[GlobalISel] Add scalable property to LLT types.

[sdesmalen]

Summary

This patch aims to add the scalable property to LLT. The rest of the
patch-series changes the interfaces to take/return ElementCount and
TypeSize, which both have the ability to represent the scalable property.

The changes are mostly mechanical and aim to be non-functional changes
for fixed-width vectors.

For scalable vectors some unit tests have been added, but no effort has
been put into making any of the GlobalISel algorithms work with scalable
vectors yet. That will be left as future work.

The work is split into a series of 5 patches to make reviews easier.

[arsenm]

LGTM as long as this isn't increasing LLT's size. If it is I would rather steal a bit from the size or elements

llvm/include/llvm/Support/LowLevelTypeImpl.h

273

Is this increasing the total LLT size beyond 64-bits?

[tschuett]

a static_assert of the size for proof and documentation?

[sdesmalen]

Added static_assert to ensure the size of the LLT struct is unchanged.

llvm/include/llvm/Support/LowLevelTypeImpl.h

 class Type;
 class raw_ostream;
 
 class LLT {
 public:
   /// Get a low-level scalar or aggregate "bag of bits".
   static LLT scalar(unsigned SizeInBits) {
     assert(SizeInBits > 0 && "invalid scalar size");
-    return LLT{/*isPointer=*/false, /*isVector=*/false, /*NumElements=*/0,
-               SizeInBits, /*AddressSpace=*/0};
+    return LLT{/*isPointer=*/false, /*isVector=*/false,
+               ElementCount::getFixed(0), SizeInBits,
+               /*AddressSpace=*/0};
   }
 
   /// Get a low-level pointer in the given address space.
   static LLT pointer(unsigned AddressSpace, unsigned SizeInBits) {
     assert(SizeInBits > 0 && "invalid pointer size");
-    return LLT{/*isPointer=*/true, /*isVector=*/false, /*NumElements=*/0,
-               SizeInBits, AddressSpace};
+    return LLT{/*isPointer=*/true, /*isVector=*/false,
+               ElementCount::getFixed(0), SizeInBits, AddressSpace};
   }
 
   /// Get a low-level vector of some number of elements and element width.
   /// \p NumElements must be at least 2.
-  static LLT vector(uint16_t NumElements, unsigned ScalarSizeInBits) {
-    assert(NumElements > 1 && "invalid number of vector elements");
+  static LLT vector(uint16_t NumElements, unsigned ScalarSizeInBits,
+                    bool Scalable = false) {
+    assert(((!Scalable && NumElements > 1) || NumElements > 0) &&
+           "invalid number of vector elements");
     assert(ScalarSizeInBits > 0 && "invalid vector element size");
-    return LLT{/*isPointer=*/false, /*isVector=*/true, NumElements,
-               ScalarSizeInBits, /*AddressSpace=*/0};
+    return LLT{/*isPointer=*/false, /*isVector=*/true,
+               ElementCount::get(NumElements, Scalable), ScalarSizeInBits,
+               /*AddressSpace=*/0};
   }
 
   /// Get a low-level vector of some number of elements and element type.
-  static LLT vector(uint16_t NumElements, LLT ScalarTy) {
-    assert(NumElements > 1 && "invalid number of vector elements");
+  static LLT vector(uint16_t NumElements, LLT ScalarTy, bool Scalable = false) {
+    assert(((!Scalable && NumElements > 1) || NumElements > 0) &&
+           "invalid number of vector elements");
     assert(!ScalarTy.isVector() && "invalid vector element type");
-    return LLT{ScalarTy.isPointer(), /*isVector=*/true, NumElements,
+    return LLT{ScalarTy.isPointer(), /*isVector=*/true,
+               ElementCount::get(NumElements, Scalable),
                ScalarTy.getSizeInBits(),
                ScalarTy.isPointer() ? ScalarTy.getAddressSpace() : 0};
   }
 
   static LLT scalarOrVector(uint16_t NumElements, LLT ScalarTy) {
     return NumElements == 1 ? ScalarTy : LLT::vector(NumElements, ScalarTy);
   }
 
   static LLT scalarOrVector(uint16_t NumElements, unsigned ScalarSize) {
     return scalarOrVector(NumElements, LLT::scalar(ScalarSize));
   }
 
