[LLVM][Inline-ASM] Adding Altmacro directive to LLVM

[m_zuckerman]

Summary

This patch adds a new directive to LLVM.
Altmacro directive is a GAS driven directive and new for LLVM.
It expands the macro behavior as described in the following link: https://sourceware.org/binutils/docs/as/Altmacro.html

This patch is the first review among several other reviews and adds the infrastructure for the directive.

[rengolin]

Well, for now, this isn't doing anything other than silently ignoring the directives.

Can you add the other patches to phab (and link to this one), so we can review the whole thing in one go?

I don't think this one should go as is without looking at the remaining ones.

[m_zuckerman]

Was combine with the D32523

MC/AsmParser/AltMacroEnable.s

+# RUN: llvm-mc %s -o -| FileCheck %s
+
+#CHECK-NOT: error
+
+.altmacro
+.noaltmacro

MC/MCParser/AsmParser.cpp

enum DirectiveKind {
     DK_CV_INLINE_LINETABLE, DK_CV_DEF_RANGE, DK_CV_STRINGTABLE,
     DK_CV_FILECHECKSUMS,
     DK_CFI_SECTIONS, DK_CFI_STARTPROC, DK_CFI_ENDPROC, DK_CFI_DEF_CFA,
     DK_CFI_DEF_CFA_OFFSET, DK_CFI_ADJUST_CFA_OFFSET, DK_CFI_DEF_CFA_REGISTER,
     DK_CFI_OFFSET, DK_CFI_REL_OFFSET, DK_CFI_PERSONALITY, DK_CFI_LSDA,
     DK_CFI_REMEMBER_STATE, DK_CFI_RESTORE_STATE, DK_CFI_SAME_VALUE,
     DK_CFI_RESTORE, DK_CFI_ESCAPE, DK_CFI_SIGNAL_FRAME, DK_CFI_UNDEFINED,
     DK_CFI_REGISTER, DK_CFI_WINDOW_SAVE,
-    DK_MACROS_ON, DK_MACROS_OFF,
+    DK_MACROS_ON, DK_MACROS_OFF, DK_ALTMACRO, DK_NOALTMACRO,
     DK_MACRO, DK_EXITM, DK_ENDM, DK_ENDMACRO, DK_PURGEM,
     DK_SLEB128, DK_ULEB128,
     DK_ERR, DK_ERROR, DK_WARNING,
     DK_END
   };
 
   /// \brief Maps directive name --> DirectiveKind enum, for
   /// directives parsed by this class.
private:
   bool parseDirectiveCFIUndefined(SMLoc DirectiveLoc);
 
   // macro directives
   bool parseDirectivePurgeMacro(SMLoc DirectiveLoc);
   bool parseDirectiveExitMacro(StringRef Directive);
   bool parseDirectiveEndMacro(StringRef Directive);
   bool parseDirectiveMacro(SMLoc DirectiveLoc);
   bool parseDirectiveMacrosOnOff(StringRef Directive);
-
+  // AltMacros
+  bool parseDirectiveAltmacro(StringRef Directive);
   // ".bundle_align_mode"
   bool parseDirectiveBundleAlignMode();
   // ".bundle_lock"
   bool parseDirectiveBundleLock();
   // ".bundle_unlock"
   bool parseDirectiveBundleUnlock();
 
   // ".space", ".skip"
case DK_CFI_REGISTER:
       return parseDirectiveCFIRegister(IDLoc);
     case DK_CFI_WINDOW_SAVE:
       return parseDirectiveCFIWindowSave();
     case DK_MACROS_ON:
     case DK_MACROS_OFF:
       return parseDirectiveMacrosOnOff(IDVal);
     case DK_MACRO:
       return parseDirectiveMacro(IDLoc);
+    case DK_ALTMACRO:
+    case DK_NOALTMACRO:
+      return parseDirectiveAltmacro(IDVal);
     case DK_EXITM:
       return parseDirectiveExitMacro(IDVal);
     case DK_ENDM:
     case DK_ENDMACRO:
       return parseDirectiveEndMacro(IDVal);
     case DK_PURGEM:
       return parseDirectivePurgeMacro(IDLoc);
     case DK_END:
bool AsmParser::parseDirectiveCFIUndefined(SMLoc DirectiveLoc) {
 
   if (parseRegisterOrRegisterNumber(Register, DirectiveLoc))
     return true;
 
   getStreamer().EmitCFIUndefined(Register);
   return false;
 }
 
+/// parseDirectiveAltmacro
+/// ::= .altmacro
+/// ::= .noaltmacro
+bool AsmParser::parseDirectiveAltmacro(StringRef Directive) {
+  if (getLexer().isNot(AsmToken::EndOfStatement))
+    return TokError("unexpected token in '" + Directive + "' directive");
+  return false;
+}
+
 /// parseDirectiveMacrosOnOff
 /// ::= .macros_on
 /// ::= .macros_off
 bool AsmParser::parseDirectiveMacrosOnOff(StringRef Directive) {
   if (parseToken(AsmToken::EndOfStatement,
                  "unexpected token in '" + Directive + "' directive"))
     return true;
 
void AsmParser::initializeDirectiveKindMap() {
   DirectiveKindMap[".macro"] = DK_MACRO;
   DirectiveKindMap[".exitm"] = DK_EXITM;
   DirectiveKindMap[".endm"] = DK_ENDM;
   DirectiveKindMap[".endmacro"] = DK_ENDMACRO;
   DirectiveKindMap[".purgem"] = DK_PURGEM;
   DirectiveKindMap[".err"] = DK_ERR;
   DirectiveKindMap[".error"] = DK_ERROR;
   DirectiveKindMap[".warning"] = DK_WARNING;
+  DirectiveKindMap[".altmacro"] = DK_ALTMACRO;
+  DirectiveKindMap[".noaltmacro"] = DK_NOALTMACRO;
   DirectiveKindMap[".reloc"] = DK_RELOC;
   DirectiveKindMap[".dc"] = DK_DC;
   DirectiveKindMap[".dc.a"] = DK_DC_A;
   DirectiveKindMap[".dc.b"] = DK_DC_B;
   DirectiveKindMap[".dc.d"] = DK_DC_D;
   DirectiveKindMap[".dc.l"] = DK_DC_L;
   DirectiveKindMap[".dc.s"] = DK_DC_S;
   DirectiveKindMap[".dc.w"] = DK_DC_W;