[HLSL] Add shader attribute

[python3kgae]

Summary

Shader attribute is for shader library identify entry functions.
Here's an example,

[shader("pixel")]
float ps_main() : SV_Target {

return 1;

}

When compile this shader to library target like -E lib_6_3, compiler needs to know ps_main is an entry function for pixel shader. Shader attribute is to offer the information.

A new attribute HLSLShader is added to support shader attribute. It has an EnumArgument which included all possible shader stages.

[aaron.ballman]

clang/include/clang/Basic/Attr.td

3978

anyhit vs closestHit in terms of capitalization seems a bit surprising to me -- is that intentional?

clang/include/clang/Basic/AttrDocs.td

6386–6388

Please add enough documentation that a user has a chance to use this feature properly (and it's fine to link to other documentation for more details if there's canonical documentation elsewhere that we don't want to duplicate).

clang/include/clang/Basic/DiagnosticSemaKinds.td

11598–11599 ↗

(On Diff #423279)

Almost every other attribute warns on this situation and then ignores the attribute; why should this be a hard error? (A warning allows other implementations to support more enumeration values without breaking the user's code in Clang.)

clang/lib/Sema/SemaDeclAttr.cpp

6944–6947

Hmm, doesn't the common attribute handling logic already deal with this case? (It does for other attribute syntaxes, but we have almost no attributes using the Microsoft [] syntax, so I wouldn't be surprised if we need to add that logic.)

6961

Are you planning to do this TODO as part of this patch, or is this a FIXME someone needs to handle later?

clang/test/SemaHLSL/shader_attr.hlsl

20 ↗

(On Diff #423279)

Formatting looks off here.

Also, the diagnostic text leaves a bit to be desired (this is more of a general problem with the HLSLEntry subject, so don't worry about it for your patch) -- this is a global function.

25 ↗

(On Diff #423279)

Formatting looks off here as well. I'm guessing clang-format doesn't do anything good with Microsoft-style attributes.

[python3kgae]

clang/include/clang/Basic/Attr.td

3978

Good catch. It is not intentional.

clang/include/clang/Basic/AttrDocs.td

6386–6388

I'll fix this.

clang/include/clang/Basic/DiagnosticSemaKinds.td

11598–11599 ↗

(On Diff #423279)

I'll change it to warning.

clang/lib/Sema/SemaDeclAttr.cpp

6944–6947

I'll double check it I can remove this.

6961

It is a FIXME.

[python3kgae]

Add more detail to the doc.
Update the attribute name according to the doc.

[aaron.ballman]

Mostly looks good, just some nits with the documentation.

clang/include/clang/Basic/AttrDocs.td

6388

6389–6391

[python3kgae]

Fix doc.

clang/include/clang/Basic/AttrDocs.td

6389–6391

Thanks for the edit.
Updated.

[aaron.ballman]

LGTM!

[python3kgae]

Thanks for the review.

[bogner]

clang/include/clang/Basic/AttrDocs.td

6390

I'm guessing you meant to actually list the options here?

[python3kgae]

clang/include/clang/Basic/AttrDocs.td

6390

Good catch. Will fix it.

[python3kgae]

Fix doc again.

[MaskRay]

clang/test/SemaHLSL/shader_type_attr.hlsl

2

Add a file-level comment what this test is about

65

Add a space after CHECK:

[python3kgae]

Add comment for test.

[MaskRay]

clang/include/clang/Basic/AttrDocs.td

6391

The one-space indentation seems unneeded

clang/lib/Sema/SemaDeclAttr.cpp

6956

Not performing a check is at most a TODO, not a FIXME, unless it may crash in a later pass without the check.

