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Use global info for alias analysis. 

llvm-svn: 31035
This commit is contained in:
Jim Laskey 2006-10-18 12:29:57 +00:00
parent b21e8d2e12
commit a15b0ebb5e
1 changed files with 38 additions and 9 deletions
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47
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -256,10 +256,18 @@ namespace {
void GatherAllAliases(SDNode *N, SDOperand OriginalChain,
SmallVector<SDOperand, 8> &Aliases);
/// isAlias - Return true if there is any possibility that the two addresses
/// overlap.
bool isAlias(SDOperand Ptr1, int64_t Size1,
const Value *SrcValue1, int SrcValueOffset1,
SDOperand Ptr2, int64_t Size2,
const Value *SrcValue2, int SrcValueOffset1);
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
bool FindAliasInfo(SDNode *N,
SDOperand &Ptr, int64_t &Size, const Value *&SrcValue);
SDOperand &Ptr, int64_t &Size,
const Value *&SrcValue, int &SrcValueOffset);
/// FindBetterChain - Walk up chain skipping non-aliasing memory nodes,
/// looking for a better chain (aliasing node.)
@ -4005,8 +4013,11 @@ static bool FindBaseOffset(SDOperand Ptr, SDOperand &Base, int64_t &Offset) {
/// isAlias - Return true if there is any possibility that the two addresses
/// overlap.
static bool isAlias(SDOperand Ptr1, int64_t Size1, const Value *SrcValue1,
SDOperand Ptr2, int64_t Size2, const Value *SrcValue2) {
bool DAGCombiner::isAlias(SDOperand Ptr1, int64_t Size1,
const Value *SrcValue1, int SrcValueOffset1,
SDOperand Ptr2, int64_t Size2,
const Value *SrcValue2, int SrcValueOffset2)
{
// If they are the same then they must be aliases.
if (Ptr1 == Ptr2) return true;
@ -4022,23 +4033,37 @@ static bool isAlias(SDOperand Ptr1, int64_t Size1, const Value *SrcValue1,
return!((Offset1 + Size1) <= Offset2 || (Offset2 + Size2) <= Offset1);
}
// Otherwise they alias if either is unknown.
return !KnownBase1 || !KnownBase2;
// If we know both bases then they can't alias.
if (KnownBase1 && KnownBase2) return false;
// Use alias analysis information.
int Overlap1 = Size1 + SrcValueOffset1 + Offset1;
int Overlap2 = Size2 + SrcValueOffset2 + Offset2;
AliasAnalysis::AliasResult AAResult =
AA.alias(SrcValue1, Overlap1, SrcValue2, Overlap2);
if (AAResult == AliasAnalysis::NoAlias)
return false;
// Otherwise we have to assume they alias.
return true;
}
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
bool DAGCombiner::FindAliasInfo(SDNode *N,
SDOperand &Ptr, int64_t &Size, const Value *&SrcValue) {
SDOperand &Ptr, int64_t &Size,
const Value *&SrcValue, int &SrcValueOffset) {
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
Ptr = LD->getBasePtr();
Size = MVT::getSizeInBits(LD->getLoadedVT()) >> 3;
SrcValue = LD->getSrcValue();
SrcValueOffset = LD->getSrcValueOffset();
return true;
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
Ptr = ST->getBasePtr();
Size = MVT::getSizeInBits(ST->getStoredVT()) >> 3;
SrcValue = ST->getSrcValue();
SrcValueOffset = ST->getSrcValueOffset();
} else {
assert(0 && "FindAliasInfo expected a memory operand");
}
@ -4057,7 +4082,8 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDOperand OriginalChain,
SDOperand Ptr;
int64_t Size;
const Value *SrcValue;
bool IsLoad = FindAliasInfo(N, Ptr, Size, SrcValue);
int SrcValueOffset;
bool IsLoad = FindAliasInfo(N, Ptr, Size, SrcValue, SrcValueOffset);
// Starting off.
Chains.push_back(OriginalChain);
@ -4084,11 +4110,14 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDOperand OriginalChain,
SDOperand OpPtr;
int64_t OpSize;
const Value *OpSrcValue;
bool IsOpLoad = FindAliasInfo(Chain.Val, OpPtr, OpSize, OpSrcValue);
int OpSrcValueOffset;
bool IsOpLoad = FindAliasInfo(Chain.Val, OpPtr, OpSize,
OpSrcValue, OpSrcValueOffset);
// If chain is alias then stop here.
if (!(IsLoad && IsOpLoad) &&
isAlias(Ptr, Size, SrcValue, OpPtr, OpSize, OpSrcValue)) {
isAlias(Ptr, Size, SrcValue, SrcValueOffset,
OpPtr, OpSize, OpSrcValue, OpSrcValueOffset)) {
Aliases.push_back(Chain);
} else {
// Look further up the chain.