[SPIR-V] Follow-up to #8616: exclude entry functions from function-target decoration

docs/ReleaseNotes.md

@@ -68,6 +68,10 @@ first shipped in the 1.10.2605 preview.
   [#8281](https://github.com/microsoft/DirectXShaderCompiler/pull/8281).
 - Function parameters can now be decorated with inline SPIR-V
   [#8103](https://github.com/microsoft/DirectXShaderCompiler/issues/8103).
+- Functions can now be decorated with inline SPIR-V, and
+  `[[vk::ext_capability]]`/`[[vk::ext_extension]]` are honored on ordinary
+  functions
+  [#8616](https://github.com/microsoft/DirectXShaderCompiler/pull/8616).
 - Fixed `vk::BufferPointer` cast methods
   [#8365](https://github.com/microsoft/DirectXShaderCompiler/pull/8365).
 - Fixed layout-rule propagation for `ConstantBuffer`/`TextureBuffer` function

tools/clang/lib/SPIRV/DeclResultIdMapper.cpp

@@ -1826,16 +1826,12 @@ SpirvFunction *DeclResultIdMapper::getOrRegisterFn(const FunctionDecl *fn) {
                                spv::LinkageType::Export, fn->getLocation());
   }
 
-  // Honor inline-SPIR-V attributes placed directly on a function. The
-  // entry-point path handles these only for entry functions, and the
-  // vk::ext_instruction path only for functions lowered to an instruction, so a
-  // plain function was previously skipped and these attributes silently
-  // dropped. These reuse the same helpers as the variable/parameter paths:
-  //   [[vk::ext_decorate(d, ...)]]  -> OpDecorate targeting the OpFunction
-  //   [[vk::ext_capability(c)]]     -> OpCapability for the module
-  //   [[vk::ext_extension("...")]]  -> OpExtension for the module
-  decorateWithIntrinsicAttrs(fn, spirvFunction);
-  registerCapabilitiesAndExtensionsForDecl(fn);
+  // Note: inline-SPIR-V attributes placed directly on a function
+  // ([[vk::ext_decorate]] / [[vk::ext_capability]] / [[vk::ext_extension]]) are
+  // applied in SpirvEmitter::doFunctionDecl, which excludes entry points. For an
+  // entry point, those attributes are consumed by the stage-variable path (they
+  // decorate the entry's interface variables, not its OpFunction), so they must
+  // not be applied to the source function here.
 
   // No need to dereference to get the pointer. Function returns that are
   // stand-alone aliases are already pointers to values. All other cases should

tools/clang/lib/SPIRV/SpirvEmitter.cpp

@@ -1635,6 +1635,18 @@ void SpirvEmitter::doFunctionDecl(const FunctionDecl *decl) {
     }
   }
 
+  // Apply inline-SPIR-V attributes written directly on an ordinary function to
+  // its OpFunction:
+  //   [[vk::ext_decorate(d, ...)]]  -> OpDecorate targeting the OpFunction
+  //   [[vk::ext_capability(c)]]     -> OpCapability for the module
+  //   [[vk::ext_extension("...")]]  -> OpExtension for the module
+  // Entry points are excluded: their function-level attributes apply to stage-
+  // variables, not the OpFunction.
+  if (!isEntry) {
+    declIdMapper.decorateWithIntrinsicAttrs(decl, func);
+    declIdMapper.registerCapabilitiesAndExtensionsForDecl(decl);
+  }
+
   if (spirvOptions.debugInfoRich) {
     if (srcDebugFunction) {
       spvContext.pushDebugLexicalScope(info, srcDebugFunction);

tools/clang/test/CodeGenSPIRV/inline-spirv/spv.intrinsicDecorate.entry.hlsl

@@ -0,0 +1,17 @@
+// RUN: %dxc -T ps_6_0 -E main -fcgl -Vd %s -spirv | FileCheck %s --implicit-check-not "OpDecorate %src_main"
+
+// A function-level inline-SPIR-V decoration on an *entry point* is consumed by
+// the stage-variable path and applied to the entry's interface variable, not to
+// the source OpFunction. (An ordinary function is handled the other way -- the
+// decoration lands on its OpFunction; see spv.intrinsicDecorate.function.hlsl.)
+//
+// The --implicit-check-not above asserts the source function (%src_main) is
+// never decorated, which is what regressed when function-target handling was
+// first added and was not caught because the check below matches any target.
+
+// CHECK: OpDecorate %out_var_SV_Target Location 23
+
+[[vk::ext_decorate(/* Location */ 30, 23)]]
+float4 main() : SV_Target {
+  return 1.0;
+}

tools/clang/test/CodeGenSPIRV/inline-spirv/spv.intrinsicDecorate.function.error.hlsl

@@ -2,19 +2,19 @@
 
 // vk::ext_decorate_id and vk::ext_decorate_string decorate a value-id target
 // and have no OpFunction-target form, so applying either to a function must be
-// diagnosed rather than silently dropped.
+// diagnosed rather than silently dropped. Both are placed on one function so a
+// single compilation reports both (translation stops after the first function
+// that errors, so separate functions would only surface one).
 
-// CHECK: error: vk::ext_decorate_string is not supported on functions
-[[vk::ext_decorate_string(/* UserTypeGOOGLE */ 5636, "myType")]]
-[noinline] uint DecorateString(uint x) { return x; }
-
-// CHECK: error: vk::ext_decorate_id is not supported on functions
+// CHECK-DAG: error: vk::ext_decorate_id is not supported on functions
+// CHECK-DAG: error: vk::ext_decorate_string is not supported on functions
 [[vk::ext_decorate_id(/* UniformId */ 27, 13)]]
-[noinline] uint DecorateId(uint x) { return x; }
+[[vk::ext_decorate_string(/* UserTypeGOOGLE */ 5636, "myType")]]
+[noinline] uint Decorated(uint x) { return x; }
 
 RWStructuredBuffer<uint> buf;
 
 [numthreads(1, 1, 1)]
 void main(uint3 tid : SV_DispatchThreadID) {
-  buf[0] = DecorateString(tid.x) + DecorateId(tid.x);
+  buf[0] = Decorated(tid.x);
 }

tools/clang/test/CodeGenSPIRV/inline-spirv/spv.intrinsicDecorate.hlsl

@@ -1,4 +1,10 @@
-// RUN: %dxc -T ps_6_0 -E main -fcgl -Vd -spirv -fcgl  %s -spirv | FileCheck %s
+// RUN: %dxc -T ps_6_0 -E main -fcgl -Vd -spirv -fcgl  %s -spirv | FileCheck %s --implicit-check-not "OpDecorate %src_main"
+
+// The --implicit-check-not above asserts the entry's source function is never
+// decorated: its function-level [[vk::ext_decorate]] (e.g. Location 23 below)
+// must land on the interface variable via the stage-variable path, not on the
+// OpFunction. Without this, an errant OpDecorate %src_main went unnoticed
+// because the Location check below matches any target.
 
 [[vk::ext_decorate(1, 0)]]
 bool b0;