Add FP_CONTRACT support for clang.

Clang will now honor the FP_CONTRACT pragma and emit LLVM
fmuladd intrinsics for expressions of the form A * B + C (when they occur in a
single statement).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@164989 91177308-0d34-0410-b5e6-96231b3b80d8

21 files changed, 229 insertions, 43 deletions

diff --git a/include/clang/AST/Expr.h b/include/clang/AST/Expr.h
index 6629e3e60c..443d8be92b 100644
--- a/include/clang/AST/Expr.h
+++ b/include/clang/AST/Expr.h
@@ -2785,6 +2785,12 @@ public:
 
 private:
   unsigned Opc : 6;
+
+  // Records the FP_CONTRACT pragma status at the point that this binary
+  // operator was parsed. This bit is only meaningful for operations on
+  // floating point types. For all other types it should default to
+  // false.
+  unsigned FPContractable : 1;
   SourceLocation OpLoc;
 
   enum { LHS, RHS, END_EXPR };
@@ -2793,7 +2799,7 @@ public:
 
   BinaryOperator(Expr *lhs, Expr *rhs, Opcode opc, QualType ResTy,
                  ExprValueKind VK, ExprObjectKind OK,
-                 SourceLocation opLoc)
+                 SourceLocation opLoc, bool fpContractable)
     : Expr(BinaryOperatorClass, ResTy, VK, OK,
            lhs->isTypeDependent() || rhs->isTypeDependent(),
            lhs->isValueDependent() || rhs->isValueDependent(),
@@ -2801,7 +2807,7 @@ public:
             rhs->isInstantiationDependent()),
            (lhs->containsUnexpandedParameterPack() ||
             rhs->containsUnexpandedParameterPack())),
-      Opc(opc), OpLoc(opLoc) {
+      Opc(opc), FPContractable(fpContractable), OpLoc(opLoc) {
     SubExprs[LHS] = lhs;
     SubExprs[RHS] = rhs;
     assert(!isCompoundAssignmentOp() &&
@@ -2902,10 +2908,18 @@ public:
     return child_range(&SubExprs[0], &SubExprs[0]+END_EXPR);
   }
 
+  // Set the FP contractability status of this operator. Only meaningful for
+  // operations on floating point types.
+  void setFPContractable(bool FPC) { FPContractable = FPC; }
+
+  // Get the FP contractability status of this operator. Only meaningful for
+  // operations on floating point types.
+  bool isFPContractable() const { return FPContractable; }
+
 protected:
   BinaryOperator(Expr *lhs, Expr *rhs, Opcode opc, QualType ResTy,
                  ExprValueKind VK, ExprObjectKind OK,
-                 SourceLocation opLoc, bool dead)
+                 SourceLocation opLoc, bool fpContractable, bool dead2)
     : Expr(CompoundAssignOperatorClass, ResTy, VK, OK,
            lhs->isTypeDependent() || rhs->isTypeDependent(),
            lhs->isValueDependent() || rhs->isValueDependent(),
@@ -2913,7 +2927,7 @@ protected:
             rhs->isInstantiationDependent()),
            (lhs->containsUnexpandedParameterPack() ||
             rhs->containsUnexpandedParameterPack())),
-      Opc(opc), OpLoc(opLoc) {
+      Opc(opc), FPContractable(fpContractable), OpLoc(opLoc) {
     SubExprs[LHS] = lhs;
     SubExprs[RHS] = rhs;
   }
@@ -2935,8 +2949,9 @@ public:
   CompoundAssignOperator(Expr *lhs, Expr *rhs, Opcode opc, QualType ResType,
                          ExprValueKind VK, ExprObjectKind OK,
                          QualType CompLHSType, QualType CompResultType,
-                         SourceLocation OpLoc)
-    : BinaryOperator(lhs, rhs, opc, ResType, VK, OK, OpLoc, true),
+                         SourceLocation OpLoc, bool fpContractable)
+    : BinaryOperator(lhs, rhs, opc, ResType, VK, OK, OpLoc, fpContractable,
+                     true),
       ComputationLHSType(CompLHSType),
       ComputationResultType(CompResultType) {
     assert(isCompoundAssignmentOp() &&
diff --git a/include/clang/AST/ExprCXX.h b/include/clang/AST/ExprCXX.h
index 0c4ca8e979..1d0e3a005b 100644
--- a/include/clang/AST/ExprCXX.h
+++ b/include/clang/AST/ExprCXX.h
@@ -53,14 +53,19 @@ class CXXOperatorCallExpr : public CallExpr {
   OverloadedOperatorKind Operator;
   SourceRange Range;
 
