llvmbot wrote:

<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Paul Walker (paulwalker-arm)

<details>
<summary>Changes</summary>

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.

---
Full diff: https://github.com/llvm/llvm-project/pull/142803.diff


10 Files Affected:

- (modified) clang/lib/CodeGen/TargetBuiltins/ARM.cpp (+1-5) 
- (modified) llvm/include/llvm/IR/IRBuilder.h (+4-5) 
- (modified) llvm/lib/CodeGen/ExpandVectorPredication.cpp (+1-2) 
- (modified) llvm/lib/IR/IRBuilder.cpp (+20-13) 
- (modified) llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp (+4-4) 
- (modified) llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp (+8-16) 
- (modified) llvm/lib/Transforms/Utils/LowerVectorIntrinsics.cpp (+3-13) 
- (modified) llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp (+1-1) 
- (modified) llvm/lib/Transforms/Vectorize/LoopIdiomVectorize.cpp (+1-1) 
- (modified) llvm/unittests/IR/IRBuilderTest.cpp (-8) 


``````````diff
diff --git a/clang/lib/CodeGen/TargetBuiltins/ARM.cpp 
b/clang/lib/CodeGen/TargetBuiltins/ARM.cpp
index 1cf8f6819b75a..9c77346389e04 100644
--- a/clang/lib/CodeGen/TargetBuiltins/ARM.cpp
+++ b/clang/lib/CodeGen/TargetBuiltins/ARM.cpp
@@ -4793,11 +4793,7 @@ Value 
*CodeGenFunction::EmitAArch64SVEBuiltinExpr(unsigned BuiltinID,
   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, VTy->getElementCount());
   }
 
   case SVE::BI__builtin_sve_svtbl2_u8:
diff --git a/llvm/include/llvm/IR/IRBuilder.h b/llvm/include/llvm/IR/IRBuilder.h
index 0db5179c7a3e4..8ed10cb803a9c 100644
--- a/llvm/include/llvm/IR/IRBuilder.h
+++ b/llvm/include/llvm/IR/IRBuilder.h
@@ -945,17 +945,16 @@ 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 = "");
 
   /// 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 = "");
diff --git a/llvm/lib/CodeGen/ExpandVectorPredication.cpp 
b/llvm/lib/CodeGen/ExpandVectorPredication.cpp
index 1bb0763fcf57b..d8e3f5fbb31de 100644
--- a/llvm/lib/CodeGen/ExpandVectorPredication.cpp
+++ b/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 {
diff --git a/llvm/lib/IR/IRBuilder.cpp b/llvm/lib/IR/IRBuilder.cpp
index 580b0af709337..868aa7a2cb799 100644
--- a/llvm/lib/IR/IRBuilder.cpp
+++ b/llvm/lib/IR/IRBuilder.cpp
@@ -120,23 +120,30 @@ 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);
+Value *IRBuilderBase::CreateVScale(Type *Ty, const Twine &Name) {
+  return CreateIntrinsic(Intrinsic::vscale, {Ty}, {}, {}, Name);
 }
 
-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());
+
+  Value *VScale = CreateVScale(Ty);
+  if (EC.getKnownMinValue() == 1)
+    return VScale;
+
+  return CreateMul(VScale, ConstantInt::get(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());
+
+  Value *VScale = CreateVScale(Ty);
+  if (Size.getKnownMinValue() == 1)
+    return VScale;
+
+  return CreateMul(VScale, ConstantInt::get(Ty, Size.getKnownMinValue()));
 }
 
 Value *IRBuilderBase::CreateStepVector(Type *DstType, const Twine &Name) {
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp 
b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index 68aec80f07e1d..f6167e4333327 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/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);
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp 
b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index d234a0566e191..2db79228bf0e6 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/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));
     }
   }
 
diff --git a/llvm/lib/Transforms/Utils/LowerVectorIntrinsics.cpp 
b/llvm/lib/Transforms/Utils/LowerVectorIntrinsics.cpp
index a34ef260dc244..71c10f5b157c7 100644
--- a/llvm/lib/Transforms/Utils/LowerVectorIntrinsics.cpp
+++ b/llvm/lib/Transforms/Utils/LowerVectorIntrinsics.cpp
@@ -21,6 +21,7 @@ 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);
@@ -28,22 +29,11 @@ bool llvm::lowerUnaryVectorIntrinsicAsLoop(Module &M, 
CallInst *CI) {
 
   // 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);
diff --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp 
b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index 88d2eca36ca51..70afd4133df7c 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/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,
diff --git a/llvm/lib/Transforms/Vectorize/LoopIdiomVectorize.cpp 
b/llvm/lib/Transforms/Vectorize/LoopIdiomVectorize.cpp
index 02ffc67c774dd..491f0b76f4ae0 100644
--- a/llvm/lib/Transforms/Vectorize/LoopIdiomVectorize.cpp
+++ b/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);
diff --git a/llvm/unittests/IR/IRBuilderTest.cpp 
b/llvm/unittests/IR/IRBuilderTest.cpp
index b7eb0af728331..3a7ba924792ef 100644
--- a/llvm/unittests/IR/IRBuilderTest.cpp
+++ b/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);
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/142803
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