[TLOF][NFC] Make emitLinkerDirectives virtual and public. (llvm#123773)

Today, emitLinkerDirectives is private to TLOFCOFF-- it isolates parsing
and processing of the linker options. Similar processing is also done by
other TLOFs inline within emitModuleMetadata. This patch promotes
emitLinkerDirectives to a virtual (public) method so that this handling
is similarly isolated in the other TLOFs.

This also enables downstream targets to override just this handling
instead of the whole of emitModuleMetadata.

Author: nvjle

llvm/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h

@@ -60,6 +60,8 @@ class TargetLoweringObjectFileELF : public TargetLoweringObjectFile {
                                         const MCSymbol *Sym,
                                         const MachineModuleInfo *MMI) const;
 
+  void emitLinkerDirectives(MCStreamer &Streamer, Module &M) const override;
+
   /// Given a constant with the SectionKind, return a section that it should be
   /// placed in.
   MCSection *getSectionForConstant(const DataLayout &DL, SectionKind Kind,
@@ -131,6 +133,8 @@ class TargetLoweringObjectFileMachO : public TargetLoweringObjectFile {
   /// Emit the module flags that specify the garbage collection information.
   void emitModuleMetadata(MCStreamer &Streamer, Module &M) const override;
 
+  void emitLinkerDirectives(MCStreamer &Streamer, Module &M) const override;
+
   MCSection *SelectSectionForGlobal(const GlobalObject *GO, SectionKind Kind,
                                     const TargetMachine &TM) const override;
 
@@ -192,6 +196,8 @@ class TargetLoweringObjectFileCOFF : public TargetLoweringObjectFile {
   /// Emit Obj-C garbage collection and linker options.
   void emitModuleMetadata(MCStreamer &Streamer, Module &M) const override;
 
+  void emitLinkerDirectives(MCStreamer &Streamer, Module &M) const override;
+
   MCSection *getStaticCtorSection(unsigned Priority,
                                   const MCSymbol *KeySym) const override;
   MCSection *getStaticDtorSection(unsigned Priority,
@@ -206,9 +212,6 @@ class TargetLoweringObjectFileCOFF : public TargetLoweringObjectFile {
   MCSection *getSectionForConstant(const DataLayout &DL, SectionKind Kind,
                                    const Constant *C,
                                    Align &Alignment) const override;
-
-private:
-  void emitLinkerDirectives(MCStreamer &Streamer, Module &M) const;
 };
 
 class TargetLoweringObjectFileWasm : public TargetLoweringObjectFile {

llvm/include/llvm/Target/TargetLoweringObjectFile.h

@@ -91,6 +91,9 @@ class TargetLoweringObjectFile : public MCObjectFileInfo {
   /// Emit Call Graph Profile metadata.
   void emitCGProfileMetadata(MCStreamer &Streamer, Module &M) const;
 
+  /// Process linker options metadata and emit platform-specific bits.
+  virtual void emitLinkerDirectives(MCStreamer &Streamer, Module &M) const {}
+
   /// Get the module-level metadata that the platform cares about.
   virtual void getModuleMetadata(Module &M) {}
 

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -306,21 +306,7 @@ void TargetLoweringObjectFileELF::emitModuleMetadata(MCStreamer &Streamer,
                                                      Module &M) const {
   auto &C = getContext();
 
-  if (NamedMDNode *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
-    auto *S = C.getELFSection(".linker-options", ELF::SHT_LLVM_LINKER_OPTIONS,
-                              ELF::SHF_EXCLUDE);
-
-    Streamer.switchSection(S);
-
-    for (const auto *Operand : LinkerOptions->operands()) {
-      if (cast<MDNode>(Operand)->getNumOperands() != 2)
-        report_fatal_error("invalid llvm.linker.options");
-      for (const auto &Option : cast<MDNode>(Operand)->operands()) {
-        Streamer.emitBytes(cast<MDString>(Option)->getString());
-        Streamer.emitInt8(0);
-      }
-    }
-  }
+  emitLinkerDirectives(Streamer, M);
 
   if (NamedMDNode *DependentLibraries = M.getNamedMetadata("llvm.dependent-libraries")) {
     auto *S = C.getELFSection(".deplibs", ELF::SHT_LLVM_DEPENDENT_LIBRARIES,
@@ -400,6 +386,26 @@ void TargetLoweringObjectFileELF::emitModuleMetadata(MCStreamer &Streamer,
   emitCGProfileMetadata(Streamer, M);
 }
 
+void TargetLoweringObjectFileELF::emitLinkerDirectives(MCStreamer &Streamer,
+                                                       Module &M) const {
+  auto &C = getContext();
+  if (NamedMDNode *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
+    auto *S = C.getELFSection(".linker-options", ELF::SHT_LLVM_LINKER_OPTIONS,
+                              ELF::SHF_EXCLUDE);
+
+    Streamer.switchSection(S);
+
+    for (const auto *Operand : LinkerOptions->operands()) {
+      if (cast<MDNode>(Operand)->getNumOperands() != 2)
+        report_fatal_error("invalid llvm.linker.options");
+      for (const auto &Option : cast<MDNode>(Operand)->operands()) {
+        Streamer.emitBytes(cast<MDString>(Option)->getString());
+        Streamer.emitInt8(0);
+      }
+    }
+  }
+}
+
 MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol(
     const GlobalValue *GV, const TargetMachine &TM,
     MachineModuleInfo *MMI) const {
@@ -1244,14 +1250,7 @@ MCSection *TargetLoweringObjectFileMachO::getStaticDtorSection(
 void TargetLoweringObjectFileMachO::emitModuleMetadata(MCStreamer &Streamer,
                                                        Module &M) const {
   // Emit the linker options if present.
-  if (auto *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
-    for (const auto *Option : LinkerOptions->operands()) {
-      SmallVector<std::string, 4> StrOptions;
-      for (const auto &Piece : cast<MDNode>(Option)->operands())
-        StrOptions.push_back(std::string(cast<MDString>(Piece)->getString()));
-      Streamer.emitLinkerOptions(StrOptions);
-    }
-  }
+  emitLinkerDirectives(Streamer, M);
 
   unsigned VersionVal = 0;
   unsigned ImageInfoFlags = 0;
@@ -1285,6 +1284,18 @@ void TargetLoweringObjectFileMachO::emitModuleMetadata(MCStreamer &Streamer,
   Streamer.addBlankLine();
 }
 
+void TargetLoweringObjectFileMachO::emitLinkerDirectives(MCStreamer &Streamer,
+                                                         Module &M) const {
+  if (auto *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
+    for (const auto *Option : LinkerOptions->operands()) {
+      SmallVector<std::string, 4> StrOptions;
+      for (const auto &Piece : cast<MDNode>(Option)->operands())
+        StrOptions.push_back(std::string(cast<MDString>(Piece)->getString()));
+      Streamer.emitLinkerOptions(StrOptions);
+    }
+  }
+}
+
 static void checkMachOComdat(const GlobalValue *GV) {
   const Comdat *C = GV->getComdat();
   if (!C)