+void BranchFolder::setCommonTailEdgeWeights(MachineBasicBlock &TailMBB) {
+ SmallVector<BlockFrequency, 2> EdgeFreqLs(TailMBB.succ_size());
+ BlockFrequency AccumulatedMBBFreq;
+
+ // Aggregate edge frequency of successor edge j:
+ // edgeFreq(j) = sum (freq(bb) * edgeProb(bb, j)),
+ // where bb is a basic block that is in SameTails.
+ for (const auto &Src : SameTails) {
+ const MachineBasicBlock *SrcMBB = Src.getBlock();
+ BlockFrequency BlockFreq = MBBFreqInfo.getBlockFreq(SrcMBB);
+ AccumulatedMBBFreq += BlockFreq;
+
+ // It is not necessary to recompute edge weights if TailBB has less than two
+ // successors.
+ if (TailMBB.succ_size() <= 1)
+ continue;
+
+ auto EdgeFreq = EdgeFreqLs.begin();
+
+ for (auto SuccI = TailMBB.succ_begin(), SuccE = TailMBB.succ_end();
+ SuccI != SuccE; ++SuccI, ++EdgeFreq)
+ *EdgeFreq += BlockFreq * MBPI.getEdgeProbability(SrcMBB, *SuccI);
+ }
+
+ MBBFreqInfo.setBlockFreq(&TailMBB, AccumulatedMBBFreq);
+
+ if (TailMBB.succ_size() <= 1)
+ return;
+
+ auto MaxEdgeFreq = *std::max_element(EdgeFreqLs.begin(), EdgeFreqLs.end());
+ uint64_t Scale = MaxEdgeFreq.getFrequency() / UINT32_MAX + 1;
+ auto EdgeFreq = EdgeFreqLs.begin();
+
+ for (auto SuccI = TailMBB.succ_begin(), SuccE = TailMBB.succ_end();
+ SuccI != SuccE; ++SuccI, ++EdgeFreq)
+ TailMBB.setSuccWeight(SuccI, EdgeFreq->getFrequency() / Scale);
+}
+