[FPEnv Core 05/14] Teach IR builder and folders about new flags

[sdmitrouk]

Summary

FastMathFlags were moved to a separate header to make it possible
to use in IR/Constants.h, which otherwise created circular dependency
between IR/Constants.h and IR/Operator.h.

[majnemer]

test/Other/fpenv-constant-fold.ll

11

You need to check the operands here as well.

[sdmitrouk]

Update test as requested, update code due to other changes.

[sdmitrouk]

Some changes are now in D14069, it didn't compile without them. There were too many rebases...

[mehdi_amini]

test/Other/fpenv-constant-fold.ll

11

Nit: the second {{.*}} seems spurious.

Also do you expect the nrnd to be dropped?

[sdmitrouk]

Update test and also one get() invocation, which was changed by mistake (it called itself after this change).

test/Other/fpenv-constant-fold.ll

11

Nit: the second {{.*}} seems spurious.

Right, thanks.

Also do you expect the nrnd to be dropped?

No. Initially I wanted to check only for presence of floating-point instructions, but then added arguments as was requested, now changed to check everything.

include/llvm/Analysis/ConstantFolding.h

 // DataLayout information. These functions cannot go in VMCore due to library
 // dependency issues.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_ANALYSIS_CONSTANTFOLDING_H
 #define LLVM_ANALYSIS_CONSTANTFOLDING_H
 
+#include "llvm/IR/FastMathFlags.h"
+
 namespace llvm {
   class Constant;
   class ConstantExpr;
   class Instruction;
   class DataLayout;
   class TargetLibraryInfo;
   class Function;
   class Type;
   template<typename T>
   class ArrayRef;
 
 /// ConstantFoldInstruction - Try to constant fold the specified instruction.
 /// If successful, the constant result is returned, if not, null is returned.
 /// Note that this fails if not all of the operands are constant.  Otherwise,
 /// this function can only fail when attempting to fold instructions like loads
 /// and stores, which have no constant expression form.
   Constant *ConstantFoldInstruction(Instruction *I, const DataLayout &DL,
                                     const TargetLibraryInfo *TLI = nullptr);
 
 /// ConstantFoldConstantExpression - Attempt to fold the constant expression
 /// using the specified DataLayout.  If successful, the constant result is
 /// result is returned, if not, null is returned.
   Constant *
   ConstantFoldConstantExpression(const ConstantExpr *CE, const DataLayout &DL,
-                                 const TargetLibraryInfo *TLI = nullptr);
+                                 const TargetLibraryInfo *TLI = nullptr,
+                                 FastMathFlags FMF = FastMathFlags());
 
 /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
 /// specified operands.  If successful, the constant result is returned, if not,
 /// null is returned.  Note that this function can fail when attempting to
 /// fold instructions like loads and stores, which have no constant expression
 /// form.
 ///
   Constant *ConstantFoldInstOperands(unsigned Opcode, Type *DestTy,
                                      ArrayRef<Constant *> Ops,
                                      const DataLayout &DL,
-                                     const TargetLibraryInfo *TLI = nullptr);
+                                     const TargetLibraryInfo *TLI = nullptr,
+                                     FastMathFlags FMF = FastMathFlags());
 
 /// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
 /// instruction (icmp/fcmp) with the specified operands.  If it fails, it
 /// returns a constant expression of the specified operands.
 ///
   Constant *
   ConstantFoldCompareInstOperands(unsigned Predicate, Constant *LHS,
                                   Constant *RHS, const DataLayout &DL,

include/llvm/Analysis/TargetFolder.h

 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_ANALYSIS_TARGETFOLDER_H
 #define LLVM_ANALYSIS_TARGETFOLDER_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/FastMathFlags.h"
 #include "llvm/IR/InstrTypes.h"
 
 namespace llvm {
 
 class DataLayout;
 