+  // Record the FP_CONTRACT state that applies to this operator call. Only
+  // meaningful for floating point types. For other types this value can be
+  // set to false.
+  unsigned FPContractable : 1;
+
   SourceRange getSourceRangeImpl() const LLVM_READONLY;
 public:
   CXXOperatorCallExpr(ASTContext& C, OverloadedOperatorKind Op, Expr *fn,
                       ArrayRef<Expr*> args, QualType t, ExprValueKind VK,
-                      SourceLocation operatorloc)
+                      SourceLocation operatorloc, bool fpContractable)
     : CallExpr(C, CXXOperatorCallExprClass, fn, 0, args, t, VK,
                operatorloc),
-      Operator(Op) {
+      Operator(Op), FPContractable(fpContractable) {
     Range = getSourceRangeImpl();
   }
   explicit CXXOperatorCallExpr(ASTContext& C, EmptyShell Empty) :
@@ -85,6 +90,14 @@ public:
   }
   static bool classof(const CXXOperatorCallExpr *) { return true; }
 
+  // Set the FP contractability status of this operator. Only meaningful for
+  // operations on floating point types.
+  void setFPContractable(bool FPC) { FPContractable = FPC; }
+
+  // Get the FP contractability status of this operator. Only meaningful for
+  // operations on floating point types.
+  bool isFPContractable() const { return FPContractable; }
+
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
 };
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index c53c4f4194..1847220ddf 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -735,6 +735,20 @@ public:
   /// should not be used elsewhere.
   void EmitCurrentDiagnostic(unsigned DiagID);
 
+  /// Records and restores the FP_CONTRACT state on entry/exit of compound
+  /// statements.
+  class FPContractStateRAII {
+  public:
+    FPContractStateRAII(Sema& S)
+      : S(S), OldFPContractState(S.FPFeatures.fp_contract) {}
+    ~FPContractStateRAII() {
+      S.FPFeatures.fp_contract = OldFPContractState;
+    }
+  private:
+    Sema& S;
+    bool OldFPContractState : 1;
+  };
+
 public:
   Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
        TranslationUnitKind TUKind = TU_Complete,
diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index a90026072b..7dd1f7de8b 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -4082,7 +4082,8 @@ Expr *ASTNodeImporter::VisitBinaryOperator(BinaryOperator *E) {
   return new (Importer.getToContext()) BinaryOperator(LHS, RHS, E->getOpcode(),
                                                       T, E->getValueKind(),
                                                       E->getObjectKind(),
-                                          Importer.Import(E->getOperatorLoc()));
+                                           Importer.Import(E->getOperatorLoc()),
+                                                      E->isFPContractable());
 }
 
 Expr *ASTNodeImporter::VisitCompoundAssignOperator(CompoundAssignOperator *E) {
@@ -4111,7 +4112,8 @@ Expr *ASTNodeImporter::VisitCompoundAssignOperator(CompoundAssignOperator *E) {
                                                T, E->getValueKind(),
                                                E->getObjectKind(),
                                                CompLHSType, CompResultType,
-                                          Importer.Import(E->getOperatorLoc()));
+                                           Importer.Import(E->getOperatorLoc()),
+                                               E->isFPContractable());
 }
 
 static bool ImportCastPath(CastExpr *E, CXXCastPath &Path) {
diff --git a/lib/Analysis/BodyFarm.cpp b/lib/Analysis/BodyFarm.cpp
index be998581d7..3dcbfb927e 100644
--- a/lib/Analysis/BodyFarm.cpp
+++ b/lib/Analysis/BodyFarm.cpp
@@ -70,7 +70,7 @@ BinaryOperator *ASTMaker::makeAssignment(const Expr *LHS, const Expr *RHS,
                                          QualType Ty) {
  return new (C) BinaryOperator(const_cast<Expr*>(LHS), const_cast<Expr*>(RHS),
                                BO_Assign, Ty, VK_RValue,
-                               OK_Ordinary, SourceLocation());
+                               OK_Ordinary, SourceLocation(), false);
 }
 
