[lld-macho] Move order file and call graph sorting into SectionPriorities

See https://reviews.llvm.org/D117354 for context and discussion.

lld/MachO/Driver.cpp

@@ -15,6 +15,7 @@
 #include "ObjC.h"
 #include "OutputSection.h"
 #include "OutputSegment.h"
+#include "SectionPriorities.h"
 #include "SymbolTable.h"
 #include "Symbols.h"
 #include "SyntheticSections.h"
@@ -460,60 +461,6 @@ static void addFileList(StringRef path, bool isLazy) {
 // entry (the one nearest to the front of the list.)
 //
 // The file can also have line comments that start with '#'.
-static void parseOrderFile(StringRef path) {
-  Optional<MemoryBufferRef> buffer = readFile(path);
-  if (!buffer) {
-    error("Could not read order file at " + path);
-    return;
-  }
-
-  MemoryBufferRef mbref = *buffer;
-  size_t priority = std::numeric_limits<size_t>::max();
-  for (StringRef line : args::getLines(mbref)) {
-    StringRef objectFile, symbol;
-    line = line.take_until([](char c) { return c == '#'; }); // ignore comments
-    line = line.ltrim();
-
-    CPUType cpuType = StringSwitch<CPUType>(line)
-                          .StartsWith("i386:", CPU_TYPE_I386)
-                          .StartsWith("x86_64:", CPU_TYPE_X86_64)
-                          .StartsWith("arm:", CPU_TYPE_ARM)
-                          .StartsWith("arm64:", CPU_TYPE_ARM64)
-                          .StartsWith("ppc:", CPU_TYPE_POWERPC)
-                          .StartsWith("ppc64:", CPU_TYPE_POWERPC64)
-                          .Default(CPU_TYPE_ANY);
-
-    if (cpuType != CPU_TYPE_ANY && cpuType != target->cpuType)
-      continue;
-
-    // Drop the CPU type as well as the colon
-    if (cpuType != CPU_TYPE_ANY)
-      line = line.drop_until([](char c) { return c == ':'; }).drop_front();
-
-    constexpr std::array<StringRef, 2> fileEnds = {".o:", ".o):"};
-    for (StringRef fileEnd : fileEnds) {
-      size_t pos = line.find(fileEnd);
-      if (pos != StringRef::npos) {
-        // Split the string around the colon
-        objectFile = line.take_front(pos + fileEnd.size() - 1);
-        line = line.drop_front(pos + fileEnd.size());
-        break;
-      }
-    }
-    symbol = line.trim();
-
-    if (!symbol.empty()) {
-      SymbolPriorityEntry &entry = config->priorities[symbol];
-      if (!objectFile.empty())
-        entry.objectFiles.insert(std::make_pair(objectFile, priority));
-      else
-        entry.anyObjectFile = std::max(entry.anyObjectFile, priority);
-    }
-
-    --priority;
-  }
-}
-
 // We expect sub-library names of the form "libfoo", which will match a dylib
 // with a path of .*/libfoo.{dylib, tbd}.
 // XXX ld64 seems to ignore the extension entirely when matching sub-libraries;
@@ -1081,25 +1028,6 @@ static void gatherInputSections() {
   assert(inputOrder <= UnspecifiedInputOrder);
 }
 
-static void extractCallGraphProfile() {
-  TimeTraceScope timeScope("Extract call graph profile");
-  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)
-        continue;
-      config->callGraphProfile[{fromSym->isec, toSym->isec}] += entry.count;
-    }
-  }
-}
-
 static void foldIdenticalLiterals() {
   // We always create a cStringSection, regardless of whether dedupLiterals is
   // true. If it isn't, we simply create a non-deduplicating CStringSection.

lld/MachO/SectionPriorities.cpp

@@ -16,14 +16,20 @@
 #include "InputFiles.h"
 #include "Symbols.h"
 #include "Target.h"
+#include "lld/Common/Args.h"
+#include "lld/Common/CommonLinkerContext.h"
 #include "lld/Common/ErrorHandler.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include <numeric>
 
 using namespace llvm;
+using namespace llvm::MachO;
+using namespace llvm::sys;
 using namespace lld;
 using namespace lld::macho;
 
