[PATCH] D113767: [IR] Change CreateStepVector to work with element types smaller than i8

[David Sherwood via Phabricator via llvm-commits]

david-arm created this revision.
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Currently the stepvector intrinsic only supports element types that
are integers of size 8 bits or more. This patch adds support for the
creation of stepvectors with smaller element types by creating
the intrinsic with i8 elements that we then truncate to the requested
size.

It's not currently possible to write a vectoriser test to exercise
this code path so I have added a unit test here:

  llvm/unittests/IR/IRBuilderTest.cpp


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D113767

Files:
  llvm/lib/IR/IRBuilder.cpp
  llvm/unittests/IR/IRBuilderTest.cpp


Index: llvm/unittests/IR/IRBuilderTest.cpp
===================================================================
--- llvm/unittests/IR/IRBuilderTest.cpp
+++ llvm/unittests/IR/IRBuilderTest.cpp
@@ -214,6 +214,25 @@
   EXPECT_EQ(Call->getIntrinsicID(), Intrinsic::experimental_stepvector);
 }
 
+TEST_F(IRBuilderTest, CreateStepVectorI3) {
+  IRBuilder<> Builder(BB);
+
+  // Scalable vectors
+  Type *DstVecTy = VectorType::get(IntegerType::get(Ctx, 3), 2, true);
+  Type *VecI8Ty = VectorType::get(Builder.getInt8Ty(), 2, true);
+  Value *StepVec = Builder.CreateStepVector(DstVecTy);
+  EXPECT_TRUE(isa<TruncInst>(StepVec));
+  TruncInst *Trunc = cast<TruncInst>(StepVec);
+  EXPECT_EQ(Trunc->getDestTy(), DstVecTy);
+  EXPECT_EQ(Trunc->getSrcTy(), VecI8Ty);
+  EXPECT_TRUE(isa<CallInst>(Trunc->getOperand(0)));
+
+  CallInst *Call = cast<CallInst>(Trunc->getOperand(0));
+  FunctionType *FTy = Call->getFunctionType();
+  EXPECT_EQ(FTy->getReturnType(), VecI8Ty);
+  EXPECT_EQ(Call->getIntrinsicID(), Intrinsic::experimental_stepvector);
+}
+
 TEST_F(IRBuilderTest, ConstrainedFP) {
   IRBuilder<> Builder(BB);
   Value *V;
Index: llvm/lib/IR/IRBuilder.cpp
===================================================================
--- llvm/lib/IR/IRBuilder.cpp
+++ llvm/lib/IR/IRBuilder.cpp
@@ -94,11 +94,19 @@
 }
 
 Value *IRBuilderBase::CreateStepVector(Type *DstType, const Twine &Name) {
-  if (isa<ScalableVectorType>(DstType))
-    return CreateIntrinsic(Intrinsic::experimental_stepvector, {DstType}, {},
-                           nullptr, Name);
-
   Type *STy = DstType->getScalarType();
+  if (isa<ScalableVectorType>(DstType)) {
+    Type *StepVecType = DstType;
+    if (STy->getScalarSizeInBits() < 8)
+      StepVecType =
+          VectorType::get(getInt8Ty(), cast<ScalableVectorType>(DstType));
+    Value *Res = CreateIntrinsic(Intrinsic::experimental_stepvector,
+                                 {StepVecType}, {}, nullptr, Name);
+    if (StepVecType != DstType)
+      Res = CreateTrunc(Res, DstType);
+    return Res;
+  }
+
   unsigned NumEls = cast<FixedVectorType>(DstType)->getNumElements();
 
   // Create a vector of consecutive numbers from zero to VF.


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