[DWARFYAML] Add helper function getDWARFEmitterByName(). NFC.

In this patch, we add a helper function getDWARFEmitterByName(). This
function returns the proper DWARF section emitting method by the name.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D84952

include/llvm/ObjectYAML/DWARFEmitter.h

@@ -43,6 +43,8 @@ Error emitDebugAddr(raw_ostream &OS, const Data &DI);
 Error emitDebugStrOffsets(raw_ostream &OS, const Data &DI);
 Error emitDebugRnglists(raw_ostream &OS, const Data &DI);
 
+std::function<Error(raw_ostream &, const Data &)>
+getDWARFEmitterByName(StringRef SecName);
 Expected<StringMap<std::unique_ptr<MemoryBuffer>>>
 emitDebugSections(StringRef YAMLString,
                   bool IsLittleEndian = sys::IsLittleEndianHost);

lib/ObjectYAML/DWARFEmitter.cpp

@@ -15,6 +15,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/ObjectYAML/DWARFYAML.h"
 #include "llvm/Support/Errc.h"
@@ -762,14 +763,40 @@ Error DWARFYAML::emitDebugRnglists(raw_ostream &OS, const Data &DI) {
       OS, *DI.DebugRnglists, DI.IsLittleEndian, DI.Is64BitAddrSize);
 }
 
-using EmitFuncType = Error (*)(raw_ostream &, const DWARFYAML::Data &);
+std::function<Error(raw_ostream &, const DWARFYAML::Data &)>
+DWARFYAML::getDWARFEmitterByName(StringRef SecName) {
+  auto EmitFunc =
+      StringSwitch<
+          std::function<Error(raw_ostream &, const DWARFYAML::Data &)>>(SecName)
+          .Case("debug_abbrev", DWARFYAML::emitDebugAbbrev)
+          .Case("debug_addr", DWARFYAML::emitDebugAddr)
+          .Case("debug_aranges", DWARFYAML::emitDebugAranges)
+          .Case("debug_gnu_pubnames", DWARFYAML::emitDebugGNUPubnames)
+          .Case("debug_gnu_pubtypes", DWARFYAML::emitDebugGNUPubtypes)
+          .Case("debug_info", DWARFYAML::emitDebugInfo)
+          .Case("debug_line", DWARFYAML::emitDebugLine)
+          .Case("debug_pubnames", DWARFYAML::emitDebugPubnames)
+          .Case("debug_pubtypes", DWARFYAML::emitDebugPubtypes)
+          .Case("debug_ranges", DWARFYAML::emitDebugRanges)
+          .Case("debug_rnglists", DWARFYAML::emitDebugRnglists)
+          .Case("debug_str", DWARFYAML::emitDebugStr)
+          .Case("debug_str_offsets", DWARFYAML::emitDebugStrOffsets)
+          .Default([&](raw_ostream &, const DWARFYAML::Data &) {
+            return createStringError(errc::not_supported,
+                                     SecName + " is not supported");
+          });
+
+  return EmitFunc;
+}
 
 static Error
-emitDebugSectionImpl(const DWARFYAML::Data &DI, EmitFuncType EmitFunc,
+emitDebugSectionImpl(const DWARFYAML::Data &DI, StringRef Sec,
-                     StringRef Sec,
                      StringMap<std::unique_ptr<MemoryBuffer>> &OutputBuffers) {
   std::string Data;
   raw_string_ostream DebugInfoStream(Data);
+
+  auto EmitFunc = DWARFYAML::getDWARFEmitterByName(Sec);
+
   if (Error Err = EmitFunc(DebugInfoStream, DI))
     return Err;
   DebugInfoStream.flush();
@@ -796,23 +823,12 @@ DWARFYAML::emitDebugSections(StringRef YAMLString, bool IsLittleEndian) {
     return createStringError(YIn.error(), GeneratedDiag.getMessage());
 
   StringMap<std::unique_ptr<MemoryBuffer>> DebugSections;
-  Error Err = emitDebugSectionImpl(DI, &DWARFYAML::emitDebugInfo, "debug_info",
+  Error Err = Error::success();
-                                   DebugSections);
+  cantFail(std::move(Err));
-  Err = joinErrors(std::move(Err),
+
-                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugLine,
+  for (StringRef SecName : DI.getNonEmptySectionNames())
-                                        "debug_line", DebugSections));
+    Err = joinErrors(std::move(Err),
-  Err = joinErrors(std::move(Err),
+                     emitDebugSectionImpl(DI, SecName, DebugSections));
-                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugStr,
-                                        "debug_str", DebugSections));
-  Err = joinErrors(std::move(Err),
-                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugAbbrev,
-                                        "debug_abbrev", DebugSections));
-  Err = joinErrors(std::move(Err),
-                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugAranges,
-                                        "debug_aranges", DebugSections));
-  Err = joinErrors(std::move(Err),
-                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugRanges,
-                                        "debug_ranges", DebugSections));
 
   if (Err)
     return std::move(Err);

lib/ObjectYAML/ELFEmitter.cpp

@@ -949,39 +949,9 @@ Expected<uint64_t> emitDWARF(typename ELFT::Shdr &SHeader, StringRef Name,
     return 0;
 
   uint64_t BeginOffset = CBA.tell();
-  Error Err = Error::success();
-  cantFail(std::move(Err));
 
-  if (Name == ".debug_str")
+  auto EmitFunc = DWARFYAML::getDWARFEmitterByName(Name.substr(1));
-    Err = DWARFYAML::emitDebugStr(*OS, DWARF);
+  if (Error Err = EmitFunc(*OS, DWARF))
-  else if (Name == ".debug_aranges")
-    Err = DWARFYAML::emitDebugAranges(*OS, DWARF);
-  else if (Name == ".debug_ranges")
-    Err = DWARFYAML::emitDebugRanges(*OS, DWARF);
-  else if (Name == ".debug_line")
-    Err = DWARFYAML::emitDebugLine(*OS, DWARF);
-  else if (Name == ".debug_addr")
-    Err = DWARFYAML::emitDebugAddr(*OS, DWARF);
-  else if (Name == ".debug_abbrev")
-    Err = DWARFYAML::emitDebugAbbrev(*OS, DWARF);
-  else if (Name == ".debug_info")
-    Err = DWARFYAML::emitDebugInfo(*OS, DWARF);
-  else if (Name == ".debug_pubnames")
-    Err = DWARFYAML::emitDebugPubnames(*OS, DWARF);
-  else if (Name == ".debug_pubtypes")
-    Err = DWARFYAML::emitDebugPubtypes(*OS, DWARF);
-  else if (Name == ".debug_gnu_pubnames")
-    Err = DWARFYAML::emitDebugGNUPubnames(*OS, DWARF);
-  else if (Name == ".debug_gnu_pubtypes")
-    Err = DWARFYAML::emitDebugGNUPubtypes(*OS, DWARF);
-  else if (Name == ".debug_str_offsets")
-    Err = DWARFYAML::emitDebugStrOffsets(*OS, DWARF);
-  else if (Name == ".debug_rnglists")
-    Err = DWARFYAML::emitDebugRnglists(*OS, DWARF);
-  else
-    llvm_unreachable("unexpected emitDWARF() call");
-
-  if (Err)
     return std::move(Err);
 
   return CBA.tell() - BeginOffset;