[IRBuilder] Refactor FMF interface (llvm#121657)

Up to now, the only way to set specified FMF flags in IRBuilder is to
use `FastMathFlagGuard`. It makes the code ugly and hard to maintain.

This patch introduces a helper class `FMFSource` to replace the original
parameter `Instruction *FMFSource` in IRBuilder. To maximize the
compatibility, it accepts an instruction or a specified FMF.
This patch also removes the use of `FastMathFlagGuard` in some simple
cases.

Compile-time impact:
https://llvm-compile-time-tracker.com/compare.php?from=f87a9db8322643ccbc324e317a75b55903129b55&to=9397e712f6010be15ccf62f12740e9b4a67de2f4&stat=instructions%3Au

Author: dtcxzyw

llvm/include/llvm/IR/IRBuilder.h

@@ -78,11 +78,11 @@ void IRBuilderBase::SetInstDebugLocation(Instruction *I) const {
 
 CallInst *
 IRBuilderBase::createCallHelper(Function *Callee, ArrayRef<Value *> Ops,
-                                const Twine &Name, Instruction *FMFSource,
+                                const Twine &Name, FMFSource FMFSource,
                                 ArrayRef<OperandBundleDef> OpBundles) {
   CallInst *CI = CreateCall(Callee, Ops, OpBundles, Name);
-  if (FMFSource)
-    CI->copyFastMathFlags(FMFSource);
+  if (isa<FPMathOperator>(CI))
+    CI->setFastMathFlags(FMFSource.get(FMF));
   return CI;
 }
 
@@ -869,28 +869,28 @@ CallInst *IRBuilderBase::CreateGCGetPointerOffset(Value *DerivedPtr,
 }
 
 CallInst *IRBuilderBase::CreateUnaryIntrinsic(Intrinsic::ID ID, Value *V,
-                                              Instruction *FMFSource,
+                                              FMFSource FMFSource,
                                               const Twine &Name) {
   Module *M = BB->getModule();
   Function *Fn = Intrinsic::getOrInsertDeclaration(M, ID, {V->getType()});
   return createCallHelper(Fn, {V}, Name, FMFSource);
 }
 
 Value *IRBuilderBase::CreateBinaryIntrinsic(Intrinsic::ID ID, Value *LHS,
-                                            Value *RHS, Instruction *FMFSource,
+                                            Value *RHS, FMFSource FMFSource,
                                             const Twine &Name) {
   Module *M = BB->getModule();
   Function *Fn = Intrinsic::getOrInsertDeclaration(M, ID, {LHS->getType()});
   if (Value *V = Folder.FoldBinaryIntrinsic(ID, LHS, RHS, Fn->getReturnType(),
-                                            FMFSource))
+                                            /*FMFSource=*/nullptr))
     return V;
   return createCallHelper(Fn, {LHS, RHS}, Name, FMFSource);
 }
 
 CallInst *IRBuilderBase::CreateIntrinsic(Intrinsic::ID ID,
                                          ArrayRef<Type *> Types,
                                          ArrayRef<Value *> Args,
-                                         Instruction *FMFSource,
+                                         FMFSource FMFSource,
                                          const Twine &Name) {
   Module *M = BB->getModule();
   Function *Fn = Intrinsic::getOrInsertDeclaration(M, ID, Types);
@@ -899,7 +899,7 @@ CallInst *IRBuilderBase::CreateIntrinsic(Intrinsic::ID ID,
 
 CallInst *IRBuilderBase::CreateIntrinsic(Type *RetTy, Intrinsic::ID ID,
                                          ArrayRef<Value *> Args,
-                                         Instruction *FMFSource,
+                                         FMFSource FMFSource,
                                          const Twine &Name) {
   Module *M = BB->getModule();
 
@@ -925,16 +925,13 @@ CallInst *IRBuilderBase::CreateIntrinsic(Type *RetTy, Intrinsic::ID ID,
 }
 
