[Clang] Support constexpr asm at global scope. (#143268)

I previously failed to realize this feature existed...

Fixes #137459
Fixes #143242

clang/include/clang/AST/ASTNodeTraverser.h

@@ -605,7 +605,7 @@ public:
   }
 
   void VisitFileScopeAsmDecl(const FileScopeAsmDecl *D) {
-    Visit(D->getAsmString());
+    Visit(D->getAsmStringExpr());
   }
 
   void VisitTopLevelStmtDecl(const TopLevelStmtDecl *D) { Visit(D->getStmt()); }

clang/include/clang/AST/Decl.h

@@ -4490,18 +4490,18 @@ private:
 };
 
 class FileScopeAsmDecl : public Decl {
-  StringLiteral *AsmString;
+  Expr *AsmString;
   SourceLocation RParenLoc;
 
-  FileScopeAsmDecl(DeclContext *DC, StringLiteral *asmstring,
-                   SourceLocation StartL, SourceLocation EndL)
-    : Decl(FileScopeAsm, DC, StartL), AsmString(asmstring), RParenLoc(EndL) {}
+  FileScopeAsmDecl(DeclContext *DC, Expr *asmstring, SourceLocation StartL,
+                   SourceLocation EndL)
+      : Decl(FileScopeAsm, DC, StartL), AsmString(asmstring), RParenLoc(EndL) {}
 
   virtual void anchor();
 
 public:
-  static FileScopeAsmDecl *Create(ASTContext &C, DeclContext *DC,
-                                  StringLiteral *Str, SourceLocation AsmLoc,
+  static FileScopeAsmDecl *Create(ASTContext &C, DeclContext *DC, Expr *Str,
+                                  SourceLocation AsmLoc,
                                   SourceLocation RParenLoc);
 
   static FileScopeAsmDecl *CreateDeserialized(ASTContext &C, GlobalDeclID ID);
@@ -4513,9 +4513,11 @@ public:
     return SourceRange(getAsmLoc(), getRParenLoc());
   }
 
-  const StringLiteral *getAsmString() const { return AsmString; }
-  StringLiteral *getAsmString() { return AsmString; }
-  void setAsmString(StringLiteral *Asm) { AsmString = Asm; }
+  const Expr *getAsmStringExpr() const { return AsmString; }
+  Expr *getAsmStringExpr() { return AsmString; }
+  void setAsmString(Expr *Asm) { AsmString = Asm; }
+
+  std::string getAsmString() const;
 
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K == FileScopeAsm; }

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -1617,7 +1617,7 @@ DEF_TRAVERSE_DECL(LifetimeExtendedTemporaryDecl, {
 })
 
 DEF_TRAVERSE_DECL(FileScopeAsmDecl,
-                  { TRY_TO(TraverseStmt(D->getAsmString())); })
+                  { TRY_TO(TraverseStmt(D->getAsmStringExpr())); })
 
 DEF_TRAVERSE_DECL(TopLevelStmtDecl, { TRY_TO(TraverseStmt(D->getStmt())); })
 

clang/lib/AST/Decl.cpp

@@ -5713,8 +5713,7 @@ SourceRange TypeAliasDecl::getSourceRange() const {
 void FileScopeAsmDecl::anchor() {}
 
 FileScopeAsmDecl *FileScopeAsmDecl::Create(ASTContext &C, DeclContext *DC,
-                                           StringLiteral *Str,
-                                           SourceLocation AsmLoc,
+                                           Expr *Str, SourceLocation AsmLoc,
                                            SourceLocation RParenLoc) {
   return new (C, DC) FileScopeAsmDecl(DC, Str, AsmLoc, RParenLoc);
 }
@@ -5725,6 +5724,10 @@ FileScopeAsmDecl *FileScopeAsmDecl::CreateDeserialized(ASTContext &C,
                                       SourceLocation());
 }
 
+std::string FileScopeAsmDecl::getAsmString() const {
+  return GCCAsmStmt::ExtractStringFromGCCAsmStmtComponent(getAsmStringExpr());
+}
+
 void TopLevelStmtDecl::anchor() {}
 
 TopLevelStmtDecl *TopLevelStmtDecl::Create(ASTContext &C, Stmt *Statement) {

clang/lib/AST/DeclPrinter.cpp

@@ -1042,8 +1042,8 @@ void DeclPrinter::VisitParmVarDecl(ParmVarDecl *D) {
 
 void DeclPrinter::VisitFileScopeAsmDecl(FileScopeAsmDecl *D) {
   Out << "__asm (";
-  D->getAsmString()->printPretty(Out, nullptr, Policy, Indentation, "\n",
-                                 &Context);
+  D->getAsmStringExpr()->printPretty(Out, nullptr, Policy, Indentation, "\n",
+                                     &Context);
   Out << ")";
 }
 

clang/lib/CodeGen/CodeGenModule.cpp

@@ -7271,7 +7271,7 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
     if (LangOpts.SYCLIsDevice)
       break;
     auto *AD = cast<FileScopeAsmDecl>(D);
-    getModule().appendModuleInlineAsm(AD->getAsmString()->getString());
+    getModule().appendModuleInlineAsm(AD->getAsmString());
     break;
   }
 

clang/lib/Sema/SemaDecl.cpp

@@ -20514,14 +20514,11 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
     CheckAlignasUnderalignment(Enum);
 }
 
-Decl *Sema::ActOnFileScopeAsmDecl(Expr *expr,
-                                  SourceLocation StartLoc,
+Decl *Sema::ActOnFileScopeAsmDecl(Expr *expr, SourceLocation StartLoc,
                                   SourceLocation EndLoc) {
-  StringLiteral *AsmString = cast<StringLiteral>(expr);
 
-  FileScopeAsmDecl *New = FileScopeAsmDecl::Create(Context, CurContext,
-                                                   AsmString, StartLoc,
-                                                   EndLoc);
+  FileScopeAsmDecl *New =
+      FileScopeAsmDecl::Create(Context, CurContext, expr, StartLoc, EndLoc);
   CurContext->addDecl(New);
   return New;
 }

clang/lib/Serialization/ASTWriterDecl.cpp

@@ -1389,7 +1389,7 @@ void ASTDeclWriter::VisitBindingDecl(BindingDecl *D) {
 
 void ASTDeclWriter::VisitFileScopeAsmDecl(FileScopeAsmDecl *D) {
   VisitDecl(D);
-  Record.AddStmt(D->getAsmString());
+  Record.AddStmt(D->getAsmStringExpr());
   Record.AddSourceLocation(D->getRParenLoc());
   Code = serialization::DECL_FILE_SCOPE_ASM;
 }

clang/test/CodeGenCXX/gnu-asm-constexpr.cpp

@@ -16,6 +16,12 @@ struct string_view {
     }
 };
 
+namespace GH143242 {
+    constexpr string_view code2 = R"(nop; nop; nop; nop)";
+    asm((code2));
+    // CHECK: module asm "nop; nop; nop; nop"
+}
+
 int func() {return 0;};
 
 void f() {
@@ -49,4 +55,4 @@ void test_srcloc() {
         foobar)o")
 
     ) ::(string_view("r"))(func()));
-  }
+}