Introduce MachineBranchProbabilityInfo class, which has similar API to

BranchProbabilityInfo (expect setEdgeWeight which is not available here).
Branch Weights are kept in MachineBasicBlocks. To turn off this analysis
set -use-mbpi=false.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133184 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 50 insertions, 11 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 4e19d2b8be..d79a5aea08 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1279,6 +1279,24 @@ bool SelectionDAGBuilder::isExportableFromCurrentBlock(const Value *V,
   return true;
 }
 
+/// Return branch probability calculated by BranchProbabilityInfo for IR blocks.
+uint32_t SelectionDAGBuilder::getEdgeWeight(MachineBasicBlock *Src,
+                                            MachineBasicBlock *Dst) {
+  BranchProbabilityInfo *BPI = FuncInfo.BPI;
+  if (!BPI)
+    return 0;
+  BasicBlock *SrcBB = const_cast<BasicBlock*>(Src->getBasicBlock());
+  BasicBlock *DstBB = const_cast<BasicBlock*>(Dst->getBasicBlock());
+  return BPI->getEdgeWeight(SrcBB, DstBB);
+}
+
+void SelectionDAGBuilder::addSuccessorWithWeight(MachineBasicBlock *Src,
+                                                 MachineBasicBlock *Dst) {
+  uint32_t weight = getEdgeWeight(Src, Dst);
+  Src->addSuccessor(Dst, weight);
+}
+
+
 static bool InBlock(const Value *V, const BasicBlock *BB) {
   if (const Instruction *I = dyn_cast<Instruction>(V))
     return I->getParent() == BB;
@@ -1548,8 +1566,8 @@ void SelectionDAGBuilder::visitSwitchCase(CaseBlock &CB,
   }
 
   // Update successor info
-  SwitchBB->addSuccessor(CB.TrueBB);
-  SwitchBB->addSuccessor(CB.FalseBB);
+  addSuccessorWithWeight(SwitchBB, CB.TrueBB);
+  addSuccessorWithWeight(SwitchBB, CB.FalseBB);
 
   // Set NextBlock to be the MBB immediately after the current one, if any.
   // This is used to avoid emitting unnecessary branches to the next block.
@@ -1693,8 +1711,8 @@ void SelectionDAGBuilder::visitBitTestHeader(BitTestBlock &B,
 
   MachineBasicBlock* MBB = B.Cases[0].ThisBB;
 
-  SwitchBB->addSuccessor(B.Default);
-  SwitchBB->addSuccessor(MBB);
+  addSuccessorWithWeight(SwitchBB, B.Default);
+  addSuccessorWithWeight(SwitchBB, MBB);
 
   SDValue BrRange = DAG.getNode(ISD::BRCOND, getCurDebugLoc(),
                                 MVT::Other, CopyTo, RangeCmp,
@@ -1739,8 +1757,8 @@ void SelectionDAGBuilder::visitBitTestCase(BitTestBlock &BB,
                        ISD::SETNE);
   }
 
-  SwitchBB->addSuccessor(B.TargetBB);
-  SwitchBB->addSuccessor(NextMBB);
+  addSuccessorWithWeight(SwitchBB, B.TargetBB);
+  addSuccessorWithWeight(SwitchBB, NextMBB);
 
   SDValue BrAnd = DAG.getNode(ISD::BRCOND, getCurDebugLoc(),
                               MVT::Other, getControlRoot(),
@@ -1980,8 +1998,9 @@ bool SelectionDAGBuilder::handleJTSwitchCase(CaseRec& CR,
   // table.
   MachineBasicBlock *JumpTableBB = CurMF->CreateMachineBasicBlock(LLVMBB);
   CurMF->insert(BBI, JumpTableBB);
-  CR.CaseBB->addSuccessor(Default);
-  CR.CaseBB->addSuccessor(JumpTableBB);
+
+  addSuccessorWithWeight(CR.CaseBB, Default);
+  addSuccessorWithWeight(CR.CaseBB, JumpTableBB);
 