 CallInst *IRBuilderBase::CreateConstrainedFPBinOp(
-    Intrinsic::ID ID, Value *L, Value *R, Instruction *FMFSource,
-    const Twine &Name, MDNode *FPMathTag,
-    std::optional<RoundingMode> Rounding,
+    Intrinsic::ID ID, Value *L, Value *R, FMFSource FMFSource,
+    const Twine &Name, MDNode *FPMathTag, std::optional<RoundingMode> Rounding,
     std::optional<fp::ExceptionBehavior> Except) {
   Value *RoundingV = getConstrainedFPRounding(Rounding);
   Value *ExceptV = getConstrainedFPExcept(Except);
 
-  FastMathFlags UseFMF = FMF;
-  if (FMFSource)
-    UseFMF = FMFSource->getFastMathFlags();
+  FastMathFlags UseFMF = FMFSource.get(FMF);
 
   CallInst *C = CreateIntrinsic(ID, {L->getType()},
                                 {L, R, RoundingV, ExceptV}, nullptr, Name);
@@ -944,14 +941,12 @@ CallInst *IRBuilderBase::CreateConstrainedFPBinOp(
 }
 
 CallInst *IRBuilderBase::CreateConstrainedFPUnroundedBinOp(
-    Intrinsic::ID ID, Value *L, Value *R, Instruction *FMFSource,
+    Intrinsic::ID ID, Value *L, Value *R, FMFSource FMFSource,
     const Twine &Name, MDNode *FPMathTag,
     std::optional<fp::ExceptionBehavior> Except) {
   Value *ExceptV = getConstrainedFPExcept(Except);
 
-  FastMathFlags UseFMF = FMF;
-  if (FMFSource)
-    UseFMF = FMFSource->getFastMathFlags();
+  FastMathFlags UseFMF = FMFSource.get(FMF);
 
   CallInst *C =
       CreateIntrinsic(ID, {L->getType()}, {L, R, ExceptV}, nullptr, Name);
@@ -976,15 +971,12 @@ Value *IRBuilderBase::CreateNAryOp(unsigned Opc, ArrayRef<Value *> Ops,
 }
 
 CallInst *IRBuilderBase::CreateConstrainedFPCast(
-    Intrinsic::ID ID, Value *V, Type *DestTy,
-    Instruction *FMFSource, const Twine &Name, MDNode *FPMathTag,
-    std::optional<RoundingMode> Rounding,
+    Intrinsic::ID ID, Value *V, Type *DestTy, FMFSource FMFSource,
+    const Twine &Name, MDNode *FPMathTag, std::optional<RoundingMode> Rounding,
     std::optional<fp::ExceptionBehavior> Except) {
   Value *ExceptV = getConstrainedFPExcept(Except);
 
-  FastMathFlags UseFMF = FMF;
-  if (FMFSource)
-    UseFMF = FMFSource->getFastMathFlags();
+  FastMathFlags UseFMF = FMFSource.get(FMF);
 
   CallInst *C;
   if (Intrinsic::hasConstrainedFPRoundingModeOperand(ID)) {
@@ -1002,9 +994,10 @@ CallInst *IRBuilderBase::CreateConstrainedFPCast(
   return C;
 }
 
-Value *IRBuilderBase::CreateFCmpHelper(
-    CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name,
-    MDNode *FPMathTag, bool IsSignaling) {
+Value *IRBuilderBase::CreateFCmpHelper(CmpInst::Predicate P, Value *LHS,
+                                       Value *RHS, const Twine &Name,
+                                       MDNode *FPMathTag, FMFSource FMFSource,
+                                       bool IsSignaling) {
   if (IsFPConstrained) {
     auto ID = IsSignaling ? Intrinsic::experimental_constrained_fcmps
                           : Intrinsic::experimental_constrained_fcmp;
@@ -1013,7 +1006,9 @@ Value *IRBuilderBase::CreateFCmpHelper(
 
   if (auto *V = Folder.FoldCmp(P, LHS, RHS))
     return V;
-  return Insert(setFPAttrs(new FCmpInst(P, LHS, RHS), FPMathTag, FMF), Name);
+  return Insert(
+      setFPAttrs(new FCmpInst(P, LHS, RHS), FPMathTag, FMFSource.get(FMF)),
+      Name);
 }
 
