[LIR] Move all the helpers to be private and re-order the methods in

[oota-llvm.git] / lib / Transforms / Scalar / LowerExpectIntrinsic.cpp

diff --git a/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp b/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
index ff89e7474402556f419c62dd534d4b320eae9303..0c47cbd5bfda6da1a891432ac82a2cd8dd2c4783 100644 (file)
--- a/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
+++ b/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
@@ -11,7 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
@@ -24,13 +25,14 @@
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
-#include <vector>
+#include "llvm/Transforms/Scalar.h"
 
 using namespace llvm;
 
 #define DEBUG_TYPE "lower-expect-intrinsic"
 
-STATISTIC(IfHandled, "Number of 'expect' intrinsic instructions handled");
+STATISTIC(ExpectIntrinsicsHandled,
+          "Number of 'expect' intrinsic instructions handled");
 
 static cl::opt<uint32_t>
 LikelyBranchWeight("likely-branch-weight", cl::Hidden, cl::init(64),
@@ -39,27 +41,8 @@ static cl::opt<uint32_t>
 UnlikelyBranchWeight("unlikely-branch-weight", cl::Hidden, cl::init(4),
                    cl::desc("Weight of the branch unlikely to be taken (default = 4)"));
 
-namespace {
-
-  class LowerExpectIntrinsic : public FunctionPass {
-
-    bool HandleSwitchExpect(SwitchInst *SI);
-
-    bool HandleIfExpect(BranchInst *BI);
-
-  public:
-    static char ID;
-    LowerExpectIntrinsic() : FunctionPass(ID) {
-      initializeLowerExpectIntrinsicPass(*PassRegistry::getPassRegistry());
-    }
-
-    bool runOnFunction(Function &F) override;
-  };
-}
-
-
-bool LowerExpectIntrinsic::HandleSwitchExpect(SwitchInst *SI) {
-  CallInst *CI = dyn_cast<CallInst>(SI->getCondition());
+static bool handleSwitchExpect(SwitchInst &SI) {
+  CallInst *CI = dyn_cast<CallInst>(SI.getCondition());
   if (!CI)
     return false;
 
@@ -72,26 +55,24 @@ bool LowerExpectIntrinsic::HandleSwitchExpect(SwitchInst *SI) {
   if (!ExpectedValue)
     return false;
 
-  SwitchInst::CaseIt Case = SI->findCaseValue(ExpectedValue);
-  unsigned n = SI->getNumCases(); // +1 for default case.
-  std::vector<uint32_t> Weights(n + 1);
+  SwitchInst::CaseIt Case = SI.findCaseValue(ExpectedValue);
+  unsigned n = SI.getNumCases(); // +1 for default case.
+  SmallVector<uint32_t, 16> Weights(n + 1, UnlikelyBranchWeight);
 
-  Weights[0] = Case == SI->case_default() ? LikelyBranchWeight
-                                          : UnlikelyBranchWeight;
-  for (unsigned i = 0; i != n; ++i)
-    Weights[i + 1] = i == Case.getCaseIndex() ? LikelyBranchWeight
-                                              : UnlikelyBranchWeight;
+  if (Case == SI.case_default())
+    Weights[0] = LikelyBranchWeight;
+  else
+    Weights[Case.getCaseIndex() + 1] = LikelyBranchWeight;
 
-  SI->setMetadata(LLVMContext::MD_prof,
-                  MDBuilder(CI->getContext()).createBranchWeights(Weights));
+  SI.setMetadata(LLVMContext::MD_prof,
+                 MDBuilder(CI->getContext()).createBranchWeights(Weights));
 
-  SI->setCondition(ArgValue);
+  SI.setCondition(ArgValue);
   return true;
 }
 
-
-bool LowerExpectIntrinsic::HandleIfExpect(BranchInst *BI) {
-  if (BI->isUnconditional())
+static bool handleBranchExpect(BranchInst &BI) {
+  if (BI.isUnconditional())
     return false;
 
