[NFC][LLVM] Refactor IRBuilder::Create{VScale,ElementCount,TypeSize}. (llvm#142803)

CreateVScale took a scaling parameter that had a single use outside of
IRBuilder with all other callers having to create a redundant
ConstantInt. To work round this some code perferred to use
CreateIntrinsic directly.

This patch simplifies CreateVScale to return a call to the llvm.vscale()
intrinsic and nothing more. As well as simplifying the existing call
sites I've also migrated the uses of CreateIntrinsic.

Whilst IRBuilder used CreateVScale's scaling parameter as part of the
implementations of CreateElementCount and CreateTypeSize, I have
follow-on work to switch them to the NUW varaiety and thus they would
stop using CreateVScale's scaling as well. To prepare for this I have
moved the multiplication and constant folding into the implementations
of CreateElementCount and CreateTypeSize.

As a final step I have replaced some callers of CreateVScale with
CreateElementCount where it's clear from the code they wanted the
latter.

Author: paulwalker-arm

clang/lib/CodeGen/TargetBuiltins/ARM.cpp

@@ -4792,12 +4792,7 @@ Value *CodeGenFunction::EmitAArch64SVEBuiltinExpr(unsigned BuiltinID,
   case SVE::BI__builtin_sve_svlen_u32:
   case SVE::BI__builtin_sve_svlen_u64: {
     SVETypeFlags TF(Builtin->TypeModifier);
-    auto VTy = cast<llvm::VectorType>(getSVEType(TF));
-    auto *NumEls =
-        llvm::ConstantInt::get(Ty, VTy->getElementCount().getKnownMinValue());
-
-    Function *F = CGM.getIntrinsic(Intrinsic::vscale, Ty);
-    return Builder.CreateMul(NumEls, Builder.CreateCall(F));
+    return Builder.CreateElementCount(Ty, getSVEType(TF)->getElementCount());
   }
 
   case SVE::BI__builtin_sve_svtbl2_u8:
@@ -4813,8 +4808,7 @@ Value *CodeGenFunction::EmitAArch64SVEBuiltinExpr(unsigned BuiltinID,
   case SVE::BI__builtin_sve_svtbl2_f32:
   case SVE::BI__builtin_sve_svtbl2_f64: {
     SVETypeFlags TF(Builtin->TypeModifier);
-    auto VTy = cast<llvm::ScalableVectorType>(getSVEType(TF));
-    Function *F = CGM.getIntrinsic(Intrinsic::aarch64_sve_tbl2, VTy);
+    Function *F = CGM.getIntrinsic(Intrinsic::aarch64_sve_tbl2, getSVEType(TF));
     return Builder.CreateCall(F, Ops);
   }
 

llvm/include/llvm/IR/IRBuilder.h

@@ -945,17 +945,18 @@ class IRBuilderBase {
   LLVM_ABI CallInst *CreateGCGetPointerOffset(Value *DerivedPtr,
                                               const Twine &Name = "");
 
-  /// Create a call to llvm.vscale, multiplied by \p Scaling. The type of VScale
-  /// will be the same type as that of \p Scaling.
-  LLVM_ABI Value *CreateVScale(Constant *Scaling, const Twine &Name = "");
+  /// Create a call to llvm.vscale.<Ty>().
+  LLVM_ABI Value *CreateVScale(Type *Ty, const Twine &Name = "") {
+    return CreateIntrinsic(Intrinsic::vscale, {Ty}, {}, {}, Name);
+  }
 
   /// Create an expression which evaluates to the number of elements in \p EC
   /// at runtime.
-  LLVM_ABI Value *CreateElementCount(Type *DstType, ElementCount EC);
+  LLVM_ABI Value *CreateElementCount(Type *Ty, ElementCount EC);
 
   /// Create an expression which evaluates to the number of units in \p Size
   /// at runtime.  This works for both units of bits and bytes.
-  LLVM_ABI Value *CreateTypeSize(Type *DstType, TypeSize Size);
+  LLVM_ABI Value *CreateTypeSize(Type *Ty, TypeSize Size);
 
   /// Creates a vector of type \p DstType with the linear sequence <0, 1, ...>
   LLVM_ABI Value *CreateStepVector(Type *DstType, const Twine &Name = "");

llvm/lib/CodeGen/ExpandVectorPredication.cpp

@@ -507,8 +507,7 @@ bool CachingVPExpander::discardEVLParameter(VPIntrinsic &VPI) {
     // TODO add caching
     IRBuilder<> Builder(VPI.getParent(), VPI.getIterator());
     Value *FactorConst = Builder.getInt32(StaticElemCount.getKnownMinValue());
-    Value *VScale = Builder.CreateIntrinsic(Intrinsic::vscale, Int32Ty, {},
-                                            /*FMFSource=*/nullptr, "vscale");
+    Value *VScale = Builder.CreateVScale(Int32Ty, "vscale");
     MaxEVL = Builder.CreateMul(VScale, FactorConst, "scalable_size",
                                /*NUW*/ true, /*NSW*/ false);
   } else {

llvm/lib/IR/IRBuilder.cpp

@@ -120,23 +120,26 @@ IRBuilderBase::createCallHelper(Function *Callee, ArrayRef<Value *> Ops,
   return CI;
 }
 
