From 2b714b56a9c8cf3a7ee6a2dbf9b7d03af331f2c2 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@google.com>
Date: Wed, 11 Oct 2017 03:12:53 +0000
Subject: [PATCH] Split decompressAndMergeSection into two separate functions.

Even though they are called sequentially, they are separate
operations, so it is better to split it.

llvm-svn: 315422
---
 lld/ELF/Driver.cpp            |  3 ++-
 lld/ELF/InputSection.cpp      |  5 +----
 lld/ELF/SyntheticSections.cpp | 37 +++++++++++++++++++++--------------
 lld/ELF/SyntheticSections.h   |  3 ++-
 4 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index b470f7094509..04c1c3fc504c 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -1107,7 +1107,8 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
   // Do size optimizations: garbage collection, merging of SHF_MERGE sections
   // and identical code folding.
   markLive<ELFT>();
-  decompressAndMergeSections();
+  decompressSections();
+  mergeSections();
   if (Config->ICF)
     doIcf<ELFT>();
 
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index b63c09a7ba78..32b946d32fbc 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -196,10 +196,7 @@ OutputSection *SectionBase::getOutputSection() {
 // Uncompress section contents if required. Note that this function
 // is called from parallelForEach, so it must be thread-safe.
 void InputSectionBase::maybeUncompress() {
-  if (UncompressBuf)
-    return;
-
-  if (!Decompressor::isCompressedELFSection(Flags, Name))
+  if (UncompressBuf || !Decompressor::isCompressedELFSection(Flags, Name))
     return;
 
   Decompressor Dec = check(Decompressor::create(Name, toStringRef(Data),
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index 1548749cde64..20d815ac216b 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -2305,21 +2305,28 @@ static MergeSyntheticSection *createMergeSynthetic(StringRef Name,
   return make<MergeNoTailSection>(Name, Type, Flags, Alignment);
 }
 
-// This function decompresses compressed sections and scans over the input
-// sections to create mergeable synthetic sections. It removes
-// MergeInputSections from the input section array and adds new synthetic
-// sections at the location of the first input section that it replaces. It then
-// finalizes each synthetic section in order to compute an output offset for
-// each piece of each input section.
-void elf::decompressAndMergeSections() {
-  // splitIntoPieces needs to be called on each MergeInputSection before calling
-  // finalizeContents(). Do that first.
-  parallelForEach(InputSections, [](InputSectionBase *S) {
-    if (!S->Live)
-      return;
-    S->maybeUncompress();
-    if (auto *MS = dyn_cast<MergeInputSection>(S))
-      MS->splitIntoPieces();
+// Debug sections may be compressed by zlib. Uncompress if exists.
+void elf::decompressSections() {
+  parallelForEach(InputSections, [](InputSectionBase *Sec) {
+    if (Sec->Live)
+      Sec->maybeUncompress();
+  });
+}
+
+// This function scans over the inputsections to create mergeable
+// synthetic sections.
+//
+// It removes MergeInputSections from the input section array and adds
+// new synthetic sections at the location of the first input section
+// that it replaces. It then finalizes each synthetic section in order
+// to compute an output offset for each piece of each input section.
+void elf::mergeSections() {
+  // splitIntoPieces needs to be called on each MergeInputSection
+  // before calling finalizeContents(). Do that first.
+  parallelForEach(InputSections, [](InputSectionBase *Sec) {
+    if (Sec->Live)
+      if (auto *S = dyn_cast<MergeInputSection>(Sec))
+        S->splitIntoPieces();
   });
 
   std::vector<MergeSyntheticSection *> MergeSections;
diff --git a/lld/ELF/SyntheticSections.h b/lld/ELF/SyntheticSections.h
index 9cc904a70d7f..c6a51ad33151 100644
--- a/lld/ELF/SyntheticSections.h
+++ b/lld/ELF/SyntheticSections.h
@@ -805,7 +805,8 @@ private:
 template <class ELFT> void createCommonSections();
 InputSection *createInterpSection();
 template <class ELFT> MergeInputSection *createCommentSection();
-void decompressAndMergeSections();
+void decompressSections();
+void mergeSections();
 
 SymbolBody *addSyntheticLocal(StringRef Name, uint8_t Type, uint64_t Value,
                               uint64_t Size, InputSectionBase *Section);
-- 
2.34.1