Reland "[HLSL][RootSignature] Define and integrate HLSLRootSignatureAttr" #134293

inbelic · 2025-04-03T19:04:37Z

This pr relands #134124.

It resolves the many linking errors during build, here. There was a missing dependency for clangParse in clangSema now that we depend on clangParse to get acces to the RootSignatureParser during semantic analysis. This library was added to the dependencies to resolve the error. It wasn't caught previously as the library was transitively linked in local and pre-merge build environments.

Resolves #119011

- Defines HLSLRootSignature Attr in `Attr.td` - Define and implement handleHLSLRootSignature in `SemaHLSL` - Adds sample test case to show AST Node is generated in `RootSignatures-AST.hlsl` This commit will "hook-up" the seperately defined RootSignature parser and invoke it to create the RootElements, then store them on the ASTContext and finally store the reference to the Elements in RootSignatureAttr

we require access to the RootSignatureParser/Lexer which are located in clang/parse and clang/lex respectively. clangLex is already listed as a linked library whereas clangParse isn't so this commit resolves this issue by linking the clangParse library to provide access to RootSignatureParser

llvmbot · 2025-04-03T19:05:11Z

@llvm/pr-subscribers-hlsl

@llvm/pr-subscribers-clang

Author: Finn Plummer (inbelic)

Changes

This pr relands #134124.

It resolves the many linking errors during build, here. There was a missing dependency for clangParse in clangSema now that we depend on clangParse to get acces to the RootSignatureParser during semantic analysis. This library was added to the dependencies to resolve the error. It wasn't caught previously as the library was transitively linked in local and pre-merge build environments

Full diff: https://github.com/llvm/llvm-project/pull/134293.diff

9 Files Affected:

(modified) clang/include/clang/AST/Attr.h (+1)
(modified) clang/include/clang/Basic/Attr.td (+19)
(modified) clang/include/clang/Basic/AttrDocs.td (+11)
(modified) clang/include/clang/Sema/SemaHLSL.h (+1)
(modified) clang/lib/Sema/CMakeLists.txt (+1)
(modified) clang/lib/Sema/SemaDeclAttr.cpp (+3)
(modified) clang/lib/Sema/SemaHLSL.cpp (+35)
(added) clang/test/AST/HLSL/RootSignatures-AST.hlsl (+24)
(added) clang/test/SemaHLSL/RootSignature-err.hlsl (+9)

diff --git a/clang/include/clang/AST/Attr.h b/clang/include/clang/AST/Attr.h
index 994f236337b99..37c3f8bbfb5f9 100644
--- a/clang/include/clang/AST/Attr.h
+++ b/clang/include/clang/AST/Attr.h
@@ -26,6 +26,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Support/Compiler.h"
 #include "llvm/Frontend/HLSL/HLSLResource.h"
+#include "llvm/Frontend/HLSL/HLSLRootSignature.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/VersionTuple.h"
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 0999d8065e9f5..93524a0c873c1 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -4709,6 +4709,25 @@ def Error : InheritableAttr {
   let Documentation = [ErrorAttrDocs];
 }
 
+def HLSLRootSignature : Attr {
+  /// [RootSignature(Signature)]
+  let Spellings = [Microsoft<"RootSignature">];
+  let Args = [StringArgument<"Signature">];
+  let Subjects = SubjectList<[Function],
+                             ErrorDiag, "'function'">;
+  let LangOpts = [HLSL];
+  let Documentation = [HLSLRootSignatureDocs];
+  let AdditionalMembers = [{
+private:
+  ArrayRef<llvm::hlsl::rootsig::RootElement> RootElements;
+public:
+  void setElements(ArrayRef<llvm::hlsl::rootsig::RootElement> Elements) {
+    RootElements = Elements;
+  }
+  auto getElements() const { return RootElements; }
+}];
+}
+
 def HLSLNumThreads: InheritableAttr {
   let Spellings = [Microsoft<"numthreads">];
   let Args = [IntArgument<"X">, IntArgument<"Y">, IntArgument<"Z">];
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index a52ece467ec70..2ac9e2a4eaf39 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -8143,6 +8143,17 @@ and https://microsoft.github.io/hlsl-specs/proposals/0013-wave-size-range.html
   }];
 }
 
