From e5d3ca50318f2449a5dc9820a1012903ffb03824 Mon Sep 17 00:00:00 2001
From: Petr Hosek <phosek@chromium.org>
Date: Wed, 31 Aug 2016 15:31:17 +0000
Subject: [PATCH] [ELF] Linkerscript: define symbols outside SECTIONS

Symbol assignments outside of SECTIONS command need to be created
even when SECTIONS command is not used.

Differential Revision: https://reviews.llvm.org/D23751

llvm-svn: 280252
---
 lld/ELF/LinkerScript.cpp                      | 22 +++++++++++++++----
 lld/ELF/LinkerScript.h                        |  3 +++
 lld/ELF/Writer.cpp                            |  2 ++
 .../ELF/linkerscript/linkerscript-symbols.s   |  9 ++++++++
 4 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index e1a99b10a95d..940323301856 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -258,6 +258,16 @@ LinkerScript<ELFT>::createInputSectionList(OutputSectionCommand &OutCmd) {
   return Ret;
 }
 
+template <class ELFT>
+void LinkerScript<ELFT>::createAssignments() {
+  for (const std::unique_ptr<SymbolAssignment> &Cmd : Opt.Assignments) {
+    if (shouldDefine<ELFT>(Cmd.get()))
+      addRegular<ELFT>(Cmd.get());
+    if (Cmd->Sym)
+      cast<DefinedRegular<ELFT>>(Cmd->Sym)->Value = Cmd->Expression(0);
+  }
+}
+
 template <class ELFT>
 void LinkerScript<ELFT>::createSections(OutputSectionFactory<ELFT> &Factory) {
   for (const std::unique_ptr<BaseCommand> &Base1 : Opt.Commands) {
@@ -714,12 +724,16 @@ void ScriptParser::readVersionScript() {
 void ScriptParser::readLinkerScript() {
   while (!atEOF()) {
     StringRef Tok = next();
-    if (Handler Fn = Cmd.lookup(Tok))
+    if (Handler Fn = Cmd.lookup(Tok)) {
       (this->*Fn)();
-    else if (SymbolAssignment *Cmd = readProvideOrAssignment(Tok))
-      Opt.Commands.emplace_back(Cmd);
-    else
+    } else if (SymbolAssignment *Cmd = readProvideOrAssignment(Tok)) {
+      if (Opt.HasContents)
+        Opt.Commands.emplace_back(Cmd);
+      else
+        Opt.Assignments.emplace_back(Cmd);
+    } else {
       setError("unknown directive: " + Tok);
+    }
   }
 }
 
diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h
index f08bd0762b5f..a866470fa034 100644
--- a/lld/ELF/LinkerScript.h
+++ b/lld/ELF/LinkerScript.h
@@ -118,6 +118,8 @@ struct PhdrsCommand {
 
 // ScriptConfiguration holds linker script parse results.
 struct ScriptConfiguration {
+  // Used to create symbol assignments outside SECTIONS command.
+  std::vector<std::unique_ptr<SymbolAssignment>> Assignments;
   // Used to assign addresses to sections.
   std::vector<std::unique_ptr<BaseCommand>> Commands;
 
@@ -142,6 +144,7 @@ template <class ELFT> class LinkerScript {
 public:
   LinkerScript();
   ~LinkerScript();
+  void createAssignments();
   void createSections(OutputSectionFactory<ELFT> &Factory);
 
   std::vector<PhdrEntry<ELFT>> createPhdrs();
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index a3c59d45261a..3475de80279d 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -249,6 +249,8 @@ template <class ELFT> void Writer<ELFT>::run() {
   CommonInputSection<ELFT> Common(getCommonSymbols<ELFT>());
   CommonInputSection<ELFT>::X = &Common;
 
+  Script<ELFT>::X->createAssignments();
+
   Script<ELFT>::X->OutputSections = &OutputSections;
   if (ScriptConfig->HasContents)
     Script<ELFT>::X->createSections(Factory);
diff --git a/lld/test/ELF/linkerscript/linkerscript-symbols.s b/lld/test/ELF/linkerscript/linkerscript-symbols.s
index 8136b5fd5c51..f8b0a31e3b93 100644
--- a/lld/test/ELF/linkerscript/linkerscript-symbols.s
+++ b/lld/test/ELF/linkerscript/linkerscript-symbols.s
@@ -67,6 +67,15 @@
 # RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=HIDDEN5 %s
 # HIDDEN5: 0000000000000000         *ABS*    00000000 somesym
 
+# Simple symbol assignment. All three symbols should have the
+# same value.
+# RUN: echo "foo = 0x100; SECTIONS { bar = foo; } baz = bar;" > %t.script
+# RUN: ld.lld -o %t1 --script %t.script %t
+# RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=SIMPLE2 %s
+# SIMPLE2: 0000000000000100         *ABS*    00000000 foo
+# SIMPLE2: 0000000000000100         *ABS*    00000000 bar
+# SIMPLE2: 0000000000000100         *ABS*    00000000 baz
+
 .global _start
 _start:
  nop