-Value *IRBuilderBase::CreateVScale(Constant *Scaling, const Twine &Name) {
-  assert(isa<ConstantInt>(Scaling) && "Expected constant integer");
-  if (cast<ConstantInt>(Scaling)->isZero())
-    return Scaling;
-  CallInst *CI =
-      CreateIntrinsic(Intrinsic::vscale, {Scaling->getType()}, {}, {}, Name);
-  return cast<ConstantInt>(Scaling)->isOne() ? CI : CreateMul(CI, Scaling);
+static Value *CreateVScaleMultiple(IRBuilderBase &B, Type *Ty, uint64_t Scale) {
+  Value *VScale = B.CreateVScale(Ty);
+  if (Scale == 1)
+    return VScale;
+
+  return B.CreateMul(VScale, ConstantInt::get(Ty, Scale));
 }
 
-Value *IRBuilderBase::CreateElementCount(Type *DstType, ElementCount EC) {
-  Constant *MinEC = ConstantInt::get(DstType, EC.getKnownMinValue());
-  return EC.isScalable() ? CreateVScale(MinEC) : MinEC;
+Value *IRBuilderBase::CreateElementCount(Type *Ty, ElementCount EC) {
+  if (EC.isFixed() || EC.isZero())
+    return ConstantInt::get(Ty, EC.getKnownMinValue());
+
+  return CreateVScaleMultiple(*this, Ty, EC.getKnownMinValue());
 }
 
-Value *IRBuilderBase::CreateTypeSize(Type *DstType, TypeSize Size) {
-  Constant *MinSize = ConstantInt::get(DstType, Size.getKnownMinValue());
-  return Size.isScalable() ? CreateVScale(MinSize) : MinSize;
+Value *IRBuilderBase::CreateTypeSize(Type *Ty, TypeSize Size) {
+  if (Size.isFixed() || Size.isZero())
+    return ConstantInt::get(Ty, Size.getKnownMinValue());
+
+  return CreateVScaleMultiple(*this, Ty, Size.getKnownMinValue());
 }
 
 Value *IRBuilderBase::CreateStepVector(Type *DstType, const Twine &Name) {

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp

@@ -2051,10 +2051,10 @@ instCombineSVECntElts(InstCombiner &IC, IntrinsicInst &II, unsigned NumElts) {
   const auto Pattern = cast<ConstantInt>(II.getArgOperand(0))->getZExtValue();
 
   if (Pattern == AArch64SVEPredPattern::all) {
-    Constant *StepVal = ConstantInt::get(II.getType(), NumElts);
-    auto *VScale = IC.Builder.CreateVScale(StepVal);
-    VScale->takeName(&II);
-    return IC.replaceInstUsesWith(II, VScale);
+    Value *Cnt = IC.Builder.CreateElementCount(
+        II.getType(), ElementCount::getScalable(NumElts));
+    Cnt->takeName(&II);
+    return IC.replaceInstUsesWith(II, Cnt);
   }
 
   unsigned MinNumElts = getNumElementsFromSVEPredPattern(Pattern);

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

@@ -935,12 +935,9 @@ Instruction *InstCombinerImpl::visitTrunc(TruncInst &Trunc) {
         Trunc.getFunction()->hasFnAttribute(Attribute::VScaleRange)) {
       Attribute Attr =
           Trunc.getFunction()->getFnAttribute(Attribute::VScaleRange);
-      if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
-        if (Log2_32(*MaxVScale) < DestWidth) {
-          Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
-          return replaceInstUsesWith(Trunc, VScale);
-        }
-      }
+      if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
+        if (Log2_32(*MaxVScale) < DestWidth)
+          return replaceInstUsesWith(Trunc, Builder.CreateVScale(DestTy));
     }
   }
 