 /// TargetFolder - Create constants with target dependent folding.
 class TargetFolder {
public:
   //===--------------------------------------------------------------------===//
   // Binary Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateAdd(Constant *LHS, Constant *RHS,
                       bool HasNUW = false, bool HasNSW = false) const {
     return Fold(ConstantExpr::getAdd(LHS, RHS, HasNUW, HasNSW));
   }
-  Constant *CreateFAdd(Constant *LHS, Constant *RHS) const {
-    return Fold(ConstantExpr::getFAdd(LHS, RHS));
+  Constant *CreateFAdd(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return Fold(ConstantExpr::getFAdd(LHS, RHS, FMF));
   }
   Constant *CreateSub(Constant *LHS, Constant *RHS,
                       bool HasNUW = false, bool HasNSW = false) const {
     return Fold(ConstantExpr::getSub(LHS, RHS, HasNUW, HasNSW));
   }
-  Constant *CreateFSub(Constant *LHS, Constant *RHS) const {
-    return Fold(ConstantExpr::getFSub(LHS, RHS));
+  Constant *CreateFSub(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return Fold(ConstantExpr::getFSub(LHS, RHS, FMF));
   }
   Constant *CreateMul(Constant *LHS, Constant *RHS,
                       bool HasNUW = false, bool HasNSW = false) const {
     return Fold(ConstantExpr::getMul(LHS, RHS, HasNUW, HasNSW));
   }
-  Constant *CreateFMul(Constant *LHS, Constant *RHS) const {
-    return Fold(ConstantExpr::getFMul(LHS, RHS));
+  Constant *CreateFMul(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return Fold(ConstantExpr::getFMul(LHS, RHS, FMF));
   }
   Constant *CreateUDiv(Constant *LHS, Constant *RHS, bool isExact = false)const{
     return Fold(ConstantExpr::getUDiv(LHS, RHS, isExact));
   }
   Constant *CreateSDiv(Constant *LHS, Constant *RHS, bool isExact = false)const{
     return Fold(ConstantExpr::getSDiv(LHS, RHS, isExact));
   }
-  Constant *CreateFDiv(Constant *LHS, Constant *RHS) const {
-    return Fold(ConstantExpr::getFDiv(LHS, RHS));
+  Constant *CreateFDiv(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return Fold(ConstantExpr::getFDiv(LHS, RHS, FMF));
   }
   Constant *CreateURem(Constant *LHS, Constant *RHS) const {
     return Fold(ConstantExpr::getURem(LHS, RHS));
   }
   Constant *CreateSRem(Constant *LHS, Constant *RHS) const {
     return Fold(ConstantExpr::getSRem(LHS, RHS));
   }
-  Constant *CreateFRem(Constant *LHS, Constant *RHS) const {
-    return Fold(ConstantExpr::getFRem(LHS, RHS));
+  Constant *CreateFRem(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return Fold(ConstantExpr::getFRem(LHS, RHS, FMF));
   }
   Constant *CreateShl(Constant *LHS, Constant *RHS,
                       bool HasNUW = false, bool HasNSW = false) const {
     return Fold(ConstantExpr::getShl(LHS, RHS, HasNUW, HasNSW));
   }
   Constant *CreateLShr(Constant *LHS, Constant *RHS, bool isExact = false)const{
     return Fold(ConstantExpr::getLShr(LHS, RHS, isExact));
   }

include/llvm/IR/ConstantFolder.h

 // use ConstantExpr and the routines in llvm/Analysis/ConstantFolding.h.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_IR_CONSTANTFOLDER_H
 #define LLVM_IR_CONSTANTFOLDER_H
 
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/FastMathFlags.h"
 #include "llvm/IR/InstrTypes.h"
 
 namespace llvm {
 
 /// ConstantFolder - Create constants with minimum, target independent, folding.
 class ConstantFolder {
 public:
   explicit ConstantFolder() {}
 
