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Substantially speed up combiner-aa in the following ways:

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1. Switch from an std::set to a SmallPtrSet for visited chain nodes.
2. Do not force the recursive flattening of token factor nodes, regardless of
   use count.
3. Immediately process newly created TokenFactor nodes.

Also, improve combiner-aa by teaching it that loads to non-overlapping offsets
of relatively aligned objects cannot alias.

These changes result in a >5x speedup for combiner-aa on most testcases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81816 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2009-09-15 00:18:30 +00:00
parent 9cae7053c0
commit b6aef5c867
1 changed files with 69 additions and 33 deletions
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102
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -239,14 +239,17 @@ namespace {
/// overlap.
bool isAlias(SDValue Ptr1, int64_t Size1,
const Value *SrcValue1, int SrcValueOffset1,
unsigned SrcValueAlign1,
SDValue Ptr2, int64_t Size2,
const Value *SrcValue2, int SrcValueOffset2) const;
const Value *SrcValue2, int SrcValueOffset2,
unsigned SrcValueAlign2) const;
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
bool FindAliasInfo(SDNode *N,
SDValue &Ptr, int64_t &Size,
const Value *&SrcValue, int &SrcValueOffset) const;
const Value *&SrcValue, int &SrcValueOffset,
unsigned &SrcValueAlignment) const;
/// FindBetterChain - Walk up chain skipping non-aliasing memory nodes,
/// looking for a better chain (aliasing node.)
@ -886,7 +889,7 @@ SDValue DAGCombiner::visitTokenFactor(SDNode *N) {
break;
case ISD::TokenFactor:
if ((CombinerAA || Op.hasOneUse()) &&
if (Op.hasOneUse() &&
std::find(TFs.begin(), TFs.end(), Op.getNode()) == TFs.end()) {
// Queue up for processing.
TFs.push_back(Op.getNode());
@ -907,7 +910,7 @@ SDValue DAGCombiner::visitTokenFactor(SDNode *N) {
}
}
}
SDValue Result;
// If we've change things around then replace token factor.
@ -4959,7 +4962,10 @@ SDValue DAGCombiner::visitLOAD(SDNode *N) {
// Create token factor to keep old chain connected.
SDValue Token = DAG.getNode(ISD::TokenFactor, N->getDebugLoc(),
MVT::Other, Chain, ReplLoad.getValue(1));
// Make sure the new and old chains are cleaned up.
AddToWorkList(Token.getNode());
// Replace uses with load result and token factor. Don't add users
// to work list.
return CombineTo(N, ReplLoad.getValue(0), Token, false);
@ -5180,8 +5186,9 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
// If there is a better chain.
if (Chain != BetterChain) {
// Replace the chain to avoid dependency.
SDValue ReplStore;
// Replace the chain to avoid dependency.
if (ST->isTruncatingStore()) {
ReplStore = DAG.getTruncStore(BetterChain, N->getDebugLoc(), Value, Ptr,
ST->getSrcValue(),ST->getSrcValueOffset(),
@ -5197,6 +5204,9 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
SDValue Token = DAG.getNode(ISD::TokenFactor, N->getDebugLoc(),
MVT::Other, Chain, ReplStore);
// Make sure the new and old chains are cleaned up.
AddToWorkList(Token.getNode());
// Don't add users to work list.
return CombineTo(N, Token, false);
}
@ -6103,8 +6113,10 @@ static bool FindBaseOffset(SDValue Ptr, SDValue &Base, int64_t &Offset) {
/// overlap.
bool DAGCombiner::isAlias(SDValue Ptr1, int64_t Size1,
const Value *SrcValue1, int SrcValueOffset1,
unsigned SrcValueAlign1,
SDValue Ptr2, int64_t Size2,
const Value *SrcValue2, int SrcValueOffset2) const {
const Value *SrcValue2, int SrcValueOffset2,
unsigned SrcValueAlign2) const {
// If they are the same then they must be aliases.
if (Ptr1 == Ptr2) return true;
@ -6122,6 +6134,22 @@ bool DAGCombiner::isAlias(SDValue Ptr1, int64_t Size1,
// If we know both bases then they can't alias.
if (KnownBase1 && KnownBase2) return false;
// If we know required SrcValue1 and SrcValue2 have relatively large alignment
// compared to the size and offset of the access, we may be able to prove they
// do not alias. This check is conservative for now to catch cases created by
// splitting vector types.
if ((SrcValueAlign1 == SrcValueAlign2) &&
(SrcValueOffset1 != SrcValueOffset2) &&
(Size1 == Size2) && (SrcValueAlign1 > Size1)) {
int64_t OffAlign1 = SrcValueOffset1 % SrcValueAlign1;
int64_t OffAlign2 = SrcValueOffset2 % SrcValueAlign1;
// There is no overlap between these relatively aligned accesses of similar
// size, return no alias.
