[PATCH] D100763: [LoopVectorize] Don't create unnecessary vscale intrinsic calls

[David Sherwood via Phabricator via llvm-commits]

david-arm updated this revision to Diff 339154.
david-arm added a comment.

- Added unit test for vscale * 0 case.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100763/new/

https://reviews.llvm.org/D100763

Files:
  llvm/lib/IR/IRBuilder.cpp
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/unittests/IR/IRBuilderTest.cpp


Index: llvm/unittests/IR/IRBuilderTest.cpp
===================================================================
--- llvm/unittests/IR/IRBuilderTest.cpp
+++ llvm/unittests/IR/IRBuilderTest.cpp
@@ -180,6 +180,14 @@
     EXPECT_EQ(FTy->getParamType(i), ArgTys[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);
 
Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4773,10 +4773,9 @@
              "Currently unsupported for scalable vectors");
       unsigned Lanes = IsUniform ? 1 : State.VF.getFixedValue();
 
-      Value *RuntimeVF = getRuntimeVF(Builder, PtrInd->getType(), VF);
       for (unsigned Part = 0; Part < UF; ++Part) {
-        Value *PartStart = Builder.CreateMul(
-            RuntimeVF, ConstantInt::get(PtrInd->getType(), Part));
+        Value *PartStart = createStepForVF(
+            Builder, ConstantInt::get(PtrInd->getType(), Part), VF);
         for (unsigned Lane = 0; Lane < Lanes; ++Lane) {
           Value *Idx = Builder.CreateAdd(
               PartStart, ConstantInt::get(PtrInd->getType(), Lane));
Index: llvm/lib/IR/IRBuilder.cpp
===================================================================
--- llvm/lib/IR/IRBuilder.cpp
+++ llvm/lib/IR/IRBuilder.cpp
@@ -81,8 +81,10 @@
 }
 
 Value *IRBuilderBase::CreateVScale(Constant *Scaling, const Twine &Name) {
-  Module *M = GetInsertBlock()->getParent()->getParent();
   assert(isa<ConstantInt>(Scaling) && "Expected constant integer");
+  if (cast<ConstantInt>(Scaling)->isZero())
+    return Scaling;
+  Module *M = GetInsertBlock()->getParent()->getParent();
   Function *TheFn =
       Intrinsic::getDeclaration(M, Intrinsic::vscale, {Scaling->getType()});
   CallInst *CI = createCallHelper(TheFn, {}, this, Name);


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