From 116d83fbe0e505f56adc217243c64781e73e3f30 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Wed, 19 Oct 2016 23:13:40 +0000
Subject: [PATCH] Don't call markLiveAt for non alloc sections.

We don't gc them anyway, so just use an early return in Enqueue.

llvm-svn: 284663
---
 lld/ELF/InputSection.cpp |  3 ++-
 lld/ELF/InputSection.h   |  5 ++++-
 lld/ELF/MarkLive.cpp     | 11 ++++++-----
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 76795a24ac62..ff91463a8fe0 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -53,7 +53,8 @@ InputSectionBase<ELFT>::InputSectionBase(elf::ObjectFile<ELFT> *File,
                                          const Elf_Shdr *Hdr, StringRef Name,
                                          Kind SectionKind)
     : InputSectionData(SectionKind, Name, getSectionContents(File, Hdr),
-                       isCompressed<ELFT>(Hdr, Name), !Config->GcSections),
+                       isCompressed<ELFT>(Hdr, Name),
+                       !Config->GcSections || !(Hdr->sh_flags & SHF_ALLOC)),
       Header(Hdr), File(File), Repl(this) {
   // The ELF spec states that a value of 0 means the section has
   // no alignment constraits.
diff --git a/lld/ELF/InputSection.h b/lld/ELF/InputSection.h
index 3fd89bd8ec89..fcac34c1b0a0 100644
--- a/lld/ELF/InputSection.h
+++ b/lld/ELF/InputSection.h
@@ -167,7 +167,10 @@ public:
   void splitIntoPieces();
 
   // Mark the piece at a given offset live. Used by GC.
-  void markLiveAt(uintX_t Offset) { LiveOffsets.insert(Offset); }
+  void markLiveAt(uintX_t Offset) {
+    assert(this->getSectionHdr()->sh_flags & llvm::ELF::SHF_ALLOC);
+    LiveOffsets.insert(Offset);
+  }
 
   // Translate an offset in the input section to an offset
   // in the output section.
diff --git a/lld/ELF/MarkLive.cpp b/lld/ELF/MarkLive.cpp
index 847575711d21..452fc29ab911 100644
--- a/lld/ELF/MarkLive.cpp
+++ b/lld/ELF/MarkLive.cpp
@@ -201,6 +201,10 @@ template <class ELFT> void elf::markLive() {
     if (!R.Sec || R.Sec == &InputSection<ELFT>::Discarded)
       return;
 
+    // We don't gc non alloc sections.
+    if (!(R.Sec->getSectionHdr()->sh_flags & SHF_ALLOC))
+      return;
+
     // Usually, a whole section is marked as live or dead, but in mergeable
     // (splittable) sections, each piece of data has independent liveness bit.
     // So we explicitly tell it which offset is in use.
@@ -210,12 +214,9 @@ template <class ELFT> void elf::markLive() {
     if (R.Sec->Live)
       return;
     R.Sec->Live = true;
-    // Add input section to the queue. We don't want to consider relocations
-    // from non-allocatable input sections, because we can bring those
-    // allocatable sections to living which otherwise would be dead.
+    // Add input section to the queue.
     if (InputSection<ELFT> *S = dyn_cast<InputSection<ELFT>>(R.Sec))
-      if (S->getSectionHdr()->sh_flags & SHF_ALLOC)
-        Q.push_back(S);
+      Q.push_back(S);
   };
 
   auto MarkSymbol = [&](const SymbolBody *Sym) {