[Clang] Constant Expressions inside of GCC' asm strings (#131003)

Implements GCC's constexpr string ASM extension
https://gcc.gnu.org/onlinedocs/gcc/Asm-constexprs.html

1 files changed, 27 insertions, 14 deletions

diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 0710542..83dd7b1 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -19,6 +19,7 @@
 #include "clang/Basic/FileManager.h"
 #include "clang/Parse/RAIIObjectsForParser.h"
 #include "clang/Sema/DeclSpec.h"
+#include "clang/Sema/EnterExpressionEvaluationContext.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/SemaCodeCompletion.h"
@@ -1668,28 +1669,40 @@ void Parser::ParseKNRParamDeclarations(Declarator &D) {
 ///         string-literal
 ///
 ExprResult Parser::ParseAsmStringLiteral(bool ForAsmLabel) {
-  if (!isTokenStringLiteral()) {
-    Diag(Tok, diag::err_expected_string_literal)
-      << /*Source='in...'*/0 << "'asm'";
-    return ExprError();
-  }
 
-  ExprResult AsmString(ParseStringLiteralExpression());
-  if (!AsmString.isInvalid()) {
+  ExprResult AsmString;
+  if (isTokenStringLiteral()) {
+    AsmString = ParseStringLiteralExpression();
+    if (AsmString.isInvalid())
+      return AsmString;
+
     const auto *SL = cast<StringLiteral>(AsmString.get());
     if (!SL->isOrdinary()) {
       Diag(Tok, diag::err_asm_operand_wide_string_literal)
-        << SL->isWide()
-        << SL->getSourceRange();
+          << SL->isWide() << SL->getSourceRange();
       return ExprError();
     }
-    if (ForAsmLabel && SL->getString().empty()) {
-      Diag(Tok, diag::err_asm_operand_wide_string_literal)
-          << 2 /* an empty */ << SL->getSourceRange();
+  } else if (!ForAsmLabel && getLangOpts().CPlusPlus11 &&
+             Tok.is(tok::l_paren)) {
+    ParenParseOption ExprType = SimpleExpr;
+    SourceLocation RParenLoc;
+    ParsedType CastTy;
+
+    EnterExpressionEvaluationContext ConstantEvaluated(
+        Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+    AsmString = ParseParenExpression(ExprType, true /*stopIfCastExpr*/, false,
+                                     CastTy, RParenLoc);
+    if (!AsmString.isInvalid())
+      AsmString = Actions.ActOnConstantExpression(AsmString);
+
+    if (AsmString.isInvalid())
       return ExprError();
-    }
+  } else {
+    Diag(Tok, diag::err_asm_expected_string) << /*and expression=*/(
+        (getLangOpts().CPlusPlus11 && !ForAsmLabel) ? 0 : 1);
   }
-  return AsmString;
+
+  return Actions.ActOnGCCAsmStmtString(AsmString.get(), ForAsmLabel);
 }
 
 /// ParseSimpleAsm