Add IRBuilder::CreateFMA (#131112)

This commit adds a function for creating fma intrinsic calls to the IRBuilder.  If the "IsFPConstrained" flag of the builder is set,
the function creates a call to "experimental.constrained.fma" instead of "llvm.fma" .
To support the creation of the constrained intrinsic, a function "CreateConstrainedFPIntrinsic" is introduced.

Author: frederik-h

llvm/include/llvm/IR/IRBuilder.h

@@ -1065,6 +1065,19 @@ class IRBuilderBase {
                            {Src, Exp}, FMFSource, Name);
   }
 
+  /// Create call to the fma intrinsic.
+  Value *CreateFMA(Value *Factor1, Value *Factor2, Value *Summand,
+                   FMFSource FMFSource = {}, const Twine &Name = "") {
+    if (IsFPConstrained) {
+      return CreateConstrainedFPIntrinsic(
+          Intrinsic::experimental_constrained_fma, {Factor1->getType()},
+          {Factor1, Factor2, Summand}, FMFSource, Name);
+    }
+
+    return CreateIntrinsic(Intrinsic::fma, {Factor1->getType()},
+                           {Factor1, Factor2, Summand}, FMFSource, Name);
+  }
+
   /// Create a call to the arithmetic_fence intrinsic.
   CallInst *CreateArithmeticFence(Value *Val, Type *DstType,
                                   const Twine &Name = "") {
@@ -1723,6 +1736,17 @@ class IRBuilderBase {
     return Accum;
   }
 
+  /// This function is like @ref CreateIntrinsic for constrained fp
+  /// intrinsics. It sets the rounding mode and exception behavior of
+  /// the created intrinsic call according to \p Rounding and \p
+  /// Except and it sets \p FPMathTag as the 'fpmath' metadata, using
+  /// defaults if a value equals nullopt/null.
+  CallInst *CreateConstrainedFPIntrinsic(
+      Intrinsic::ID ID, ArrayRef<Type *> Types, ArrayRef<Value *> Args,
+      FMFSource FMFSource, const Twine &Name, MDNode *FPMathTag = nullptr,
+      std::optional<RoundingMode> Rounding = std::nullopt,
+      std::optional<fp::ExceptionBehavior> Except = std::nullopt);
+
   CallInst *CreateConstrainedFPBinOp(
       Intrinsic::ID ID, Value *L, Value *R, FMFSource FMFSource = {},
       const Twine &Name = "", MDNode *FPMathTag = nullptr,

llvm/lib/IR/AutoUpgrade.cpp

@@ -3755,7 +3755,7 @@ static Value *upgradeX86IntrinsicCall(StringRef Name, CallBase *CI, Function *F,
         IID = Intrinsic::x86_avx512_vfmadd_f32;
       Rep = Builder.CreateIntrinsic(IID, {}, Ops);
     } else {
-      Rep = Builder.CreateIntrinsic(Intrinsic::fma, A->getType(), {A, B, C});
+      Rep = Builder.CreateFMA(A, B, C);
     }
 
     Value *PassThru = IsMaskZ   ? Constant::getNullValue(Rep->getType())
@@ -3808,7 +3808,7 @@ static Value *upgradeX86IntrinsicCall(StringRef Name, CallBase *CI, Function *F,
 
       Rep = Builder.CreateIntrinsic(IID, {}, {A, B, C, CI->getArgOperand(4)});
     } else {
-      Rep = Builder.CreateIntrinsic(Intrinsic::fma, A->getType(), {A, B, C});
+      Rep = Builder.CreateFMA(A, B, C);
     }
 
     Value *PassThru = IsMaskZ   ? llvm::Constant::getNullValue(CI->getType())

llvm/lib/IR/IRBuilder.cpp

@@ -950,6 +950,26 @@ CallInst *IRBuilderBase::CreateConstrainedFPBinOp(
   return C;
 }
 
