[llvm] [SPIRV] Emit RuntimeDescriptorArrayEXT capability for all unbounded array types (PR #222819)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-spir-v

Author: Helena Kotas (hekota)

<details>
<summary>Changes</summary>

Previously, the `RuntimeDescriptorArrayEXT` capability was emitted only for image descriptor arrays. This change emits the capability for the shader whenever `ArraySize == 0`.

This covers all supported runtime descriptor array types, including images, structured buffers, samplers, and counter descriptor arrays. Emitting the capability for these arrays is necessary to support dynamic resources in SPIR-V.

---
Full diff: https://github.com/llvm/llvm-project/pull/222819.diff


2 Files Affected:

- (modified) llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp (+1-1) 
- (added) llvm/test/CodeGen/SPIRV/hlsl-resources/unbounded-struct-arr.ll (+28) 


``````````diff
diff --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index 41e4dc290c099..2d38332b0e48e 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -7639,7 +7639,7 @@ bool SPIRVInstructionSelector::loadHandleBeforePosition(
     SC = GR.getPointerStorageClass(ResType);
   }
 
-  if (ResType->getOpcode() == SPIRV::OpTypeImage && ArraySize == 0)
+  if (ArraySize == 0)
     MIRBuilder.buildInstr(SPIRV::OpCapability)
         .addImm(SPIRV::Capability::RuntimeDescriptorArrayEXT);
 
diff --git a/llvm/test/CodeGen/SPIRV/hlsl-resources/unbounded-struct-arr.ll b/llvm/test/CodeGen/SPIRV/hlsl-resources/unbounded-struct-arr.ll
new file mode 100644
index 0000000000000..1fe90f3e05809
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/hlsl-resources/unbounded-struct-arr.ll
@@ -0,0 +1,28 @@
+; RUN: llc -O0 -verify-machineinstrs -mtriple=spirv1.6-vulkan1.3-library %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv1.6-vulkan1.3-library %s -o - -filetype=obj | spirv-val %}
+
+; Verify that unbounded arrays of structured buffers and their associated
+; counters enable RuntimeDescriptorArrayEXT.
+
+; CHECK-DAG: OpCapability RuntimeDescriptorArrayEXT
+; CHECK-DAG: %[[FLOAT:[0-9]+]] = OpTypeFloat 32
+; CHECK-DAG: %[[UINT:[0-9]+]] = OpTypeInt 32 0
+; CHECK-DAG: %[[DATA_ARRAY:[0-9]+]] = OpTypeRuntimeArray %[[FLOAT]]
+; CHECK-DAG: %[[BUFFER:[0-9]+]] = OpTypeStruct %[[DATA_ARRAY]]
+; CHECK-DAG: OpTypeRuntimeArray %[[BUFFER]]
+; CHECK-DAG: %[[COUNTER:[0-9]+]] = OpTypeStruct %[[UINT]]
+; CHECK-DAG: OpTypeRuntimeArray %[[COUNTER]]
+
+ at Bufs.str = private unnamed_addr constant [5 x i8] c"Bufs\00", align 1
+
+define void @main() #0 {
+entry:
+  %handle = call target("spirv.VulkanBuffer", [0 x float], 12, 1) @llvm.spv.resource.handlefrombinding(i32 0, i32 0, i32 0, i32 0, ptr @Bufs.str)
+  %counter.handle = call target("spirv.VulkanBuffer", i32, 12, 1) @llvm.spv.resource.counterhandlefrombinding(target("spirv.VulkanBuffer", [0 x float], 12, 1) %handle, i32 0, i32 1)
+  %counter = call i32 @llvm.spv.resource.updatecounter(target("spirv.VulkanBuffer", i32, 12, 1) %counter.handle, i8 1)
+  %pointer = call ptr addrspace(11) @llvm.spv.resource.getpointer(target("spirv.VulkanBuffer", [0 x float], 12, 1) %handle, i32 %counter)
+  store float 0.000000e+00, ptr addrspace(11) %pointer, align 4
+  ret void
+}
+
+attributes #0 = { "hlsl.numthreads"="1,1,1" "hlsl.shader"="compute" }

``````````

</details>


https://github.com/llvm/llvm-project/pull/222819