-  explicit LLT(bool isPointer, bool isVector, uint16_t NumElements,
+  explicit LLT(bool isPointer, bool isVector, ElementCount EC,
                unsigned SizeInBits, unsigned AddressSpace) {
-    init(isPointer, isVector, NumElements, SizeInBits, AddressSpace);
+    init(isPointer, isVector, EC, SizeInBits, AddressSpace);
   }
   explicit LLT() : IsPointer(false), IsVector(false), RawData(0) {}
 
   explicit LLT(MVT VT);
 
   bool isValid() const { return RawData != 0; }
 
   bool isScalar() const { return isValid() && !IsPointer && !IsVector; }
 
   bool isPointer() const { return isValid() && IsPointer && !IsVector; }
 
   bool isVector() const { return isValid() && IsVector; }
 
   /// Returns the number of elements in a vector LLT. Must only be called on
   /// vector types.
   uint16_t getNumElements() const {
+    if (isScalable())
+      llvm::reportInvalidSizeRequest(
+          "Possible incorrect use of LLT::getNumElements() for "
+          "scalable vector. Scalable flag may be dropped, use "
+          "LLT::getElementCount() instead");
+    return getElementCount().getKnownMinValue();
+  }
+
+  /// Returns true if the LLT is a scalable vector. Must only be called on
+  /// vector types.
+  bool isScalable() const {
+    assert(isVector() && "Expected a vector type");
+    return IsPointer ? getFieldValue(PointerVectorScalableFieldInfo)
+                     : getFieldValue(VectorScalableFieldInfo);
+  }
+
+  ElementCount getElementCount() const {
     assert(IsVector && "cannot get number of elements on scalar/aggregate");
-    if (!IsPointer)
-      return getFieldValue(VectorElementsFieldInfo);
-    else
-      return getFieldValue(PointerVectorElementsFieldInfo);
+    return ElementCount::get(IsPointer
+                                 ? getFieldValue(PointerVectorElementsFieldInfo)
+                                 : getFieldValue(VectorElementsFieldInfo),
+                             isScalable());
   }
 
   /// Returns the total size of the type. Must only be called on sized types.
   unsigned getSizeInBits() const {
     if (isPointer() || isScalar())
       return getScalarSizeInBits();
-    return getScalarSizeInBits() * getNumElements();
+    // FIXME: This should return a TypeSize in order to work for scalable
+    // vectors.
+    return getScalarSizeInBits() * getElementCount().getKnownMinValue();
   }
 
   /// Returns the total size of the type in bytes, i.e. number of whole bytes
   /// needed to represent the size in bits. Must only be called on sized types.
   unsigned getSizeInBytes() const {
     return (getSizeInBits() + 7) / 8;
   }
 
   LLT getScalarType() const {
     return isVector() ? getElementType() : *this;
   }
 
   /// If this type is a vector, return a vector with the same number of elements
   /// but the new element type. Otherwise, return the new element type.
   LLT changeElementType(LLT NewEltTy) const {
-    return isVector() ? LLT::vector(getNumElements(), NewEltTy) : NewEltTy;
+    return isVector() ? LLT::vector(getElementCount().getKnownMinValue(),
+                                    NewEltTy, isScalable())
+                      : NewEltTy;
   }
 
   /// If this type is a vector, return a vector with the same number of elements
   /// but the new element size. Otherwise, return the new element type. Invalid
   /// for pointer types. For pointer types, use changeElementType.
   LLT changeElementSize(unsigned NewEltSize) const {
     assert(!getScalarType().isPointer() &&
            "invalid to directly change element size for pointers");
-    return isVector() ? LLT::vector(getNumElements(), NewEltSize)
+    return isVector() ? LLT::vector(getElementCount().getKnownMinValue(),
+                                    NewEltSize, isScalable())
                       : LLT::scalar(NewEltSize);
   }
 
