bool LowerExpectIntrinsic::HandleSwitchExpect(SwitchInst *SI) {
CallInst *CI = dyn_cast<CallInst>(SI->getCondition());
if (!CI)
return false;
Function *Fn = CI->getCalledFunction();
if (!Fn || Fn->getIntrinsicID() != Intrinsic::expect)
return false;
Value *ArgValue = CI->getArgOperand(0);
ConstantInt *ExpectedValue = dyn_cast<ConstantInt>(CI->getArgOperand(1));
if (!ExpectedValue)
return false;
SwitchInst::CaseIt Case = SI->findCaseValue(ExpectedValue);
unsigned n = SI->getNumCases(); // +1 for default case.
std::vector<uint32_t> Weights(n + 1);
Weights[0] = Case == SI->case_default() ? LikelyBranchWeight
: UnlikelyBranchWeight;
for (unsigned i = 0; i != n; ++i)
Weights[i + 1] = i == Case.getCaseIndex() ? LikelyBranchWeight
: UnlikelyBranchWeight;
SI->setMetadata(LLVMContext::MD_prof,
MDBuilder(CI->getContext()).createBranchWeights(Weights));
SI->setCondition(ArgValue);
return true;
}
bool LowerExpectIntrinsic::HandleSwitchExpect(SwitchInst *SI) {
CallInst *CI = dyn_cast<CallInst>(SI->getCondition());
if (!CI)
return false;
Function *Fn = CI->getCalledFunction();
if (!Fn || Fn->getIntrinsicID() != Intrinsic::expect)
return false;
Value *ArgValue = CI->getArgOperand(0);
ConstantInt *ExpectedValue = dyn_cast<ConstantInt>(CI->getArgOperand(1));
if (!ExpectedValue)
return false;
LLVMContext &Context = CI->getContext();
Type *Int32Ty = Type::getInt32Ty(Context);
SwitchInst::CaseIt Case = SI->findCaseValue(ExpectedValue);
std::vector<Value *> Vec;
unsigned n = SI->getNumCases();
Vec.resize(n + 1 + 1); // +1 for MDString and +1 for default case
Vec[0] = MDString::get(Context, "branch_weights");
Vec[1] = ConstantInt::get(Int32Ty, Case == SI->case_default() ?
LikelyBranchWeight : UnlikelyBranchWeight);
for (unsigned i = 0; i < n; ++i) {
Vec[i + 1 + 1] = ConstantInt::get(Int32Ty, i == Case.getCaseIndex() ?
LikelyBranchWeight : UnlikelyBranchWeight);
}
MDNode *WeightsNode = llvm::MDNode::get(Context, Vec);
SI->setMetadata(LLVMContext::MD_prof, WeightsNode);
SI->setCondition(ArgValue);
return true;
}
