From f1652d4c60291c20b153915cf334bf323cd82df5 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Fri, 27 Apr 2018 18:17:36 +0000
Subject: [PATCH] Split .eh_frame sections in parellel.

We can now split them in the same spot we split merge sections.

llvm-svn: 331064
---
 lld/ELF/Driver.cpp            |  2 +-
 lld/ELF/InputSection.cpp      |  4 ----
 lld/ELF/MarkLive.cpp          |  4 ----
 lld/ELF/SyntheticSections.cpp | 13 ++++++++-----
 lld/ELF/SyntheticSections.h   |  2 +-
 5 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 2c29c51..bcf4eeb 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -1304,7 +1304,7 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
   // Do size optimizations: garbage collection, merging of SHF_MERGE sections
   // and identical code folding.
   decompressSections();
-  splitSections();
+  splitSections<ELFT>();
   markLive<ELFT>();
   demoteSymbols<ELFT>();
   mergeSections();
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 7b64621a..9612c29 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -836,10 +836,6 @@ static unsigned getReloc(IntTy Begin, IntTy Size, const ArrayRef<RelTy> &Rels,
 // .eh_frame is a sequence of CIE or FDE records.
 // This function splits an input section into records and returns them.
 template <class ELFT> void EhInputSection::split() {
-  // Early exit if already split.
-  if (!Pieces.empty())
-    return;
-
   if (AreRelocsRela)
     split<ELFT>(relas<ELFT>());
   else
diff --git a/lld/ELF/MarkLive.cpp b/lld/ELF/MarkLive.cpp
index d7cc74e..afdb69e 100644
--- a/lld/ELF/MarkLive.cpp
+++ b/lld/ELF/MarkLive.cpp
@@ -159,10 +159,6 @@ scanEhFrameSection(EhInputSection &EH,
   if (!EH.NumRelocations)
     return;
 
-  // Unfortunately we need to split .eh_frame early since some relocations in
-  // .eh_frame keep other section alive and some don't.
-  EH.split<ELFT>();
-
   if (EH.AreRelocsRela)
     scanEhFrameSection<ELFT>(EH, EH.template relas<ELFT>(), Fn);
   else
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index 306bee4..6f91a64 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -460,10 +460,6 @@ template <class ELFT> void EhFrameSection::addSection(InputSectionBase *C) {
   for (auto *DS : Sec->DependentSections)
     DependentSections.push_back(DS);
 
-  // .eh_frame is a sequence of CIE or FDE records. This function
-  // splits it into pieces so that we can call
-  // SplitInputSection::getSectionPiece on the section.
-  Sec->split<ELFT>();
   if (Sec->Pieces.empty())
     return;
 
@@ -2540,12 +2536,14 @@ void elf::decompressSections() {
                   [](InputSectionBase *Sec) { Sec->maybeDecompress(); });
 }
 
-void elf::splitSections() {
+template <class ELFT> void elf::splitSections() {
   // splitIntoPieces needs to be called on each MergeInputSection
   // before calling finalizeContents().
   parallelForEach(InputSections, [](InputSectionBase *Sec) {
     if (auto *S = dyn_cast<MergeInputSection>(Sec))
       S->splitIntoPieces();
+    else if (auto *Eh = dyn_cast<EhInputSection>(Sec))
+      Eh->split<ELFT>();
   });
 }
 
@@ -2702,6 +2700,11 @@ template GdbIndexSection *elf::createGdbIndex<ELF32BE>();
 template GdbIndexSection *elf::createGdbIndex<ELF64LE>();
 template GdbIndexSection *elf::createGdbIndex<ELF64BE>();
 
+template void elf::splitSections<ELF32LE>();
+template void elf::splitSections<ELF32BE>();
+template void elf::splitSections<ELF64LE>();
+template void elf::splitSections<ELF64BE>();
+
 template void EhFrameSection::addSection<ELF32LE>(InputSectionBase *);
 template void EhFrameSection::addSection<ELF32BE>(InputSectionBase *);
 template void EhFrameSection::addSection<ELF64LE>(InputSectionBase *);
diff --git a/lld/ELF/SyntheticSections.h b/lld/ELF/SyntheticSections.h
index bd442a5..f27b91b 100644
--- a/lld/ELF/SyntheticSections.h
+++ b/lld/ELF/SyntheticSections.h
@@ -834,7 +834,7 @@ private:
 InputSection *createInterpSection();
 MergeInputSection *createCommentSection();
 void decompressSections();
-void splitSections();
+template <class ELFT> void splitSections();
 void mergeSections();
 
 Defined *addSyntheticLocal(StringRef Name, uint8_t Type, uint64_t Value,
-- 
2.7.4