   //===--------------------------------------------------------------------===//
   // Binary Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateAdd(Constant *LHS, Constant *RHS,
                       bool HasNUW = false, bool HasNSW = false) const {
     return ConstantExpr::getAdd(LHS, RHS, HasNUW, HasNSW);
   }
-  Constant *CreateFAdd(Constant *LHS, Constant *RHS) const {
-    return ConstantExpr::getFAdd(LHS, RHS);
+  Constant *CreateFAdd(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return ConstantExpr::getFAdd(LHS, RHS, FMF);
   }
   Constant *CreateSub(Constant *LHS, Constant *RHS,
                       bool HasNUW = false, bool HasNSW = false) const {
     return ConstantExpr::getSub(LHS, RHS, HasNUW, HasNSW);
   }
-  Constant *CreateFSub(Constant *LHS, Constant *RHS) const {
-    return ConstantExpr::getFSub(LHS, RHS);
+  Constant *CreateFSub(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return ConstantExpr::getFSub(LHS, RHS, FMF);
   }
   Constant *CreateMul(Constant *LHS, Constant *RHS,
                       bool HasNUW = false, bool HasNSW = false) const {
     return ConstantExpr::getMul(LHS, RHS, HasNUW, HasNSW);
   }
-  Constant *CreateFMul(Constant *LHS, Constant *RHS) const {
-    return ConstantExpr::getFMul(LHS, RHS);
+  Constant *CreateFMul(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return ConstantExpr::getFMul(LHS, RHS, FMF);
   }
   Constant *CreateUDiv(Constant *LHS, Constant *RHS,
                        bool isExact = false) const {
     return ConstantExpr::getUDiv(LHS, RHS, isExact);
   }
   Constant *CreateSDiv(Constant *LHS, Constant *RHS,
                        bool isExact = false) const {
     return ConstantExpr::getSDiv(LHS, RHS, isExact);
   }
-  Constant *CreateFDiv(Constant *LHS, Constant *RHS) const {
-    return ConstantExpr::getFDiv(LHS, RHS);
+  Constant *CreateFDiv(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return ConstantExpr::getFDiv(LHS, RHS, FMF);
   }
   Constant *CreateURem(Constant *LHS, Constant *RHS) const {
     return ConstantExpr::getURem(LHS, RHS);
   }
   Constant *CreateSRem(Constant *LHS, Constant *RHS) const {
     return ConstantExpr::getSRem(LHS, RHS);
   }
-  Constant *CreateFRem(Constant *LHS, Constant *RHS) const {
-    return ConstantExpr::getFRem(LHS, RHS);
+  Constant *CreateFRem(Constant *LHS, Constant *RHS,
+                       FastMathFlags FMF = FastMathFlags()) const {
+    return ConstantExpr::getFRem(LHS, RHS, FMF);
   }
   Constant *CreateShl(Constant *LHS, Constant *RHS,
                       bool HasNUW = false, bool HasNSW = false) const {
     return ConstantExpr::getShl(LHS, RHS, HasNUW, HasNSW);
   }
   Constant *CreateLShr(Constant *LHS, Constant *RHS,
                        bool isExact = false) const {
     return ConstantExpr::getLShr(LHS, RHS, isExact);
   }
   Constant *CreateAShr(Constant *LHS, Constant *RHS,
                        bool isExact = false) const {
     return ConstantExpr::getAShr(LHS, RHS, isExact);
   }
   Constant *CreateAnd(Constant *LHS, Constant *RHS) const {
     return ConstantExpr::getAnd(LHS, RHS);
   }
   Constant *CreateOr(Constant *LHS, Constant *RHS) const {
     return ConstantExpr::getOr(LHS, RHS);
   }
   Constant *CreateXor(Constant *LHS, Constant *RHS) const {
     return ConstantExpr::getXor(LHS, RHS);
   }
 
   Constant *CreateBinOp(Instruction::BinaryOps Opc,
-                        Constant *LHS, Constant *RHS) const {
-    return ConstantExpr::get(Opc, LHS, RHS);
+                        Constant *LHS, Constant *RHS,
+                        FastMathFlags FMF = FastMathFlags()) const {
+    return ConstantExpr::get(Opc, LHS, RHS, 0, nullptr, FMF);
   }
 
   //===--------------------------------------------------------------------===//
   // Unary Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateNeg(Constant *C,
                       bool HasNUW = false, bool HasNSW = false) const {

include/llvm/IR/Constants.h

public:
   ///
   static Constant *getOffsetOf(Type *Ty, Constant *FieldNo);
 
   static Constant *getNeg(Constant *C, bool HasNUW = false, bool HasNSW =false);
   static Constant *getFNeg(Constant *C);
   static Constant *getNot(Constant *C);
   static Constant *getAdd(Constant *C1, Constant *C2,
                           bool HasNUW = false, bool HasNSW = false);
-  static Constant *getFAdd(Constant *C1, Constant *C2);
+  static Constant *getFAdd(Constant *C1, Constant *C2,
+                           FastMathFlags FMF = FastMathFlags());
   static Constant *getSub(Constant *C1, Constant *C2,
                           bool HasNUW = false, bool HasNSW = false);
-  static Constant *getFSub(Constant *C1, Constant *C2);
+  static Constant *getFSub(Constant *C1, Constant *C2,
+                           FastMathFlags FMF = FastMathFlags());
   static Constant *getMul(Constant *C1, Constant *C2,
                           bool HasNUW = false, bool HasNSW = false);
-  static Constant *getFMul(Constant *C1, Constant *C2);
+  static Constant *getFMul(Constant *C1, Constant *C2,
+                           FastMathFlags FMF = FastMathFlags());
   static Constant *getUDiv(Constant *C1, Constant *C2, bool isExact = false);
   static Constant *getSDiv(Constant *C1, Constant *C2, bool isExact = false);
-  static Constant *getFDiv(Constant *C1, Constant *C2);
+  static Constant *getFDiv(Constant *C1, Constant *C2,
+                           FastMathFlags FMF = FastMathFlags());
   static Constant *getURem(Constant *C1, Constant *C2);
   static Constant *getSRem(Constant *C1, Constant *C2);
-  static Constant *getFRem(Constant *C1, Constant *C2);
+  static Constant *getFRem(Constant *C1, Constant *C2,
+                           FastMathFlags FMF = FastMathFlags());
   static Constant *getAnd(Constant *C1, Constant *C2);
   static Constant *getOr(Constant *C1, Constant *C2);
   static Constant *getXor(Constant *C1, Constant *C2);
   static Constant *getShl(Constant *C1, Constant *C2,
                           bool HasNUW = false, bool HasNSW = false);
   static Constant *getLShr(Constant *C1, Constant *C2, bool isExact = false);
   static Constant *getAShr(Constant *C1, Constant *C2, bool isExact = false);
   static Constant *getTrunc(Constant *C, Type *Ty, bool OnlyIfReduced = false);