@@ -1314,10 +1311,8 @@ Instruction *InstCombinerImpl::visitZExt(ZExtInst &Zext) {
           Zext.getFunction()->getFnAttribute(Attribute::VScaleRange);
       if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
         unsigned TypeWidth = Src->getType()->getScalarSizeInBits();
-        if (Log2_32(*MaxVScale) < TypeWidth) {
-          Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
-          return replaceInstUsesWith(Zext, VScale);
-        }
+        if (Log2_32(*MaxVScale) < TypeWidth)
+          return replaceInstUsesWith(Zext, Builder.CreateVScale(DestTy));
       }
     }
   }
@@ -1604,12 +1599,9 @@ Instruction *InstCombinerImpl::visitSExt(SExtInst &Sext) {
         Sext.getFunction()->hasFnAttribute(Attribute::VScaleRange)) {
       Attribute Attr =
           Sext.getFunction()->getFnAttribute(Attribute::VScaleRange);
-      if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
-        if (Log2_32(*MaxVScale) < (SrcBitSize - 1)) {
-          Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
-          return replaceInstUsesWith(Sext, VScale);
-        }
-      }
+      if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
+        if (Log2_32(*MaxVScale) < (SrcBitSize - 1))
+          return replaceInstUsesWith(Sext, Builder.CreateVScale(DestTy));
     }
   }
 

llvm/lib/Transforms/Utils/LowerVectorIntrinsics.cpp

@@ -21,29 +21,19 @@ bool llvm::lowerUnaryVectorIntrinsicAsLoop(Module &M, CallInst *CI) {
   BasicBlock *PostLoopBB = nullptr;
   Function *ParentFunc = PreLoopBB->getParent();
   LLVMContext &Ctx = PreLoopBB->getContext();
+  Type *Int64Ty = IntegerType::get(Ctx, 64);
 
   PostLoopBB = PreLoopBB->splitBasicBlock(CI);
   BasicBlock *LoopBB = BasicBlock::Create(Ctx, "", ParentFunc, PostLoopBB);
   PreLoopBB->getTerminator()->setSuccessor(0, LoopBB);
 
   // Loop preheader
   IRBuilder<> PreLoopBuilder(PreLoopBB->getTerminator());
-  Value *LoopEnd = nullptr;
-  if (auto *ScalableVecTy = dyn_cast<ScalableVectorType>(VecTy)) {
-    Value *VScale = PreLoopBuilder.CreateVScale(
-        ConstantInt::get(PreLoopBuilder.getInt64Ty(), 1));
-    Value *N = ConstantInt::get(PreLoopBuilder.getInt64Ty(),
-                                ScalableVecTy->getMinNumElements());
-    LoopEnd = PreLoopBuilder.CreateMul(VScale, N);
-  } else {
-    FixedVectorType *FixedVecTy = cast<FixedVectorType>(VecTy);
-    LoopEnd = ConstantInt::get(PreLoopBuilder.getInt64Ty(),
-                               FixedVecTy->getNumElements());
-  }
+  Value *LoopEnd =
+      PreLoopBuilder.CreateElementCount(Int64Ty, VecTy->getElementCount());
 
   // Loop body
   IRBuilder<> LoopBuilder(LoopBB);
-  Type *Int64Ty = LoopBuilder.getInt64Ty();
 
   PHINode *LoopIndex = LoopBuilder.CreatePHI(Int64Ty, 2);
   LoopIndex->addIncoming(ConstantInt::get(Int64Ty, 0U), PreLoopBB);

llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp

@@ -1440,7 +1440,7 @@ Value *SCEVExpander::visitSequentialUMinExpr(const SCEVSequentialUMinExpr *S) {
 }
 
 Value *SCEVExpander::visitVScale(const SCEVVScale *S) {
-  return Builder.CreateVScale(ConstantInt::get(S->getType(), 1));
+  return Builder.CreateVScale(S->getType());
 }
 
 Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty,

llvm/lib/Transforms/Vectorize/LoopIdiomVectorize.cpp

@@ -437,7 +437,7 @@ Value *LoopIdiomVectorize::createMaskedFindMismatch(
   Value *InitialPred = Builder.CreateIntrinsic(
       Intrinsic::get_active_lane_mask, {PredVTy, I64Type}, {ExtStart, ExtEnd});
 
-  Value *VecLen = Builder.CreateIntrinsic(Intrinsic::vscale, {I64Type}, {});
+  Value *VecLen = Builder.CreateVScale(I64Type);
   VecLen =
       Builder.CreateMul(VecLen, ConstantInt::get(I64Type, ByteCompareVF), "",
                         /*HasNUW=*/true, /*HasNSW=*/true);

llvm/unittests/IR/IRBuilderTest.cpp

@@ -212,14 +212,6 @@ TEST_F(IRBuilderTest, IntrinsicsWithScalableVectors) {
     EXPECT_EQ(FTy->getParamType(i), Args[i]->getType());
 }
 
-TEST_F(IRBuilderTest, CreateVScale) {
-  IRBuilder<> Builder(BB);
-
-  Constant *Zero = Builder.getInt32(0);
-  Value *VScale = Builder.CreateVScale(Zero);
-  EXPECT_TRUE(isa<ConstantInt>(VScale) && cast<ConstantInt>(VScale)->isZero());
-}
-
 TEST_F(IRBuilderTest, CreateStepVector) {
   IRBuilder<> Builder(BB);