   /// Return a vector or scalar with the same element type and the new number of
   /// elements.
   LLT changeNumElements(unsigned NewNumElts) const {
+    assert((!isVector() || !isScalable()) &&
+           "Cannot use changeNumElements on a scalable vector");
     return LLT::scalarOrVector(NewNumElts, getScalarType());
   }
 
   /// Return a type that is \p Factor times smaller. Reduces the number of
   /// elements if this is a vector, or the bitwidth for scalar/pointers. Does
   /// not attempt to handle cases that aren't evenly divisible.
   LLT divide(int Factor) const {
     assert(Factor != 1);
private:
   ///   SizeInBits: 16;
   ///   AddressSpace: 24;
   static const constexpr BitFieldInfo PointerSizeFieldInfo{16, 0};
   static const constexpr BitFieldInfo PointerAddressSpaceFieldInfo{
       24, PointerSizeFieldInfo[0] + PointerSizeFieldInfo[1]};
   /// * Vector-of-non-pointer (isPointer == 0 && isVector == 1):
   ///   NumElements: 16;
   ///   SizeOfElement: 32;
+  ///   Scalable: 1;
   static const constexpr BitFieldInfo VectorElementsFieldInfo{16, 0};
   static const constexpr BitFieldInfo VectorSizeFieldInfo{
       32, VectorElementsFieldInfo[0] + VectorElementsFieldInfo[1]};
+  static const constexpr BitFieldInfo VectorScalableFieldInfo{
+      1, VectorSizeFieldInfo[0] + VectorSizeFieldInfo[1]};
   /// * Vector-of-pointer (isPointer == 1 && isVector == 1):
   ///   NumElements: 16;
   ///   SizeOfElement: 16;
   ///   AddressSpace: 24;
+  ///   Scalable: 1;
   static const constexpr BitFieldInfo PointerVectorElementsFieldInfo{16, 0};
   static const constexpr BitFieldInfo PointerVectorSizeFieldInfo{
       16,
       PointerVectorElementsFieldInfo[1] + PointerVectorElementsFieldInfo[0]};
   static const constexpr BitFieldInfo PointerVectorAddressSpaceFieldInfo{
       24, PointerVectorSizeFieldInfo[1] + PointerVectorSizeFieldInfo[0]};
+  static const constexpr BitFieldInfo PointerVectorScalableFieldInfo{
+      1, PointerVectorAddressSpaceFieldInfo[0] +
+             PointerVectorAddressSpaceFieldInfo[1]};
 
   uint64_t IsPointer : 1;
   uint64_t IsVector : 1;
   uint64_t RawData : 62;
 
   static uint64_t getMask(const BitFieldInfo FieldInfo) {
     const int FieldSizeInBits = FieldInfo[0];
     return (((uint64_t)1) << FieldSizeInBits) - 1;
   }
   static uint64_t maskAndShift(uint64_t Val, uint64_t Mask, uint8_t Shift) {
     assert(Val <= Mask && "Value too large for field");
     return (Val & Mask) << Shift;
   }
   static uint64_t maskAndShift(uint64_t Val, const BitFieldInfo FieldInfo) {
     return maskAndShift(Val, getMask(FieldInfo), FieldInfo[1]);
   }
   uint64_t getFieldValue(const BitFieldInfo FieldInfo) const {
     return getMask(FieldInfo) & (RawData >> FieldInfo[1]);
   }
 
