[mlir][spirv] Fix crash when decorating physical storage buffer pointers

[kuhar]

Summary

Add a comment explaining PhysicalStorageBufferAddresses are not
supported yet.

Fixes: https://github.com/llvm/llvm-project/issues/60196

mlir/include/mlir/Dialect/SPIRV/Utils/LayoutUtils.h

 class VectorType;
 
 namespace spirv {
 class ArrayType;
 class RuntimeArrayType;
 class StructType;
 } // namespace spirv
 
-/// According to the Vulkan spec "14.5.4. Offset and Stride Assignment":
+/// According to the Vulkan spec "15.6.4. Offset and Stride Assignment":
 /// "There are different alignment requirements depending on the specific
 /// resources and on the features enabled on the device."
 ///
 /// There are 3 types of alignment: scalar, base, extended.
 /// See the spec for details.
 ///
 /// Note: Even if scalar alignment is supported, it is generally more
 /// performant to use the base alignment. So here the calculation is based on

mlir/lib/Dialect/SPIRV/Transforms/DecorateCompositeTypeLayoutPass.cpp

 #include "mlir/Dialect/SPIRV/Transforms/Passes.h"
 
 #include "mlir/Dialect/Func/IR/FuncOps.h"
 #include "mlir/Dialect/SPIRV/IR/SPIRVDialect.h"
 #include "mlir/Dialect/SPIRV/IR/SPIRVOps.h"
 #include "mlir/Dialect/SPIRV/Utils/LayoutUtils.h"
 #include "mlir/Transforms/DialectConversion.h"
 
+#include "llvm/Support/FormatVariadic.h"
+
 using namespace mlir;
 
 namespace mlir {
 namespace spirv {
 #define GEN_PASS_DEF_SPIRVCOMPOSITETYPELAYOUTPASS
 #include "mlir/Dialect/SPIRV/Transforms/Passes.h.inc"
 } // namespace spirv
 } // namespace mlir
 
 namespace {
 class SPIRVGlobalVariableOpLayoutInfoDecoration
     : public OpRewritePattern<spirv::GlobalVariableOp> {
 public:
   using OpRewritePattern<spirv::GlobalVariableOp>::OpRewritePattern;
 
   LogicalResult matchAndRewrite(spirv::GlobalVariableOp op,
                                 PatternRewriter &rewriter) const override {
     SmallVector<NamedAttribute, 4> globalVarAttrs;
 
     auto ptrType = op.getType().cast<spirv::PointerType>();
-    auto structType = VulkanLayoutUtils::decorateType(
-        ptrType.getPointeeType().cast<spirv::StructType>());
+    auto pointeeType = ptrType.getPointeeType().cast<spirv::StructType>();
+    spirv::StructType structType = VulkanLayoutUtils::decorateType(pointeeType);
 
     if (!structType)
-      return failure();
+      return op->emitError(llvm::formatv(
+          "failed to decorate (unsuported pointee type: '{0}')", pointeeType));
 
     auto decoratedType =
         spirv::PointerType::get(structType, ptrType.getStorageClass());
 
     // Save all named attributes except "type" attribute.
     for (const auto &attr : op->getAttrs()) {
       if (attr.getName() == "type")
         continue;

mlir/lib/Dialect/SPIRV/Utils/LayoutUtils.cpp

Type VulkanLayoutUtils::decorateType(Type type, VulkanLayoutUtils::Size &size,
   if (auto arrayType = type.dyn_cast<spirv::ArrayType>())
     return decorateType(arrayType, size, alignment);
   if (auto vectorType = type.dyn_cast<VectorType>())
     return decorateType(vectorType, size, alignment);
   if (auto arrayType = type.dyn_cast<spirv::RuntimeArrayType>()) {
     size = std::numeric_limits<Size>().max();
     return decorateType(arrayType, alignment);
   }
+  if (type.isa<spirv::PointerType>()) {
+    // TODO: Add support for `PhysicalStorageBufferAddresses`.
+    return nullptr;
+  }
   llvm_unreachable("unhandled SPIR-V type");
 }
 
 Type VulkanLayoutUtils::decorateType(VectorType vectorType,
                                      VulkanLayoutUtils::Size &size,
                                      VulkanLayoutUtils::Size &alignment) {
   const auto numElements = vectorType.getNumElements();
   auto elementType = vectorType.getElementType();

mlir/test/Dialect/SPIRV/Transforms/layout-decoration.mlir

 // -----
 
 spirv.module Logical GLSL450 {
   // CHECK: spirv.GlobalVariable @var0 : !spirv.ptr<!spirv.struct<(i32 [0])>, PushConstant>
   spirv.GlobalVariable @var0 : !spirv.ptr<!spirv.struct<(i32)>, PushConstant>
   // CHECK: spirv.GlobalVariable @var1 : !spirv.ptr<!spirv.struct<(i32 [0])>, PhysicalStorageBuffer>
   spirv.GlobalVariable @var1 : !spirv.ptr<!spirv.struct<(i32)>, PhysicalStorageBuffer>
 }
+
+// -----
+
+spirv.module Physical64 GLSL450 {
+  // expected-error @+2 {{failed to decorate (unsuported pointee type: '!spirv.struct<rec, (!spirv.ptr<!spirv.struct<rec>, StorageBuffer>)>')}}
+  // expected-error @+1 {{failed to legalize operation 'spirv.GlobalVariable'}}
+  spirv.GlobalVariable @recursive:
+    !spirv.ptr<!spirv.struct<rec, (!spirv.ptr<!spirv.struct<rec>, StorageBuffer>)>, StorageBuffer>
+}