include/llvm/IR/IRBuilder.h

public:
   }
   Value *CreateNUWAdd(Value *LHS, Value *RHS, const Twine &Name = "") {
     return CreateAdd(LHS, RHS, Name, true, false);
   }
   Value *CreateFAdd(Value *LHS, Value *RHS, const Twine &Name = "",
                     MDNode *FPMathTag = nullptr) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
-        return Insert(Folder.CreateFAdd(LC, RC), Name);
+        return Insert(Folder.CreateFAdd(LC, RC, FMF), Name);
     return Insert(AddFPMathAttributes(BinaryOperator::CreateFAdd(LHS, RHS),
                                       FPMathTag, FMF), Name);
   }
   Value *CreateSub(Value *LHS, Value *RHS, const Twine &Name = "",
                    bool HasNUW = false, bool HasNSW = false) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
         return Insert(Folder.CreateSub(LC, RC, HasNUW, HasNSW), Name);
     return CreateInsertNUWNSWBinOp(Instruction::Sub, LHS, RHS, Name,
                                    HasNUW, HasNSW);
   }
   Value *CreateNSWSub(Value *LHS, Value *RHS, const Twine &Name = "") {
     return CreateSub(LHS, RHS, Name, false, true);
   }
   Value *CreateNUWSub(Value *LHS, Value *RHS, const Twine &Name = "") {
     return CreateSub(LHS, RHS, Name, true, false);
   }
   Value *CreateFSub(Value *LHS, Value *RHS, const Twine &Name = "",
                     MDNode *FPMathTag = nullptr) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
-        return Insert(Folder.CreateFSub(LC, RC), Name);
+        return Insert(Folder.CreateFSub(LC, RC, FMF), Name);
     return Insert(AddFPMathAttributes(BinaryOperator::CreateFSub(LHS, RHS),
                                       FPMathTag, FMF), Name);
   }
   Value *CreateMul(Value *LHS, Value *RHS, const Twine &Name = "",
                    bool HasNUW = false, bool HasNSW = false) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
         return Insert(Folder.CreateMul(LC, RC, HasNUW, HasNSW), Name);
     return CreateInsertNUWNSWBinOp(Instruction::Mul, LHS, RHS, Name,
                                    HasNUW, HasNSW);
   }
   Value *CreateNSWMul(Value *LHS, Value *RHS, const Twine &Name = "") {
     return CreateMul(LHS, RHS, Name, false, true);
   }
   Value *CreateNUWMul(Value *LHS, Value *RHS, const Twine &Name = "") {
     return CreateMul(LHS, RHS, Name, true, false);
   }
   Value *CreateFMul(Value *LHS, Value *RHS, const Twine &Name = "",
                     MDNode *FPMathTag = nullptr) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
-        return Insert(Folder.CreateFMul(LC, RC), Name);
+        return Insert(Folder.CreateFMul(LC, RC, FMF), Name);
     return Insert(AddFPMathAttributes(BinaryOperator::CreateFMul(LHS, RHS),
                                       FPMathTag, FMF), Name);
   }
   Value *CreateUDiv(Value *LHS, Value *RHS, const Twine &Name = "",
                     bool isExact = false) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
         return Insert(Folder.CreateUDiv(LC, RC, isExact), Name);
public:
   }
   Value *CreateExactSDiv(Value *LHS, Value *RHS, const Twine &Name = "") {
     return CreateSDiv(LHS, RHS, Name, true);
   }
   Value *CreateFDiv(Value *LHS, Value *RHS, const Twine &Name = "",
                     MDNode *FPMathTag = nullptr) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
-        return Insert(Folder.CreateFDiv(LC, RC), Name);
+        return Insert(Folder.CreateFDiv(LC, RC, FMF), Name);
     return Insert(AddFPMathAttributes(BinaryOperator::CreateFDiv(LHS, RHS),
                                       FPMathTag, FMF), Name);
   }
   Value *CreateURem(Value *LHS, Value *RHS, const Twine &Name = "") {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
         return Insert(Folder.CreateURem(LC, RC), Name);
     return Insert(BinaryOperator::CreateURem(LHS, RHS), Name);
   }
   Value *CreateSRem(Value *LHS, Value *RHS, const Twine &Name = "") {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
         return Insert(Folder.CreateSRem(LC, RC), Name);
     return Insert(BinaryOperator::CreateSRem(LHS, RHS), Name);
   }
   Value *CreateFRem(Value *LHS, Value *RHS, const Twine &Name = "",
                     MDNode *FPMathTag = nullptr) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))
-        return Insert(Folder.CreateFRem(LC, RC), Name);
+        return Insert(Folder.CreateFRem(LC, RC, FMF), Name);
     return Insert(AddFPMathAttributes(BinaryOperator::CreateFRem(LHS, RHS),
                                       FPMathTag, FMF), Name);
   }
 
