From 53e9be1b70a83f0af0d10e56ffcbc0f2811ca7c2 Mon Sep 17 00:00:00 2001
From: Mike Hommey <mh+mozilla@glandium.org>
Date: Tue, 23 Jul 2013 07:26:08 +0900
Subject: [PATCH] Bug 894829 - Avoid symbol resolution for relocations for the
 same symbol in faulty.lib. r=nfroyd

---
 mozglue/linker/CustomElf.cpp | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/mozglue/linker/CustomElf.cpp b/mozglue/linker/CustomElf.cpp
index 8df6c596c65..b9e83d955d5 100644
--- a/mozglue/linker/CustomElf.cpp
+++ b/mozglue/linker/CustomElf.cpp
@@ -637,6 +637,8 @@ bool
 CustomElf::Relocate()
 {
   DEBUG_LOG("Relocate %s @%p", GetPath(), static_cast<void *>(base));
+  uint32_t symtab_index = (uint32_t) -1;
+  void *symptr = NULL;
   for (Array<Reloc>::iterator rel = relocations.begin();
        rel < relocations.end(); ++rel) {
     /* Location of the relocation */
@@ -648,15 +650,16 @@ CustomElf::Relocate()
       continue;
     }
     /* Other relocation types need a symbol resolution */
-    const Sym sym = symtab[ELF_R_SYM(rel->r_info)];
-    void *symptr;
-    if (sym.st_shndx != SHN_UNDEF) {
-      symptr = GetPtr(sym.st_value);
-    } else {
-      /* TODO: avoid symbol resolution when it's the same symbol as last
-       * iteration */
-      /* TODO: handle symbol resolving to NULL vs. being undefined. */
-      symptr = GetSymbolPtrInDeps(strtab.GetStringAt(sym.st_name));
+    /* Avoid symbol resolution when it's the same symbol as last iteration */
+    if (symtab_index != ELF_R_SYM(rel->r_info)) {
+      symtab_index = ELF_R_SYM(rel->r_info);
+      const Sym sym = symtab[symtab_index];
+      if (sym.st_shndx != SHN_UNDEF) {
+        symptr = GetPtr(sym.st_value);
+      } else {
+        /* TODO: handle symbol resolving to NULL vs. being undefined. */
+        symptr = GetSymbolPtrInDeps(strtab.GetStringAt(sym.st_name));
+      }
     }
 
     if (symptr == NULL)