if ((OffAlign1 + Size1) <= OffAlign2 || (OffAlign2 + Size2) <= OffAlign1)
return false;
}
if (CombinerGlobalAA) {
// Use alias analysis information.
int64_t MinOffset = std::min(SrcValueOffset1, SrcValueOffset2);
@ -6141,18 +6169,22 @@ bool DAGCombiner::isAlias(SDValue Ptr1, int64_t Size1,
/// node. Returns true if the operand was a load.
bool DAGCombiner::FindAliasInfo(SDNode *N,
SDValue &Ptr, int64_t &Size,
const Value *&SrcValue, int &SrcValueOffset) const {
const Value *&SrcValue,
int &SrcValueOffset,
unsigned &SrcValueAlign) const {
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
Ptr = LD->getBasePtr();
Size = LD->getMemoryVT().getSizeInBits() >> 3;
SrcValue = LD->getSrcValue();
SrcValueOffset = LD->getSrcValueOffset();
SrcValueAlign = LD->getOriginalAlignment();
return true;
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
Ptr = ST->getBasePtr();
Size = ST->getMemoryVT().getSizeInBits() >> 3;
SrcValue = ST->getSrcValue();
SrcValueOffset = ST->getSrcValueOffset();
SrcValueAlign = ST->getOriginalAlignment();
} else {
llvm_unreachable("FindAliasInfo expected a memory operand");
}
@ -6165,14 +6197,16 @@ bool DAGCombiner::FindAliasInfo(SDNode *N,
void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain,
SmallVector<SDValue, 8> &Aliases) {
SmallVector<SDValue, 8> Chains; // List of chains to visit.
std::set<SDNode *> Visited; // Visited node set.
SmallPtrSet<SDNode *, 16> Visited; // Visited node set.
// Get alias information for node.
SDValue Ptr;
int64_t Size = 0;
const Value *SrcValue = 0;
int SrcValueOffset = 0;
bool IsLoad = FindAliasInfo(N, Ptr, Size, SrcValue, SrcValueOffset);
int64_t Size;
const Value *SrcValue;
int SrcValueOffset;
unsigned SrcValueAlign;
bool IsLoad = FindAliasInfo(N, Ptr, Size, SrcValue, SrcValueOffset,
SrcValueAlign);
// Starting off.
Chains.push_back(OriginalChain);
@ -6184,9 +6218,9 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain,
SDValue Chain = Chains.back();
Chains.pop_back();
// Don't bother if we've been before.
if (Visited.find(Chain.getNode()) != Visited.end()) continue;
Visited.insert(Chain.getNode());
// Don't bother if we've been before.
if (!Visited.insert(Chain.getNode()))
continue;
switch (Chain.getOpcode()) {
case ISD::EntryToken:
@ -6197,16 +6231,19 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain,
case ISD::STORE: {
// Get alias information for Chain.
SDValue OpPtr;
int64_t OpSize = 0;
const Value *OpSrcValue = 0;
int OpSrcValueOffset = 0;
int64_t OpSize;
const Value *OpSrcValue;
int OpSrcValueOffset;
unsigned OpSrcValueAlign;
bool IsOpLoad = FindAliasInfo(Chain.getNode(), OpPtr, OpSize,
OpSrcValue, OpSrcValueOffset);
OpSrcValue, OpSrcValueOffset,
OpSrcValueAlign);
// If chain is alias then stop here.
if (!(IsLoad && IsOpLoad) &&
isAlias(Ptr, Size, SrcValue, SrcValueOffset,
OpPtr, OpSize, OpSrcValue, OpSrcValueOffset)) {
isAlias(Ptr, Size, SrcValue, SrcValueOffset, SrcValueAlign,
OpPtr, OpSize, OpSrcValue, OpSrcValueOffset,
OpSrcValueAlign)) {
Aliases.push_back(Chain);
} else {
// Look further up the chain.
@ -6218,10 +6255,14 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain,
}
case ISD::TokenFactor:
// We have to check each of the operands of the token factor, so we queue
// then up. Adding the operands to the queue (stack) in reverse order
// maintains the original order and increases the likelihood that getNode
// will find a matching token factor (CSE.)
// We have to check each of the operands of the token factor for "small"
// token factors, so we queue them up. Adding the operands to the queue
// (stack) in reverse order maintains the original order and increases the
// likelihood that getNode will find a matching token factor (CSE.)
if (Chain.getNumOperands() > 16) {
Aliases.push_back(Chain);
break;
}
for (unsigned n = Chain.getNumOperands(); n;)
Chains.push_back(Chain.getOperand(--n));
// Eliminate the token factor if we can.
@ -6253,13 +6294,8 @@ SDValue DAGCombiner::FindBetterChain(SDNode *N, SDValue OldChain) {
}
// Construct a custom tailored token factor.
SDValue NewChain = DAG.getNode(ISD::TokenFactor, N->getDebugLoc(), MVT::Other,
&Aliases[0], Aliases.size());
// Make sure the old chain gets cleaned up.
if (NewChain != OldChain) AddToWorkList(OldChain.getNode());
return NewChain;
return DAG.getNode(ISD::TokenFactor, N->getDebugLoc(), MVT::Other,
&Aliases[0], Aliases.size());
}
// SelectionDAG::Combine - This is the entry point for the file.