   Value *CreateShl(Value *LHS, Value *RHS, const Twine &Name = "",
                    bool HasNUW = false, bool HasNSW = false) {
     if (Constant *LC = dyn_cast<Constant>(LHS))
       if (Constant *RC = dyn_cast<Constant>(RHS))

lib/Analysis/ConstantFolding.cpp

 
 /// Try to constant fold the specified instruction.
 /// If successful, the constant result is returned, if not, null is returned.
 /// Note that this fails if not all of the operands are constant.  Otherwise,
 /// this function can only fail when attempting to fold instructions like loads
 /// and stores, which have no constant expression form.
 Constant *llvm::ConstantFoldInstruction(Instruction *I, const DataLayout &DL,
                                         const TargetLibraryInfo *TLI) {
+  FastMathFlags FMF;
+
+  if (isa<FPMathOperator>(I)) {
+    FMF = I->getFastMathFlags();
+  }
+
   // Handle PHI nodes quickly here...
   if (PHINode *PN = dyn_cast<PHINode>(I)) {
     Constant *CommonValue = nullptr;
 
     for (Value *Incoming : PN->incoming_values()) {
       // If the incoming value is undef then skip it.  Note that while we could
       // skip the value if it is equal to the phi node itself we choose not to
       // because that would break the rule that constant folding only applies if
       // all operands are constants.
       if (isa<UndefValue>(Incoming))
         continue;
       // If the incoming value is not a constant, then give up.
       Constant *C = dyn_cast<Constant>(Incoming);
       if (!C)
         return nullptr;
       // Fold the PHI's operands.
       if (ConstantExpr *NewC = dyn_cast<ConstantExpr>(C))
-        C = ConstantFoldConstantExpression(NewC, DL, TLI);
+        C = ConstantFoldConstantExpression(NewC, DL, TLI, FMF);
       // If the incoming value is a different constant to
       // the one we saw previously, then give up.
       if (CommonValue && C != CommonValue)
         return nullptr;
       CommonValue = C;
     }
 
 
     // If we reach here, all incoming values are the same constant or undef.
     return CommonValue ? CommonValue : UndefValue::get(PN->getType());
   }
 
   // Scan the operand list, checking to see if they are all constants, if so,
   // hand off to ConstantFoldInstOperands.
   SmallVector<Constant*, 8> Ops;
   for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) {
     Constant *Op = dyn_cast<Constant>(*i);
     if (!Op)
       return nullptr;  // All operands not constant!
 
     // Fold the Instruction's operands.
     if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(Op))
-      Op = ConstantFoldConstantExpression(NewCE, DL, TLI);
+      if (Constant *C = ConstantFoldConstantExpression(NewCE, DL, TLI, FMF))
+        Op = C;
 
     Ops.push_back(Op);
   }
 
   if (const CmpInst *CI = dyn_cast<CmpInst>(I))
     return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1],
                                            DL, TLI);
 
   if (const LoadInst *LI = dyn_cast<LoadInst>(I))
     return ConstantFoldLoadInst(LI, DL);
 
   if (InsertValueInst *IVI = dyn_cast<InsertValueInst>(I)) {
     return ConstantExpr::getInsertValue(
                                 cast<Constant>(IVI->getAggregateOperand()),
                                 cast<Constant>(IVI->getInsertedValueOperand()),
                                 IVI->getIndices());
   }
 
   if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I)) {
     return ConstantExpr::getExtractValue(
                                     cast<Constant>(EVI->getAggregateOperand()),
                                     EVI->getIndices());
   }
 