[python3kgae]

Committed.
Updated line number check for test.

clang/include/clang/Basic/Attr.td

 
 def HLSLSV_GroupIndex: InheritableAttr {
   let Spellings = [HLSLSemantic<"SV_GroupIndex">];
   let Subjects = SubjectList<[ParmVar, GlobalVar]>;
   let LangOpts = [HLSL];
   let Documentation = [HLSLSV_GroupIndexDocs];
 }
 
+def HLSLShader : InheritableAttr {
+  let Spellings = [Microsoft<"shader">];
+  let Subjects = SubjectList<[HLSLEntry]>;
+  let LangOpts = [HLSL];
+  let Args = [EnumArgument<"Type", "ShaderType",
+                           ["pixel", "vertex", "geometry", "hull", "domain",
+                            "compute", "raygeneration", "intersection",
+                            "anyhit", "closesthit", "miss", "callable", "mesh",
+                            "amplification"],
+                           ["Pixel", "Vertex", "Geometry", "Hull", "Domain",
+                            "Compute", "RayGeneration", "Intersection",
+                            "AnyHit", "ClosestHit", "Miss", "Callable", "Mesh",
+                            "Amplification"]
+                           >];
+  let Documentation = [HLSLSV_ShaderTypeAttrDocs];
+}
+
 def RandomizeLayout : InheritableAttr {
   let Spellings = [GCC<"randomize_layout">];
   let Subjects = SubjectList<[Record]>;
   let Documentation = [ClangRandomizeLayoutDocs];
   let LangOpts = [COnly];
 }
 
 def NoRandomizeLayout : InheritableAttr {
   let Spellings = [GCC<"no_randomize_layout">];
   let Subjects = SubjectList<[Record]>;
   let Documentation = [ClangRandomizeLayoutDocs];
   let LangOpts = [COnly];
 }
 def : MutualExclusions<[RandomizeLayout, NoRandomizeLayout]>;

clang/include/clang/Basic/AttrDocs.td

 The ``numthreads`` attribute applies to HLSL shaders where explcit thread counts
 are required. The ``X``, ``Y``, and ``Z`` values provided to the attribute
 dictate the thread id. Total number of threads executed is ``X * Y * Z``.
 
 The full documentation is available here: https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/sm5-attributes-numthreads
   }];
 }
 
+def HLSLSV_ShaderTypeAttrDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+The ``shader`` type attribute applies to HLSL shader entry functions to 
+identify the shader type for the entry function.
+The syntax is:
+  ``[shader(string-literal)]``
+where the string literal is one of: "pixel", "vertex", "geometry", "hull",
+ "domain", "compute", "raygeneration", "intersection", "anyhit", "closesthit",
+ "miss", "callable", "mesh", "amplification".
+Normally the shader type is set by shader target with the ``-T`` option like
+``-Tps_6_1``.
+When compiling to a library target like ``lib_6_3``, the shader type attribute
+ can help the compiler to identify the shader type.
+It is mostly used by Raytracing shaders where shaders must be compiled into a
+library and linked at runtime.
+  }];
+}
+
 def ClangRandomizeLayoutDocs : Documentation {
   let Category = DocCatDecl;
   let Heading = "randomize_layout, no_randomize_layout";
   let Content = [{
 The attribute ``randomize_layout``, when attached to a C structure, selects it
 for structure layout field randomization; a compile-time hardening technique. A
 "seed" value, is specified via the ``-frandomize-layout-seed=`` command line flag.
 For example:

clang/include/clang/Sema/Sema.h

WebAssemblyImportModuleAttr *mergeImportModuleAttr(
       Decl *D, const WebAssemblyImportModuleAttr &AL);
   EnforceTCBAttr *mergeEnforceTCBAttr(Decl *D, const EnforceTCBAttr &AL);
   EnforceTCBLeafAttr *mergeEnforceTCBLeafAttr(Decl *D,
                                               const EnforceTCBLeafAttr &AL);
   BTFDeclTagAttr *mergeBTFDeclTagAttr(Decl *D, const BTFDeclTagAttr &AL);
   HLSLNumThreadsAttr *mergeHLSLNumThreadsAttr(Decl *D,
                                               const AttributeCommonInfo &AL,
                                               int X, int Y, int Z);
+  HLSLShaderAttr *mergeHLSLShaderAttr(Decl *D, const AttributeCommonInfo &AL,
+                                      HLSLShaderAttr::ShaderType ShaderType);
 
