[mlir][spirv]: Add ImageSsupport in ABI Lowering

[FranklandJack]

Add support for generating shader arguments as global variables in the SPIR-V module when the argument in question is a SPIR-V image.

Add lit tests to execute the new logic and check global variables are being generated.

[llvmbot]

@llvm/pr-subscribers-mlir-spirv

@llvm/pr-subscribers-mlir

Author: Jack Frankland (FranklandJack)

Changes

Add support for generating shader arguments as global variables in the SPIR-V module when the argument in question is a SPIR-V image.

Add lit tests to execute the new logic and check global variables are being generated.

---

Full diff: https://github.com/llvm/llvm-project/pull/150996.diff

2 Files Affected:

• (modified) mlir/lib/Dialect/SPIRV/Transforms/LowerABIAttributesPass.cpp (+11-1)
• (modified) mlir/test/Dialect/SPIRV/Transforms/abi-interface.mlir (+24)

diff --git a/mlir/lib/Dialect/SPIRV/Transforms/LowerABIAttributesPass.cpp b/mlir/lib/Dialect/SPIRV/Transforms/LowerABIAttributesPass.cpp
index 85525a5a02fa2..e447e4bfae9dc 100644
--- a/mlir/lib/Dialect/SPIRV/Transforms/LowerABIAttributesPass.cpp
+++ b/mlir/lib/Dialect/SPIRV/Transforms/LowerABIAttributesPass.cpp
@@ -58,7 +58,17 @@ createGlobalVarForEntryPointArgument(OpBuilder &builder, spirv::FuncOp funcOp,
         spirv::PointerType::get(spirv::StructType::get(varType), *storageClass);
   }
   auto varPtrType = cast<spirv::PointerType>(varType);
-  auto varPointeeType = cast<spirv::StructType>(varPtrType.getPointeeType());
+  auto pointeeType = varPtrType.getPointeeType();
+
+  // Images are an opaque type and so we can just return a pointer to an image.
+  // Note that currently only sampled images are supported in the SPIR-V
+  // lowering.
+  if (isa<spirv::SampledImageType>(pointeeType))
+    return builder.create<spirv::GlobalVariableOp>(
+        funcOp.getLoc(), varType, varName, abiInfo.getDescriptorSet(),
+        abiInfo.getBinding());
+
+  auto varPointeeType = cast<spirv::StructType>(pointeeType);
 
   // Set the offset information.
   varPointeeType =
diff --git a/mlir/test/Dialect/SPIRV/Transforms/abi-interface.mlir b/mlir/test/Dialect/SPIRV/Transforms/abi-interface.mlir
index bd51a07843652..f3a3218e5aec0 100644
--- a/mlir/test/Dialect/SPIRV/Transforms/abi-interface.mlir
+++ b/mlir/test/Dialect/SPIRV/Transforms/abi-interface.mlir
@@ -66,3 +66,27 @@ spirv.module Logical GLSL450 attributes {spirv.target_env = #spirv.target_env<#s
   // CHECK: spirv.EntryPoint "GLCompute" [[FN]], [[VAR0]], [[VAR1]]
   // CHECK: spirv.ExecutionMode [[FN]] "LocalSize", 32, 1, 1
 } // end spirv.module
+
+// -----
+
+module {
+  spirv.module Logical GLSL450 attributes {spirv.target_env = #spirv.target_env<#spirv.vce<v1.6, [Shader, Sampled1D], []>, #spirv.resource_limits<>>} {
+    // CHECK-DAG: spirv.GlobalVariable @[[IMAGE_GV:.*]] bind(0, 0) : !spirv.ptr<!spirv.sampled_image<!spirv.image<f32, Dim1D, DepthUnknown, NonArrayed, SingleSampled, NeedSampler, R32f>>, UniformConstant>
+    // CHECK: spirv.func @read_image
+    spirv.func @read_image(%arg0: !spirv.ptr<!spirv.sampled_image<!spirv.image<f32, Dim1D, DepthUnknown, NonArrayed, SingleSampled, NeedSampler, R32f>>, UniformConstant> {spirv.interface_var_abi = #spirv.interface_var_abi<(0, 0)>}, %arg1: !spirv.ptr<!spirv.struct<(!spirv.array<1 x f32, stride=4> [0])>, StorageBuffer> {spirv.interface_var_abi = #spirv.interface_var_abi<(0, 1)>}) "None" attributes {spirv.entry_point_abi = #spirv.entry_point_abi<workgroup_size = [1, 1, 1]>} {
+      // CHECK: %[[IMAGE_ADDR:.*]] = spirv.mlir.addressof @[[IMAGE_GV]] : !spirv.ptr<!spirv.sampled_image<!spirv.image<f32, Dim1D, DepthUnknown, NonArrayed, SingleSampled, NeedSampler, R32f>>, UniformConstant>
+      %cst0_i32 = spirv.Constant 0 : i32
+      // CHECK: spirv.Load "UniformConstant" %[[IMAGE_ADDR]]
+      %0 = spirv.Load "UniformConstant" %arg0 : !spirv.sampled_image<!spirv.image<f32, Dim1D, DepthUnknown, NonArrayed, SingleSampled, NeedSampler, R32f>>
+      %1 = spirv.Image %0 : !spirv.sampled_image<!spirv.image<f32, Dim1D, DepthUnknown, NonArrayed, SingleSampled, NeedSampler, R32f>>
+      %2 = spirv.ImageFetch %1, %cst0_i32  : !spirv.image<f32, Dim1D, DepthUnknown, NonArrayed, SingleSampled, NeedSampler, R32f>, i32 -> vector<4xf32>
+      %3 = spirv.CompositeExtract %2[0 : i32] : vector<4xf32>
+      %cst0_i32_0 = spirv.Constant 0 : i32
+      %cst0_i32_1 = spirv.Constant 0 : i32
+      %cst1_i32 = spirv.Constant 1 : i32
+      %4 = spirv.AccessChain %arg1[%cst0_i32_0, %cst0_i32] : !spirv.ptr<!spirv.struct<(!spirv.array<1 x f32, stride=4> [0])>, StorageBuffer>, i32, i32 -> !spirv.ptr<f32, StorageBuffer>
+      spirv.Store "StorageBuffer" %4, %3 : f32
+      spirv.Return
+    }
+  }
+}

[IgWod-IMG]

LGTM with a small nit