 DeclRefExpr *ASTMaker::makeDeclRefExpr(const VarDecl *D) {
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index ad373095de..28062456cc 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -45,6 +45,7 @@ struct BinOpInfo {
   Value *RHS;
   QualType Ty;  // Computation Type.
   BinaryOperator::Opcode Opcode; // Opcode of BinOp to perform
+  bool FPContractable;
   const Expr *E;      // Entire expr, for error unsupported.  May not be binop.
 };
 
@@ -1654,6 +1655,7 @@ BinOpInfo ScalarExprEmitter::EmitBinOps(const BinaryOperator *E) {
   Result.RHS = Visit(E->getRHS());
   Result.Ty  = E->getType();
   Result.Opcode = E->getOpcode();
+  Result.FPContractable = E->isFPContractable();
   Result.E = E;
   return Result;
 }
@@ -1982,6 +1984,77 @@ static Value *emitPointerArithmetic(CodeGenFunction &CGF,
   return CGF.Builder.CreateInBoundsGEP(pointer, index, "add.ptr");
 }
 
+// Construct an fmuladd intrinsic to represent a fused mul-add of MulOp and
+// Addend. Use negMul and negAdd to negate the first operand of the Mul or
+// the add operand respectively. This allows fmuladd to represent a*b-c, or
+// c-a*b. Patterns in LLVM should catch the negated forms and translate them to
+// efficient operations.
+static Value* buildFMulAdd(llvm::BinaryOperator *MulOp, Value *Addend,
+                           const CodeGenFunction &CGF, CGBuilderTy &Builder,
+                           bool negMul, bool negAdd) {
+  assert(!(negMul && negAdd) && "Only one of negMul and negAdd should be set.");
+ 
+  Value *MulOp0 = MulOp->getOperand(0);
+  Value *MulOp1 = MulOp->getOperand(1);
+  if (negMul) {
+    MulOp0 =
+      Builder.CreateFSub(
+        llvm::ConstantFP::getZeroValueForNegation(MulOp0->getType()), MulOp0,
+        "neg");
+  } else if (negAdd) {
+    Addend =
+      Builder.CreateFSub(
+        llvm::ConstantFP::getZeroValueForNegation(Addend->getType()), Addend,
+        "neg");
+  }
+
+  Value *FMulAdd =
+    Builder.CreateCall3(
+      CGF.CGM.getIntrinsic(llvm::Intrinsic::fmuladd, Addend->getType()),
+                           MulOp0, MulOp1, Addend);
+   MulOp->eraseFromParent();
+
+   return FMulAdd;
+}
+
+// Check whether it would be legal to emit an fmuladd intrinsic call to
+// represent op and if so, build the fmuladd.
+//
+// Checks that (a) the operation is fusable, and (b) -ffp-contract=on.
+// Does NOT check the type of the operation - it's assumed that this function
+// will be called from contexts where it's known that the type is contractable.
+static Value* tryEmitFMulAdd(const BinOpInfo &op, 
+                         const CodeGenFunction &CGF, CGBuilderTy &Builder,
+                         bool isSub=false) {
+
+  assert((op.Opcode == BO_Add || op.Opcode == BO_AddAssign ||
+          op.Opcode == BO_Sub || op.Opcode == BO_SubAssign) &&
+         "Only fadd/fsub can be the root of an fmuladd.");
+
+  // Check whether this op is marked as fusable.
+  if (!op.FPContractable)
+    return 0;
+
+  // Check whether -ffp-contract=on. (If -ffp-contract=off/fast, fusing is
+  // either disabled, or handled entirely by the LLVM backend).
+  if (CGF.getContext().getLangOpts().getFPContractMode() != LangOptions::FPC_On)
+    return 0;
+
+  // We have a potentially fusable op. Look for a mul on one of the operands.
+  if (llvm::BinaryOperator* LHSBinOp = dyn_cast<llvm::BinaryOperator>(op.LHS)) {
+    if (LHSBinOp->getOpcode() == llvm::Instruction::FMul) {
+      return buildFMulAdd(LHSBinOp, op.RHS, CGF, Builder, false, isSub);
+    }
+  } else if (llvm::BinaryOperator* RHSBinOp =
+               dyn_cast<llvm::BinaryOperator>(op.RHS)) {
+    if (RHSBinOp->getOpcode() == llvm::Instruction::FMul) {
+      return buildFMulAdd(RHSBinOp, op.LHS, CGF, Builder, isSub, false);
+    }
+  }
+
+  return 0;
+}
+
 Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &op) {
   if (op.LHS->getType()->isPointerTy() ||
       op.RHS->getType()->isPointerTy())
@@ -2000,8 +2073,13 @@ Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &op) {
     }
   }
     