   void mergeDeclAttributes(NamedDecl *New, Decl *Old,
                            AvailabilityMergeKind AMK = AMK_Redeclaration);
   void MergeTypedefNameDecl(Scope *S, TypedefNameDecl *New,
                             LookupResult &OldDecls);
   bool MergeFunctionDecl(FunctionDecl *New, NamedDecl *&Old, Scope *S,
                          bool MergeTypeWithOld, bool NewDeclIsDefn);
   bool MergeCompatibleFunctionDecls(FunctionDecl *New, FunctionDecl *Old,

clang/lib/Sema/SemaDecl.cpp

else if (const auto *TCBA = dyn_cast<EnforceTCBAttr>(Attr))
     NewAttr = S.mergeEnforceTCBAttr(D, *TCBA);
   else if (const auto *TCBLA = dyn_cast<EnforceTCBLeafAttr>(Attr))
     NewAttr = S.mergeEnforceTCBLeafAttr(D, *TCBLA);
   else if (const auto *BTFA = dyn_cast<BTFDeclTagAttr>(Attr))
     NewAttr = S.mergeBTFDeclTagAttr(D, *BTFA);
   else if (const auto *NT = dyn_cast<HLSLNumThreadsAttr>(Attr))
     NewAttr =
         S.mergeHLSLNumThreadsAttr(D, *NT, NT->getX(), NT->getY(), NT->getZ());
+  else if (const auto *SA = dyn_cast<HLSLShaderAttr>(Attr))
+    NewAttr = S.mergeHLSLShaderAttr(D, *SA, SA->getType());
   else if (Attr->shouldInheritEvenIfAlreadyPresent() || !DeclHasAttr(D, Attr))
     NewAttr = cast<InheritableAttr>(Attr->clone(S.Context));
 
   if (NewAttr) {
     NewAttr->setInherited(true);
     D->addAttr(NewAttr);
     if (isa<MSInheritanceAttr>(NewAttr))
       S.Consumer.AssignInheritanceModel(cast<CXXRecordDecl>(D));

clang/lib/Sema/SemaDeclAttr.cpp

if (Target.getEnvironment() != Triple::Compute) {
     S.Diag(AL.getLoc(), diag::err_hlsl_attr_unsupported_in_stage)
         << AL << Pipeline << "Compute";
     return;
   }
 
   D->addAttr(::new (S.Context) HLSLSV_GroupIndexAttr(S.Context, AL));
 }
 
+static void handleHLSLShaderAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+  StringRef Str;
+  SourceLocation ArgLoc;
+  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, &ArgLoc))
+    return;
+
+  HLSLShaderAttr::ShaderType ShaderType;
+  if (!HLSLShaderAttr::ConvertStrToShaderType(Str, ShaderType)) {
+    S.Diag(AL.getLoc(), diag::warn_attribute_type_not_supported)
+        << AL << Str << ArgLoc;
+    return;
+  }
+
+  // FIXME: check function match the shader stage.
+
+  HLSLShaderAttr *NewAttr = S.mergeHLSLShaderAttr(D, AL, ShaderType);
+  if (NewAttr)
+    D->addAttr(NewAttr);
+}
+
+HLSLShaderAttr *
+Sema::mergeHLSLShaderAttr(Decl *D, const AttributeCommonInfo &AL,
+                          HLSLShaderAttr::ShaderType ShaderType) {
+  if (HLSLShaderAttr *NT = D->getAttr<HLSLShaderAttr>()) {
+    if (NT->getType() != ShaderType) {
+      Diag(NT->getLocation(), diag::err_hlsl_attribute_param_mismatch) << AL;
+      Diag(AL.getLoc(), diag::note_conflicting_attribute);
+    }
+    return nullptr;
+  }
+  return HLSLShaderAttr::Create(Context, ShaderType, AL);
+}
+
 static void handleMSInheritanceAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   if (!S.LangOpts.CPlusPlus) {
     S.Diag(AL.getLoc(), diag::err_attribute_not_supported_in_lang)
         << AL << AttributeLangSupport::C;
     return;
   }
   MSInheritanceAttr *IA = S.mergeMSInheritanceAttr(
       D, AL, /*BestCase=*/true, (MSInheritanceModel)AL.getSemanticSpelling());
static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   
   // HLSL attributes:
   case ParsedAttr::AT_HLSLNumThreads:
     handleHLSLNumThreadsAttr(S, D, AL);
     break;
   case ParsedAttr::AT_HLSLSV_GroupIndex:
     handleHLSLSVGroupIndexAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_HLSLShader:
+    handleHLSLShaderAttr(S, D, AL);
+    break;
 