-  return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops, DL, TLI);
+  return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops, DL, TLI,
+                                  FMF);
 }
 
 static Constant *
 ConstantFoldConstantExpressionImpl(const ConstantExpr *CE, const DataLayout &DL,
                                    const TargetLibraryInfo *TLI,
-                                   SmallPtrSetImpl<ConstantExpr *> &FoldedOps) {
+                                   SmallPtrSetImpl<ConstantExpr *> &FoldedOps,
+                                   FastMathFlags FMF) {
   SmallVector<Constant *, 8> Ops;
   for (User::const_op_iterator i = CE->op_begin(), e = CE->op_end(); i != e;
        ++i) {
     Constant *NewC = cast<Constant>(*i);
     // Recursively fold the ConstantExpr's operands. If we have already folded
     // a ConstantExpr, we don't have to process it again.
     if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC)) {
       if (FoldedOps.insert(NewCE).second)
-        NewC = ConstantFoldConstantExpressionImpl(NewCE, DL, TLI, FoldedOps);
+        if (Constant *C = ConstantFoldConstantExpressionImpl(NewCE, DL, TLI,
+                                                             FoldedOps, FMF))
+          NewC = C;
     }
     Ops.push_back(NewC);
   }
 
   if (CE->isCompare())
     return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
                                            DL, TLI);
-  return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(), Ops, DL, TLI);
+  return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(), Ops, DL, TLI,
+                                  FMF);
 }
 
 /// Attempt to fold the constant expression
 /// using the specified DataLayout.  If successful, the constant result is
 /// result is returned, if not, null is returned.
 Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE,
                                                const DataLayout &DL,
-                                               const TargetLibraryInfo *TLI) {
+                                               const TargetLibraryInfo *TLI,
+                                               FastMathFlags FMF) {
   SmallPtrSet<ConstantExpr *, 4> FoldedOps;
-  return ConstantFoldConstantExpressionImpl(CE, DL, TLI, FoldedOps);
+  return ConstantFoldConstantExpressionImpl(CE, DL, TLI, FoldedOps, FMF);
 }
 
 /// Attempt to constant fold an instruction with the
 /// specified opcode and operands.  If successful, the constant result is
 /// returned, if not, null is returned.  Note that this function can fail when
 /// attempting to fold instructions like loads and stores, which have no
 /// constant expression form.
 ///
 /// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc
 /// information, due to only being passed an opcode and operands. Constant
 /// folding using this function strips this information.
 ///
 Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, Type *DestTy,
                                          ArrayRef<Constant *> Ops,
                                          const DataLayout &DL,
-                                         const TargetLibraryInfo *TLI) {
+                                         const TargetLibraryInfo *TLI,
+                                         FastMathFlags FMF) {
   // Handle easy binops first.
   if (Instruction::isBinaryOp(Opcode)) {
     if (isa<ConstantExpr>(Ops[0]) || isa<ConstantExpr>(Ops[1])) {
       if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], DL))
         return C;
     }
 
-    return ConstantExpr::get(Opcode, Ops[0], Ops[1]);
+    return ConstantExpr::get(Opcode, Ops[0], Ops[1], 0, nullptr, FMF);
   }
 
   switch (Opcode) {
   default: return nullptr;
   case Instruction::ICmp:
   case Instruction::FCmp: llvm_unreachable("Invalid for compares");
   case Instruction::Call:
     if (Function *F = dyn_cast<Function>(Ops.back()))

lib/Analysis/ValueTracking.cpp

bool llvm::isSafeToSpeculativelyExecute(const Value *V,
   case Instruction::FSub:
   case Instruction::FDiv:
   case Instruction::FRem:
     if (KeepExceptions) {
       APFloat::opStatus S;
       if (!ConstantExpr::getFPOpExceptions(Inst, S))
         return false;
 
-      if (KeepExceptions && (S != APFloat::opOK || (S & APFloat::opInexact)))
+      if (S != APFloat::opOK || (S & APFloat::opInexact))
         return false;
     }
     return true;
   case Instruction::UDiv:
   case Instruction::URem: {
     // x / y is undefined if y == 0.
     const APInt *V;
     if (match(Inst->getOperand(1), m_APInt(V)))

lib/IR/Constants.cpp

 
 Constant *ConstantExpr::getAdd(Constant *C1, Constant *C2,
                                bool HasNUW, bool HasNSW) {
   unsigned Flags = (HasNUW ? OverflowingBinaryOperator::NoUnsignedWrap : 0) |
                    (HasNSW ? OverflowingBinaryOperator::NoSignedWrap   : 0);
   return get(Instruction::Add, C1, C2, Flags);
 }
 