-  if (op.LHS->getType()->isFPOrFPVectorTy())
+  if (op.LHS->getType()->isFPOrFPVectorTy()) {
+    // Try to form an fmuladd.
+    if (Value *FMulAdd = tryEmitFMulAdd(op, CGF, Builder))
+      return FMulAdd;
+
     return Builder.CreateFAdd(op.LHS, op.RHS, "add");
+  }
 
   return Builder.CreateAdd(op.LHS, op.RHS, "add");
 }
@@ -2022,8 +2100,12 @@ Value *ScalarExprEmitter::EmitSub(const BinOpInfo &op) {
       }
     }
     
-    if (op.LHS->getType()->isFPOrFPVectorTy())
+    if (op.LHS->getType()->isFPOrFPVectorTy()) {
+      // Try to form an fmuladd.
+      if (Value *FMulAdd = tryEmitFMulAdd(op, CGF, Builder, true))
+        return FMulAdd;
       return Builder.CreateFSub(op.LHS, op.RHS, "sub");
+    }
 
     return Builder.CreateSub(op.LHS, op.RHS, "sub");
   }
diff --git a/lib/CodeGen/CGObjC.cpp b/lib/CodeGen/CGObjC.cpp
index fe525fa151..9e01b39748 100644
--- a/lib/CodeGen/CGObjC.cpp
+++ b/lib/CodeGen/CGObjC.cpp
@@ -1213,7 +1213,7 @@ CodeGenFunction::generateObjCSetterBody(const ObjCImplementationDecl *classImpl,
 
   BinaryOperator assign(&ivarRef, finalArg, BO_Assign,
                         ivarRef.getType(), VK_RValue, OK_Ordinary,
-                        SourceLocation());
+                        SourceLocation(), false);
   EmitStmt(&assign);
 }
 
@@ -2850,7 +2850,7 @@ CodeGenFunction::GenerateObjCAtomicSetterCopyHelperFunction(
   CallExpr *CalleeExp = cast<CallExpr>(PID->getSetterCXXAssignment());
   CXXOperatorCallExpr TheCall(C, OO_Equal, CalleeExp->getCallee(),
                               Args, DestTy->getPointeeType(),
-                              VK_LValue, SourceLocation());
+                              VK_LValue, SourceLocation(), false);
   
   EmitStmt(&TheCall);
 
