if (StoreSrc == StoreSource::Extract) {
// Do not merge truncated stores here.
if (Other->isTruncatingStore())
return false;
@ -16261,16 +16272,12 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
// Perform an early exit check. Do not bother looking at stored values that
// are not constants, loads, or extracted vector elements.
SDValue StoredVal = peekThroughBitcasts(St->getValue());
bool IsLoadSrc = isa<LoadSDNode>(StoredVal);
bool IsConstantSrc = isa<ConstantSDNode>(StoredVal) ||
isa<ConstantFPSDNode>(StoredVal);
bool IsExtractVecSrc = (StoredVal.getOpcode() == ISD::EXTRACT_VECTOR_ELT ||
StoredVal.getOpcode() == ISD::EXTRACT_SUBVECTOR);
StoreSource StoreSrc = getStoreSource(StoredVal);
bool IsNonTemporalStore = St->isNonTemporal();
bool IsNonTemporalLoad =
IsLoadSrc && cast<LoadSDNode>(StoredVal)->isNonTemporal();
bool IsNonTemporalLoad = StoreSrc == StoreSource::Load &&
cast<LoadSDNode>(StoredVal)->isNonTemporal();
if (!IsConstantSrc && !IsLoadSrc && !IsExtractVecSrc)
if (StoreSrc == StoreSource::Unknown)
return false;
SmallVector<MemOpLink, 8> StoreNodes;
@ -16335,7 +16342,7 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
const DataLayout &DL = DAG.getDataLayout();
// Store the constants into memory as one consecutive store.
if (IsConstantSrc) {
if (StoreSrc == StoreSource::Constant) {
while (NumConsecutiveStores >= 2) {
LSBaseSDNode *FirstInChain = StoreNodes[0].MemNode;
unsigned FirstStoreAS = FirstInChain->getAddressSpace();
@ -16454,7 +16461,7 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
// When extracting multiple vector elements, try to store them
// in one vector store rather than a sequence of scalar stores.
if (IsExtractVecSrc) {
if (StoreSrc == StoreSource::Extract) {
// Loop on Consecutive Stores on success.
while (NumConsecutiveStores >= 2) {
LSBaseSDNode *FirstInChain = StoreNodes[0].MemNode;
@ -16522,6 +16529,7 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
// Below we handle the case of multiple consecutive stores that
// come from multiple consecutive loads. We merge them into a single
// wide load and a single wide store.
assert(StoreSrc == StoreSource::Load && "Expected load source for store");
// Look for load nodes which are used by the stored values.
SmallVector<MemOpLink, 8> LoadNodes;