Add support for branch weight metadata to MDBuilder and use it in various places.

llvm-svn: 157515

include/llvm/Support/MDBuilder.h

@@ -49,6 +49,29 @@ namespace llvm {
       return MDNode::get(Context, Op);
     }
 
+    //===------------------------------------------------------------------===//
+    // Prof metadata.
+    //===------------------------------------------------------------------===//
+
+    /// \brief Return metadata containing two branch weights.
+    MDNode *createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight) {
+      uint32_t Weights[] = { TrueWeight, FalseWeight };
+      return createBranchWeights(Weights);
+    }
+
+    /// \brief Return metadata containing a number of branch weights.
+    MDNode *createBranchWeights(ArrayRef<uint32_t> Weights) {
+      assert(Weights.size() >= 2 && "Need at least two branch weights!");
+
+      SmallVector<Value *, 4> Vals(Weights.size()+1);
+      Vals[0] = createString("branch_weights");
+
+      Type *Int32Ty = Type::getInt32Ty(Context);
+      for (unsigned i = 0, e = Weights.size(); i != e; ++i)
+        Vals[i+1] = ConstantInt::get(Int32Ty, Weights[i]);
+
+      return MDNode::get(Context, Vals);
+    }
 
     //===------------------------------------------------------------------===//
     // Range metadata.

lib/Transforms/Utils/LowerExpectIntrinsic.cpp

@@ -23,6 +23,7 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/MDBuilder.h"
 #include "llvm/ADT/Statistic.h"
 #include <vector>
 
@@ -70,24 +71,18 @@ bool LowerExpectIntrinsic::HandleSwitchExpect(SwitchInst *SI) {
   if (!ExpectedValue)
     return false;
 
-  LLVMContext &Context = CI->getContext();
-  Type *Int32Ty = Type::getInt32Ty(Context);
-
   SwitchInst::CaseIt Case = SI->findCaseValue(ExpectedValue);
-  std::vector<Value *> Vec;
-  unsigned n = SI->getNumCases();
-  Vec.resize(n + 1 + 1); // +1 for MDString and +1 for default case
+  unsigned n = SI->getNumCases(); // +1 for default case.
+  std::vector<uint32_t> Weights(n + 1);
 
-  Vec[0] = MDString::get(Context, "branch_weights");
-  Vec[1] = ConstantInt::get(Int32Ty, Case == SI->case_default() ?
-                            LikelyBranchWeight : UnlikelyBranchWeight);
-  for (unsigned i = 0; i < n; ++i) {
-    Vec[i + 1 + 1] = ConstantInt::get(Int32Ty, i == Case.getCaseIndex() ?
-        LikelyBranchWeight : UnlikelyBranchWeight);
-  }
+  Weights[0] = Case == SI->case_default() ? LikelyBranchWeight
+                                          : UnlikelyBranchWeight;
+  for (unsigned i = 0; i != n; ++i)
+    Weights[i + 1] = i == Case.getCaseIndex() ? LikelyBranchWeight
+                                              : UnlikelyBranchWeight;
 
-  MDNode *WeightsNode = llvm::MDNode::get(Context, Vec);
-  SI->setMetadata(LLVMContext::MD_prof, WeightsNode);
+  SI->setMetadata(LLVMContext::MD_prof,
+                  MDBuilder(CI->getContext()).createBranchWeights(Weights));
 
   SI->setCondition(ArgValue);
   return true;
@@ -120,20 +115,17 @@ bool LowerExpectIntrinsic::HandleIfExpect(BranchInst *BI) {
   if (!ExpectedValue)
     return false;
 
-  LLVMContext &Context = CI->getContext();
-  Type *Int32Ty = Type::getInt32Ty(Context);
-  bool Likely = ExpectedValue->isOne();
+  MDBuilder MDB(CI->getContext());
+  MDNode *Node;
 
   // If expect value is equal to 1 it means that we are more likely to take
   // branch 0, in other case more likely is branch 1.
-  Value *Ops[] = {
-    MDString::get(Context, "branch_weights"),
-    ConstantInt::get(Int32Ty, Likely ? LikelyBranchWeight : UnlikelyBranchWeight),
-    ConstantInt::get(Int32Ty, Likely ? UnlikelyBranchWeight : LikelyBranchWeight)
-  };
+  if (ExpectedValue->isOne())
+    Node = MDB.createBranchWeights(LikelyBranchWeight, UnlikelyBranchWeight);
+  else
+    Node = MDB.createBranchWeights(UnlikelyBranchWeight, LikelyBranchWeight);
 
-  MDNode *WeightsNode = MDNode::get(Context, Ops);
-  BI->setMetadata(LLVMContext::MD_prof, WeightsNode);
+  BI->setMetadata(LLVMContext::MD_prof, Node);
 
   CmpI->setOperand(0, ArgValue);
   return true;

lib/Transforms/Utils/SimplifyCFG.cpp

@@ -37,6 +37,7 @@
 #include "llvm/Support/ConstantRange.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/IRBuilder.h"
+#include "llvm/Support/MDBuilder.h"
 #include "llvm/Support/NoFolder.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
@@ -1740,12 +1741,10 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI) {
         ProbTrue = ProbTrue.udiv(GCD);
         ProbFalse = ProbFalse.udiv(GCD);
 
-        LLVMContext &Context = BI->getContext();
-        Value *Ops[3];
-        Ops[0] = BI->getMetadata(LLVMContext::MD_prof)->getOperand(0);
-        Ops[1] = ConstantInt::get(Context, ProbTrue);
-        Ops[2] = ConstantInt::get(Context, ProbFalse);
-        PBI->setMetadata(LLVMContext::MD_prof, MDNode::get(Context, Ops));
+        MDBuilder MDB(BI->getContext());
+        MDNode *N = MDB.createBranchWeights(ProbTrue.getZExtValue(),
+                                            ProbFalse.getZExtValue());
+        PBI->setMetadata(LLVMContext::MD_prof, N);
       } else {
         PBI->setMetadata(LLVMContext::MD_prof, NULL);
       }