   // Build a vector of destination BBs, corresponding to each target
   // of the jump table. If the value of the jump table slot corresponds to
@@ -2008,7 +2027,7 @@ bool SelectionDAGBuilder::handleJTSwitchCase(CaseRec& CR,
          E = DestBBs.end(); I != E; ++I) {
     if (!SuccsHandled[(*I)->getNumber()]) {
       SuccsHandled[(*I)->getNumber()] = true;
-      JumpTableBB->addSuccessor(*I);
+      addSuccessorWithWeight(JumpTableBB, *I);
     }
   }
 
@@ -2427,8 +2446,10 @@ void SelectionDAGBuilder::visitIndirectBr(const IndirectBrInst &I) {
     succs.push_back(I.getSuccessor(i));
   array_pod_sort(succs.begin(), succs.end());
   succs.erase(std::unique(succs.begin(), succs.end()), succs.end());
-  for (unsigned i = 0, e = succs.size(); i != e; ++i)
-    IndirectBrMBB->addSuccessor(FuncInfo.MBBMap[succs[i]]);
+  for (unsigned i = 0, e = succs.size(); i != e; ++i) {
+    MachineBasicBlock *Succ = FuncInfo.MBBMap[succs[i]];
+    addSuccessorWithWeight(IndirectBrMBB, Succ);
+  }
 
   DAG.setRoot(DAG.getNode(ISD::BRIND, getCurDebugLoc(),
                           MVT::Other, getControlRoot(),
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 8376d41e15..a1ca891148 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -434,6 +434,9 @@ private:
                                 const Value* SV,
                                 MachineBasicBlock* Default,
                                 MachineBasicBlock *SwitchBB);
+
+  uint32_t getEdgeWeight(MachineBasicBlock *Src, MachineBasicBlock *Dst);
+  void addSuccessorWithWeight(MachineBasicBlock *Src, MachineBasicBlock *Dst);
 public:
   void visitSwitchCase(CaseBlock &CB,
                        MachineBasicBlock *SwitchBB);
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 771b0089fd..dc8044b7a7 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -17,6 +17,7 @@
 #include "llvm/CodeGen/FunctionLoweringInfo.h"
 #include "llvm/CodeGen/SelectionDAGISel.h"
 #include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/BranchProbabilityInfo.h"
 #include "llvm/Analysis/DebugInfo.h"
 #include "llvm/Constants.h"
 #include "llvm/Function.h"
@@ -68,6 +69,11 @@ static cl::opt<bool>
 EnableFastISelAbort("fast-isel-abort", cl::Hidden,
           cl::desc("Enable abort calls when \"fast\" instruction fails"));
 
+static cl::opt<bool>
+UseMBPI("use-mbpi",
+        cl::desc("use Machine Branch Probability Info"),
+        cl::init(true), cl::Hidden);
+
 #ifndef NDEBUG
 static cl::opt<bool>
 ViewDAGCombine1("view-dag-combine1-dags", cl::Hidden,
@@ -186,6 +192,7 @@ SelectionDAGISel::SelectionDAGISel(const TargetMachine &tm,
   DAGSize(0) {
     initializeGCModuleInfoPass(*PassRegistry::getPassRegistry());
     initializeAliasAnalysisAnalysisGroup(*PassRegistry::getPassRegistry());
+    initializeBranchProbabilityInfoPass(*PassRegistry::getPassRegistry());
   }
 
 SelectionDAGISel::~SelectionDAGISel() {
@@ -199,6 +206,8 @@ void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addPreserved<AliasAnalysis>();
   AU.addRequired<GCModuleInfo>();
   AU.addPreserved<GCModuleInfo>();
+  if (UseMBPI && OptLevel != CodeGenOpt::None)
+    AU.addRequired<BranchProbabilityInfo>();
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
@@ -262,6 +271,12 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
 
   CurDAG->init(*MF);
   FuncInfo->set(Fn, *MF);
+
+  if (UseMBPI && OptLevel != CodeGenOpt::None)
+    FuncInfo->BPI = &getAnalysis<BranchProbabilityInfo>();
+  else
+    FuncInfo->BPI = 0;
+
   SDB->init(GFI, *AA);
 
   SelectAllBasicBlocks(Fn);