void MachineBranchProbabilityInfo::anchor() { }
-uint32_t MachineBranchProbabilityInfo::
-getSumForBlock(const MachineBasicBlock *MBB, uint32_t &Scale) const {
- // First we compute the sum with 64-bits of precision, ensuring that cannot
- // overflow by bounding the number of weights considered. Hopefully no one
- // actually needs 2^32 successors.
- assert(MBB->succ_size() < UINT32_MAX);
- uint64_t Sum = 0;
- Scale = 1;
+uint32_t
+MachineBranchProbabilityInfo::getSumForBlock(MachineBasicBlock *MBB) const {
+ // Normalize the weights of MBB's all successors so that the sum is guaranteed
+ // to be no greater than UINT32_MAX.
+ MBB->normalizeSuccWeights();
+
+ SmallVector<uint32_t, 8> Weights;
for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
- E = MBB->succ_end(); I != E; ++I) {
- uint32_t Weight = getEdgeWeight(MBB, I);
- Sum += Weight;
- }
+ E = MBB->succ_end();
+ I != E; ++I)
+ Weights.push_back(getEdgeWeight(MBB, I));
- // If the computed sum fits in 32-bits, we're done.
- if (Sum <= UINT32_MAX)
- return Sum;
+ return std::accumulate(Weights.begin(), Weights.end(), 0u);
+}
- // Otherwise, compute the scale necessary to cause the weights to fit, and
- // re-sum with that scale applied.
- assert((Sum / UINT32_MAX) < UINT32_MAX);
- Scale = (Sum / UINT32_MAX) + 1;
- Sum = 0;
+uint32_t
+MachineBranchProbabilityInfo::getSumForBlock(const MachineBasicBlock *MBB,
+ uint32_t &Scale) const {
+ SmallVector<uint32_t, 8> Weights;
for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
- E = MBB->succ_end(); I != E; ++I) {
- uint32_t Weight = getEdgeWeight(MBB, I);
- Sum += Weight / Scale;
- }
- assert(Sum <= UINT32_MAX);
- return Sum;
+ E = MBB->succ_end();
+ I != E; ++I)
+ Weights.push_back(getEdgeWeight(MBB, I));
+
+ if (MBB->areSuccWeightsNormalized())
+ Scale = 1;
+ else
+ Scale = MachineBranchProbabilityInfo::normalizeEdgeWeights(Weights);
+ return std::accumulate(Weights.begin(), Weights.end(), 0u);
}
uint32_t MachineBranchProbabilityInfo::