4 files changed, 58 insertions, 2 deletions
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index bd4e553991..9ad3ae8352 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -23,6 +23,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/Frontend/CodeGenOptions.h"
 #include "llvm/Intrinsics.h"
+#include "llvm/LLVMContext.h"
 #include "llvm/Target/TargetData.h"
 using namespace clang;
 using namespace CodeGen;
@@ -2752,3 +2753,18 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E, llvm::Value *Dest) {
     return RValue::get(0);
   return ConvertTempToRValue(*this, E->getType(), OrigDest);
 }
+
+void CodeGenFunction::SetFPAccuracy(llvm::Value *Val, unsigned AccuracyN,
+                                    unsigned AccuracyD) {
+  assert(Val->getType()->isFPOrFPVectorTy());
+  if (!AccuracyN || !isa<llvm::Instruction>(Val))
+    return;
+
+  llvm::Value *Vals[2];
+  Vals[0] = llvm::ConstantInt::get(Int32Ty, AccuracyN);
+  Vals[1] = llvm::ConstantInt::get(Int32Ty, AccuracyD);
+  llvm::MDNode *Node = llvm::MDNode::get(getLLVMContext(), Vals);
+
+  cast<llvm::Instruction>(Val)->setMetadata(llvm::LLVMContext::MD_fpaccuracy,
+                                            Node);
+}
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index 582d1c4572..25b4a0a0e7 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -1772,8 +1772,18 @@ Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
       Builder.SetInsertPoint(DivCont);
     }
   }
-  if (Ops.LHS->getType()->isFPOrFPVectorTy())
-    return Builder.CreateFDiv(Ops.LHS, Ops.RHS, "div");
+  if (Ops.LHS->getType()->isFPOrFPVectorTy()) {
+    llvm::Value *Val = Builder.CreateFDiv(Ops.LHS, Ops.RHS, "div");
+    if (CGF.getContext().getLangOptions().OpenCL) {
+      // OpenCL 1.1 7.4: minimum accuracy of single precision / is 2.5ulp
+      llvm::Type *ValTy = Val->getType();
+      if (ValTy->isFloatTy() ||
+          (isa<llvm::VectorType>(ValTy) &&
+           cast<llvm::VectorType>(ValTy)->getElementType()->isFloatTy()))
+        CGF.SetFPAccuracy(Val, 5, 2);
+    }
+    return Val;
+  }
   else if (Ops.Ty->hasUnsignedIntegerRepresentation())
     return Builder.CreateUDiv(Ops.LHS, Ops.RHS, "div");
   else
diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index 858962d337..4940e21c8b 100644
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -2382,6 +2382,11 @@ public:
   /// a r-value suitable for passing the given parameter.
   void EmitDelegateCallArg(CallArgList &args, const VarDecl *param);
 
+  /// SetFPAccuracy - Set the minimum required accuracy of the given floating
+  /// point operation, expressed as the maximum relative error in ulp.
+  void SetFPAccuracy(llvm::Value *Val, unsigned AccuracyN,
+                     unsigned AccuracyD = 1);
+
 private:
   void EmitReturnOfRValue(RValue RV, QualType Ty);
 
diff --git a/test/CodeGenOpenCL/fpaccuracy.cl b/test/CodeGenOpenCL/fpaccuracy.cl
new file mode 100644
index 0000000000..47fca696f9
--- /dev/null
+++ b/test/CodeGenOpenCL/fpaccuracy.cl
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
+
+typedef __attribute__(( ext_vector_type(4) )) float float4;
+
+float spscalardiv(float a, float b) {
+  // CHECK: @spscalardiv
+  // CHECK: fdiv{{.*}}, !fpaccuracy ![[MD:[0-9]+]]
+  return a / b;
+}
+
+float4 spvectordiv(float4 a, float4 b) {
+  // CHECK: @spvectordiv
+  // CHECK: fdiv{{.*}}, !fpaccuracy ![[MD]]
+  return a / b;
+}
+
+#pragma OPENCL EXTENSION cl_khr_fp64 : enable
+
+double dpscalardiv(double a, double b) {
+  // CHECK: @dpscalardiv
+  // CHECK-NOT: !fpaccuracy
+  return a / b;
+}
+
+// CHECK: ![[MD]] = metadata !{i{{[0-9]+}} 5, i{{[0-9]+}} 2}