[llvm] 6b1ea24 - [llvm-stress] Support scalable vectors and out of bounds indices to vector ops

[Philip Reames via llvm-commits]

Author: Philip Reames
Date: 2022-12-13T07:47:19-08:00
New Revision: 6b1ea24c265205190d3e73b08ed76e85988d76f5

URL: https://github.com/llvm/llvm-project/commit/6b1ea24c265205190d3e73b08ed76e85988d76f5
DIFF: https://github.com/llvm/llvm-project/commit/6b1ea24c265205190d3e73b08ed76e85988d76f5.diff

LOG: [llvm-stress] Support scalable vectors and out of bounds indices to vector ops

This change does two things.

First, it supports scalable vectors in llvm-stress output.  There's an off-by-default flag -enable-scalable-vectors which generates a scalable vector with 50% probability when a random vector type is selected.  Because of the existing implementation, this tends to skew an entire test towards either scalable or fixed since we most select initial values, not random types.

Second, it selects a random value for the index of an insertelement or extractelement.  As a result, out of bounds indices can not appear for fixed lengh vectors.  Previously, it chose a random constant which was, by construction, in range.

Added: 
    

Modified: 
    llvm/tools/llvm-stress/llvm-stress.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/tools/llvm-stress/llvm-stress.cpp b/llvm/tools/llvm-stress/llvm-stress.cpp
index f27ee802c0b96..d4593d5a1e0fd 100644
--- a/llvm/tools/llvm-stress/llvm-stress.cpp
+++ b/llvm/tools/llvm-stress/llvm-stress.cpp
@@ -71,6 +71,12 @@ static cl::list<StringRef> AdditionalScalarTypes(
     cl::desc("Additional IR scalar types "
              "(always includes i1, i8, i16, i32, i64, float and double)"));
 
+static cl::opt<bool> EnableScalableVectors(
+    "enable-scalable-vectors",
+    cl::desc("Generate IR involving scalable vector types"),
+    cl::init(false), cl::cat(StressCategory));
+
+
 namespace {
 
 /// A utility class to provide a pseudo-random number generator which is
@@ -287,21 +293,25 @@ struct Modifier {
 
   /// Pick a random vector type.
   Type *pickVectorType(VectorType *VTy = nullptr) {
-    // Pick a random vector width in the range 2**0 to 2**4.
-    // by adding two randoms we are generating a normal-like distribution
-    // around 2**3.
-    unsigned width = 1<<((getRandom() % 3) + (getRandom() % 3));
-    if (VTy) {
-      auto *VecTy = cast<FixedVectorType>(VTy);
-      width = VecTy->getNumElements();
-    }
 
     // Vectors of x86mmx are illegal; keep trying till we get something else.
     Type *Ty;
     do {
       Ty = pickScalarType();
     } while (Ty->isX86_MMXTy());
-    return FixedVectorType::get(Ty, width);
+
+    if (VTy)
+      return VectorType::get(Ty, VTy->getElementCount());
+
+    // Select either fixed length or scalable vectors with 50% probability
+    // (only if scalable vectors are enabled)
+    bool Scalable = EnableScalableVectors && getRandom() & 1;
+
+    // Pick a random vector width in the range 2**0 to 2**4.
+    // by adding two randoms we are generating a normal-like distribution
+    // around 2**3.
+    unsigned width = 1<<((getRandom() % 3) + (getRandom() % 3));
+    return VectorType::get(Ty, width, Scalable);
   }
 
   /// Pick a random scalar type.
@@ -475,10 +485,7 @@ struct ExtractElementModifier: public Modifier {
     Value *Val0 = getRandomVectorValue();
     Value *V = ExtractElementInst::Create(
         Val0,
-        ConstantInt::get(
-            Type::getInt32Ty(BB->getContext()),
-            getRandom() %
-                cast<FixedVectorType>(Val0->getType())->getNumElements()),
+        getRandomValue(Type::getInt32Ty(BB->getContext())),
         "E", BB->getTerminator());
     return PT->push_back(V);
   }
@@ -492,6 +499,10 @@ struct ShuffModifier: public Modifier {
     Value *Val0 = getRandomVectorValue();
     Value *Val1 = getRandomValue(Val0->getType());
 
+    // Can't express arbitrary shufflevectors for scalable vectors
+    if (isa<ScalableVectorType>(Val0->getType()))
+      return;
+
     unsigned Width = cast<FixedVectorType>(Val0->getType())->getNumElements();
     std::vector<Constant*> Idxs;
 
@@ -522,10 +533,7 @@ struct InsertElementModifier: public Modifier {
 
     Value *V = InsertElementInst::Create(
         Val0, Val1,
-        ConstantInt::get(
-            Type::getInt32Ty(BB->getContext()),
-            getRandom() %
-                cast<FixedVectorType>(Val0->getType())->getNumElements()),
+        getRandomValue(Type::getInt32Ty(BB->getContext())),
         "I", BB->getTerminator());
     return PT->push_back(V);
   }
@@ -622,9 +630,9 @@ struct SelectModifier: public Modifier {
 
     // If the value type is a vector, and we allow vector select, then in 50%
     // of the cases generate a vector select.
-    if (auto *VTy = dyn_cast<FixedVectorType>(Val0->getType()))
+    if (auto *VTy = dyn_cast<VectorType>(Val0->getType()))
       if (getRandom() & 1)
-        CondTy = FixedVectorType::get(CondTy, VTy->getNumElements());
+        CondTy = VectorType::get(CondTy, VTy->getElementCount());
 
     Value *Cond = getRandomValue(CondTy);
     Value *V = SelectInst::Create(Cond, Val0, Val1, "Sl", BB->getTerminator());