 CallInst *IRBuilderBase::CreateConstrainedFPCmp(
@@ -1047,6 +1042,12 @@ CallInst *IRBuilderBase::CreateConstrainedFPCall(
 
 Value *IRBuilderBase::CreateSelect(Value *C, Value *True, Value *False,
                                    const Twine &Name, Instruction *MDFrom) {
+  return CreateSelectFMF(C, True, False, {}, Name, MDFrom);
+}
+
+Value *IRBuilderBase::CreateSelectFMF(Value *C, Value *True, Value *False,
+                                      FMFSource FMFSource, const Twine &Name,
+                                      Instruction *MDFrom) {
   if (auto *V = Folder.FoldSelect(C, True, False))
     return V;
 
@@ -1057,7 +1058,7 @@ Value *IRBuilderBase::CreateSelect(Value *C, Value *True, Value *False,
     Sel = addBranchMetadata(Sel, Prof, Unpred);
   }
   if (isa<FPMathOperator>(Sel))
-    setFPAttrs(Sel, nullptr /* MDNode* */, FMF);
+    setFPAttrs(Sel, /*MDNode=*/nullptr, FMFSource.get(FMF));
   return Insert(Sel, Name);
 }
 

llvm/lib/IR/IRBuilder.cpp

@@ -1638,10 +1638,8 @@ instCombineSVEVectorBinOp(InstCombiner &IC, IntrinsicInst &II) {
       !match(OpPredicate, m_Intrinsic<Intrinsic::aarch64_sve_ptrue>(
                               m_ConstantInt<AArch64SVEPredPattern::all>())))
     return std::nullopt;
-  IRBuilderBase::FastMathFlagGuard FMFGuard(IC.Builder);
-  IC.Builder.setFastMathFlags(II.getFastMathFlags());
-  auto BinOp =
-      IC.Builder.CreateBinOp(BinOpCode, II.getOperand(1), II.getOperand(2));
+  auto BinOp = IC.Builder.CreateBinOpFMF(
+      BinOpCode, II.getOperand(1), II.getOperand(2), II.getFastMathFlags());
   return IC.replaceInstUsesWith(II, BinOp);
 }
 

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp

@@ -425,11 +425,8 @@ static bool foldSqrt(CallInst *Call, LibFunc Func, TargetTransformInfo &TTI,
            Arg, 0,
            SimplifyQuery(Call->getDataLayout(), &TLI, &DT, &AC, Call)))) {
     IRBuilder<> Builder(Call);
-    IRBuilderBase::FastMathFlagGuard Guard(Builder);
-    Builder.setFastMathFlags(Call->getFastMathFlags());
-
-    Value *NewSqrt = Builder.CreateIntrinsic(Intrinsic::sqrt, Ty, Arg,
-                                             /*FMFSource=*/nullptr, "sqrt");
+    Value *NewSqrt =
+        Builder.CreateIntrinsic(Intrinsic::sqrt, Ty, Arg, Call, "sqrt");
     Call->replaceAllUsesWith(NewSqrt);
 