@@ -241,12 +247,133 @@ DenseMap<const InputSection *, size_t> CallGraphSort::run() {
   return orderMap;
 }
 
+static size_t getSymbolPriority(const SymbolPriorityEntry &entry,
+                                const InputFile *f) {
+  // We don't use toString(InputFile *) here because it returns the full path
+  // for object files, and we only want the basename.
+  StringRef filename;
+  if (f->archiveName.empty())
+    filename = path::filename(f->getName());
+  else
+    filename = saver().save(path::filename(f->archiveName) + "(" +
+                            path::filename(f->getName()) + ")");
+  return std::max(entry.objectFiles.lookup(filename), entry.anyObjectFile);
+}
+
+void macho::extractCallGraphProfile() {
+  TimeTraceScope timeScope("Extract call graph profile");
+  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)
+        continue;
+      config->callGraphProfile[{fromSym->isec, toSym->isec}] += entry.count;
+    }
+  }
+}
+
+void macho::parseOrderFile(StringRef path) {
+  Optional<MemoryBufferRef> buffer = readFile(path);
+  if (!buffer) {
+    error("Could not read order file at " + path);
+    return;
+  }
+
+  MemoryBufferRef mbref = *buffer;
+  size_t priority = std::numeric_limits<size_t>::max();
+  for (StringRef line : args::getLines(mbref)) {
+    StringRef objectFile, symbol;
+    line = line.take_until([](char c) { return c == '#'; }); // ignore comments
+    line = line.ltrim();
+
+    CPUType cpuType = StringSwitch<CPUType>(line)
+                          .StartsWith("i386:", CPU_TYPE_I386)
+                          .StartsWith("x86_64:", CPU_TYPE_X86_64)
+                          .StartsWith("arm:", CPU_TYPE_ARM)
+                          .StartsWith("arm64:", CPU_TYPE_ARM64)
+                          .StartsWith("ppc:", CPU_TYPE_POWERPC)
+                          .StartsWith("ppc64:", CPU_TYPE_POWERPC64)
+                          .Default(CPU_TYPE_ANY);
+
+    if (cpuType != CPU_TYPE_ANY && cpuType != target->cpuType)
+      continue;
+
+    // Drop the CPU type as well as the colon
+    if (cpuType != CPU_TYPE_ANY)
+      line = line.drop_until([](char c) { return c == ':'; }).drop_front();
+
+    constexpr std::array<StringRef, 2> fileEnds = {".o:", ".o):"};
+    for (StringRef fileEnd : fileEnds) {
+      size_t pos = line.find(fileEnd);
+      if (pos != StringRef::npos) {
+        // Split the string around the colon
+        objectFile = line.take_front(pos + fileEnd.size() - 1);
+        line = line.drop_front(pos + fileEnd.size());
+        break;
+      }
+    }
+    symbol = line.trim();
+
+    if (!symbol.empty()) {
+      SymbolPriorityEntry &entry = config->priorities[symbol];
+      if (!objectFile.empty())
+        entry.objectFiles.insert(std::make_pair(objectFile, priority));
+      else
+        entry.anyObjectFile = std::max(entry.anyObjectFile, priority);
+    }
+
+    --priority;
+  }
+}
+
 // Sort sections by the profile data provided by __LLVM,__cg_profile sections.
 //
 // This first builds a call graph based on the profile data then merges sections
 // according to the C³ heuristic. All clusters are then sorted by a density
 // metric to further improve locality.
-DenseMap<const InputSection *, size_t> macho::computeCallGraphProfileOrder() {
+static DenseMap<const InputSection *, size_t> computeCallGraphProfileOrder() {
   TimeTraceScope timeScope("Call graph profile sort");
   return CallGraphSort().run();
 }
+
+// Each section gets assigned the priority of the highest-priority symbol it
+// contains.
+DenseMap<const InputSection *, size_t> macho::buildInputSectionPriorities() {
+  if (config->callGraphProfileSort)
+    return computeCallGraphProfileOrder();
+  DenseMap<const InputSection *, size_t> sectionPriorities;
+
+  if (config->priorities.empty())
+    return sectionPriorities;
+
+  auto addSym = [&](Defined &sym) {
+    if (sym.isAbsolute())
+      return;
+
+    auto it = config->priorities.find(sym.getName());
+    if (it == config->priorities.end())
+      return;
+
+    SymbolPriorityEntry &entry = it->second;
+    size_t &priority = sectionPriorities[sym.isec];
+    priority =
+        std::max(priority, getSymbolPriority(entry, sym.isec->getFile()));
+  };
+
+  // TODO: Make sure this handles weak symbols correctly.
+  for (const InputFile *file : inputFiles) {
+    if (isa<ObjFile>(file))
+      for (Symbol *sym : file->symbols)
+        if (auto *d = dyn_cast_or_null<Defined>(sym))
+          addSym(*d);
+  }
+
+  return sectionPriorities;
+}

