[mlir][spirv] Add support for converting memref of vector to SPIR-V

[ThomasRaoux]

Summary

This allow declaring buffers and alloc of vectors so that we can support vector load/store.

[mravishankar]

mlir/lib/Dialect/SPIRV/SPIRVLowering.cpp

353–363

Maybe we can have something like

Type elementType = type.getElementType();
Type arrayElemType = nullptr;
if (auto vecType = dyn_cast<VectorType>(elementType)) {
   arrayElementType = ...
} else if (auto scalarType = ...) {
   arrayElementType = ...
} else {
   return llvm::None
}

?

357

double negative is confusing. Maybe say

"illegal: can convert memrefs of either scalar or vector element type only"

Though I dont know why these are "illegal". It should be "unhandled"

[ThomasRaoux]

Address review comments

[ThomasRaoux]

mlir/lib/Dialect/SPIRV/SPIRVLowering.cpp

357

Sure, I rephrased it.

[mravishankar]

mlir/lib/Dialect/SPIRV/SPIRVLowering.cpp

353–363

I dont think this needs to be Optional<...> . You can initialize it to nullptr.

357

Nit: Maybe just compute the type.getElementType() once before the if? Would be easier to read and same number of lines.

[ThomasRaoux]

mlir/lib/Dialect/SPIRV/SPIRVLowering.cpp

353–363

convertScalarType and convertVectorType return Optional<Type> so I would need extra handling if I don't use Optional<>. I think that's the most natural way to do it? What do you think?

[mravishankar]

mlir/lib/Dialect/SPIRV/SPIRVLowering.cpp

353–363

I didnt realize that. Then this is fine. Sorry for the noise.

mlir/lib/Conversion/StandardToSPIRV/ConvertStandardToSPIRV.cpp

 CHECK_UNSIGNED_OP(spirv::ULessThanOp)
 CHECK_UNSIGNED_OP(spirv::UModOp)
 
 #undef CHECK_UNSIGNED_OP
 
 /// Returns true if the allocations of type `t` can be lowered to SPIR-V.
 static bool isAllocationSupported(MemRefType t) {
   // Currently only support workgroup local memory allocations with static
-  // shape and int or float element type.
-  return t.hasStaticShape() &&
-         SPIRVTypeConverter::getMemorySpaceForStorageClass(
-             spirv::StorageClass::Workgroup) == t.getMemorySpace() &&
-         t.getElementType().isIntOrFloat();
+  // shape and int or float or vector of int or float element type.
+  if (!(t.hasStaticShape() &&
+            spirv::StorageClass::Workgroup) == t.getMemorySpace()))
+    return false;
+  Type elementType = t.getElementType();
+  if (auto vecType = elementType.dyn_cast<VectorType>())
+    elementType = vecType.getElementType();
+  return elementType.isIntOrFloat();
 }
 
 /// Returns the scope to use for atomic operations use for emulating store
 /// operations of unsupported integer bitwidths, based on the memref
 /// type. Returns None on failure.
 static Optional<spirv::Scope> getAtomicOpScope(MemRefType t) {
   Optional<spirv::StorageClass> storageClass =
       SPIRVTypeConverter::getStorageClassForMemorySpace(t.getMemorySpace());

