[lld-macho] Parallelize __LINKEDIT generation

Benchmarking chromium_framework on a 3.2 GHz 16-Core Intel Xeon W Mac Pro:

      N           Min           Max        Median           Avg        Stddev
  x  20          4.33          4.42          4.37          4.37   0.021026299
  +  20          4.12          4.23          4.18         4.175   0.035318103
  Difference at 95.0% confidence
    -0.195 +/- 0.0186025
    -4.46224% +/- 0.425686%
    (Student's t, pooled s = 0.0290644)

Reviewed By: #lld-macho, gkm

Differential Revision: https://reviews.llvm.org/D99998

2 files changed, 21 insertions, 21 deletions

diff --git a/lld/MachO/SyntheticSections.h b/lld/MachO/SyntheticSections.h
index cf9e2cac95ab..eaad8aa3455f 100644
--- a/lld/MachO/SyntheticSections.h
+++ b/lld/MachO/SyntheticSections.h
@@ -56,6 +56,8 @@ public:
     align = target->wordSize;
   }
 
+  virtual void finalizeContents() {}
+
   // Sections in __LINKEDIT are special: their offsets are recorded in the
   // load commands like LC_DYLD_INFO_ONLY and LC_SYMTAB, instead of in section
   // headers.
@@ -155,7 +157,7 @@ struct Location {
 class RebaseSection : public LinkEditSection {
 public:
   RebaseSection();
-  void finalizeContents();
+  void finalizeContents() override;
   uint64_t getRawSize() const override { return contents.size(); }
   bool isNeeded() const override { return !locations.empty(); }
   void writeTo(uint8_t *buf) const override;
@@ -182,7 +184,7 @@ struct BindingEntry {
 class BindingSection : public LinkEditSection {
 public:
   BindingSection();
-  void finalizeContents();
+  void finalizeContents() override;
   uint64_t getRawSize() const override { return contents.size(); }
   bool isNeeded() const override { return !bindings.empty(); }
   void writeTo(uint8_t *buf) const override;
@@ -218,7 +220,7 @@ struct WeakBindingEntry {
 class WeakBindingSection : public LinkEditSection {
 public:
   WeakBindingSection();
-  void finalizeContents();
+  void finalizeContents() override;
   uint64_t getRawSize() const override { return contents.size(); }
   bool isNeeded() const override {
     return !bindings.empty() || !definitions.empty();
@@ -327,7 +329,7 @@ public:
 class LazyBindingSection : public LinkEditSection {
 public:
   LazyBindingSection();
-  void finalizeContents();
+  void finalizeContents() override;
   uint64_t getRawSize() const override { return contents.size(); }
   bool isNeeded() const override { return !entries.empty(); }
   void writeTo(uint8_t *buf) const override;
@@ -348,7 +350,7 @@ private:
 class ExportSection : public LinkEditSection {
 public:
   ExportSection();
-  void finalizeContents();
+  void finalizeContents() override;
   uint64_t getRawSize() const override { return size; }
   void writeTo(uint8_t *buf) const override;
 
@@ -362,7 +364,7 @@ private:
 class FunctionStartsSection : public LinkEditSection {
 public:
   FunctionStartsSection();
-  void finalizeContents();
+  void finalizeContents() override;
   uint64_t getRawSize() const override { return contents.size(); }
   void writeTo(uint8_t *buf) const override;
 
@@ -411,7 +413,7 @@ struct StabsEntry {
 // range (start index and total number) of those symbols in the symbol table.
 class SymtabSection : public LinkEditSection {
 public:
-  void finalizeContents();
+  void finalizeContents() override;
   uint32_t getNumSymbols() const;
   uint32_t getNumLocalSymbols() const {
     return stabs.size() + localSymbols.size();
@@ -453,7 +455,7 @@ template <class LP> SymtabSection *makeSymtabSection(StringTableSection &);
 class IndirectSymtabSection : public LinkEditSection {
 public:
   IndirectSymtabSection();
-  void finalizeContents();
+  void finalizeContents() override;
   uint32_t getNumSymbols() const;
   uint64_t getRawSize() const override {
     return getNumSymbols() * sizeof(uint32_t);
diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp
index f37322bb3ca4..8b10e176bf89 100644
--- a/lld/MachO/Writer.cpp
+++ b/lld/MachO/Writer.cpp
@@ -51,7 +51,7 @@ public:
   void scanSymbols();
   template <class LP> void createOutputSections();
   template <class LP> void createLoadCommands();
-  void finalizeAddressses();
+  void finalizeAddresses();
   void finalizeLinkEditSegment();
   void assignAddresses(OutputSegment *);
 
@@ -852,7 +852,7 @@ template <class LP> void Writer::createOutputSections() {
   linkEditSegment = getOrCreateOutputSegment(segment_names::linkEdit);
 }
 
-void Writer::finalizeAddressses() {
+void Writer::finalizeAddresses() {
   TimeTraceScope timeScope("Finalize addresses");
   // Ensure that segments (and the sections they contain) are allocated
   // addresses in ascending order, which dyld requires.
@@ -870,16 +870,14 @@ void Writer::finalizeAddressses() {
 void Writer::finalizeLinkEditSegment() {
   TimeTraceScope timeScope("Finalize __LINKEDIT segment");
   // Fill __LINKEDIT contents.
-  in.rebase->finalizeContents();
-  in.binding->finalizeContents();
-  in.weakBinding->finalizeContents();
-  in.lazyBinding->finalizeContents();
-  in.exports->finalizeContents();
-  symtabSection->finalizeContents();
-  indirectSymtabSection->finalizeContents();
-
-  if (functionStartsSection)
-    functionStartsSection->finalizeContents();
+  std::vector<LinkEditSection *> linkEditSections{
+      in.rebase,  in.binding,    in.weakBinding,        in.lazyBinding,
+      in.exports, symtabSection, indirectSymtabSection, functionStartsSection,
+  };
+  parallelForEach(linkEditSections, [](LinkEditSection *osec) {
+    if (osec)
+      osec->finalizeContents();
+  });
 
   // Now that __LINKEDIT is filled out, do a proper calculation of its
   // addresses and offsets.
@@ -972,7 +970,7 @@ template <class LP> void Writer::run() {
   // No more sections nor segments are created beyond this point.
   sortSegmentsAndSections();
   createLoadCommands<LP>();
-  finalizeAddressses();
+  finalizeAddresses();
   finalizeLinkEditSegment();
   writeMapFile();
   writeOutputFile();