-Constant *ConstantExpr::getFAdd(Constant *C1, Constant *C2) {
-  return get(Instruction::FAdd, C1, C2);
+Constant *ConstantExpr::getFAdd(Constant *C1, Constant *C2, FastMathFlags FMF) {
+  return get(Instruction::FAdd, C1, C2, 0, nullptr, FMF);
 }
 
 Constant *ConstantExpr::getSub(Constant *C1, Constant *C2,
                                bool HasNUW, bool HasNSW) {
   unsigned Flags = (HasNUW ? OverflowingBinaryOperator::NoUnsignedWrap : 0) |
                    (HasNSW ? OverflowingBinaryOperator::NoSignedWrap   : 0);
   return get(Instruction::Sub, C1, C2, Flags);
 }
 
-Constant *ConstantExpr::getFSub(Constant *C1, Constant *C2) {
-  return get(Instruction::FSub, C1, C2);
+Constant *ConstantExpr::getFSub(Constant *C1, Constant *C2, FastMathFlags FMF) {
+  return get(Instruction::FSub, C1, C2, 0, nullptr, FMF);
 }
 
 Constant *ConstantExpr::getMul(Constant *C1, Constant *C2,
                                bool HasNUW, bool HasNSW) {
   unsigned Flags = (HasNUW ? OverflowingBinaryOperator::NoUnsignedWrap : 0) |
                    (HasNSW ? OverflowingBinaryOperator::NoSignedWrap   : 0);
-  return get(Instruction::Mul, C1, C2, Flags);
+  return get(Instruction::Mul, C1, C2, Flags, nullptr);
 }
 
-Constant *ConstantExpr::getFMul(Constant *C1, Constant *C2) {
-  return get(Instruction::FMul, C1, C2);
+Constant *ConstantExpr::getFMul(Constant *C1, Constant *C2, FastMathFlags FMF) {
+  return get(Instruction::FMul, C1, C2, 0, nullptr, FMF);
 }
 
 Constant *ConstantExpr::getUDiv(Constant *C1, Constant *C2, bool isExact) {
   return get(Instruction::UDiv, C1, C2,
              isExact ? PossiblyExactOperator::IsExact : 0);
 }
 
 Constant *ConstantExpr::getSDiv(Constant *C1, Constant *C2, bool isExact) {
   return get(Instruction::SDiv, C1, C2,
              isExact ? PossiblyExactOperator::IsExact : 0);
 }
 
-Constant *ConstantExpr::getFDiv(Constant *C1, Constant *C2) {
-  return get(Instruction::FDiv, C1, C2);
+Constant *ConstantExpr::getFDiv(Constant *C1, Constant *C2, FastMathFlags FMF) {
+  return get(Instruction::FDiv, C1, C2, 0, nullptr, FMF);
 }
 
 Constant *ConstantExpr::getURem(Constant *C1, Constant *C2) {
   return get(Instruction::URem, C1, C2);
 }
 
 Constant *ConstantExpr::getSRem(Constant *C1, Constant *C2) {
   return get(Instruction::SRem, C1, C2);
 }
 
-Constant *ConstantExpr::getFRem(Constant *C1, Constant *C2) {
-  return get(Instruction::FRem, C1, C2);
+Constant *ConstantExpr::getFRem(Constant *C1, Constant *C2, FastMathFlags FMF) {
+  return get(Instruction::FRem, C1, C2, 0, nullptr, FMF);
 }
 
 Constant *ConstantExpr::getAnd(Constant *C1, Constant *C2) {
   return get(Instruction::And, C1, C2);
 }
 
 Constant *ConstantExpr::getOr(Constant *C1, Constant *C2) {
   return get(Instruction::Or, C1, C2);