diff --git a/lib/Parse/ParseStmt.cpp b/lib/Parse/ParseStmt.cpp
index db6b3d48f3..eb2a672fdc 100644
--- a/lib/Parse/ParseStmt.cpp
+++ b/lib/Parse/ParseStmt.cpp
@@ -679,6 +679,11 @@ StmtResult Parser::ParseCompoundStatementBody(bool isStmtExpr) {
   PrettyStackTraceLoc CrashInfo(PP.getSourceManager(),
                                 Tok.getLocation(),
                                 "in compound statement ('{}')");
+
+  // Record the state of the FP_CONTRACT pragma, restore on leaving the
+  // compound statement.
+  Sema::FPContractStateRAII SaveFPContractState(Actions);
+
   InMessageExpressionRAIIObject InMessage(*this, false);
   BalancedDelimiterTracker T(*this, tok::l_brace);
   if (T.consumeOpen())
diff --git a/lib/Rewrite/Frontend/RewriteModernObjC.cpp b/lib/Rewrite/Frontend/RewriteModernObjC.cpp
index b2ba0f0359..245e809c90 100644
--- a/lib/Rewrite/Frontend/RewriteModernObjC.cpp
+++ b/lib/Rewrite/Frontend/RewriteModernObjC.cpp
@@ -3576,7 +3576,8 @@ Stmt *RewriteModernObjC::SynthMessageExpr(ObjCMessageExpr *Exp,
                                                    SourceLocation());
     BinaryOperator *lessThanExpr = 
       new (Context) BinaryOperator(sizeofExpr, limit, BO_LE, Context->IntTy,
-                                   VK_RValue, OK_Ordinary, SourceLocation());
+                                   VK_RValue, OK_Ordinary, SourceLocation(),
+                                   false);
     // (sizeof(returnType) <= 8 ? objc_msgSend(...) : objc_msgSend_stret(...))
     ConditionalOperator *CondExpr =
       new (Context) ConditionalOperator(lessThanExpr,
@@ -7473,7 +7474,7 @@ Stmt *RewriteModernObjC::RewriteObjCIvarRefExpr(ObjCIvarRefExpr *IV) {
       BinaryOperator *addExpr = 
         new (Context) BinaryOperator(castExpr, DRE, BO_Add, 
                                      Context->getPointerType(Context->CharTy),
-                                     VK_RValue, OK_Ordinary, SourceLocation());
+                                     VK_RValue, OK_Ordinary, SourceLocation(), false);
       // Don't forget the parens to enforce the proper binding.
       ParenExpr *PE = new (Context) ParenExpr(SourceLocation(),
                                               SourceLocation(),
diff --git a/lib/Rewrite/Frontend/RewriteObjC.cpp b/lib/Rewrite/Frontend/RewriteObjC.cpp
index 62def16ab5..a6dcc6b8d8 100644
--- a/lib/Rewrite/Frontend/RewriteObjC.cpp
+++ b/lib/Rewrite/Frontend/RewriteObjC.cpp
@@ -3078,7 +3078,8 @@ Stmt *RewriteObjC::SynthMessageExpr(ObjCMessageExpr *Exp,
                                                    SourceLocation());
     BinaryOperator *lessThanExpr = 
       new (Context) BinaryOperator(sizeofExpr, limit, BO_LE, Context->IntTy,
-                                   VK_RValue, OK_Ordinary, SourceLocation());
+                                   VK_RValue, OK_Ordinary, SourceLocation(),
+                                   false);
     // (sizeof(returnType) <= 8 ? objc_msgSend(...) : objc_msgSend_stret(...))
     ConditionalOperator *CondExpr =
       new (Context) ConditionalOperator(lessThanExpr,
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index dccce6ef90..b3836a2602 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -7504,7 +7504,7 @@ BuildSingleCopyAssign(Sema &S, SourceLocation Loc, QualType T,
     = new (S.Context) BinaryOperator(IterationVarRefRVal,
                      IntegerLiteral::Create(S.Context, Upper, SizeType, Loc),
                                      BO_NE, S.Context.BoolTy,
-                                     VK_RValue, OK_Ordinary, Loc);
+                                     VK_RValue, OK_Ordinary, Loc, false);
   
   // Create the pre-increment of the iteration variable.
   Expr *Increment
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 0570dd38c7..75bc8658c6 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -8416,7 +8416,8 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
 
   if (CompResultTy.isNull())
     return Owned(new (Context) BinaryOperator(LHS.take(), RHS.take(), Opc,
-                                              ResultTy, VK, OK, OpLoc));
+                                              ResultTy, VK, OK, OpLoc,
+                                              FPFeatures.fp_contract));
   if (getLangOpts().CPlusPlus && LHS.get()->getObjectKind() !=
       OK_ObjCProperty) {
     VK = VK_LValue;
@@ -8424,7 +8425,8 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
   }
   return Owned(new (Context) CompoundAssignOperator(LHS.take(), RHS.take(), Opc,
                                                     ResultTy, VK, OK, CompLHSTy,
-                                                    CompResultTy, OpLoc));
+                                                    CompResultTy, OpLoc,
+                                                    FPFeatures.fp_contract));
 }
 
 /// DiagnoseBitwisePrecedence - Emit a warning when bitwise and comparison
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 763ef28919..ad4a17f99c 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -4833,7 +4833,8 @@ ExprResult Sema::ActOnDecltypeExpression(Expr *E) {
                                                 BO_Comma, BO->getType(),
                                                 BO->getValueKind(),
                                                 BO->getObjectKind(),
-                                                BO->getOperatorLoc()));
+                                                BO->getOperatorLoc(),
+                                                BO->isFPContractable()));
     }
   }
 
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index e9c2c6c5f6..10b96c9ec3 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -9981,7 +9981,7 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, unsigned OpcIn,
                                               llvm::makeArrayRef(Args, NumArgs),
                                                    Context.DependentTy,
                                                    VK_RValue,
-                                                   OpLoc));
+                                                   OpLoc, false));
   }
 
