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Switch lowering: use uint32_t for weights everywhere

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I previously thought switch clusters would need to use uint64_t in case
the weights of multiple cases overflowed a 32-bit int. It turns
out that the weights on a terminator instruction are capped to allow for
being added together, so using a uint32_t should be safe.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235945 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hans Wennborg 2015-04-27 23:52:19 +00:00
parent 0b29dea9f1
commit 5d004276ec
2 changed files with 12 additions and 6 deletions
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16
lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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@ -2126,6 +2126,7 @@ void SelectionDAGBuilder::sortAndRangeify(CaseClusterVector &Clusters) {
// the previous cluster. // the previous cluster.
Clusters[DstIndex - 1].High = CaseVal; Clusters[DstIndex - 1].High = CaseVal;
Clusters[DstIndex - 1].Weight += CC.Weight; Clusters[DstIndex - 1].Weight += CC.Weight;
assert(Clusters[DstIndex - 1].Weight >= CC.Weight && "Weight overflow!");
} else { } else {
std::memmove(&Clusters[DstIndex++], &Clusters[SrcIndex], std::memmove(&Clusters[DstIndex++], &Clusters[SrcIndex],
sizeof(Clusters[SrcIndex])); sizeof(Clusters[SrcIndex]));
@ -7230,13 +7231,14 @@ bool SelectionDAGBuilder::buildJumpTable(CaseClusterVector &Clusters,
CaseCluster &JTCluster) { CaseCluster &JTCluster) {
assert(First <= Last); assert(First <= Last);
uint64_t Weight = 0; uint32_t Weight = 0;
unsigned NumCmps = 0; unsigned NumCmps = 0;
std::vector<MachineBasicBlock*> Table; std::vector<MachineBasicBlock*> Table;
DenseMap<MachineBasicBlock*, uint32_t> JTWeights; DenseMap<MachineBasicBlock*, uint32_t> JTWeights;
for (unsigned I = First; I <= Last; ++I) { for (unsigned I = First; I <= Last; ++I) {
assert(Clusters[I].Kind == CC_Range); assert(Clusters[I].Kind == CC_Range);
Weight += Clusters[I].Weight; Weight += Clusters[I].Weight;
assert(Weight >= Clusters[I].Weight && "Weight overflow!");
APInt Low = Clusters[I].Low->getValue(); APInt Low = Clusters[I].Low->getValue();
APInt High = Clusters[I].High->getValue(); APInt High = Clusters[I].High->getValue();
NumCmps += (Low == High) ? 1 : 2; NumCmps += (Low == High) ? 1 : 2;
@ -7463,7 +7465,7 @@ bool SelectionDAGBuilder::buildBitTests(CaseClusterVector &Clusters,
} }
CaseBitsVector CBV; CaseBitsVector CBV;
uint64_t TotalWeight = 0; uint32_t TotalWeight = 0;
for (unsigned i = First; i <= Last; ++i) { for (unsigned i = First; i <= Last; ++i) {
// Find the CaseBits for this destination. // Find the CaseBits for this destination.
unsigned j; unsigned j;
@ -7482,8 +7484,8 @@ bool SelectionDAGBuilder::buildBitTests(CaseClusterVector &Clusters,
CB->Bits++; CB->Bits++;
} }
CB->ExtraWeight += Clusters[i].Weight; CB->ExtraWeight += Clusters[i].Weight;
assert(CB->ExtraWeight >= Clusters[i].Weight && "Weight sum overflowed!");
TotalWeight += Clusters[i].Weight; TotalWeight += Clusters[i].Weight;
assert(TotalWeight >= Clusters[i].Weight && "Weight overflow!");
} }
BitTestInfo BTI; BitTestInfo BTI;
@ -7693,8 +7695,10 @@ void SelectionDAGBuilder::lowerWorkItem(SwitchWorkListItem W, Value *Cond,
// Compute total weight. // Compute total weight.
uint32_t UnhandledWeights = 0; uint32_t UnhandledWeights = 0;
for (CaseClusterIt I = W.FirstCluster; I <= W.LastCluster; ++I) for (CaseClusterIt I = W.FirstCluster; I <= W.LastCluster; ++I) {
UnhandledWeights += I->Weight; UnhandledWeights += I->Weight;
assert(UnhandledWeights >= I->Weight && "Weight overflow!");
}
MachineBasicBlock *CurMBB = W.MBB; MachineBasicBlock *CurMBB = W.MBB;
for (CaseClusterIt I = W.FirstCluster, E = W.LastCluster; I <= E; ++I) { for (CaseClusterIt I = W.FirstCluster, E = W.LastCluster; I <= E; ++I) {
@ -7859,8 +7863,10 @@ void SelectionDAGBuilder::visitSwitch(const SwitchInst &SI) {
MachineBasicBlock *Succ = FuncInfo.MBBMap[I.getCaseSuccessor()]; MachineBasicBlock *Succ = FuncInfo.MBBMap[I.getCaseSuccessor()];
const ConstantInt *CaseVal = I.getCaseValue(); const ConstantInt *CaseVal = I.getCaseValue();
uint32_t Weight = 0; // FIXME: Use 1 instead? uint32_t Weight = 0; // FIXME: Use 1 instead?
if (BPI) if (BPI) {
Weight = BPI->getEdgeWeight(SI.getParent(), I.getSuccessorIndex()); Weight = BPI->getEdgeWeight(SI.getParent(), I.getSuccessorIndex());
assert(Weight <= UINT32_MAX / SI.getNumSuccessors());
}
Clusters.push_back(CaseCluster::range(CaseVal, CaseVal, Succ, Weight)); Clusters.push_back(CaseCluster::range(CaseVal, CaseVal, Succ, Weight));
} }

2
lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
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@ -153,7 +153,7 @@ private:
unsigned JTCasesIndex; unsigned JTCasesIndex;
unsigned BTCasesIndex; unsigned BTCasesIndex;
}; };
uint64_t Weight; uint32_t Weight;
static CaseCluster range(const ConstantInt *Low, const ConstantInt *High, static CaseCluster range(const ConstantInt *Low, const ConstantInt *High,
MachineBasicBlock *MBB, uint32_t Weight) { MachineBasicBlock *MBB, uint32_t Weight) {