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

docs/ReleaseNotes.md

@@ -22,23 +22,27 @@ The included licenses apply to the following files:
 Place release notes for the upcoming release below this line and remove this
 line upon naming the release. Refer to previous for appropriate section names.
 
-#### Bug Fixes
-
-- Fixed derivative operations being moved into divergent control flow, which
-  could produce incorrect results
-  [#8001](https://github.com/microsoft/DirectXShaderCompiler/issues/8001).
-- SPIR-V: Fixed an invalid `OpSelect` being generated when optimizing for
-  SPIR-V 1.3 and earlier
-  [#8603](https://github.com/microsoft/DirectXShaderCompiler/issues/8603).
-
 #### HLSL Language
 
 - Casting a scalar to a struct or array containing a resource is now an error
   instead of crashing
   [#6661](https://github.com/microsoft/DirectXShaderCompiler/issues/6661).
 
+#### SPIR-V
+
+- Functions can now be decorated with inline SPIR-V. `[[vk::ext_capability]]`
+  and `[[vk::ext_extension]]` are now honored on ordinary functions
+  [#8616](https://github.com/microsoft/DirectXShaderCompiler/pull/8616)
+  [#8719](https://github.com/microsoft/DirectXShaderCompiler/pull/8719).
+
 #### Bug Fixes
 
+- Fixed derivative operations being moved into divergent control flow, which
+  could produce incorrect results
+  [#8001](https://github.com/microsoft/DirectXShaderCompiler/issues/8001).
+- SPIR-V: Fixed an invalid `OpSelect` being generated when optimizing for
+  SPIR-V 1.3 and earlier
+  [#8603](https://github.com/microsoft/DirectXShaderCompiler/issues/8603).
 - Fixed internal compiler errors when a member method is called on a ray payload
   or on one of its fields with payload access qualifiers enabled
   [#6464](https://github.com/microsoft/DirectXShaderCompiler/issues/6464).

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 +1635,21 @@ void SpirvEmitter::doFunctionDecl(const FunctionDecl *decl) {
     }
   }
 
+  // Apply inline-SPIR-V attributes written directly on an ordinary function:
+  //   [[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 because both are already handled for them:
+  //   - decorations: by the stage-variable path (applied to the entry's
+  //     interface variables)
+  //   - capabilities/extensions: by processInlineSpirvAttributes
+  // Doing it here would mis-target any decorations and redundantly
+  // re-register capabilities/extensions.
+  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 +1,16 @@
+// 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 in another way, see
+// spv.intrinsicDecorate.function.hlsl.)
+//
+// The --implicit-check-not above asserts the source function (%src_main) was
+// not decorated by the inline assembly intended for the stage variables.
+
+// 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 +1,8 @@
-// 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 not
+// decorated by [[vk::ext_decorate]] (e.g. Location 23 below) intended for the
+// interface variable.
 
 [[vk::ext_decorate(1, 0)]]
 bool b0;