-  void init(bool IsPointer, bool IsVector, uint16_t NumElements,
-            unsigned SizeInBits, unsigned AddressSpace) {
+  void init(bool IsPointer, bool IsVector, ElementCount EC, unsigned SizeInBits,
+            unsigned AddressSpace) {
     this->IsPointer = IsPointer;
     this->IsVector = IsVector;
     if (!IsVector) {
       if (!IsPointer)
         RawData = maskAndShift(SizeInBits, ScalarSizeFieldInfo);
       else
         RawData = maskAndShift(SizeInBits, PointerSizeFieldInfo) |
                   maskAndShift(AddressSpace, PointerAddressSpaceFieldInfo);
     } else {
-      assert(NumElements > 1 && "invalid number of vector elements");
+      assert(EC.isVector() && "invalid number of vector elements");
       if (!IsPointer)
-        RawData = maskAndShift(NumElements, VectorElementsFieldInfo) |
-                  maskAndShift(SizeInBits, VectorSizeFieldInfo);
+        RawData =
+            maskAndShift(EC.getKnownMinValue(), VectorElementsFieldInfo) |
+            maskAndShift(SizeInBits, VectorSizeFieldInfo) |
+            maskAndShift(EC.isScalable() ? 1 : 0, VectorScalableFieldInfo);
       else
         RawData =
-            maskAndShift(NumElements, PointerVectorElementsFieldInfo) |
+            maskAndShift(EC.getKnownMinValue(),
+                         PointerVectorElementsFieldInfo) |
             maskAndShift(SizeInBits, PointerVectorSizeFieldInfo) |
-            maskAndShift(AddressSpace, PointerVectorAddressSpaceFieldInfo);
+            maskAndShift(AddressSpace, PointerVectorAddressSpaceFieldInfo) |
+            maskAndShift(EC.isScalable() ? 1 : 0,
+                         PointerVectorScalableFieldInfo);
     }
   }
 
   uint64_t getUniqueRAWLLTData() const {
     return ((uint64_t)RawData) << 2 | ((uint64_t)IsPointer) << 1 |
            ((uint64_t)IsVector);
   }
 };

llvm/lib/CodeGen/LowLevelType.cpp

 #include "llvm/ADT/APFloat.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 LLT llvm::getLLTForType(Type &Ty, const DataLayout &DL) {
   if (auto VTy = dyn_cast<VectorType>(&Ty)) {
-    auto NumElements = cast<FixedVectorType>(VTy)->getNumElements();
+    auto EC = VTy->getElementCount();
     LLT ScalarTy = getLLTForType(*VTy->getElementType(), DL);
-    if (NumElements == 1)
+    if (EC.isScalar())
       return ScalarTy;
-    return LLT::vector(NumElements, ScalarTy);
+    return LLT::vector(EC.getKnownMinValue(), ScalarTy, EC.isScalable());
   }
 
   if (auto PTy = dyn_cast<PointerType>(&Ty)) {
     unsigned AddrSpace = PTy->getAddressSpace();
     return LLT::pointer(AddrSpace, DL.getPointerSizeInBits(AddrSpace));
   }
 
   if (Ty.isSized()) {

llvm/lib/Support/LowLevelType.cpp

 
 #include "llvm/Support/LowLevelTypeImpl.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 LLT::LLT(MVT VT) {
   if (VT.isVector()) {
     init(/*IsPointer=*/false, VT.getVectorNumElements() > 1,
-         VT.getVectorNumElements(), VT.getVectorElementType().getSizeInBits(),
+         VT.getVectorElementCount(), VT.getVectorElementType().getSizeInBits(),
          /*AddressSpace=*/0);
   } else if (VT.isValid()) {
     // Aggregates are no different from real scalars as far as GlobalISel is
     // concerned.
     assert(VT.getSizeInBits().isNonZero() && "invalid zero-sized type");
-    init(/*IsPointer=*/false, /*IsVector=*/false, /*NumElements=*/0,
+    init(/*IsPointer=*/false, /*IsVector=*/false, ElementCount::getFixed(0),
          VT.getSizeInBits(), /*AddressSpace=*/0);
   } else {
     IsPointer = false;
     IsVector = false;
     RawData = 0;
   }
 }
 
 void LLT::print(raw_ostream &OS) const {
-  if (isVector())
-    OS << "<" << getNumElements() << " x " << getElementType() << ">";
-  else if (isPointer())
+  if (isVector()) {
+    OS << "<";
+    OS << getElementCount() << " x " << getElementType() << ">";
+  } else if (isPointer())
     OS << "p" << getAddressSpace();
   else if (isValid()) {
     assert(isScalar() && "unexpected type");
     OS << "s" << getScalarSizeInBits();
   } else
     OS << "LLT_invalid";
 }
 
