[NFC] clean up the AsmPrinter::emitLinkage for AIX part

SUMMARY:

Since we deal with aix emitLinkage in the PPCAIXAsmPrinter::emitLinkage() in the patch https://reviews.llvm.org/D75866. It do not go to AsmPrinter::emitLinkage() any more, we clean up some aix related code in the AsmPrinter::emitLinkage()

Reviewers:  Jason liu

Differential Revision: https://reviews.llvm.org/D81613

llvm/include/llvm/MC/MCAsmInfo.h

@@ -311,10 +311,6 @@ protected:
   /// false.
   bool HasAltEntry = false;
 
-  /// True if this target supports the XCOFF .extern directive.  Defaults to
-  /// false.
-  bool HasDotExternDirective = false;
-
   /// Used to declare a global as being a weak symbol. Defaults to ".weak".
   const char *WeakDirective;
 
@@ -335,10 +331,6 @@ protected:
   /// Defaults to false.
   bool AvoidWeakIfComdat = false;
 
-  /// True if we have a .lglobl directive, which is used to emit the information
-  /// of a static symbol into the symbol table. Defaults to false.
-  bool HasDotLGloblDirective = false;
-
   /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
   /// hidden visibility.  Defaults to MCSA_Hidden.
   MCSymbolAttr HiddenVisibilityAttr = MCSA_Hidden;
@@ -594,7 +586,6 @@ public:
   bool hasIdentDirective() const { return HasIdentDirective; }
   bool hasNoDeadStrip() const { return HasNoDeadStrip; }
   bool hasAltEntry() const { return HasAltEntry; }
-  bool hasDotExternDirective() const { return HasDotExternDirective; }
   const char *getWeakDirective() const { return WeakDirective; }
   const char *getWeakRefDirective() const { return WeakRefDirective; }
   bool hasWeakDefDirective() const { return HasWeakDefDirective; }
@@ -605,8 +596,6 @@ public:
 
   bool avoidWeakIfComdat() const { return AvoidWeakIfComdat; }
 
-  bool hasDotLGloblDirective() const { return HasDotLGloblDirective; }
-
   MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr; }
 
   MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -395,9 +395,6 @@ void AsmPrinter::emitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
   GlobalValue::LinkageTypes Linkage = GV->getLinkage();
   switch (Linkage) {
   case GlobalValue::CommonLinkage:
-    assert(!TM.getTargetTriple().isOSBinFormatXCOFF() &&
-           "CommonLinkage of XCOFF should not come to this path.");
-    LLVM_FALLTHROUGH;
   case GlobalValue::LinkOnceAnyLinkage:
   case GlobalValue::LinkOnceODRLinkage:
   case GlobalValue::WeakAnyLinkage:
@@ -421,29 +418,13 @@ void AsmPrinter::emitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
     }
     return;
   case GlobalValue::ExternalLinkage:
-    if (MAI->hasDotExternDirective() && GV->isDeclaration())
-      OutStreamer->emitSymbolAttribute(GVSym, MCSA_Extern);
-    else
-      OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
+    OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
     return;
   case GlobalValue::PrivateLinkage:
-    return;
   case GlobalValue::InternalLinkage:
-    if (MAI->hasDotLGloblDirective())
-      OutStreamer->emitSymbolAttribute(GVSym, MCSA_LGlobal);
     return;
   case GlobalValue::ExternalWeakLinkage:
-    if (TM.getTargetTriple().isOSBinFormatXCOFF()) {
-      OutStreamer->emitSymbolAttribute(GVSym, MCSA_Weak);
-      return;
-    }
-    LLVM_FALLTHROUGH;
   case GlobalValue::AvailableExternallyLinkage:
-    if (MAI->hasDotExternDirective()) {
-      OutStreamer->emitSymbolAttribute(GVSym, MCSA_Extern);
-      return;
-    }
-    LLVM_FALLTHROUGH;
   case GlobalValue::AppendingLinkage:
     llvm_unreachable("Should never emit this");
   }

llvm/lib/MC/MCAsmInfoXCOFF.cpp

@@ -32,8 +32,6 @@ MCAsmInfoXCOFF::MCAsmInfoXCOFF() {
   COMMDirectiveAlignmentIsInBytes = false;
   LCOMMDirectiveAlignmentType = LCOMM::Log2Alignment;
   HasDotTypeDotSizeDirective = false;
-  HasDotExternDirective = true;
-  HasDotLGloblDirective = true;
   SymbolsHaveSMC = true;
   UseIntegratedAssembler = false;
   NeedsFunctionDescriptors = true;

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

@@ -1603,8 +1603,6 @@ void PPCAIXAsmPrinter::emitLinkage(const GlobalValue *GV,
   case GlobalValue::PrivateLinkage:
     return;
   case GlobalValue::InternalLinkage:
-    assert(MAI->hasDotLGloblDirective() &&
-           "Expecting .lglobl to be supported for AIX.");
     OutStreamer->emitSymbolAttribute(GVSym, MCSA_LGlobal);
     return;
   case GlobalValue::AppendingLinkage: