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Combiner alias analysis passes Multisource (release-asserts.) 

llvm-svn: 30818
This commit is contained in:
Jim Laskey 2006-10-07 23:37:56 +00:00
parent 398195ebbe
commit 0463e08005
1 changed files with 71 additions and 88 deletions
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159
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -46,90 +46,13 @@ namespace {
static Statistic<> NodesCombined ("dagcombiner",
"Number of dag nodes combined");
static cl::opt<bool>
CombinerAA("combiner-alias-analysis", cl::Hidden,
cl::desc("Turn on alias analysis turning testing"));
static cl::opt<bool>
CombinerAA("combiner-alias-analysis", cl::Hidden,
cl::desc("Turn on alias analysis turning testing"));
/// FindBaseOffset - Return true if base is known not to alias with anything
/// but itself. Provides base object and offset as results.
bool FindBaseOffset(SDOperand Ptr, SDOperand &Object, int64_t &Offset) {
// If it's an adding or subtracting a simple constant then add the constant
// to the offset.
if (Ptr.getOpcode() == ISD::ADD) {
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Ptr.getOperand(1))) {
bool IsNonAliasing = FindBaseOffset(Ptr.getOperand(0), Object, Offset);
Offset += C->getValue();
return IsNonAliasing;
}
} else if (Ptr.getOpcode() == ISD::SUB) {
// FIXME - Aren't all subtract constants converted to add negative constant.
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Ptr.getOperand(1))) {
bool IsNonAliasing = FindBaseOffset(Ptr.getOperand(0), Object, Offset);
Offset -= C->getValue();
return IsNonAliasing;
}
}
// Primitive operation.
Object = Ptr; Offset = 0;
// If it's any of the following then it can't alias with anything but itself.
return isa<FrameIndexSDNode>(Ptr) ||
isa<ConstantPoolSDNode>(Ptr) ||
isa<GlobalAddressSDNode>(Ptr);
}
/// isAlias - Return true if there is any possibility that the two addresses
/// overlap.
bool isAlias(SDOperand Ptr1, int64_t Size1, SDOperand SrcValue1,
SDOperand Ptr2, int64_t Size2, SDOperand SrcValue2) {
// If they are the same then they must be aliases.
if (Ptr1 == Ptr2) return true;
// Gather base node and offset information.
SDOperand Object1, Object2;
int64_t Offset1, Offset2;
bool IsNonAliasing1 = FindBaseOffset(Ptr1, Object1, Offset1);
bool IsNonAliasing2 = FindBaseOffset(Ptr2, Object2, Offset2);
// If they have a same base address then...
if (Object1 == Object2) {
// Check to see if the addresses overlap.
return !((Offset1 + Size1) <= Offset2 || (Offset2 + Size2) <= Offset1);
}
// Otherwise they alias if they are both non aliasing.
return !IsNonAliasing1 && IsNonAliasing2;
}
/// 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, SDOperand &SrcValue) {
switch (N->getOpcode()) {
case ISD::LOAD:
Ptr = N->getOperand(1);
Size = MVT::getSizeInBits(N->getValueType(0)) >> 3;
SrcValue = N->getOperand(2);
return true;
case ISD::STORE:
Ptr = N->getOperand(2);
Size = MVT::getSizeInBits(N->getOperand(1).getValueType()) >> 3;
SrcValue = N->getOperand(3);
return false;
default:
assert(0 && "FindAliasInfo expected a memory operand");
return false;
}
return false;
}
//------------------------------ DAGCombiner ---------------------------------//
class VISIBILITY_HIDDEN DAGCombiner {
class VISIBILITY_HIDDEN DAGCombiner {
SelectionDAG &DAG;
TargetLowering &TLI;
bool AfterLegalize;
@ -603,7 +526,7 @@ SDOperand DAGCombiner::visitTokenFactor(SDNode *N) {
// Start out with this token factor.
TFs.push_back(N);
// Iterate through token factors. The TFs grows a new token factors are
// Iterate through token factors. The TFs grows when new token factors are
// encountered.
for (unsigned i = 0; i < TFs.size(); ++i) {
SDNode *TF = TFs[i];
@ -3316,12 +3239,6 @@ bool DAGCombiner::SimplifySelectOps(SDNode *TheSelect, SDOperand LHS,
// If this is a select from two identical things, try to pull the operation
// through the select.
if (LHS.getOpcode() == RHS.getOpcode() && LHS.hasOneUse() && RHS.hasOneUse()){
#if 0
std::cerr << "SELECT: ["; LHS.Val->dump();
std::cerr << "] ["; RHS.Val->dump();
std::cerr << "]\n";
#endif
// If this is a load and the token chain is identical, replace the select
// of two loads with a load through a select of the address to load from.
// This triggers in things like "select bool X, 10.0, 123.0" after the FP
@ -3978,6 +3895,72 @@ SDOperand DAGCombiner::BuildUDIV(SDNode *N) {
return S;
}
/// FindBaseOffset - Return true if base is known not to alias with anything
/// but itself. Provides base object and offset as results.
static bool FindBaseOffset(SDOperand Ptr, SDOperand &Base, int64_t &Offset) {
// Assume it is a primitive operation.
Base = Ptr; Offset = 0;
// If it's an adding a simple constant then integrate the offset.
if (Base.getOpcode() == ISD::ADD) {
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Base.getOperand(1))) {
Base = Base.getOperand(0);
Offset += C->getValue();
}
}
// If it's any of the following then it can't alias with anything but itself.
return isa<FrameIndexSDNode>(Base) ||
isa<ConstantPoolSDNode>(Base) ||
isa<GlobalAddressSDNode>(Base);
}
/// isAlias - Return true if there is any possibility that the two addresses
/// overlap.
static bool isAlias(SDOperand Ptr1, int64_t Size1, SDOperand SrcValue1,
SDOperand Ptr2, int64_t Size2, SDOperand SrcValue2) {
// If they are the same then they must be aliases.
if (Ptr1 == Ptr2) return true;
// Gather base node and offset information.
SDOperand Base1, Base2;
int64_t Offset1, Offset2;
bool KnownBase1 = FindBaseOffset(Ptr1, Base1, Offset1);
bool KnownBase2 = FindBaseOffset(Ptr2, Base2, Offset2);
// If they have a same base address then...
if (Base1 == Base2) {
// Check to see if the addresses overlap.
return!((Offset1 + Size1) <= Offset2 || (Offset2 + Size2) <= Offset1);
}
// Otherwise they alias if either is unknown.
return !KnownBase1 || !KnownBase2;
}
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
static bool FindAliasInfo(SDNode *N,
SDOperand &Ptr, int64_t &Size, SDOperand &SrcValue) {
switch (N->getOpcode()) {
case ISD::LOAD:
Ptr = N->getOperand(1);
Size = MVT::getSizeInBits(N->getValueType(0)) >> 3;
SrcValue = N->getOperand(2);
return true;
case ISD::STORE:
Ptr = N->getOperand(2);
Size = MVT::getSizeInBits(N->getOperand(1).getValueType()) >> 3;
SrcValue = N->getOperand(3);
break;
default:
assert(0 && "FindAliasInfo expected a memory operand");
break;
}
return false;
}
/// GatherAllAliases - Walk up chain skipping non-aliasing memory nodes,
/// looking for aliasing nodes and adding them to the Aliases vector.
void DAGCombiner::GatherAllAliases(SDNode *N, SDOperand OriginalChain,