mlir/lib/Dialect/SPIRV/SPIRVLowering.cpp

if (t.isa<spirv::ScalarType>()) {
     // type. If they are stored (in conjunction with OpVariable), they can only
     // be used with logical addressing operations, not physical, and only with
     // non-externally visible shader Storage Classes: Workgroup, CrossWorkgroup,
     // Private, Function, Input, and Output."
     if (bitWidth == 1) {
       return llvm::None;
     }
     return bitWidth / 8;
-  } else if (auto memRefType = t.dyn_cast<MemRefType>()) {
+  }
+  if (auto vecType = t.dyn_cast<VectorType>()) {
+    auto elementSize = getTypeNumBytes(vecType.getElementType());
+    if (!elementSize)
+      return llvm::None;
+    return vecType.getNumElements() * *elementSize;
+  }
+  if (auto memRefType = t.dyn_cast<MemRefType>()) {
     // TODO: Layout should also be controlled by the ABI attributes. For now
     // using the layout from MemRef.
     int64_t offset;
     SmallVector<int64_t, 4> strides;
     if (!memRefType.hasStaticShape() ||
         failed(getStridesAndOffset(memRefType, strides, offset))) {
       return llvm::None;
     }
static Optional<Type> convertMemrefType(const spirv::TargetEnv &targetEnv,
   Optional<spirv::StorageClass> storageClass =
       SPIRVTypeConverter::getStorageClassForMemorySpace(type.getMemorySpace());
   if (!storageClass) {
     LLVM_DEBUG(llvm::dbgs()
                << type << " illegal: cannot convert memory space\n");
     return llvm::None;
   }
 
-  auto scalarType = type.getElementType().dyn_cast<spirv::ScalarType>();
-  if (!scalarType) {
-    LLVM_DEBUG(llvm::dbgs()
-               << type << " illegal: cannot convert non-scalar element type\n");
+  Optional<Type> arrayElemType;
+  Type elementType = type.getElementType();
+  if (auto vecType = elementType.dyn_cast<VectorType>()) {
+    arrayElemType = convertVectorType(targetEnv, vecType, storageClass);
+  } else if (auto scalarType = elementType.dyn_cast<spirv::ScalarType>()) {
+    arrayElemType = convertScalarType(targetEnv, scalarType, storageClass);
+  } else {
+    LLVM_DEBUG(
+        llvm::dbgs()
+        << type
+        << " unhandled: can only convert scalar or vector element type\n");
     return llvm::None;
   }
-
-  auto arrayElemType = convertScalarType(targetEnv, scalarType, storageClass);
   if (!arrayElemType)
     return llvm::None;
 
-  Optional<int64_t> scalarSize = getTypeNumBytes(scalarType);
-  if (!scalarSize) {
+  Optional<int64_t> elementSize = getTypeNumBytes(elementType);
+  if (!elementSize) {
     LLVM_DEBUG(llvm::dbgs()
                << type << " illegal: cannot deduce element size\n");
     return llvm::None;
   }
 
   if (!type.hasStaticShape()) {
-    auto arrayType = spirv::RuntimeArrayType::get(*arrayElemType, *scalarSize);
+    auto arrayType = spirv::RuntimeArrayType::get(*arrayElemType, *elementSize);
     // Wrap in a struct to satisfy Vulkan interface requirements.
     auto structType = spirv::StructType::get(arrayType, 0);
     return spirv::PointerType::get(structType, *storageClass);
   }
 
   Optional<int64_t> memrefSize = getTypeNumBytes(type);
   if (!memrefSize) {
     LLVM_DEBUG(llvm::dbgs()
                << type << " illegal: cannot deduce element count\n");
     return llvm::None;
   }
 
-  auto arrayElemCount = *memrefSize / *scalarSize;
+  auto arrayElemCount = *memrefSize / *elementSize;
 
   Optional<int64_t> arrayElemSize = getTypeNumBytes(*arrayElemType);
   if (!arrayElemSize) {
     LLVM_DEBUG(llvm::dbgs()
                << type << " illegal: cannot deduce converted element size\n");
     return llvm::None;
   }
 