+def HLSLRootSignatureDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+The ``RootSignature`` attribute applies to HLSL entry functions to define what
+types of resources are bound to the graphics pipeline.
+
+For details about the use and specification of Root Signatures please see here:
+https://learn.microsoft.com/en-us/windows/win32/direct3d12/root-signatures
+  }];
+}
+
 def NumThreadsDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
diff --git a/clang/include/clang/Sema/SemaHLSL.h b/clang/include/clang/Sema/SemaHLSL.h
index f333fe30e8da0..1bd35332612cd 100644
--- a/clang/include/clang/Sema/SemaHLSL.h
+++ b/clang/include/clang/Sema/SemaHLSL.h
@@ -118,6 +118,7 @@ class SemaHLSL : public SemaBase {
                                        bool IsCompAssign);
   void emitLogicalOperatorFixIt(Expr *LHS, Expr *RHS, BinaryOperatorKind Opc);
 
+  void handleRootSignatureAttr(Decl *D, const ParsedAttr &AL);
   void handleNumThreadsAttr(Decl *D, const ParsedAttr &AL);
   void handleWaveSizeAttr(Decl *D, const ParsedAttr &AL);
   void handleSV_DispatchThreadIDAttr(Decl *D, const ParsedAttr &AL);
diff --git a/clang/lib/Sema/CMakeLists.txt b/clang/lib/Sema/CMakeLists.txt
index d3fe80f659f69..4a25d61e06409 100644
--- a/clang/lib/Sema/CMakeLists.txt
+++ b/clang/lib/Sema/CMakeLists.txt
@@ -110,5 +110,6 @@ add_clang_library(clangSema
   clangBasic
   clangEdit
   clangLex
+  clangParse
   clangSupport
   )
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 6cb6f6d105a32..60b8c98eeec0d 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -7480,6 +7480,9 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
     break;
 
   // HLSL attributes:
+  case ParsedAttr::AT_HLSLRootSignature:
+    S.HLSL().handleRootSignatureAttr(D, AL);
+    break;
   case ParsedAttr::AT_HLSLNumThreads:
     S.HLSL().handleNumThreadsAttr(D, AL);
     break;
diff --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp
index 07d03e2c58b9a..eafb2b97d7db1 100644
--- a/clang/lib/Sema/SemaHLSL.cpp
+++ b/clang/lib/Sema/SemaHLSL.cpp
@@ -28,6 +28,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TargetInfo.h"
+#include "clang/Parse/ParseHLSLRootSignature.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/ParsedAttr.h"
 #include "clang/Sema/Sema.h"
@@ -941,6 +942,40 @@ void SemaHLSL::emitLogicalOperatorFixIt(Expr *LHS, Expr *RHS,
       << NewFnName << FixItHint::CreateReplacement(FullRange, OS.str());
 }
 
