[llvm] Adding Matching and Inference Functionality to Propeller-PR4: Implement matching and inference and create clusters (PR #167622)

[via llvm-commits]

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@@ -175,6 +177,79 @@ updateBranches(MachineFunction &MF,
   }
 }
 
+// This function generates the machine basic block clusters of "hot" blocks.
+// Currently, only support one cluster creation.
+// TODO: Support multi-cluster creation and path cloning.
+static SmallVector<BBClusterInfo>
+createBBClusterInfoForFunction(MachineFunction &MF,
+                               BasicBlockMatchingAndInference *BMI) {
+  unsigned CurrentCluster = 0;
+  SmallVector<BBClusterInfo> BBClusterInfos;
+  auto OptWeightInfo = BMI->getWeightInfo(MF.getName());
+  if (!OptWeightInfo)
+    return BBClusterInfos;
+  auto BlockWeights = OptWeightInfo->BlockWeights;
+  auto EdgeWeights = OptWeightInfo->EdgeWeights;
+
+  SmallVector<const MachineBasicBlock *, 4> HotMBBs;
+  if (MF.size() <= 2) {
+    for (auto &MBB : MF) {
+      if (MBB.isEntryBlock() || BlockWeights[&MBB] > 0) {
+        HotMBBs.push_back(&MBB);
+      }
+    }
+  } else {
+    SmallVector<uint64_t, 0> BlockSizes(MF.size());
+    SmallVector<uint64_t, 0> BlockCounts(MF.size());
+    std::vector<const MachineBasicBlock *> OrigOrder;
+    OrigOrder.reserve(MF.size());
+    SmallVector<codelayout::EdgeCount, 0> JumpCounts;
+
+    // Renumber blocks for running the layout algorithm.
+    MF.RenumberBlocks();
+
+    // Init the MBB size and count.
+    for (auto &MBB : MF) {
+      auto NonDbgInsts =
+          instructionsWithoutDebug(MBB.instr_begin(), MBB.instr_end());
+      int NumInsts = std::distance(NonDbgInsts.begin(), NonDbgInsts.end());
+      BlockSizes[MBB.getNumber()] = 4 * NumInsts;
+      BlockCounts[MBB.getNumber()] = BlockWeights[&MBB];
+      OrigOrder.push_back(&MBB);
+    }
+
+    // Init the edge count.
+    for (auto &MBB : MF) {
+      for (auto *Succ : MBB.successors()) {
+        auto EdgeWeight = EdgeWeights[std::make_pair(&MBB, Succ)];
+        JumpCounts.push_back({static_cast<uint64_t>(MBB.getNumber()),
+                              static_cast<uint64_t>(Succ->getNumber()),
+                              EdgeWeight});
+      }
+    }
+
+    // Run the layout algorithm.
+    auto Result = computeExtTspLayout(BlockSizes, BlockCounts, JumpCounts);
+    for (uint64_t R : Result) {
+      auto Block = OrigOrder[R];
+      if (Block->isEntryBlock() || BlockWeights[Block] > 0)
+        HotMBBs.push_back(Block);
+    }
+  }
+
+  // Generate the "hot" basic block cluster.
+  if (!HotMBBs.empty()) {
+    unsigned CurrentPosition = 0;
+    for (auto &MBB : HotMBBs) {
+      if (MBB->getBBID()) {
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wdx727 wrote:

In our production environment usage, invalid BBID issues have occurred here. Therefore, we added this condition to ensure absolute safety, though the specific root cause remains unanalyzed.

https://github.com/llvm/llvm-project/pull/167622