   case ParsedAttr::AT_AbiTag:
     handleAbiTagAttr(S, D, AL);
     break;
   case ParsedAttr::AT_CFGuard:
     handleCFGuardAttr(S, D, AL);
     break;
 

clang/test/SemaHLSL/shader_type_attr.hlsl

+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -x hlsl -ast-dump -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -x hlsl -ast-dump -o - %s -DFAIL -verify
+
+// FileCheck test make sure HLSLShaderAttr is generated in AST.
+// verify test make sure validation on shader type attribute works as expected.
+
+#ifdef FAIL
+
+// expected-warning@+1 {{'shader' attribute only applies to global functions}}
+[shader("compute")]
+struct Fido {
+  // expected-warning@+1 {{'shader' attribute only applies to global functions}}
+  [shader("pixel")]
+  void wag() {}
+  // expected-warning@+1 {{'shader' attribute only applies to global functions}}
+  [shader("vertex")]
+  static void oops() {}
+};
+
+// expected-warning@+1 {{'shader' attribute only applies to global functions}}
+[shader("vertex")]
+static void oops() {}
+
+namespace spec {
+// expected-warning@+1 {{'shader' attribute only applies to global functions}}
+[shader("vertex")]
+static void oops() {}
+} // namespace spec
+
+// expected-error@+1 {{'shader' attribute parameters do not match the previous declaration}}
+[shader("compute")]
+// expected-note@+1 {{conflicting attribute is here}}
+[shader("vertex")]
+int doubledUp() {
+  return 1;
+}
+
+// expected-note@+1 {{conflicting attribute is here}}
+[shader("vertex")]
+int forwardDecl();
+
+// expected-error@+1 {{'shader' attribute parameters do not match the previous declaration}}
+[shader("compute")]
+int forwardDecl() {
+  return 1;
+}
+
+// expected-error@+1 {{'shader' attribute takes one argument}}
+[shader()]
+// expected-error@+1 {{'shader' attribute takes one argument}}
+[shader(1, 2)]
+// expected-error@+1 {{'shader' attribute requires a string}}
+[shader(1)]
+// expected-warning@+1 {{'shader' attribute argument not supported: cs}}
+[shader("cs")]
+
+#endif // END of FAIL
+
+// CHECK:HLSLShaderAttr 0x{{[0-9a-fA-F]+}} <line:60:2, col:18> Compute
+[shader("compute")]
+int entry() {
+  return 1;
+}
+
+// Because these two attributes match, they should both appear in the AST
+[shader("compute")]
+// CHECK:HLSLShaderAttr 0x{{[0-9a-fA-F]+}} <line:66:2, col:18> Compute
+int secondFn();
+
+[shader("compute")]
+// CHECK:HLSLShaderAttr 0x{{[0-9a-fA-F]+}} <line:70:2, col:18> Compute
+int secondFn() {
+  return 1;
+}