[CIR] Add support for FileScopeAsm

Author: wizardengineer

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

@@ -221,6 +221,18 @@ def CIR_TypeSizeInfoAttr : CIR_Attr<"TypeSizeInfo", "type_size_info"> {
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// FileScopeAsm
+//===----------------------------------------------------------------------===//
+
+def CIR_ModuleAsmAttr : CIR_Attr<"ModuleAsm", "module_asm"> {
+  let summary = "Module-level inline assembly";
+  let description = [{
+    Stores file-scope inline assembly strings.
+  }];
+  let parameters = (ins "mlir::ArrayAttr":$asm_strings);
+  let assemblyFormat = [{ `<` $asm_strings `>`}];
+}
 
 //===----------------------------------------------------------------------===//
 // BoolAttr

clang/lib/CIR/CodeGen/CIRGenDecl.cpp

@@ -832,7 +832,10 @@ void CIRGenFunction::emitDecl(const Decl &D) {
   case Decl::LinkageSpec:
   case Decl::Export:
   case Decl::ObjCPropertyImpl:
-  case Decl::FileScopeAsm:
+  case Decl::FileScopeAsm: {
+    CGM.buildFileScopeAsm(cast<FileScopeAsmDecl>(&D));
+    return;
+  }
   case Decl::Friend:
   case Decl::FriendTemplate:
   case Decl::Block:

clang/lib/CIR/CodeGen/CIRGenModule.cpp

@@ -31,6 +31,7 @@
 #include "mlir/IR/OperationSupport.h"
 #include "mlir/IR/SymbolTable.h"
 #include "mlir/IR/Verifier.h"
+#include "clang/AST/Decl.h"
 #include "clang/AST/Expr.h"
 #include "clang/Basic/Cuda.h"
 #include "clang/CIR/Dialect/IR/CIRTypes.h"
@@ -2072,6 +2073,9 @@ void CIRGenModule::emitTopLevelDecl(Decl *decl) {
         emitTopLevelDecl(childDecl);
     break;
   }
+  case Decl::FileScopeAsm:
+    buildFileScopeAsm(cast<FileScopeAsmDecl>(decl));
+    break;
   case Decl::PragmaComment: {
     const auto *PCD = cast<PragmaCommentDecl>(decl);
     switch (PCD->getCommentKind()) {
@@ -3776,6 +3780,9 @@ void CIRGenModule::Release() {
   if (getTriple().isPPC() && !MissingFeatures::mustTailCallUndefinedGlobals()) {
     llvm_unreachable("NYI");
   }
+
+  // Finalize module attributes (including inline assembly)
+  finalizeModuleAttributes();
 }
 
 namespace {
@@ -4430,3 +4437,28 @@ cir::LabelOp
 CIRGenModule::lookupBlockAddressInfo(cir::BlockAddrInfoAttr blockInfo) {
   return blockAddressInfoToLabel.lookup(blockInfo);
 }
+
+void CIRGenModule::buildFileScopeAsm(const FileScopeAsmDecl *D) {
+  // Get assembly string from declaration
+  appendModuleInlineAsm(D->getAsmString());
+}
+
+void CIRGenModule::finalizeModuleAttributes() {
+  if (moduleAsm.empty())
+    return;
+
+  // Build array of string attributes
+  llvm::SmallVector<mlir::Attribute> asmStrings;
+  for (const auto &asmStr : moduleAsm) {
+    asmStrings.push_back(builder.getStringAttr(asmStr));
+  }
+
+  // Create array attribute
+  mlir::ArrayAttr asmArray = builder.getArrayAttr(asmStrings);
+
+  // Create ModuleAsmAttr
+  auto moduleAsmAttr = cir::ModuleAsmAttr::get(builder.getContext(), asmArray);
+
+  // Set as module attribute
+  theModule->setAttr("cir.module_asm", moduleAsmAttr);
+}

clang/lib/CIR/CodeGen/CIRGenModule.h

@@ -23,6 +23,7 @@
 #include "CIRGenTypes.h"
 #include "CIRGenVTables.h"
 #include "CIRGenValue.h"
+#include "clang/AST/Decl.h"
 #include "clang/CIR/MissingFeatures.h"
 
 #include "clang/AST/ASTContext.h"
@@ -154,6 +155,8 @@ class CIRGenModule : public CIRGenTypeCache {
   llvm::DenseMap<const Expr *, mlir::Operation *>
       materializedGlobalTemporaryMap;
 