+void SemaHLSL::handleRootSignatureAttr(Decl *D, const ParsedAttr &AL) {
+  if (AL.getNumArgs() != 1) {
+    Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 1;
+    return;
+  }
+
+  StringRef Signature;
+  if (!SemaRef.checkStringLiteralArgumentAttr(AL, 0, Signature))
+    return;
+
+  SourceLocation Loc = AL.getArgAsExpr(0)->getExprLoc();
+  // TODO(#126565): pass down below to lexer when fp is supported
+  // llvm::RoundingMode RM = SemaRef.CurFPFeatures.getRoundingMode();
+  hlsl::RootSignatureLexer Lexer(Signature, Loc);
+  SmallVector<llvm::hlsl::rootsig::RootElement> Elements;
+  hlsl::RootSignatureParser Parser(Elements, Lexer, SemaRef.getPreprocessor());
+
+  if (Parser.parse())
+    return;
+
+  // Allocate elements onto AST context
+  unsigned N = Elements.size();
+  auto RootElements = MutableArrayRef<llvm::hlsl::rootsig::RootElement>(
+      ::new (getASTContext()) llvm::hlsl::rootsig::RootElement[N], N);
+  for (unsigned I = 0; I < N; ++I)
+    RootElements[I] = Elements[I];
+
+  // Set elements
+  auto *Result = ::new (getASTContext())
+      HLSLRootSignatureAttr(getASTContext(), AL, Signature);
+  Result->setElements(ArrayRef<llvm::hlsl::rootsig::RootElement>(RootElements));
+  D->addAttr(Result);
+}
+
 void SemaHLSL::handleNumThreadsAttr(Decl *D, const ParsedAttr &AL) {
   llvm::VersionTuple SMVersion =
       getASTContext().getTargetInfo().getTriple().getOSVersion();
diff --git a/clang/test/AST/HLSL/RootSignatures-AST.hlsl b/clang/test/AST/HLSL/RootSignatures-AST.hlsl
new file mode 100644
index 0000000000000..948f2484ff5d0
--- /dev/null
+++ b/clang/test/AST/HLSL/RootSignatures-AST.hlsl
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.0-library -ast-dump \
+// RUN:  -disable-llvm-passes -o - %s | FileCheck %s
+
+// This test ensures that the sample root signature is parsed without error and
+// the Attr AST Node is created succesfully. If an invalid root signature was
+// passed in then we would exit out of Sema before the Attr is created.
+
+#define SampleRS \
+  "DescriptorTable( " \
+  "  CBV(), " \
+  "  SRV(), " \
+  "  UAV()" \
+  "), " \
+  "DescriptorTable(Sampler())"
+
+// CHECK:      HLSLRootSignatureAttr
+// CHECK-SAME: "DescriptorTable(
+// CHECK-SAME:   CBV(),
+// CHECK-SAME:   SRV(),
+// CHECK-SAME:   UAV()
+// CHECK-SAME: ),
+// CHECK-SAME: DescriptorTable(Sampler())"
+[RootSignature(SampleRS)]
+void main() {}
diff --git a/clang/test/SemaHLSL/RootSignature-err.hlsl b/clang/test/SemaHLSL/RootSignature-err.hlsl
new file mode 100644
index 0000000000000..647a4ba2470a7
--- /dev/null
+++ b/clang/test/SemaHLSL/RootSignature-err.hlsl
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -x hlsl -o - %s -verify
+
+// Attr test
+
+[RootSignature()] // expected-error {{'RootSignature' attribute takes one argument}}
+void bad_root_signature_0() {}
+
+[RootSignature("Arg1", "Arg2")] // expected-error {{'RootSignature' attribute takes one argument}}
+void bad_root_signature_1() {}

spall

LGTM based on previous pr approval and looking at the change in the latest reland commit

inbelic · 2025-04-24T21:07:16Z

Closing as this would actually introduce a circular dependency between clangParse and clangSema, as surprisingly, clangParse has a dependency on clangSema. This will need to reland after we move the HLSLRootSignatureParser into an accessible location (most likely within clangSema itself)

Finn Plummer added 2 commits April 3, 2025 17:22

llvmbot added clang Clang issues not falling into any other category clang:frontend Language frontend issues, e.g. anything involving "Sema" HLSL HLSL Language Support labels Apr 3, 2025

github-project-automation bot added this to HLSL Support Apr 3, 2025

inbelic force-pushed the inbelic/rootsig-attr branch from 6d46d30 to 7d4e84c Compare April 3, 2025 19:05

bob80905 approved these changes Apr 16, 2025

View reviewed changes

spall approved these changes Apr 22, 2025

View reviewed changes

inbelic closed this Apr 24, 2025

github-project-automation bot moved this to Closed in HLSL Support Apr 24, 2025

inbelic deleted the inbelic/rootsig-attr branch May 16, 2025 18:07

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Reland "[HLSL][RootSignature] Define and integrate HLSLRootSignatureAttr" #134293

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inbelic commented Apr 3, 2025 •

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inbelic commented Apr 24, 2025

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Reland "[HLSL][RootSignature] Define and integrate HLSLRootSignatureAttr" #134293

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