mlir/test/Conversion/StandardToSPIRV/alloc.mlir

 
 module attributes {
   spv.target_env = #spv.target_env<
     #spv.vce<v1.0, [Shader], [SPV_KHR_storage_buffer_storage_class]>,
     {max_compute_workgroup_invocations = 128 : i32,
      max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
   }
 {
+  func @two_allocs_vector() {
+    %0 = alloc() : memref<4xvector<4xf32>, 3>
+    %1 = alloc() : memref<2xvector<2xi32>, 3>
+    return
+  }
+}
+
+//  CHECK-DAG: spv.globalVariable @__workgroup_mem__{{[0-9]+}}
+// CHECK-SAME:   !spv.ptr<!spv.struct<!spv.array<2 x vector<2xi32>, stride=8>>, Workgroup>
+//  CHECK-DAG: spv.globalVariable @__workgroup_mem__{{[0-9]+}}
+// CHECK-SAME:   !spv.ptr<!spv.struct<!spv.array<4 x vector<4xf32>, stride=16>>, Workgroup>
+//      CHECK: spv.func @two_allocs_vector()
+//      CHECK: spv.Return
+
+
+// -----
+
+module attributes {
+  spv.target_env = #spv.target_env<
+    #spv.vce<v1.0, [Shader], [SPV_KHR_storage_buffer_storage_class]>,
+    {max_compute_workgroup_invocations = 128 : i32,
+     max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
+  }
+{
   func @alloc_dealloc_dynamic_workgroup_mem(%arg0 : index) {
     // expected-error @+2 {{unhandled allocation type}}
     // expected-error @+1 {{'std.alloc' op operand #0 must be index}}
     %0 = alloc(%arg0) : memref<4x?xf32, 3>
     return
   }
 }
 

mlir/test/Conversion/StandardToSPIRV/std-types-to-spirv.mlir

 func @dynamic_dim_memref(%arg0: memref<8x?xi32>,
                          %arg1: memref<?x?xf32>)
 { return }
 
 } // end module
 
 // -----
 
+// Vector types
+module attributes {
+  spv.target_env = #spv.target_env<
+    #spv.vce<v1.0, [], []>,
+    {max_compute_workgroup_invocations = 128 : i32,
+     max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
+} {
+
+// CHECK-LABEL: func @memref_vector
+// CHECK-SAME: !spv.ptr<!spv.struct<!spv.array<4 x vector<2xf32>, stride=8> [0]>, StorageBuffer>
+// CHECK-SAME: !spv.ptr<!spv.struct<!spv.array<4 x vector<4xf32>, stride=16> [0]>, Uniform>
+func @memref_vector(
+    %arg0: memref<4xvector<2xf32>, 0>,
+    %arg1: memref<4xvector<4xf32>, 4>)
+{ return }
+
+// CHECK-LABEL: func @dynamic_dim_memref_vector
+// CHECK-SAME: !spv.ptr<!spv.struct<!spv.rtarray<vector<4xi32>, stride=16> [0]>, StorageBuffer>
+// CHECK-SAME: !spv.ptr<!spv.struct<!spv.rtarray<vector<2xf32>, stride=8> [0]>, StorageBuffer>
+func @dynamic_dim_memref_vector(%arg0: memref<8x?xvector<4xi32>>,
+                         %arg1: memref<?x?xvector<2xf32>>)
+{ return }
+
+} // end module
+
+// -----
+
+// Vector types, check that sizes not available in SPIR-V are not transformed.
+module attributes {
+  spv.target_env = #spv.target_env<
+    #spv.vce<v1.0, [], []>,
+    {max_compute_workgroup_invocations = 128 : i32,
+     max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
+} {
+
+// CHECK-LABEL: func @memref_vector_wrong_size
+// CHECK-SAME: memref<4xvector<5xf32>>
+func @memref_vector_wrong_size(
+    %arg0: memref<4xvector<5xf32>, 0>)
+{ return }
+
+} // end module
+
+// -----
+
 //===----------------------------------------------------------------------===//
 // Tensor types
 //===----------------------------------------------------------------------===//
 
 // Check that tensor element types are kept untouched with proper capabilities.
 module attributes {
   spv.target_env = #spv.target_env<
     #spv.vce<v1.0, [Int8, Int16, Int64, Float16, Float64], []>,