[lld-macho][NFC] Encapsulate symbol priority implementation.

[Roger]

Summary

Just some code clean up.

[int3]

lgtm

lld/MachO/Config.h

 
 #include <vector>
 
 namespace lld {
 namespace macho {
 
 class InputSection;
 class Symbol;
-struct SymbolPriorityEntry;
 
 using NamePair = std::pair<llvm::StringRef, llvm::StringRef>;
 using SectionRenameMap = llvm::DenseMap<NamePair, NamePair>;
 using SegmentRenameMap = llvm::DenseMap<llvm::StringRef, llvm::StringRef>;
 
 struct PlatformInfo {
   llvm::MachO::Target target;
   llvm::VersionTuple minimum;
struct Configuration {
 
   llvm::MachO::Architecture arch() const { return platformInfo.target.Arch; }
 
   llvm::MachO::PlatformType platform() const {
     return platformInfo.target.Platform;
   }
 };
 
-// The symbol with the highest priority should be ordered first in the output
-// section (modulo input section contiguity constraints). Using priority
-// (highest first) instead of order (lowest first) has the convenient property
-// that the default-constructed zero priority -- for symbols/sections without a
-// user-defined order -- naturally ends up putting them at the end of the
-// output.
-struct SymbolPriorityEntry {
-  // The priority given to a matching symbol, regardless of which object file
-  // it originated from.
-  size_t anyObjectFile = 0;
-  // The priority given to a matching symbol from a particular object file.
-  llvm::DenseMap<llvm::StringRef, size_t> objectFiles;
-};
-
 // Whether to force-load an archive.
 enum class ForceLoad {
   Default, // Apply -all_load or -ObjC behaviors if those flags are enabled
   Yes,     // Always load the archive, regardless of other flags
   No,      // Never load the archive, regardless of other flags
 };
 
 extern std::unique_ptr<Configuration> config;
 
 } // namespace macho
 } // namespace lld
 
 #endif

lld/MachO/SectionPriorities.h

public:
   // precedence, but the call graph profile is still used for symbols that don't
   // appear in the order file. If neither is present, an empty map is returned.
   //
   // Each section gets assigned the priority of the highest-priority symbol it
   // contains.
   llvm::DenseMap<const InputSection *, size_t> buildInputSectionPriorities();
 
 private:
+  // The symbol with the highest priority should be ordered first in the output
+  // section (modulo input section contiguity constraints). Using priority
+  // (highest first) instead of order (lowest first) has the convenient property
+  // that the default-constructed zero priority -- for symbols/sections without
+  // a user-defined order -- naturally ends up putting them at the end of the
+  // output.
+  struct SymbolPriorityEntry {
+    // The priority given to a matching symbol, regardless of which object file
+    // it originated from.
+    size_t anyObjectFile = 0;
+    // The priority given to a matching symbol from a particular object file.
+    llvm::DenseMap<llvm::StringRef, size_t> objectFiles;
+  };
+
   llvm::Optional<size_t> getSymbolPriority(const Defined *sym);
   llvm::DenseMap<llvm::StringRef, SymbolPriorityEntry> priorities;
   llvm::MapVector<SectionPair, uint64_t> callGraphProfile;
 };
 
 extern PriorityBuilder priorityBuilder;
 } // namespace macho
 } // namespace lld
 
 #endif

lld/MachO/SectionPriorities.cpp

for (const InputFile *file : inputFiles) {
     auto *obj = dyn_cast_or_null<ObjFile>(file);
     if (!obj)
       continue;
     for (const CallGraphEntry &entry : obj->callGraph) {
       assert(entry.fromIndex < obj->symbols.size() &&
              entry.toIndex < obj->symbols.size());
       auto *fromSym = dyn_cast_or_null<Defined>(obj->symbols[entry.fromIndex]);
       auto *toSym = dyn_cast_or_null<Defined>(obj->symbols[entry.toIndex]);
-      if (!fromSym || !toSym ||
-          (hasOrderFile &&
-           (getSymbolPriority(fromSym) || getSymbolPriority(toSym))))
-        continue;
+      if (fromSym && toSym &&
+          (!hasOrderFile ||
+           (!getSymbolPriority(fromSym) && !getSymbolPriority(toSym))))
         callGraphProfile[{fromSym->isec, toSym->isec}] += entry.count;
     }
   }
 }
 
 void macho::PriorityBuilder::parseOrderFile(StringRef path) {
   assert(callGraphProfile.empty() &&
          "Order file must be parsed before call graph profile is processed");
   Optional<MemoryBufferRef> buffer = readFile(path);