+CallInst *IRBuilderBase::CreateConstrainedFPIntrinsic(
+    Intrinsic::ID ID, ArrayRef<Type *> Types, ArrayRef<Value *> Args,
+    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 = FMFSource.get(FMF);
+
+  llvm::SmallVector<Value *, 5> ExtArgs(Args);
+  ExtArgs.push_back(RoundingV);
+  ExtArgs.push_back(ExceptV);
+
+  CallInst *C = CreateIntrinsic(ID, Types, ExtArgs, nullptr, Name);
+  setConstrainedFPCallAttr(C);
+  setFPAttrs(C, FPMathTag, UseFMF);
+  return C;
+}
+
 CallInst *IRBuilderBase::CreateConstrainedFPUnroundedBinOp(
     Intrinsic::ID ID, Value *L, Value *R, FMFSource FMFSource,
     const Twine &Name, MDNode *FPMathTag,

llvm/unittests/IR/IRBuilderTest.cpp

@@ -109,25 +109,23 @@ TEST_F(IRBuilderTest, Intrinsics) {
   EXPECT_TRUE(II->hasNoInfs());
   EXPECT_FALSE(II->hasNoNaNs());
 
-  Result = Builder.CreateIntrinsic(Intrinsic::fma, {V->getType()}, {V, V, V});
+  Result = Builder.CreateFMA(V, V, V);
   II = cast<IntrinsicInst>(Result);
   EXPECT_EQ(II->getIntrinsicID(), Intrinsic::fma);
   EXPECT_FALSE(II->hasNoInfs());
   EXPECT_FALSE(II->hasNoNaNs());
 
-  Result =
-      Builder.CreateIntrinsic(Intrinsic::fma, {V->getType()}, {V, V, V}, I);
+  Result = Builder.CreateFMA(V, V, V, I);
   II = cast<IntrinsicInst>(Result);
   EXPECT_EQ(II->getIntrinsicID(), Intrinsic::fma);
   EXPECT_TRUE(II->hasNoInfs());
   EXPECT_FALSE(II->hasNoNaNs());
 
-  Result =
-      Builder.CreateIntrinsic(Intrinsic::fma, {V->getType()}, {V, V, V}, I);
+  Result = Builder.CreateFMA(V, V, V, FastMathFlags::getFast());
   II = cast<IntrinsicInst>(Result);
   EXPECT_EQ(II->getIntrinsicID(), Intrinsic::fma);
   EXPECT_TRUE(II->hasNoInfs());
-  EXPECT_FALSE(II->hasNoNaNs());
+  EXPECT_TRUE(II->hasNoNaNs());
 
   Result = Builder.CreateUnaryIntrinsic(Intrinsic::roundeven, V);
   II = cast<IntrinsicInst>(Result);
@@ -307,6 +305,11 @@ TEST_F(IRBuilderTest, ConstrainedFP) {
   II = cast<IntrinsicInst>(V);
   EXPECT_EQ(II->getIntrinsicID(), Intrinsic::experimental_constrained_frem);
 
+  V = Builder.CreateFMA(V, V, V);
+  ASSERT_TRUE(isa<IntrinsicInst>(V));
+  II = cast<IntrinsicInst>(V);
+  EXPECT_EQ(II->getIntrinsicID(), Intrinsic::experimental_constrained_fma);
+
   VInt = Builder.CreateFPToUI(VDouble, Builder.getInt32Ty());
   ASSERT_TRUE(isa<IntrinsicInst>(VInt));
   II = cast<IntrinsicInst>(VInt);
@@ -398,6 +401,15 @@ TEST_F(IRBuilderTest, ConstrainedFP) {
   EXPECT_EQ(fp::ebMayTrap, CII->getExceptionBehavior());
   EXPECT_EQ(RoundingMode::TowardNegative, CII->getRoundingMode());
 
+  // Same as previous test for CreateConstrainedFPIntrinsic
+  Call = Builder.CreateConstrainedFPIntrinsic(
+      Intrinsic::experimental_constrained_fadd, {V->getType()}, {V, V}, nullptr,
+      "", nullptr, RoundingMode::TowardNegative, fp::ebMayTrap);
+  CII = cast<ConstrainedFPIntrinsic>(Call);
+  EXPECT_EQ(CII->getIntrinsicID(), Intrinsic::experimental_constrained_fadd);
+  EXPECT_EQ(fp::ebMayTrap, CII->getExceptionBehavior());
+  EXPECT_EQ(RoundingMode::TowardNegative, CII->getRoundingMode());
+
   Builder.CreateRetVoid();
   EXPECT_FALSE(verifyModule(*M));
 }