   // Build an empty overload set.
@@ -10058,7 +10058,7 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, unsigned OpcIn,
       CallExpr *TheCall =
         new (Context) CXXOperatorCallExpr(Context, Op, FnExpr.take(),
                                           llvm::makeArrayRef(Args, NumArgs),
-                                          ResultTy, VK, OpLoc);
+                                          ResultTy, VK, OpLoc, false);
 
       if (CheckCallReturnType(FnDecl->getResultType(), OpLoc, TheCall,
                               FnDecl))
@@ -10159,7 +10159,8 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
         return Owned(new (Context) BinaryOperator(Args[0], Args[1], Opc,
                                                   Context.DependentTy,
                                                   VK_RValue, OK_Ordinary,
-                                                  OpLoc));
+                                                  OpLoc,
+                                                  FPFeatures.fp_contract));
 
       return Owned(new (Context) CompoundAssignOperator(Args[0], Args[1], Opc,
                                                         Context.DependentTy,
@@ -10167,7 +10168,8 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
                                                         OK_Ordinary,
                                                         Context.DependentTy,
                                                         Context.DependentTy,
-                                                        OpLoc));
+                                                        OpLoc,
+                                                        FPFeatures.fp_contract));
     }
 
     // FIXME: save results of ADL from here?
@@ -10179,11 +10181,9 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
                                      NestedNameSpecifierLoc(), OpNameInfo, 
                                      /*ADL*/ true, IsOverloaded(Fns),
                                      Fns.begin(), Fns.end());
-    return Owned(new (Context) CXXOperatorCallExpr(Context, Op, Fn,
-                                                   Args,
-                                                   Context.DependentTy,
-                                                   VK_RValue,
-                                                   OpLoc));
+    return Owned(new (Context) CXXOperatorCallExpr(Context, Op, Fn, Args,
+                                                Context.DependentTy, VK_RValue,
+                                                OpLoc, FPFeatures.fp_contract));
   }
 
   // Always do placeholder-like conversions on the RHS.
@@ -10298,7 +10298,8 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
 
         CXXOperatorCallExpr *TheCall =
           new (Context) CXXOperatorCallExpr(Context, Op, FnExpr.take(),
-                                            Args, ResultTy, VK, OpLoc);
+                                            Args, ResultTy, VK, OpLoc,
+                                            FPFeatures.fp_contract);
 
         if (CheckCallReturnType(FnDecl->getResultType(), OpLoc, TheCall,
                                 FnDecl))
@@ -10430,7 +10431,7 @@ Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
                                                    Args,
                                                    Context.DependentTy,
                                                    VK_RValue,
-                                                   RLoc));
+                                                   RLoc, false));
   }
 
   // Handle placeholders on both operands.
@@ -10507,7 +10508,8 @@ Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
         CXXOperatorCallExpr *TheCall =
           new (Context) CXXOperatorCallExpr(Context, OO_Subscript,
                                             FnExpr.take(), Args,
-                                            ResultTy, VK, RLoc);
+                                            ResultTy, VK, RLoc,
+                                            false);
 
         if (CheckCallReturnType(FnDecl->getResultType(), LLoc, TheCall,
                                 FnDecl))
@@ -11035,7 +11037,7 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
   CXXOperatorCallExpr *TheCall =
     new (Context) CXXOperatorCallExpr(Context, OO_Call, NewFn.take(),
                                       llvm::makeArrayRef(MethodArgs, NumArgs+1),
-                                      ResultTy, VK, RParenLoc);
+                                      ResultTy, VK, RParenLoc, false);
   delete [] MethodArgs;
 
   if (CheckCallReturnType(Method->getResultType(), LParenLoc, TheCall,
@@ -11208,7 +11210,7 @@ Sema::BuildOverloadedArrowExpr(Scope *S, Expr *Base, SourceLocation OpLoc) {
   ResultTy = ResultTy.getNonLValueExprType(Context);
   CXXOperatorCallExpr *TheCall =
     new (Context) CXXOperatorCallExpr(Context, OO_Arrow, FnExpr.take(),
-                                      Base, ResultTy, VK, OpLoc);
+                                      Base, ResultTy, VK, OpLoc, false);
 