     // Explicitly erase the old call because a call with side effects is not

llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp

@@ -2845,12 +2845,11 @@ Instruction *InstCombinerImpl::hoistFNegAboveFMulFDiv(Value *FNegOp,
     // Make sure to preserve flags and metadata on the call.
     if (II->getIntrinsicID() == Intrinsic::ldexp) {
       FastMathFlags FMF = FMFSource.getFastMathFlags() | II->getFastMathFlags();
-      IRBuilder<>::FastMathFlagGuard FMFGuard(Builder);
-      Builder.setFastMathFlags(FMF);
-
-      CallInst *New = Builder.CreateCall(
-          II->getCalledFunction(),
-          {Builder.CreateFNeg(II->getArgOperand(0)), II->getArgOperand(1)});
+      CallInst *New =
+          Builder.CreateCall(II->getCalledFunction(),
+                             {Builder.CreateFNegFMF(II->getArgOperand(0), FMF),
+                              II->getArgOperand(1)});
+      New->setFastMathFlags(FMF);
       New->copyMetadata(*II);
       return New;
     }
@@ -2932,12 +2931,8 @@ Instruction *InstCombinerImpl::visitFNeg(UnaryOperator &I) {
     // flags the copysign doesn't also have.
     FastMathFlags FMF = I.getFastMathFlags();
     FMF &= cast<FPMathOperator>(OneUse)->getFastMathFlags();
-
-    IRBuilder<>::FastMathFlagGuard FMFGuard(Builder);
-    Builder.setFastMathFlags(FMF);
-
-    Value *NegY = Builder.CreateFNeg(Y);
-    Value *NewCopySign = Builder.CreateCopySign(X, NegY);
+    Value *NegY = Builder.CreateFNegFMF(Y, FMF);
+    Value *NewCopySign = Builder.CreateCopySign(X, NegY, FMF);
     return replaceInstUsesWith(I, NewCopySign);
   }
 

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

@@ -39,11 +39,12 @@ static Value *getNewICmpValue(unsigned Code, bool Sign, Value *LHS, Value *RHS,
 /// This is the complement of getFCmpCode, which turns an opcode and two
 /// operands into either a FCmp instruction, or a true/false constant.
 static Value *getFCmpValue(unsigned Code, Value *LHS, Value *RHS,
-                           InstCombiner::BuilderTy &Builder) {
+                           InstCombiner::BuilderTy &Builder,
+                           FastMathFlags FMF) {
   FCmpInst::Predicate NewPred;
   if (Constant *TorF = getPredForFCmpCode(Code, LHS->getType(), NewPred))
     return TorF;
-  return Builder.CreateFCmp(NewPred, LHS, RHS);
+  return Builder.CreateFCmpFMF(NewPred, LHS, RHS, FMF);
 }
 
 /// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise
@@ -1429,12 +1430,9 @@ static Value *matchIsFiniteTest(InstCombiner::BuilderTy &Builder, FCmpInst *LHS,
       !matchUnorderedInfCompare(PredR, RHS0, RHS1))
     return nullptr;
 
-  IRBuilder<>::FastMathFlagGuard FMFG(Builder);
-  FastMathFlags FMF = LHS->getFastMathFlags();
-  FMF &= RHS->getFastMathFlags();
-  Builder.setFastMathFlags(FMF);
-
-  return Builder.CreateFCmp(FCmpInst::getOrderedPredicate(PredR), RHS0, RHS1);
+  return Builder.CreateFCmpFMF(FCmpInst::getOrderedPredicate(PredR), RHS0, RHS1,
+                               LHS->getFastMathFlags() &
+                                   RHS->getFastMathFlags());
 }
 
 Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
@@ -1470,12 +1468,8 @@ Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
 
     // Intersect the fast math flags.
     // TODO: We can union the fast math flags unless this is a logical select.
-    IRBuilder<>::FastMathFlagGuard FMFG(Builder);
-    FastMathFlags FMF = LHS->getFastMathFlags();
-    FMF &= RHS->getFastMathFlags();
-    Builder.setFastMathFlags(FMF);
-
-    return getFCmpValue(NewPred, LHS0, LHS1, Builder);
+    return getFCmpValue(NewPred, LHS0, LHS1, Builder,
+                        LHS->getFastMathFlags() & RHS->getFastMathFlags());
   }
 
   // This transform is not valid for a logical select.
@@ -1492,10 +1486,8 @@ Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
       // Ignore the constants because they are obviously not NANs:
       // (fcmp ord x, 0.0) & (fcmp ord y, 0.0)  -> (fcmp ord x, y)
       // (fcmp uno x, 0.0) | (fcmp uno y, 0.0)  -> (fcmp uno x, y)
-      IRBuilder<>::FastMathFlagGuard FMFG(Builder);
-      Builder.setFastMathFlags(LHS->getFastMathFlags() &
-                               RHS->getFastMathFlags());
-      return Builder.CreateFCmp(PredL, LHS0, RHS0);
+      return Builder.CreateFCmpFMF(
+          PredL, LHS0, RHS0, LHS->getFastMathFlags() & RHS->getFastMathFlags());
     }
   }
 
