[PATCH] D13169: [ELF2] - Implemented --allow-multiple-definition flag

[George Rimar via llvm-commits]

grimar created this revision.
grimar added reviewers: ruiu, rui314, rafael.
grimar added subscribers: llvm-commits, grimar.
grimar added a project: lld.

Implementation of --allow-multiple-definition flag

For tests I created 2 functions with the same name but different first instruction. Then checking that order of files in linker cmd line affects on which one is used.
Should anything else be checked ?

http://reviews.llvm.org/D13169

Files:
  ELF/Config.h
  ELF/Driver.cpp
  ELF/Options.td
  ELF/SymbolTable.cpp
  test/elf2/Inputs/muldefs.s
  test/elf2/allow-multiple-definition.s

Index: test/elf2/allow-multiple-definition.s
===================================================================
--- test/elf2/allow-multiple-definition.s
+++ test/elf2/allow-multiple-definition.s
@@ -0,0 +1,29 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/muldefs.s -o %t2
+# RUN: not lld -flavor gnu2 %t %t1 %t2 -o %t3
+# RUN: lld -flavor gnu2 --allow-multiple-definition %t %t1 %t2 -o %t3
+# RUN: lld -flavor gnu2 --allow-multiple-definition %t %t2 %t1 -o %t4
+# RUN: llvm-objdump -d %t3 | FileCheck %s
+# RUN: llvm-objdump -d %t4 | FileCheck -check-prefix=REVERT %s
+
+# inputs contain different constants for instuction movl.
+# Tests below checks that order of files in command line 
+# affects on what symbol will be used.
+# If flag allow-multiple-definition is enabled the first 
+# meet symbol should be used.
+
+# CHECK: _bar:
+# CHECK-NEXT: 11008:   b8 01 00 00 00   movl   $1, %eax
+
+# REVERT: _bar:
+# REVERT-NEXT: 11008:   b8 02 00 00 00   movl   $2, %eax
+
+.globl _bar
+.type _bar, @function
+_bar:
+  mov $1, %eax
+  
+.globl _start;
+_start:  
Index: test/elf2/Inputs/muldefs.s
===================================================================
--- test/elf2/Inputs/muldefs.s
+++ test/elf2/Inputs/muldefs.s
@@ -0,0 +1,4 @@
+.globl _bar
+.type _bar, @function
+_bar:
+  mov $2, %eax
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -137,8 +137,13 @@
       NewFile = F.get();
   }
 
-  error(Twine("duplicate symbol: ") + Old.getName() + " in " +
-        OldFile->getName() + " and " + NewFile->getName());
+  const std::string Message = "duplicate symbol: " + Old.getName().str() +
+                              " in " + OldFile->getName().str() + " and " +
+                              NewFile->getName().str();
+  if (Config->AllowMultipleDefinition)
+    warning(Message);
+  else
+    error(Message);
 }
 
 // This function resolves conflicts if there's an existing symbol with
Index: ELF/Options.td
===================================================================
--- ELF/Options.td
+++ ELF/Options.td
@@ -33,3 +33,6 @@
 
 def export_dynamic : Flag<["--"], "export-dynamic">,
      HelpText<"Put symbols in the dynamic symbol table">;
+
+def allow_multiple_definition: Flag<["--"], "allow-multiple-definition">,
+    HelpText<"Allow multiple definitions">;
Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -94,6 +94,9 @@
   if (Args.hasArg(OPT_export_dynamic))
     Config->ExportDynamic = true;
 
+  if (Args.hasArg(OPT_allow_multiple_definition))
+    Config->AllowMultipleDefinition = true;
+
   // Create a list of input files.
   std::vector<MemoryBufferRef> Inputs;
 
Index: ELF/Config.h
===================================================================
--- ELF/Config.h
+++ ELF/Config.h
@@ -24,6 +24,7 @@
   bool DiscardLocals = false;
   bool DiscardNone = false;
   bool ExportDynamic = false;
+  bool AllowMultipleDefinition = false;
 };
 
 extern Configuration *Config;


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