MDNode *Loop::getLoopID() const {
MDNode *LoopID = nullptr;
if (isLoopSimplifyForm()) {
LoopID = getLoopLatch()->getTerminator()->getMetadata(LoopMDName);
} else {
// Go through each predecessor of the loop header and check the
// terminator for the metadata.
BasicBlock *H = getHeader();
for (block_iterator I = block_begin(), IE = block_end(); I != IE; ++I) {
TerminatorInst *TI = (*I)->getTerminator();
MDNode *MD = nullptr;
// Check if this terminator branches to the loop header.
for (unsigned i = 0, ie = TI->getNumSuccessors(); i != ie; ++i) {
if (TI->getSuccessor(i) == H) {
MD = TI->getMetadata(LoopMDName);
break;
}
}
if (!MD)
return nullptr;
if (!LoopID)
LoopID = MD;
else if (MD != LoopID)
return nullptr;
}
}
if (!LoopID || LoopID->getNumOperands() == 0 ||
LoopID->getOperand(0) != LoopID)
return nullptr;
return LoopID;
}
MDNode *Loop::getLoopID() const {
MDNode *LoopID = nullptr;
if (isLoopSimplifyForm()) {
LoopID = getLoopLatch()->getTerminator()->getMetadata(LLVMContext::MD_loop);
} else {
// Go through each predecessor of the loop header and check the
// terminator for the metadata.
BasicBlock *H = getHeader();
for (BasicBlock *BB : this->blocks()) {
TerminatorInst *TI = BB->getTerminator();
MDNode *MD = nullptr;
// Check if this terminator branches to the loop header.
for (BasicBlock *Successor : TI->successors()) {
if (Successor == H) {
MD = TI->getMetadata(LLVMContext::MD_loop);
break;
}
}
if (!MD)
return nullptr;
if (!LoopID)
LoopID = MD;
else if (MD != LoopID)
return nullptr;
}
}
if (!LoopID || LoopID->getNumOperands() == 0 ||
LoopID->getOperand(0) != LoopID)
return nullptr;
return LoopID;
}
// Propagate existing explicit probabilities from either profile data or
// 'expect' intrinsic processing.
bool BranchProbabilityAnalysis::calcMetadataWeights(BasicBlock *BB) {
TerminatorInst *TI = BB->getTerminator();
if (TI->getNumSuccessors() == 1)
return false;
if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
return false;
MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof);
if (!WeightsNode)
return false;
// Ensure there are weights for all of the successors. Note that the first
// operand to the metadata node is a name, not a weight.
if (WeightsNode->getNumOperands() != TI->getNumSuccessors() + 1)
return false;
// Build up the final weights that will be used in a temporary buffer, but
// don't add them until all weihts are present. Each weight value is clamped
// to [1, getMaxWeightFor(BB)].
uint32_t WeightLimit = getMaxWeightFor(BB);
SmallVector<uint32_t, 2> Weights;
Weights.reserve(TI->getNumSuccessors());
for (unsigned i = 1, e = WeightsNode->getNumOperands(); i != e; ++i) {
ConstantInt *Weight = dyn_cast<ConstantInt>(WeightsNode->getOperand(i));
if (!Weight)
return false;
Weights.push_back(
std::max<uint32_t>(1, Weight->getLimitedValue(WeightLimit)));
}
assert(Weights.size() == TI->getNumSuccessors() && "Checked above");
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
BP->setEdgeWeight(BB, TI->getSuccessor(i), Weights[i]);
return true;
}
// Propagate existing explicit probabilities from either profile data or
// 'expect' intrinsic processing.
bool BranchProbabilityInfo::calcMetadataWeights(BasicBlock *BB) {
TerminatorInst *TI = BB->getTerminator();
if (TI->getNumSuccessors() == 1)
return false;
if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
return false;
MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof);
if (!WeightsNode)
return false;
// Check that the number of successors is manageable.
assert(TI->getNumSuccessors() < UINT32_MAX && "Too many successors");
// Ensure there are weights for all of the successors. Note that the first
// operand to the metadata node is a name, not a weight.
if (WeightsNode->getNumOperands() != TI->getNumSuccessors() + 1)
return false;
// Build up the final weights that will be used in a temporary buffer.
// Compute the sum of all weights to later decide whether they need to
// be scaled to fit in 32 bits.
uint64_t WeightSum = 0;
SmallVector<uint32_t, 2> Weights;
Weights.reserve(TI->getNumSuccessors());
for (unsigned i = 1, e = WeightsNode->getNumOperands(); i != e; ++i) {
ConstantInt *Weight =
mdconst::dyn_extract<ConstantInt>(WeightsNode->getOperand(i));
if (!Weight)
return false;
assert(Weight->getValue().getActiveBits() <= 32 &&
"Too many bits for uint32_t");
Weights.push_back(Weight->getZExtValue());
WeightSum += Weights.back();
}
assert(Weights.size() == TI->getNumSuccessors() && "Checked above");
// If the sum of weights does not fit in 32 bits, scale every weight down
// accordingly.
uint64_t ScalingFactor =
(WeightSum > UINT32_MAX) ? WeightSum / UINT32_MAX + 1 : 1;
WeightSum = 0;
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
uint32_t W = Weights[i] / ScalingFactor;
WeightSum += W;
setEdgeWeight(BB, i, W);
}
assert(WeightSum <= UINT32_MAX &&
"Expected weights to scale down to 32 bits");
return true;
}