lld/MachO/SectionPriorities.h

@@ -15,7 +15,40 @@
 namespace lld {
 namespace macho {
 
-llvm::DenseMap<const InputSection *, size_t> computeCallGraphProfileOrder();
+// Reads every input section's call graph profile, and combines them into
+// config->callGraphProfile. If an order file is present, any edges where one
+// or both of the vertices are specified in the order file are discarded.
+void extractCallGraphProfile();
+
+// Reads the order file at `path` into config->priorities.
+//
+// An order file has one entry per line, in the following format:
+//
+//   <cpu>:<object file>:<symbol name>
+//
+// <cpu> and <object file> are optional. If not specified, then that entry
+// matches any symbol of that name. Parsing this format is not quite
+// straightforward because the symbol name itself can contain colons, so when
+// encountering a colon, we consider the preceding characters to decide if it
+// can be a valid CPU type or file path.
+//
+// If a symbol is matched by multiple entries, then it takes the lowest-ordered
+// entry (the one nearest to the front of the list.)
+//
+// The file can also have line comments that start with '#'.
+void parseOrderFile(StringRef path);
+
+// Returns layout priorities for some or all input sections. Sections are laid
+// out in decreasing order; that is, a higher priority section will be closer
+// to the beginning of its output section.
+//
+// If either an order file or a call graph profile are present, this is used
+// as the source of priorities. If both are present, the order file takes
+// precedence. 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();
 } // namespace macho
 } // namespace lld
 

lld/MachO/Writer.cpp

@@ -849,54 +849,6 @@ template <class LP> void Writer::createLoadCommands() {
                               : 0));
 }
 
-static size_t getSymbolPriority(const SymbolPriorityEntry &entry,
-                                const InputFile *f) {
-  // We don't use toString(InputFile *) here because it returns the full path
-  // for object files, and we only want the basename.
-  StringRef filename;
-  if (f->archiveName.empty())
-    filename = path::filename(f->getName());
-  else
-    filename = saver().save(path::filename(f->archiveName) + "(" +
-                            path::filename(f->getName()) + ")");
-  return std::max(entry.objectFiles.lookup(filename), entry.anyObjectFile);
-}
-
-// Each section gets assigned the priority of the highest-priority symbol it
-// contains.
-static DenseMap<const InputSection *, size_t> buildInputSectionPriorities() {
-  if (config->callGraphProfileSort)
-    return computeCallGraphProfileOrder();
-  DenseMap<const InputSection *, size_t> sectionPriorities;
-
-  if (config->priorities.empty())
-    return sectionPriorities;
-
-  auto addSym = [&](Defined &sym) {
-    if (sym.isAbsolute())
-      return;
-
-    auto it = config->priorities.find(sym.getName());
-    if (it == config->priorities.end())
-      return;
-
-    SymbolPriorityEntry &entry = it->second;
-    size_t &priority = sectionPriorities[sym.isec];
-    priority =
-        std::max(priority, getSymbolPriority(entry, sym.isec->getFile()));
-  };
-
-  // TODO: Make sure this handles weak symbols correctly.
-  for (const InputFile *file : inputFiles) {
-    if (isa<ObjFile>(file))
-      for (Symbol *sym : file->symbols)
-        if (auto *d = dyn_cast_or_null<Defined>(sym))
-          addSym(*d);
-  }
-
-  return sectionPriorities;
-}
-
 // Sorting only can happen once all outputs have been collected. Here we sort
 // segments, output sections within each segment, and input sections within each
 // output segment.