 const constexpr LLT::BitFieldInfo LLT::ScalarSizeFieldInfo;
 const constexpr LLT::BitFieldInfo LLT::PointerSizeFieldInfo;
 const constexpr LLT::BitFieldInfo LLT::PointerAddressSpaceFieldInfo;
 const constexpr LLT::BitFieldInfo LLT::VectorElementsFieldInfo;
+const constexpr LLT::BitFieldInfo LLT::VectorScalableFieldInfo;
 const constexpr LLT::BitFieldInfo LLT::VectorSizeFieldInfo;
 const constexpr LLT::BitFieldInfo LLT::PointerVectorElementsFieldInfo;
+const constexpr LLT::BitFieldInfo LLT::PointerVectorScalableFieldInfo;
 const constexpr LLT::BitFieldInfo LLT::PointerVectorSizeFieldInfo;
 const constexpr LLT::BitFieldInfo LLT::PointerVectorAddressSpaceFieldInfo;

llvm/unittests/CodeGen/LowLevelTypeTest.cpp

 //===- llvm/unittest/CodeGen/GlobalISel/LowLevelTypeTest.cpp --------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/LowLevelType.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Type.h"
+#include "llvm/Support/TypeSize.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
 
 namespace {
 
 TEST(LowLevelTypeTest, Scalar) {
   LLVMContext C;
TEST(LowLevelTypeTest, Scalar) {
   }
 }
 
 TEST(LowLevelTypeTest, Vector) {
   LLVMContext C;
   DataLayout DL("");
 
   for (unsigned S : {1U, 17U, 32U, 64U, 0xfffU}) {
-    for (uint16_t Elts : {2U, 3U, 4U, 32U, 0xffU}) {
+    for (auto EC :
+         {ElementCount::getFixed(2), ElementCount::getFixed(3),
+          ElementCount::getFixed(4), ElementCount::getFixed(32),
+          ElementCount::getFixed(0xff), ElementCount::getScalable(2),
+          ElementCount::getScalable(3), ElementCount::getScalable(4),
+          ElementCount::getScalable(32), ElementCount::getScalable(0xff)}) {
       const LLT STy = LLT::scalar(S);
-      const LLT VTy = LLT::vector(Elts, S);
+      const LLT VTy = LLT::vector(EC.getKnownMinValue(), S, EC.isScalable());
 
       // Test the alternative vector().
       {
-        const LLT VSTy = LLT::vector(Elts, STy);
+        const LLT VSTy =
+            LLT::vector(EC.getKnownMinValue(), STy, EC.isScalable());
         EXPECT_EQ(VTy, VSTy);
       }
 
       // Test getElementType().
       EXPECT_EQ(STy, VTy.getElementType());
 
       // Test kind.
       ASSERT_TRUE(VTy.isValid());
       ASSERT_TRUE(VTy.isVector());
 
       ASSERT_FALSE(VTy.isScalar());
       ASSERT_FALSE(VTy.isPointer());
 
       // Test sizes.
-      EXPECT_EQ(S * Elts, VTy.getSizeInBits());
       EXPECT_EQ(S, VTy.getScalarSizeInBits());
-      EXPECT_EQ(Elts, VTy.getNumElements());
+      EXPECT_EQ(EC, VTy.getElementCount());
+      if (!EC.isScalable())
+        EXPECT_EQ(S * EC.getFixedValue(), VTy.getSizeInBits());
 
       // Test equality operators.
       EXPECT_TRUE(VTy == VTy);
       EXPECT_FALSE(VTy != VTy);
 
       // Test inequality operators on..
       // ..different kind.
       EXPECT_NE(VTy, STy);
 
       // Test Type->LLT conversion.
       Type *IRSTy = IntegerType::get(C, S);
-      Type *IRTy = FixedVectorType::get(IRSTy, Elts);
+      Type *IRTy = VectorType::get(IRSTy, EC);
       EXPECT_EQ(VTy, getLLTForType(*IRTy, DL));
     }
   }
 }
 
 TEST(LowLevelTypeTest, ScalarOrVector) {
   // Test version with number of bits for scalar type.
   EXPECT_EQ(LLT::scalar(32), LLT::scalarOrVector(1, 32));
TEST(LowLevelTypeTest, ChangeElementType) {
   EXPECT_EQ(V2S64, V2S32.changeElementSize(64));
   EXPECT_EQ(V2S32, V2S64.changeElementSize(32));
 
