[CIR] Backport FileScopeAsm support from upstream (#2055)

Author: wizardengineer

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

@@ -40,6 +40,7 @@ def CIR_Dialect : Dialect {
     static llvm::StringRef getTripleAttrName() { return "cir.triple"; }
     static llvm::StringRef getOptInfoAttrName() { return "cir.opt_info"; }
     static llvm::StringRef getUWTableAttrName() { return "cir.uwtable"; }
+    static llvm::StringRef getModuleLevelAsmAttrName() { return "cir.module_asm"; }
 
     static llvm::StringRef getGlobalCtorsAttrName() { return "cir.global_ctors"; }
     static llvm::StringRef getGlobalDtorsAttrName() { return "cir.global_dtors"; }

clang/lib/CIR/CodeGen/CIRGenModule.cpp

@@ -2190,6 +2190,20 @@ void CIRGenModule::emitTopLevelDecl(Decl *decl) {
   case Decl::Enum:
     assert(!cir::MissingFeatures::generateDebugInfo() && "NYI");
     break;
+  case Decl::FileScopeAsm:
+    // File-scope asm is ignored during device-side CUDA compilation.
+    if (langOpts.CUDA && langOpts.CUDAIsDevice)
+      break;
+    // File-scope asm is ignored during device-side OpenMP compilation.
+    if (langOpts.OpenMPIsTargetDevice)
+      break;
+    // File-scope asm is ignored during device-side SYCL compilation.
+    if (langOpts.SYCLIsDevice)
+      break;
+    auto *file_asm = cast<FileScopeAsmDecl>(decl);
+    std::string line = file_asm->getAsmString();
+    globalScopeAsm.push_back(builder.getStringAttr(line));
+    break;
   }
 }
 
@@ -3603,6 +3617,11 @@ void CIRGenModule::Release() {
   emitVTablesOpportunistically();
   assert(!MissingFeatures::applyGlobalValReplacements());
   applyReplacements();
+
+  // Set module-level assembly attribute
+  theModule->setAttr(cir::CIRDialect::getModuleLevelAsmAttrName(),
+                     builder.getArrayAttr(globalScopeAsm));
+
   assert(!MissingFeatures::emitMultiVersionFunctions());
 
   assert(!MissingFeatures::incrementalExtensions());

clang/lib/CIR/CodeGen/CIRGenModule.h

@@ -993,6 +993,8 @@ class CIRGenModule : public CIRGenTypeCache {
   /// one of them.
   cir::AnnotationAttr emitAnnotateAttr(const clang::AnnotateAttr *aa);
 
+  llvm::SmallVector<mlir::Attribute> globalScopeAsm;
+
 private:
   // An ordered map of canonical GlobalDecls to their mangled names.
   llvm::MapVector<clang::GlobalDecl, llvm::StringRef> MangledDeclNames;

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

@@ -5425,6 +5425,11 @@ void ConvertCIRToLLVMPass::processCIRAttrs(mlir::ModuleOp module) {
     module->setAttr(mlir::LLVM::LLVMDialect::getTargetTripleAttrName(),
                     tripleAttr);
 
+  if (mlir::Attribute asmAttr =
+          module->getAttr(cir::CIRDialect::getModuleLevelAsmAttrName()))
+    module->setAttr(mlir::LLVM::LLVMDialect::getModuleLevelAsmAttrName(),
+                    asmAttr);
+
   // Strip the CIR attributes.
   module->removeAttr(cir::CIRDialect::getSOBAttrName());
   module->removeAttr(cir::CIRDialect::getSourceLanguageAttrName());

clang/test/CIR/CodeGen/module-asm.c

@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-cir %s -o %t.cir 
+// RUN: FileCheck --input-file=%t.cir %s
+
+// CHECK:  cir.module_asm = [".globl bar", ".globl foo"]
+__asm (".globl bar");
+__asm (".globl foo");

clang/test/CIR/Lowering/module-asm.cir

@@ -0,0 +1,11 @@
+// RUN: cir-opt %s -cir-to-llvm -o %t.cir
+// RUN: FileCheck %s --input-file=%t.cir
+
+// RUN: cir-translate -cir-to-llvmir --disable-cc-lowering -o %t.ll %s
+// RUN: FileCheck -check-prefix=LLVM --input-file=%t.ll %s
+
+// CHECK: llvm.module_asm =  [".globl bar", ".globl foo"]
+// LLVM: module asm ".globl bar"
+// LLVM: module asm ".globl foo"
+module attributes {cir.module_asm = [".globl bar", ".globl foo"]} {
+}