   if (CheckCallReturnType(Method->getResultType(), OpLoc, TheCall,
                           Method))
diff --git a/lib/Sema/SemaPseudoObject.cpp b/lib/Sema/SemaPseudoObject.cpp
index 501fa113ce..22a24a947f 100644
--- a/lib/Sema/SemaPseudoObject.cpp
+++ b/lib/Sema/SemaPseudoObject.cpp
@@ -356,7 +356,7 @@ PseudoOpBuilder::buildAssignmentOperation(Scope *Sc, SourceLocation opcLoc,
     syntactic = new (S.Context) BinaryOperator(syntacticLHS, capturedRHS,
                                                opcode, capturedRHS->getType(),
                                                capturedRHS->getValueKind(),
-                                               OK_Ordinary, opcLoc);
+                                               OK_Ordinary, opcLoc, false);
   } else {
     ExprResult opLHS = buildGet();
     if (opLHS.isInvalid()) return ExprError();
@@ -375,7 +375,7 @@ PseudoOpBuilder::buildAssignmentOperation(Scope *Sc, SourceLocation opcLoc,
                                              OK_Ordinary,
                                              opLHS.get()->getType(),
                                              result.get()->getType(),
-                                             opcLoc);
+                                             opcLoc, false);
   }
 
   // The result of the assignment, if not void, is the value set into
@@ -1366,7 +1366,7 @@ ExprResult Sema::checkPseudoObjectAssignment(Scope *S, SourceLocation opcLoc,
   // Do nothing if either argument is dependent.
   if (LHS->isTypeDependent() || RHS->isTypeDependent())
     return new (Context) BinaryOperator(LHS, RHS, opcode, Context.DependentTy,
-                                        VK_RValue, OK_Ordinary, opcLoc);
+                                        VK_RValue, OK_Ordinary, opcLoc, false);
 
   // Filter out non-overload placeholder types in the RHS.
   if (RHS->getType()->isNonOverloadPlaceholderType()) {
@@ -1437,14 +1437,14 @@ Expr *Sema::recreateSyntacticForm(PseudoObjectExpr *E) {
                                                 cop->getObjectKind(),
                                                 cop->getComputationLHSType(),
                                                 cop->getComputationResultType(),
-                                                cop->getOperatorLoc());
+                                                cop->getOperatorLoc(), false);
   } else if (BinaryOperator *bop = dyn_cast<BinaryOperator>(syntax)) {
     Expr *lhs = stripOpaqueValuesFromPseudoObjectRef(*this, bop->getLHS());
     Expr *rhs = cast<OpaqueValueExpr>(bop->getRHS())->getSourceExpr();
     return new (Context) BinaryOperator(lhs, rhs, bop->getOpcode(),
                                         bop->getType(), bop->getValueKind(),
                                         bop->getObjectKind(),
-                                        bop->getOperatorLoc());
+                                        bop->getOperatorLoc(), false);
   } else {
     assert(syntax->hasPlaceholderType(BuiltinType::PseudoObject));
     return stripOpaqueValuesFromPseudoObjectRef(*this, syntax);
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index e0451c4c49..f76c947e31 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -6429,6 +6429,9 @@ TreeTransform<Derived>::TransformBinaryOperator(BinaryOperator *E) {
       RHS.get() == E->getRHS())
     return SemaRef.Owned(E);
 
+  Sema::FPContractStateRAII FPContractState(getSema());
+  getSema().FPFeatures.fp_contract = E->isFPContractable();
+
   return getDerived().RebuildBinaryOperator(E->getOperatorLoc(), E->getOpcode(),
                                             LHS.get(), RHS.get());
 }
@@ -6852,6 +6855,9 @@ TreeTransform<Derived>::TransformCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
       (E->getNumArgs() != 2 || Second.get() == E->getArg(1)))
     return SemaRef.MaybeBindToTemporary(E);
 
+  Sema::FPContractStateRAII FPContractState(getSema());
+  getSema().FPFeatures.fp_contract = E->isFPContractable();
+
   return getDerived().RebuildCXXOperatorCallExpr(E->getOperator(),
                                                  E->getOperatorLoc(),
                                                  Callee.get(),
diff --git a/lib/Serialization/ASTReaderStmt.cpp b/lib/Serialization/ASTReaderStmt.cpp
index cfe22b5208..3a02e76d19 100644
--- a/lib/Serialization/ASTReaderStmt.cpp
+++ b/lib/Serialization/ASTReaderStmt.cpp
@@ -565,6 +565,7 @@ void ASTStmtReader::VisitBinaryOperator(BinaryOperator *E) {
   E->setRHS(Reader.ReadSubExpr());
   E->setOpcode((BinaryOperator::Opcode)Record[Idx++]);
   E->setOperatorLoc(ReadSourceLocation(Record, Idx));
+  E->setFPContractable((bool)Record[Idx++]);
 }
 