test/Other/fpenv-constant-fold.ll

+; InstCombine is used just for its calls to constant folder.
+; RUN: opt -S -instcombine -o - < %s | FileCheck %s
+
+; Target independent constant folder should not fold floating-point operations
+; that have constant expression as their operands when FEnv access is requested
+; and such folding leads to differences in observable effects at runtime.
+
+define double @do-not-fold-fadd-that-can-trap() {
+; CHECK-LABEL: @do-not-fold-fadd-that-can-trap
+; CHECK: fadd {{.*}} 1.000000e+308, {{.*}} 1.000000e+308
+entry:
+  %val = fadd nrnd double 1.000000e+308, 1.000000e+308
+  ret double %val
+}
+
+define double @do-not-fold-fsub-that-can-trap() {
+; CHECK-LABEL: @do-not-fold-fsub-that-can-trap
+; CHECK: fsub {{.*}} 1.000000e-308, {{.*}} 1.000000e+308
+entry:
+  %val = fsub nrnd double 1.000000e-308, 1.000000e+308
+  ret double %val
+}
+
+define double @do-not-fold-fmul-that-can-trap() {
+; CHECK-LABEL: @do-not-fold-fmul-that-can-trap
+; CHECK: fmul {{.*}} 1.000000e+300, {{.*}} 1.000000e+300
+entry:
+  %val = fmul nrnd double 1.000000e+300, 1.000000e+300
+  ret double %val
+}
+
+define double @do-not-fold-fdiv-that-can-trap() {
+; CHECK-LABEL: @do-not-fold-fdiv-that-can-trap
+; CHECK: fdiv {{.*}} 1.000000e+300, {{.*}} 1.000000e-300
+entry:
+  %val = fdiv nrnd double 1.000000e+300, 1.000000e-300
+  ret double %val
+}
+
+define double @do-not-fold-frem-that-can-trap() {
+; CHECK-LABEL: @do-not-fold-frem-that-can-trap
+; CHECK: frem {{.*}} 1.000000e+300, {{.*}} 1.000000e-300
+entry:
+  %val = frem nrnd double 1.000000e+300, 1.000000e-300
+  ret double %val
+}
+
+define double @do-not-fold-fadd-because-of-rounding() {
+; CHECK-LABEL: @do-not-fold-fadd-because-of-rounding
+; CHECK: fadd {{.*}} 1.010000e-01, {{.*}} 9.300000e-01
+entry:
+  %val = fadd nexc double 0.101, 0.93
+  ret double %val
+}
+
+define double @do-not-fold-fsub-because-of-rounding() {
+; CHECK-LABEL: @do-not-fold-fsub-because-of-rounding
+; CHECK: fsub {{.*}} 1.010000e-01, {{.*}} 9.300000e-01
+entry:
+  %val = fsub nexc double 0.101, 0.93
+  ret double %val
+}
+
+define double @do-not-fold-fmul-because-of-rounding() {
+; CHECK-LABEL: @do-not-fold-fmul-because-of-rounding
+; CHECK: fmul {{.*}} 1.010000e-01, {{.*}} 9.300000e-01
+entry:
+  %val = fmul nexc double 0.101, 0.93
+  ret double %val
+}
+
+define double @do-not-fold-fdiv-because-of-rounding() {
+; CHECK-LABEL: @do-not-fold-fdiv-because-of-rounding
+; CHECK: fdiv {{.*}} 1.010000e-01, {{.*}} 9.300000e-01
+entry:
+  %val = fdiv nexc double 0.101, 0.93
+  ret double %val
+}
+
+; "frem" instruction falls into the same category, but none of tried test-cases
+; could raised inexact exception.
+
+define double @fold-fadd-that-cant-trap() {
+; CHECK-LABEL: @fold-fadd-that-cant-trap
+; CHECK-NOT: fadd
+entry:
+  %val = fadd double 1.0, 1.0
+  ret double %val
+}
+
+define double @fold-fsub-that-cant-trap() {
+; CHECK-LABEL: @fold-fsub-that-cant-trap
+; CHECK-NOT: fsub
+entry:
+  %val = fsub double 1.0, 1.0
+  ret double %val
+}
+
+define double @fold-fmul-that-cant-trap() {
+; CHECK-LABEL: @fold-fmul-that-cant-trap
+; CHECK-NOT: fmul
+entry:
+  %val = fmul double 1.0, 1.0
+  ret double %val
+}
+
+define double @fold-fdiv-that-cant-trap() {
+; CHECK-LABEL: @fold-fdiv-that-cant-trap
+; CHECK-NOT: fdiv
+entry:
+  %val = fdiv double 1.0, 1.0
+  ret double %val
+}
+
+define double @fold-frem-that-cant-trap() {
+; CHECK-LABEL: @fold-frem-that-cant-trap
+; CHECK-NOT: frem
+entry:
+  %val = frem double 1.0, 1.0
+  ret double %val
+}
+
+define double @correcly-handle-nested-expressions() {
+; CHECK-LABEL: @correcly-handle-nested-expressions
+; CHECK: fmul {{.*}} 1.000000e+300, {{.*}} 1.000000e+300
+entry:
+  %val1 = fmul nrnd double 1.000000e+300, 1.000000e+300
+  %val2 = fdiv nrnd double %val1, 1.000000e+300
+  ret double %val2
+}