   // Handle non-optimized IR code like:
@@ -105,9 +86,9 @@ bool LowerExpectIntrinsic::HandleIfExpect(BranchInst *BI) {
 
   CallInst *CI;
 
-  ICmpInst *CmpI = dyn_cast<ICmpInst>(BI->getCondition());
+  ICmpInst *CmpI = dyn_cast<ICmpInst>(BI.getCondition());
   if (!CmpI) {
-    CI = dyn_cast<CallInst>(BI->getCondition());
+    CI = dyn_cast<CallInst>(BI.getCondition());
   } else {
     if (CmpI->getPredicate() != CmpInst::ICMP_NE)
       return false;
@@ -136,32 +117,30 @@ bool LowerExpectIntrinsic::HandleIfExpect(BranchInst *BI) {
   else
     Node = MDB.createBranchWeights(UnlikelyBranchWeight, LikelyBranchWeight);
 
-  BI->setMetadata(LLVMContext::MD_prof, Node);
+  BI.setMetadata(LLVMContext::MD_prof, Node);
 
   if (CmpI)
     CmpI->setOperand(0, ArgValue);
   else
-    BI->setCondition(ArgValue);
+    BI.setCondition(ArgValue);
   return true;
 }
 
+static bool lowerExpectIntrinsic(Function &F) {
+  bool Changed = false;
 
-bool LowerExpectIntrinsic::runOnFunction(Function &F) {
-  for (Function::iterator I = F.begin(), E = F.end(); I != E;) {
-    BasicBlock *BB = I++;
-
+  for (BasicBlock &BB : F) {
     // Create "block_weights" metadata.
-    if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) {
-      if (HandleIfExpect(BI))
-        IfHandled++;
-    } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
-      if (HandleSwitchExpect(SI))
-        IfHandled++;
+    if (BranchInst *BI = dyn_cast<BranchInst>(BB.getTerminator())) {
+      if (handleBranchExpect(*BI))
+        ExpectIntrinsicsHandled++;
+    } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB.getTerminator())) {
+      if (handleSwitchExpect(*SI))
+        ExpectIntrinsicsHandled++;
     }
 
     // remove llvm.expect intrinsics.
-    for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
-         BI != BE; ) {
+    for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
       CallInst *CI = dyn_cast<CallInst>(BI++);
       if (!CI)
         continue;
@@ -171,17 +150,42 @@ bool LowerExpectIntrinsic::runOnFunction(Function &F) {
         Value *Exp = CI->getArgOperand(0);
         CI->replaceAllUsesWith(Exp);
         CI->eraseFromParent();
+        Changed = true;
       }
     }
   }
 
-  return false;
+  return Changed;
 }
 
+PreservedAnalyses LowerExpectIntrinsicPass::run(Function &F) {
+  if (lowerExpectIntrinsic(F))
+    return PreservedAnalyses::none();
+
+  return PreservedAnalyses::all();
+}
+
+namespace {
+/// \brief Legacy pass for lowering expect intrinsics out of the IR.
+///
+/// When this pass is run over a function it uses expect intrinsics which feed
+/// branches and switches to provide branch weight metadata for those
+/// terminators. It then removes the expect intrinsics from the IR so the rest
+/// of the optimizer can ignore them.
+class LowerExpectIntrinsic : public FunctionPass {
+public:
+  static char ID;
+  LowerExpectIntrinsic() : FunctionPass(ID) {
+    initializeLowerExpectIntrinsicPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnFunction(Function &F) override { return lowerExpectIntrinsic(F); }
+};
+}
 
 char LowerExpectIntrinsic::ID = 0;
-INITIALIZE_PASS(LowerExpectIntrinsic, "lower-expect", "Lower 'expect' "
-                "Intrinsics", false, false)
+INITIALIZE_PASS(LowerExpectIntrinsic, "lower-expect",
+                "Lower 'expect' Intrinsics", false, false)
 
 FunctionPass *llvm::createLowerExpectIntrinsicPass() {
   return new LowerExpectIntrinsic();