X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FIfConversion.cpp;h=1a18b1a00c8c46701e8d6bf71c5ea0179df6b877;hb=3bfc4d8e13edd83534b733f0f1de5b1d5f6bf828;hp=c6cef9b114b8f0c0bd44d60dd651ee1b1d187c1d;hpb=57c38e3faa02d660ea09e88c8aa34d6fe1cccb88;p=oota-llvm.git

diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index c6cef9b114b..1a18b1a00c8 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -17,13 +17,13 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/LivePhysRegs.h"
 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/TargetSchedule.h"
-#include "llvm/CodeGen/LivePhysRegs.h"
 #include "llvm/MC/MCInstrItineraries.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
@@ -174,12 +174,12 @@ namespace {
       initializeIfConverterPass(*PassRegistry::getPassRegistry());
     }
 
-    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.addRequired<MachineBranchProbabilityInfo>();
       MachineFunctionPass::getAnalysisUsage(AU);
     }
 
-    virtual bool runOnMachineFunction(MachineFunction &MF);
+    bool runOnMachineFunction(MachineFunction &MF) override;
 
   private:
     bool ReverseBranchCondition(BBInfo &BBI);
@@ -921,7 +921,7 @@ void IfConverter::AnalyzeBlocks(MachineFunction &MF,
 /// next block).
 static bool canFallThroughTo(MachineBasicBlock *BB, MachineBasicBlock *ToBB) {
   MachineFunction::iterator PI = BB;
-  MachineFunction::iterator I = llvm::next(PI);
+  MachineFunction::iterator I = std::next(PI);
   MachineFunction::iterator TI = ToBB;
   MachineFunction::iterator E = BB->getParent()->end();
   while (I != TI) {
@@ -1102,6 +1102,28 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) {
   return true;
 }
 
+/// Scale down weights to fit into uint32_t. NewTrue is the new weight
+/// for successor TrueBB, and NewFalse is the new weight for successor
+/// FalseBB.
+static void ScaleWeights(uint64_t NewTrue, uint64_t NewFalse,
+                         MachineBasicBlock *MBB,
+                         const MachineBasicBlock *TrueBB,
+                         const MachineBasicBlock *FalseBB,
+                         const MachineBranchProbabilityInfo *MBPI) {
+  uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
+  uint32_t Scale = (NewMax / UINT32_MAX) + 1;
+  for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
+                                        SE = MBB->succ_end();
+       SI != SE; ++SI) {
+    if (*SI == TrueBB)
+      MBB->setSuccWeight(SI, (uint32_t)(NewTrue / Scale));
+    else if (*SI == FalseBB)
+      MBB->setSuccWeight(SI, (uint32_t)(NewFalse / Scale));
+    else
+      MBB->setSuccWeight(SI, MBPI->getEdgeWeight(MBB, SI) / Scale);
+  }
+}
+
 /// IfConvertTriangle - If convert a triangle sub-CFG.
 ///
 bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
@@ -1158,6 +1180,16 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
   DontKill.clear();
 
   bool HasEarlyExit = CvtBBI->FalseBB != NULL;
+  uint64_t CvtNext = 0, CvtFalse = 0, BBNext = 0, BBCvt = 0, SumWeight = 0;
+  uint32_t WeightScale = 0;
+  if (HasEarlyExit) {
+    // Get weights before modifying CvtBBI->BB and BBI.BB.
+    CvtNext = MBPI->getEdgeWeight(CvtBBI->BB, NextBBI->BB);
+    CvtFalse = MBPI->getEdgeWeight(CvtBBI->BB, CvtBBI->FalseBB);
+    BBNext = MBPI->getEdgeWeight(BBI.BB, NextBBI->BB);
+    BBCvt = MBPI->getEdgeWeight(BBI.BB, CvtBBI->BB);
+    SumWeight = MBPI->getSumForBlock(CvtBBI->BB, WeightScale);
+  }
   if (CvtBBI->BB->pred_size() > 1) {
     BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
     // Copy instructions in the true block, predicate them, and add them to
@@ -1185,6 +1217,20 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
       llvm_unreachable("Unable to reverse branch condition!");
     TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, NULL, RevCond, dl);
     BBI.BB->addSuccessor(CvtBBI->FalseBB);
+    // Update the edge weight for both CvtBBI->FalseBB and NextBBI.
+    // New_Weight(BBI.BB, NextBBI->BB) =
+    //   Weight(BBI.BB, NextBBI->BB) * getSumForBlock(CvtBBI->BB) +
+    //   Weight(BBI.BB, CvtBBI->BB) * Weight(CvtBBI->BB, NextBBI->BB)
+    // New_Weight(BBI.BB, CvtBBI->FalseBB) =
+    //   Weight(BBI.BB, CvtBBI->BB) * Weight(CvtBBI->BB, CvtBBI->FalseBB)
+
+    uint64_t NewNext = BBNext * SumWeight + (BBCvt * CvtNext) / WeightScale;
+    uint64_t NewFalse = (BBCvt * CvtFalse) / WeightScale;
+    // We need to scale down all weights of BBI.BB to fit uint32_t.
+    // Here BBI.BB is connected to CvtBBI->FalseBB and will fall through to
+    // the next block.
+    ScaleWeights(NewNext, NewFalse, BBI.BB, getNextBlock(BBI.BB),
+                 CvtBBI->FalseBB, MBPI);
   }
 
   // Merge in the 'false' block if the 'false' block has no other