   EXPECT_EQ(P0, S32.changeElementType(P0));
   EXPECT_EQ(S32, P0.changeElementType(S32));
 
   EXPECT_EQ(V2P1, V2P0.changeElementType(P1));
   EXPECT_EQ(V2S32, V2P0.changeElementType(S32));
+
+  // Similar tests for for scalable vectors.
+  const LLT NXV2S32 = LLT::vector(2, 32, true);
+  const LLT NXV2S64 = LLT::vector(2, 64, true);
+
+  const LLT NXV2P0 = LLT::vector(2, P0, true);
+  const LLT NXV2P1 = LLT::vector(2, P1, true);
+
+  EXPECT_EQ(NXV2S64, NXV2S32.changeElementType(S64));
+  EXPECT_EQ(NXV2S32, NXV2S64.changeElementType(S32));
+
+  EXPECT_EQ(NXV2S64, NXV2S32.changeElementSize(64));
+  EXPECT_EQ(NXV2S32, NXV2S64.changeElementSize(32));
+
+  EXPECT_EQ(NXV2P1, NXV2P0.changeElementType(P1));
+  EXPECT_EQ(NXV2S32, NXV2P0.changeElementType(S32));
 }
 
 TEST(LowLevelTypeTest, ChangeNumElements) {
   const LLT P0 = LLT::pointer(0, 32);
   const LLT V2P0 = LLT::vector(2, P0);
   const LLT V3P0 = LLT::vector(3, P0);
 
   const LLT S64 = LLT::scalar(64);

 
 TEST(LowLevelTypeTest, Pointer) {
   LLVMContext C;
   DataLayout DL("p64:64:64-p127:512:512:512-p16777215:65528:8");
 
   for (unsigned AS : {0U, 1U, 127U, 0xffffU,
         static_cast<unsigned>(maxUIntN(23)),
         static_cast<unsigned>(maxUIntN(24))}) {
-    for (unsigned NumElts : {2, 3, 4, 256, 65535}) {
+    for (ElementCount EC :
+         {ElementCount::getFixed(2), ElementCount::getFixed(3),
+          ElementCount::getFixed(4), ElementCount::getFixed(256),
+          ElementCount::getFixed(65535), ElementCount::getScalable(2),
+          ElementCount::getScalable(3), ElementCount::getScalable(4),
+          ElementCount::getScalable(256), ElementCount::getScalable(65535)}) {
       const LLT Ty = LLT::pointer(AS, DL.getPointerSizeInBits(AS));
-      const LLT VTy = LLT::vector(NumElts, Ty);
+      const LLT VTy = LLT::vector(EC.getKnownMinValue(), Ty, EC.isScalable());
 
       // Test kind.
       ASSERT_TRUE(Ty.isValid());
       ASSERT_TRUE(Ty.isPointer());
 
       ASSERT_FALSE(Ty.isScalar());
       ASSERT_FALSE(Ty.isVector());
 
for (ElementCount EC :
       EXPECT_TRUE(Ty == Ty);
       EXPECT_FALSE(Ty != Ty);
       EXPECT_TRUE(VTy == VTy);
       EXPECT_FALSE(VTy != VTy);
 
       // Test Type->LLT conversion.
       Type *IRTy = PointerType::get(IntegerType::get(C, 8), AS);
       EXPECT_EQ(Ty, getLLTForType(*IRTy, DL));
-      Type *IRVTy = FixedVectorType::get(
-          PointerType::get(IntegerType::get(C, 8), AS), NumElts);
+      Type *IRVTy =
+          VectorType::get(PointerType::get(IntegerType::get(C, 8), AS), EC);
       EXPECT_EQ(VTy, getLLTForType(*IRVTy, DL));
     }
   }
 }
 
