[llvm] 2f85201 - [SPIRV] Emit RuntimeDescriptorArrayEXT capability for all unbounded array types (#222819)

[via llvm-commits]

Author: Helena Kotas
Date: 2026-09-15T13:56:05-07:00
New Revision: 2f852016addf27fd9eb83ff9faba66633b0fafe8

URL: https://github.com/llvm/llvm-project/commit/2f852016addf27fd9eb83ff9faba66633b0fafe8
DIFF: https://github.com/llvm/llvm-project/commit/2f852016addf27fd9eb83ff9faba66633b0fafe8.diff

LOG: [SPIRV] Emit RuntimeDescriptorArrayEXT capability for all unbounded array types (#222819)

Previously, the `RuntimeDescriptorArrayEXT` capability was emitted only
for image descriptor arrays. This change emits the capability for the
shader whenever resource array has `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.

Assisted by GPT-5.6 Sol.

Added: 
    llvm/test/CodeGen/SPIRV/hlsl-resources/unbounded-struct-arr.ll

Modified: 
    llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index 41e4dc290c099..1d821c5aec993 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -7639,7 +7639,9 @@ bool SPIRVInstructionSelector::loadHandleBeforePosition(
     SC = GR.getPointerStorageClass(ResType);
   }
 
-  if (ResType->getOpcode() == SPIRV::OpTypeImage && ArraySize == 0)
+  // ArraySize 0 means an unbounded array and we need to set to required
+  // capability.
+  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..ad42bacc8bc3d
--- /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" }