From 1f492893ac015ed6aae8427a6de4f30dd9d2feb8 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@google.com>
Date: Fri, 8 Apr 2016 20:49:31 +0000
Subject: [PATCH] Fix a crash bug in --start-lib.

Previously, Lazy symbols were created for undefined symbols even though
such symbols cannot be resolved by loading object files. This patch
fixes that bug.

llvm-svn: 265847
---
 lld/ELF/InputFiles.cpp           |  7 +++++--
 lld/test/ELF/Inputs/start-lib1.s |  3 +++
 lld/test/ELF/Inputs/start-lib2.s |  2 ++
 lld/test/ELF/start-lib.s         | 23 ++++++++++++++++-------
 4 files changed, 26 insertions(+), 9 deletions(-)
 create mode 100644 lld/test/ELF/Inputs/start-lib1.s
 create mode 100644 lld/test/ELF/Inputs/start-lib2.s

diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index 52b6d44..b8681e5 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -594,7 +594,8 @@ template <class ELFT> std::vector<StringRef> LazyObjectFile::getElfSymbols() {
     StringRef StringTable = check(Obj.getStringTableForSymtab(Sec));
     std::vector<StringRef> V;
     for (const Elf_Sym &Sym : Syms.slice(FirstNonLocal))
-      V.push_back(check(Sym.getName(StringTable)));
+      if (Sym.st_shndx != SHN_UNDEF)
+        V.push_back(check(Sym.getName(StringTable)));
     return V;
   }
   return {};
@@ -608,6 +609,8 @@ std::vector<StringRef> LazyObjectFile::getBitcodeSymbols() {
   for (const BasicSymbolRef &Sym : Obj->symbols()) {
     if (BitcodeFile::shouldSkip(Sym))
       continue;
+    if (Sym.getFlags() == BasicSymbolRef::SF_Undefined)
+      continue;
     SmallString<64> Name;
     raw_svector_ostream OS(Name);
     Sym.printName(OS);
@@ -616,7 +619,7 @@ std::vector<StringRef> LazyObjectFile::getBitcodeSymbols() {
   return V;
 }
 
-// Returns a vector of globally-visible symbol names.
+// Returns a vector of globally-visible defined symbol names.
 std::vector<StringRef> LazyObjectFile::getSymbols() {
   if (isBitcode(this->MB))
     return getBitcodeSymbols();
diff --git a/lld/test/ELF/Inputs/start-lib1.s b/lld/test/ELF/Inputs/start-lib1.s
new file mode 100644
index 0000000..d401b20
--- /dev/null
+++ b/lld/test/ELF/Inputs/start-lib1.s
@@ -0,0 +1,3 @@
+.globl foo
+foo:
+  call bar
diff --git a/lld/test/ELF/Inputs/start-lib2.s b/lld/test/ELF/Inputs/start-lib2.s
new file mode 100644
index 0000000..f500936
--- /dev/null
+++ b/lld/test/ELF/Inputs/start-lib2.s
@@ -0,0 +1,2 @@
+.globl bar
+bar:
diff --git a/lld/test/ELF/start-lib.s b/lld/test/ELF/start-lib.s
index caec1a5..013a2b2 100644
--- a/lld/test/ELF/start-lib.s
+++ b/lld/test/ELF/start-lib.s
@@ -2,15 +2,24 @@
 
 // RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1.o
 // RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
-// RUN:   %p/Inputs/whole-archive.s -o %t2.o
+// RUN:   %p/Inputs/start-lib1.s -o %t2.o
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
+// RUN:   %p/Inputs/start-lib2.s -o %t3.o
+
+// RUN: ld.lld -o %t3 %t1.o %t2.o %t3.o
+// RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=TEST1 %s
+// TEST1: Name: bar
+// TEST1: Name: foo
 
-// RUN: ld.lld -o %t3 %t1.o %t2.o
-// RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=ADDED %s
-// ADDED: Name: _bar
+// RUN: ld.lld -o %t3 %t1.o -u bar --start-lib %t2.o %t3.o
+// RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=TEST2 %s
+// TEST2: Name: bar
+// TEST2-NOT: Name: foo
 
-// RUN: ld.lld -o %t3 %t1.o --start-lib %t2.o
-// RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=LIB %s
-// LIB-NOT: Name: _bar
+// RUN: ld.lld -o %t3 %t1.o --start-lib %t2.o %t3.o
+// RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=TEST3 %s
+// TEST3-NOT: Name: bar
+// TEST3-NOT: Name: foo
 
 .globl _start
 _start:
-- 
2.7.4