 TEST(LowLevelTypeTest, Invalid) {
   const LLT Ty;
 

llvm/utils/TableGen/GlobalISelEmitter.cpp

public:
   }
 
   void emitCxxEnumValue(raw_ostream &OS) const {
     if (Ty.isScalar()) {
       OS << "GILLT_s" << Ty.getSizeInBits();
       return;
     }
     if (Ty.isVector()) {
-      OS << "GILLT_v" << Ty.getNumElements() << "s" << Ty.getScalarSizeInBits();
+      OS << (Ty.isScalable() ? "GILLT_nxv" : "GILLT_v")
+         << Ty.getElementCount().getKnownMinValue() << "s"
+         << Ty.getScalarSizeInBits();
       return;
     }
     if (Ty.isPointer()) {
       OS << "GILLT_p" << Ty.getAddressSpace();
       if (Ty.getSizeInBits() > 0)
         OS << "s" << Ty.getSizeInBits();
       return;
     }
     llvm_unreachable("Unhandled LLT");
   }
 
   void emitCxxConstructorCall(raw_ostream &OS) const {
     if (Ty.isScalar()) {
       OS << "LLT::scalar(" << Ty.getSizeInBits() << ")";
       return;
     }
     if (Ty.isVector()) {
-      OS << "LLT::vector(" << Ty.getNumElements() << ", "
-         << Ty.getScalarSizeInBits() << ")";
+      OS << "LLT::vector(" << Ty.getElementCount().getKnownMinValue() << ", "
+         << Ty.getScalarSizeInBits() << ", " << Ty.isScalable() << ")";
       return;
     }
     if (Ty.isPointer() && Ty.getSizeInBits() > 0) {
       OS << "LLT::pointer(" << Ty.getAddressSpace() << ", "
          << Ty.getSizeInBits() << ")";
       return;
     }
     llvm_unreachable("Unhandled LLT");
bool operator<(const LLTCodeGen &Other) const {
     if (Ty.isScalar() != Other.Ty.isScalar())
       return Ty.isScalar() < Other.Ty.isScalar();
     if (Ty.isPointer() != Other.Ty.isPointer())
       return Ty.isPointer() < Other.Ty.isPointer();
 
     if (Ty.isPointer() && Ty.getAddressSpace() != Other.Ty.getAddressSpace())
       return Ty.getAddressSpace() < Other.Ty.getAddressSpace();
 
-    if (Ty.isVector() && Ty.getNumElements() != Other.Ty.getNumElements())
-      return Ty.getNumElements() < Other.Ty.getNumElements();
+    if (Ty.isVector() && Ty.getElementCount() != Other.Ty.getElementCount())
+      return std::make_tuple(Ty.isScalable(),
+                             Ty.getElementCount().getKnownMinValue()) <
+             std::make_tuple(Other.Ty.isScalable(),
+                             Other.Ty.getElementCount().getKnownMinValue());
 
+    assert((!Ty.isVector() || Ty.isScalable() == Other.Ty.isScalable()) &&
+           "Unexpected mismatch of scalable property");
     return Ty.getSizeInBits() < Other.Ty.getSizeInBits();
   }
 
   bool operator==(const LLTCodeGen &B) const { return Ty == B.Ty; }
 };
 
 // Track all types that are used so we can emit the corresponding enum.
 std::set<LLTCodeGen> KnownTypes;
 
 class InstructionMatcher;
 /// Convert an MVT to an equivalent LLT if possible, or the invalid LLT() for
 /// MVTs that don't map cleanly to an LLT (e.g., iPTR, *any, ...).
 static Optional<LLTCodeGen> MVTToLLT(MVT::SimpleValueType SVT) {
   MVT VT(SVT);
 
-  if (VT.isScalableVector())
-    return None;
-
-  if (VT.isFixedLengthVector() && VT.getVectorNumElements() != 1)
-    return LLTCodeGen(
-        LLT::vector(VT.getVectorNumElements(), VT.getScalarSizeInBits()));
+  if (VT.isVector() && !VT.getVectorElementCount().isScalar())
+    return LLTCodeGen(LLT::vector(VT.getVectorNumElements(),
+                                  VT.getScalarSizeInBits(),
+                                  VT.isScalableVector()));
 
   if (VT.isInteger() || VT.isFloatingPoint())
     return LLTCodeGen(LLT::scalar(VT.getSizeInBits()));
 
   return None;
 }
 
 static std::string explainPredicates(const TreePatternNode *N) {