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SimplifyCFG: Simplify the weight scaling algorithm.

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No change in functionality.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203413 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2014-03-09 14:42:55 +00:00
parent c52fffeb17
commit 4b484628f4
1 changed files with 6 additions and 15 deletions
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21
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -732,8 +732,7 @@ static void GetBranchWeights(TerminatorInst *TI,
MDNode* MD = TI->getMetadata(LLVMContext::MD_prof);
assert(MD);
for (unsigned i = 1, e = MD->getNumOperands(); i < e; ++i) {
ConstantInt* CI = dyn_cast<ConstantInt>(MD->getOperand(i));
assert(CI);
ConstantInt *CI = cast<ConstantInt>(MD->getOperand(i));
Weights.push_back(CI->getValue().getZExtValue());
}
@ -750,19 +749,11 @@ static void GetBranchWeights(TerminatorInst *TI,
/// Keep halving the weights until all can fit in uint32_t.
static void FitWeights(MutableArrayRef<uint64_t> Weights) {
while (true) {
bool Halve = false;
for (unsigned i = 0; i < Weights.size(); ++i)
if (Weights[i] > UINT_MAX) {
Halve = true;
break;
}
if (! Halve)
return;
for (unsigned i = 0; i < Weights.size(); ++i)
Weights[i] /= 2;
uint64_t Max = *std::max_element(Weights.begin(), Weights.end());
if (Max > UINT_MAX) {
unsigned Offset = 32 - countLeadingZeros(Max);
for (uint64_t &I : Weights)
I >>= Offset;
}
}