[NFC][XCOFF][AIX] Return function entry point symbol with dedicate function

Use getFunctionEntryPointSymbol whenever possible to enclose the
implementation detail and reduce duplicate logic.

Differential Revision: https://reviews.llvm.org/D80402

Author: jasonliudev

llvm/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h

@@ -262,6 +262,9 @@ class TargetLoweringObjectFileXCOFF : public TargetLoweringObjectFile {
   /// For functions, this will always return a function descriptor symbol.
   MCSymbol *getTargetSymbol(const GlobalValue *GV,
                             const TargetMachine &TM) const override;
+
+  MCSymbol *getFunctionEntryPointSymbol(const Function *F,
+                                        const TargetMachine &TM) const override;
 };
 
 } // end namespace llvm

llvm/include/llvm/Target/TargetLoweringObjectFile.h

@@ -245,6 +245,13 @@ class TargetLoweringObjectFile : public MCObjectFileInfo {
     return nullptr;
   }
 
+  /// If supported, return the function entry point symbol.
+  /// Otherwise, returns nulltpr.
+  virtual MCSymbol *getFunctionEntryPointSymbol(const Function *F,
+                                                const TargetMachine &TM) const {
+    return nullptr;
+  }
+
 protected:
   virtual MCSection *SelectSectionForGlobal(const GlobalObject *GO,
                                             SectionKind Kind,

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1503,6 +1503,8 @@ bool AsmPrinter::doFinalization(Module &M) {
   // Emit remaining GOT equivalent globals.
   emitGlobalGOTEquivs();
 
+  const TargetLoweringObjectFile &TLOF = getObjFileLowering();
+
   // Emit linkage(XCOFF) and visibility info for declarations
   for (const Function &F : M) {
     if (!F.isDeclarationForLinker())
@@ -1513,8 +1515,7 @@ bool AsmPrinter::doFinalization(Module &M) {
     if (TM.getTargetTriple().isOSBinFormatXCOFF() && !F.isIntrinsic()) {
 
       // Get the function entry point symbol.
-      MCSymbol *FnEntryPointSym = OutContext.getOrCreateSymbol(
-          "." + cast<MCSymbolXCOFF>(Name)->getUnqualifiedName());
+      MCSymbol *FnEntryPointSym = TLOF.getFunctionEntryPointSymbol(&F, TM);
       if (cast<MCSymbolXCOFF>(FnEntryPointSym)->hasRepresentedCsectSet())
         // Emit linkage for the function entry point.
         emitLinkage(&F, FnEntryPointSym);
@@ -1536,8 +1537,6 @@ bool AsmPrinter::doFinalization(Module &M) {
   if (remarks::RemarkStreamer *RS = M.getContext().getMainRemarkStreamer())
     emitRemarksSection(*RS);
 
-  const TargetLoweringObjectFile &TLOF = getObjFileLowering();
-
   TLOF.emitModuleMetadata(*OutStreamer, M);
 
   if (TM.getTargetTriple().isOSBinFormatELF()) {
@@ -1786,8 +1785,7 @@ void AsmPrinter::SetupMachineFunction(MachineFunction &MF) {
                                " initalized first.");
 
     // Get the function entry point symbol.
-    CurrentFnSym = OutContext.getOrCreateSymbol(
-        "." + cast<MCSymbolXCOFF>(CurrentFnDescSym)->getUnqualifiedName());
+    CurrentFnSym = getObjFileLowering().getFunctionEntryPointSymbol(&F, TM);
   }
 
   CurrentFnSymForSize = CurrentFnSym;

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -2150,6 +2150,14 @@ XCOFF::StorageClass TargetLoweringObjectFileXCOFF::getStorageClassForGlobal(
   llvm_unreachable("Unknown linkage type!");
 }
 
+MCSymbol *TargetLoweringObjectFileXCOFF::getFunctionEntryPointSymbol(
+    const Function *F, const TargetMachine &TM) const {
+  SmallString<128> NameStr;
+  NameStr.push_back('.');
+  getNameWithPrefix(NameStr, F, TM);
+  return getContext().getOrCreateSymbol(NameStr);
+}
+
 MCSection *TargetLoweringObjectFileXCOFF::getSectionForFunctionDescriptor(
     const Function *F, const TargetMachine &TM) const {
   SmallString<128> NameStr;