+  llvm::SmallVector<llvm::StringRef> moduleAsm;
+
 public:
   mlir::ModuleOp getModule() const { return theModule; }
   CIRGenBuilderTy &getBuilder() { return builder; }
@@ -958,6 +961,11 @@ class CIRGenModule : public CIRGenTypeCache {
   /// one of them.
   cir::AnnotationAttr emitAnnotateAttr(const clang::AnnotateAttr *aa);
 
+  /// Process file-scope inline assembly (e.g., `asm(".text");` at global
+  /// scope). Collects assembly strings into moduleAsm vector for later
+  /// finalization.
+  void buildFileScopeAsm(const FileScopeAsmDecl *D);
+
 private:
   // An ordered map of canonical GlobalDecls to their mangled names.
   llvm::MapVector<clang::GlobalDecl, llvm::StringRef> MangledDeclNames;
@@ -989,6 +997,14 @@ class CIRGenModule : public CIRGenTypeCache {
   /// Add global annotations for a global value.
   /// Those annotations are emitted during lowering to the LLVM code.
   void addGlobalAnnotations(const ValueDecl *d, mlir::Operation *gv);
+
+  /// Append module-level inline assembly
+  void appendModuleInlineAsm(llvm::StringRef asmStr) {
+    moduleAsm.push_back(asmStr);
+  }
+
+  /// Finalize module attribute (call at the end of codegen)
+  void finalizeModuleAttributes();
 };
 } // namespace clang::CIRGen
 

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVMIR.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "mlir/Dialect/LLVMIR/LLVMDialect.h"
+#include "mlir/IR/Attributes.h"
 #include "mlir/IR/DialectRegistry.h"
 #include "mlir/Target/LLVMIR/LLVMTranslationInterface.h"
 #include "mlir/Target/LLVMIR/ModuleTranslation.h"
@@ -86,6 +87,17 @@ class CIRDialectLLVMIRTranslationInterface
             mlir::dyn_cast<cir::UWTableAttr>(attribute.getValue()))
       llvmModule->setUwtable(convertUWTableKind(uwTableAttr.getValue()));
 
+    // Handle module-level inline assembly
+    if (auto moduleAsmAttr =
+            mlir::dyn_cast<cir::ModuleAsmAttr>(attribute.getValue())) {
+      mlir::ArrayAttr asmStrings = moduleAsmAttr.getAsmStrings();
+      for (mlir::Attribute attr : asmStrings) {
+        if (auto strAttr = mlir::dyn_cast<mlir::StringAttr>(attr)) {
+          llvmModule->appendModuleInlineAsm(strAttr.getValue());
+        }
+      }
+    }
+
     // Drop ammended CIR attribute from LLVM op.
     module->removeAttr(attribute.getName());
   }

clang/test/CIR/CodeGen/file-scope-asm.c

@@ -0,0 +1,51 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir \
+// RUN:   -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s --check-prefix=CIR
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir \
+// RUN:   -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s --check-prefix=LLVM
+
+// Test basic file-scope assembly
+asm(".section .text");
+asm(".global my_func");
+asm("my_func: ret");
+
+// Test file-scope assembly with functions
+int foo() { 
+  return 42; 
+}
+
+asm(".data");
+asm(".align 8");
+
+int bar() { 
+  return 24; 
+}
+
+// Test file-scope assembly at end of file
+asm(".section .rodata");
+asm(".string \"hello\"");
+
+int main() {
+  return foo() + bar();
+}
+
+// CIR: cir.module_asm = #cir.module_asm<[".section .text", ".global my_func", "my_func: ret", ".data", ".align 8", ".section .rodata", ".string {{\\22}}hello{{\\22}}"
+
+// CIR: cir.func {{.*}}@foo
+// CIR: cir.func {{.*}}@bar
+// CIR: cir.func {{.*}}@main
+
+// LLVM: module asm ".section .text"
+// LLVM: module asm ".global my_func"
+// LLVM: module asm "my_func: ret"
+// LLVM: module asm ".data"
+// LLVM: module asm ".align 8"
+// LLVM: module asm ".section .rodata"
+// LLVM: module asm ".string {{\\22}}hello{{\\22}}"
+
+// LLVM: define{{.*}} i32 @foo()
+// LLVM: define{{.*}} i32 @bar()
+// LLVM: define{{.*}} i32 @main()
+