 void ASTStmtReader::VisitCompoundAssignOperator(CompoundAssignOperator *E) {
@@ -1086,6 +1087,7 @@ void ASTStmtReader::VisitCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
   VisitCallExpr(E);
   E->Operator = (OverloadedOperatorKind)Record[Idx++];
   E->Range = Reader.ReadSourceRange(F, Record, Idx);
+  E->setFPContractable((bool)Record[Idx++]);
 }
 
 void ASTStmtReader::VisitCXXConstructExpr(CXXConstructExpr *E) {
diff --git a/lib/Serialization/ASTWriterStmt.cpp b/lib/Serialization/ASTWriterStmt.cpp
index 9ca8130586..0337089659 100644
--- a/lib/Serialization/ASTWriterStmt.cpp
+++ b/lib/Serialization/ASTWriterStmt.cpp
@@ -536,6 +536,7 @@ void ASTStmtWriter::VisitBinaryOperator(BinaryOperator *E) {
   Writer.AddStmt(E->getRHS());
   Record.push_back(E->getOpcode()); // FIXME: stable encoding
   Writer.AddSourceLocation(E->getOperatorLoc(), Record);
+  Record.push_back(E->isFPContractable());
   Code = serialization::EXPR_BINARY_OPERATOR;
 }
 
@@ -1055,6 +1056,7 @@ void ASTStmtWriter::VisitCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
   VisitCallExpr(E);
   Record.push_back(E->getOperator());
   Writer.AddSourceRange(E->Range, Record);
+  Record.push_back(E->isFPContractable());
   Code = serialization::EXPR_CXX_OPERATOR_CALL;
 }
 
diff --git a/test/CodeGen/fp-contract.c b/test/CodeGen/ffp-contract-option.c
index eb95f1e217..eb95f1e217 100644
--- a/test/CodeGen/fp-contract.c
+++ b/test/CodeGen/ffp-contract-option.c
diff --git a/test/CodeGen/fp-contract-pragma.cpp b/test/CodeGen/fp-contract-pragma.cpp
new file mode 100644
index 0000000000..8c51469c47
--- /dev/null
+++ b/test/CodeGen/fp-contract-pragma.cpp
@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -O3 -emit-llvm -o - %s | FileCheck %s
+
+// Is FP_CONTRACT is honored in a simple case?
+float fp_contract_1(float a, float b, float c) {
+// CHECK: _Z13fp_contract_1fff
+// CHECK-NEXT: entry
+// CHECK-NEXT: %0 = tail call float @llvm.fmuladd
+  #pragma STDC FP_CONTRACT ON
+  return a * b + c;
+}
+
+// Is FP_CONTRACT state cleared on exiting compound statements?
+float fp_contract_2(float a, float b, float c) {
+// CHECK: _Z13fp_contract_2fff
+// CHECK-NEXT: entry
+// CHECK-NEXT: %mul = fmul float %a, %b
+// CHECK-NEXT: %add = fadd float %mul, %c
+  {
+    #pragma STDC FP_CONTRACT ON
+  }
+  return a * b + c;  
+}
+
+// Does FP_CONTRACT survive template instatiation?
+class Foo {};
+Foo operator+(Foo, Foo);
+
+template <typename T>
+T template_muladd(T a, T b, T c) {
+  #pragma STDC FP_CONTRACT ON
+  return a * b + c;
+}
+
+float fp_contract_3(float a, float b, float c) {
+// CHECK: _Z13fp_contract_3fff
+// CHECK-NEXT: entry
+// CHECK-NEXT: %0 = tail call float @llvm.fmuladd
+  return template_muladd<float>(a, b, c);
+}
diff --git a/test/CodeGenOpenCL/single-precision-constant.cl b/test/CodeGenOpenCL/single-precision-constant.cl
index 62b37c1361..9ad1fb4ea0 100644
--- a/test/CodeGenOpenCL/single-precision-constant.cl
+++ b/test/CodeGenOpenCL/single-precision-constant.cl
@@ -1,7 +1,6 @@
 // RUN: %clang_cc1 %s -cl-single-precision-constant -emit-llvm -o - | FileCheck %s
 
 float fn(float f) {
-  // CHECK: fmul float
-  // CHECK: fadd float
+  // CHECK: %0 = tail call float @llvm.fmuladd.f32(float %f, float 2.000000e+00, float 1.000000e+00)
   return f*2. + 1.;
 }