[Inline asm] Correctly parse GCC-style asm line following MS-style asm line

[• d.zobnin.bugzilla]

Summary

Clang fails to compile the following code:

void f() {

__asm mov ebx, ecx
__asm__("movl %ecx, %edx");

}

reporting unexpected token "asm" at start of statement.
Quit parsing MS-style assembly if the following statement has GCC style to handle such code.

[rsmith]

lib/Parse/ParseStmtAsm.cpp

423

The next token in GCC-style inline asm could also be volatile (or const or goto -- though we don't support the latter).

Please make this GCC / MS dialect selection the same way that ParseAsmStatement does (and factor out a static isGCCAsmStatement(Token &TokAfterAsm) function or similar).

[• d.zobnin.bugzilla]

Richard, thank you for the review!

I've created a static function to check if this is a GCC asm statement as you recommended to do, and also made "isTypeQualifier" function static.
I've added a check for "goto" after "asm" to treat such statements as GCC-style assembly.
Also, do you think it will be better to diagnose unsupported "asm goto" statements rather than fall into parsing them and emit "expected identifier" error or something like that?

Thank you,
Denis Zobnin

[• d.zobnin.bugzilla]

Richard, Eric,

Please take a look at the patch.

Thank you,
Denis Zobnin

[rsmith]

LGTM, thank you!

lib/Parse/ParseStmtAsm.cpp

if (!InAsmComment && Tok.is(tok::l_brace)) {
       // new line.
       std::pair<FileID, unsigned> ExpLoc =
           SrcMgr.getDecomposedExpansionLoc(TokLoc);
       if (ExpLoc.first != FID ||
           SrcMgr.getLineNumber(ExpLoc.first, ExpLoc.second) != LineNo) {
         // If this is a single-line __asm, we're done, except if the next
         // line begins with an __asm too, in which case we finish a comment
         // if needed and then keep processing the next line as a single
-        // line __asm.
+        // line __asm. Also break if the next __asm is followed by an '(' -
+        // GCC-style asm.
         bool isAsm = Tok.is(tok::kw_asm);
-        if (SingleLineMode && !isAsm)
+        if (SingleLineMode && (!isAsm || NextToken().is(tok::l_paren)))
           break;
         // We're no longer in a comment.
         InAsmComment = false;
         if (isAsm) {
           // If this is a new __asm {} block we want to process it seperately
           // from the single-line __asm statements
           if (PP.LookAhead(0).is(tok::l_brace))
             break;

test/CodeGen/inline-asm-mixed-style.c

+// RUN: %clang_cc1 -triple i386-unknown-unknown -fasm-blocks -fsyntax-only -verify %s
+// expected-no-diagnostics
+// RUN: %clang_cc1 -triple i386-unknown-unknown -fasm-blocks -emit-llvm -S %s -o - | FileCheck %s
+
+void f() {
+  __asm mov eax, ebx
+  __asm mov ebx, ecx
+  __asm__("movl %ecx, %edx");
+
+  // CHECK: movl    %ebx, %eax
+  // CHECK: movl    %ecx, %ebx
+  // CHECK: movl    %ecx, %edx
+}