@@ -1557,15 +1549,14 @@ Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
       std::swap(PredL, PredR);
     }
     if (IsLessThanOrLessEqual(IsAnd ? PredL : PredR)) {
-      BuilderTy::FastMathFlagGuard Guard(Builder);
       FastMathFlags NewFlag = LHS->getFastMathFlags();
       if (!IsLogicalSelect)
         NewFlag |= RHS->getFastMathFlags();
-      Builder.setFastMathFlags(NewFlag);
 
-      Value *FAbs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, LHS0);
-      return Builder.CreateFCmp(PredL, FAbs,
-                                ConstantFP::get(LHS0->getType(), *LHSC));
+      Value *FAbs =
+          Builder.CreateUnaryIntrinsic(Intrinsic::fabs, LHS0, NewFlag);
+      return Builder.CreateFCmpFMF(
+          PredL, FAbs, ConstantFP::get(LHS0->getType(), *LHSC), NewFlag);
     }
   }
 

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

@@ -1852,15 +1852,13 @@ Instruction *InstCombinerImpl::visitFPTrunc(FPTruncInst &FPT) {
   Value *X;
   Instruction *Op = dyn_cast<Instruction>(FPT.getOperand(0));
   if (Op && Op->hasOneUse()) {
-    IRBuilder<>::FastMathFlagGuard FMFG(Builder);
     FastMathFlags FMF = FPT.getFastMathFlags();
     if (auto *FPMO = dyn_cast<FPMathOperator>(Op))
       FMF &= FPMO->getFastMathFlags();
-    Builder.setFastMathFlags(FMF);
 
     if (match(Op, m_FNeg(m_Value(X)))) {
-      Value *InnerTrunc = Builder.CreateFPTrunc(X, Ty);
-      Value *Neg = Builder.CreateFNeg(InnerTrunc);
+      Value *InnerTrunc = Builder.CreateFPTruncFMF(X, Ty, FMF);
+      Value *Neg = Builder.CreateFNegFMF(InnerTrunc, FMF);
       return replaceInstUsesWith(FPT, Neg);
     }
 
@@ -1870,15 +1868,17 @@ Instruction *InstCombinerImpl::visitFPTrunc(FPTruncInst &FPT) {
     if (match(Op, m_Select(m_Value(Cond), m_FPExt(m_Value(X)), m_Value(Y))) &&
         X->getType() == Ty) {
       // fptrunc (select Cond, (fpext X), Y --> select Cond, X, (fptrunc Y)
-      Value *NarrowY = Builder.CreateFPTrunc(Y, Ty);
-      Value *Sel = Builder.CreateSelect(Cond, X, NarrowY, "narrow.sel", Op);
+      Value *NarrowY = Builder.CreateFPTruncFMF(Y, Ty, FMF);
+      Value *Sel =
+          Builder.CreateSelectFMF(Cond, X, NarrowY, FMF, "narrow.sel", Op);
       return replaceInstUsesWith(FPT, Sel);
     }
     if (match(Op, m_Select(m_Value(Cond), m_Value(Y), m_FPExt(m_Value(X)))) &&
         X->getType() == Ty) {
       // fptrunc (select Cond, Y, (fpext X) --> select Cond, (fptrunc Y), X
-      Value *NarrowY = Builder.CreateFPTrunc(Y, Ty);
-      Value *Sel = Builder.CreateSelect(Cond, NarrowY, X, "narrow.sel", Op);
+      Value *NarrowY = Builder.CreateFPTruncFMF(Y, Ty, FMF);
+      Value *Sel =
+          Builder.CreateSelectFMF(Cond, NarrowY, X, FMF, "narrow.sel", Op);
       return replaceInstUsesWith(FPT, Sel);
     }
   }