[lld] r249512 - Create linker generated symbols earlier.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Tue Oct  6 21:51:44 2015
New Revision: 249512

URL: http://llvm.org/viewvc/llvm-project?rev=249512&view=rev
Log:
Create linker generated symbols earlier.

We were incorrectly deciding that a dynamic relocation was needed for them.

Modified:
    lld/trunk/ELF/SymbolTable.cpp
    lld/trunk/ELF/Writer.cpp
    lld/trunk/test/elf2/pre_init_fini_array.s

Modified: lld/trunk/ELF/SymbolTable.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.cpp?rev=249512&r1=249511&r2=249512&view=diff
==============================================================================
--- lld/trunk/ELF/SymbolTable.cpp (original)
+++ lld/trunk/ELF/SymbolTable.cpp Tue Oct  6 21:51:44 2015
@@ -105,6 +105,7 @@ void SymbolTable::addSyntheticSym(String
 }
 
 template <class ELFT> void SymbolTable::addIgnoredSym(StringRef Name) {
+  DefinedAbsolute<ELFT>::IgnoreUndef.setBinding(STB_WEAK);
   DefinedAbsolute<ELFT>::IgnoreUndef.setVisibility(STV_HIDDEN);
   auto Sym = new (Alloc)
       DefinedAbsolute<ELFT>(Name, DefinedAbsolute<ELFT>::IgnoreUndef);

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=249512&r1=249511&r2=249512&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Tue Oct  6 21:51:44 2015
@@ -292,6 +292,23 @@ template <class ELFT> void Writer<ELFT>:
   Map[{BssSec.getName(), BssSec.getType(), BssSec.getFlags()}] = &BssSec;
 
   SymbolTable &Symtab = SymTabSec.getSymTable();
+
+  // Declare linker generated symbols.
+  // This must be done before the relocation scan to make sure we can correctly
+  // decide if a dynamic relocation is needed or not.
+  // FIXME: Make this more declarative.
+  for (StringRef Name :
+       {"__preinit_array_start", "__preinit_array_end", "__init_array_start",
+        "__init_array_end", "__fini_array_start", "__fini_array_end"})
+    Symtab.addIgnoredSym<ELFT>(Name);
+
+  // __tls_get_addr is defined by the dynamic linker for dynamic ELFs. For
+  // static linking the linker is required to optimize away any references to
+  // __tls_get_addr, so it's not defined anywhere. Create a hidden definition
+  // to avoid the undefined symbol error.
+  if (!isOutputDynamic())
+    Symtab.addIgnoredSym<ELFT>("__tls_get_addr");
+
   for (const std::unique_ptr<ObjectFileBase> &FileB : Symtab.getObjectFiles()) {
     auto &File = cast<ObjectFile<ELFT>>(*FileB);
     if (!Config->DiscardAll) {
@@ -331,9 +348,6 @@ template <class ELFT> void Writer<ELFT>:
     if (OS) {
       Symtab.addSyntheticSym<ELFT>(Start, *OS, 0);
       Symtab.addSyntheticSym<ELFT>(End, *OS, OS->getSize());
-    } else {
-      Symtab.addIgnoredSym<ELFT>(Start);
-      Symtab.addIgnoredSym<ELFT>(End);
     }
   };
 
@@ -344,13 +358,6 @@ template <class ELFT> void Writer<ELFT>:
   AddStartEnd("__fini_array_start", "__fini_array_end",
               DynamicSec.FiniArraySec);
 
-  // __tls_get_addr is defined by the dynamic linker for dynamic ELFs. For
-  // static linking the linker is required to optimize away any references to
-  // __tls_get_addr, so it's not defined anywhere. Create a hidden definition
-  // to avoid the undefined symbol error.
-  if (!isOutputDynamic())
-    Symtab.addIgnoredSym<ELFT>("__tls_get_addr");
-
   // FIXME: Try to avoid the extra walk over all global symbols.
   std::vector<DefinedCommon<ELFT> *> CommonSymbols;
   for (auto &P : Symtab.getSymbols()) {

Modified: lld/trunk/test/elf2/pre_init_fini_array.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf2/pre_init_fini_array.s?rev=249512&r1=249511&r2=249512&view=diff
==============================================================================
--- lld/trunk/test/elf2/pre_init_fini_array.s (original)
+++ lld/trunk/test/elf2/pre_init_fini_array.s Tue Oct  6 21:51:44 2015
@@ -2,7 +2,7 @@
 // RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/shared.s -o %t2
 // RUN: lld -flavor gnu2 %t2 -o %t2.so -shared
 // RUN: lld -flavor gnu2 %t %t2.so -o %t2
-// RUN: llvm-readobj -symbols -sections -dynamic-table %t2 | FileCheck %s
+// RUN: llvm-readobj -r -symbols -sections -dynamic-table %t2 | FileCheck %s
 // RUN: llvm-objdump -d %t2 | FileCheck --check-prefix=DISASM %s
 // REQUIRES: x86
 
@@ -59,12 +59,15 @@ _start:
 // CHECK-NEXT: Offset:
 // CHECK-NEXT: Size: [[FINI_SIZE:.*]]
 
+// CHECK:      Relocations [
+// CHECK-NEXT: ]
+
 // CHECK:        Name: __fini_array_end
 // CHECK-NEXT:   Value: 0x1301B
 // CHECK-NEXT:   Size: 0
 // CHECK-NEXT:   Binding: Local
 // CHECK-NEXT:   Type: None
-// CHECK-NEXT:   Other: 0
+// CHECK-NEXT:   Other: 2
 // CHECK-NEXT:   Section: .fini_array
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
@@ -73,7 +76,7 @@ _start:
 // CHECK-NEXT:   Size: 0
 // CHECK-NEXT:   Binding: Local
 // CHECK-NEXT:   Type: None
-// CHECK-NEXT:   Other: 0
+// CHECK-NEXT:   Other: 2
 // CHECK-NEXT:   Section: .fini_array
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
@@ -82,7 +85,7 @@ _start:
 // CHECK-NEXT:   Size: 0
 // CHECK-NEXT:   Binding: Local
 // CHECK-NEXT:   Type: None
-// CHECK-NEXT:   Other: 0
+// CHECK-NEXT:   Other: 2
 // CHECK-NEXT:   Section: .init_array
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
@@ -91,7 +94,7 @@ _start:
 // CHECK-NEXT:   Size: 0
 // CHECK-NEXT:   Binding: Local
 // CHECK-NEXT:   Type: None
-// CHECK-NEXT:   Other: 0
+// CHECK-NEXT:   Other: 2
 // CHECK-NEXT:   Section: .init_array
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
@@ -100,7 +103,7 @@ _start:
 // CHECK-NEXT:   Size: 0
 // CHECK-NEXT:   Binding: Local
 // CHECK-NEXT:   Type: None
-// CHECK-NEXT:   Other: 0
+// CHECK-NEXT:   Other: 2
 // CHECK-NEXT:   Section: .preinit_array
 // CHECK-NEXT: }
 // CHECK-NEXT: Symbol {
@@ -109,7 +112,7 @@ _start:
 // CHECK-NEXT:   Size: 0
 // CHECK-NEXT:   Binding: Local
 // CHECK-NEXT:   Type: None
-// CHECK-NEXT:   Other: 0
+// CHECK-NEXT:   Other: 2
 // CHECK-NEXT:   Section: .preinit_array
 // CHECK-NEXT: }