[lld] r306292 - Add GlobalOffsetTable to ElfSym. NFC.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Mon Jun 26 08:11:24 2017
New Revision: 306292

URL: http://llvm.org/viewvc/llvm-project?rev=306292&view=rev
Log:
Add GlobalOffsetTable to ElfSym. NFC.

Most "reserved" symbols are in ElfSym and it looks like there's no
reason to not do the same thing for _GLOBAL_OFFSET_TABLE_. This should
help https://reviews.llvm.org/D34618 too.

Modified:
    lld/trunk/ELF/Symbols.cpp
    lld/trunk/ELF/Symbols.h
    lld/trunk/ELF/Writer.cpp

Modified: lld/trunk/ELF/Symbols.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.cpp?rev=306292&r1=306291&r2=306292&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.cpp (original)
+++ lld/trunk/ELF/Symbols.cpp Mon Jun 26 08:11:24 2017
@@ -35,6 +35,7 @@ DefinedRegular *ElfSym::Edata1;
 DefinedRegular *ElfSym::Edata2;
 DefinedRegular *ElfSym::End1;
 DefinedRegular *ElfSym::End2;
+DefinedRegular *ElfSym::GlobalOffsetTable;
 DefinedRegular *ElfSym::MipsGp;
 DefinedRegular *ElfSym::MipsGpDisp;
 DefinedRegular *ElfSym::MipsLocalGp;

Modified: lld/trunk/ELF/Symbols.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.h?rev=306292&r1=306291&r2=306292&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.h (original)
+++ lld/trunk/ELF/Symbols.h Mon Jun 26 08:11:24 2017
@@ -318,6 +318,11 @@ struct ElfSym {
   static DefinedRegular *End1;
   static DefinedRegular *End2;
 
+  // The _GLOBAL_OFFSET_TABLE_ symbol is defined by target convention to
+  // be at some offset from the base of the .got section, usually 0 or
+  // the end of the .got.
+  static DefinedRegular *GlobalOffsetTable;
+
   // _gp, _gp_disp and __gnu_local_gp symbols. Only for MIPS.
   static DefinedRegular *MipsGp;
   static DefinedRegular *MipsGpDisp;

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=306292&r1=306291&r2=306292&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Mon Jun 26 08:11:24 2017
@@ -820,10 +820,10 @@ template <class ELFT> void Writer<ELFT>:
   // The _GLOBAL_OFFSET_TABLE_ symbol is defined by target convention to
   // be at some offset from the base of the .got section, usually 0 or the end
   // of the .got
-  InputSection *GotSection = (InX::MipsGot) ? cast<InputSection>(InX::MipsGot)
-                                            : cast<InputSection>(InX::Got);
-  HasGotBaseSym = addOptionalRegular<ELFT>("_GLOBAL_OFFSET_TABLE_", GotSection,
-                                           Target->GotBaseSymOff) != nullptr;
+  InputSection *GotSection = InX::MipsGot ? cast<InputSection>(InX::MipsGot)
+                                          : cast<InputSection>(InX::Got);
+  ElfSym::GlobalOffsetTable = addOptionalRegular<ELFT>(
+      "_GLOBAL_OFFSET_TABLE_", GotSection, Target->GotBaseSymOff);
 
   // __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
@@ -1132,8 +1132,7 @@ static void applySynthetic(const std::ve
 // to make them visible from linkescript side. But not all sections are always
 // required to be in output. For example we don't need dynamic section content
 // sometimes. This function filters out such unused sections from the output.
-static void removeUnusedSyntheticSections(std::vector<OutputSection *> &V,
-                                          bool HasGotBaseSym) {
+static void removeUnusedSyntheticSections(std::vector<OutputSection *> &V) {
   // All input synthetic sections that can be empty are placed after
   // all regular ones. We iterate over them all and exit at first
   // non-synthetic.
@@ -1144,7 +1143,7 @@ static void removeUnusedSyntheticSection
     OutputSection *OS = SS->getParent();
     if (!SS->empty() || !OS)
       continue;
-    if ((SS == InX::Got || SS == InX::MipsGot) && HasGotBaseSym)
+    if ((SS == InX::Got || SS == InX::MipsGot) && ElfSym::GlobalOffsetTable)
       continue;
     OS->Sections.erase(std::find(OS->Sections.begin(), OS->Sections.end(), SS));
     SS->Live = false;
@@ -1219,7 +1218,7 @@ template <class ELFT> void Writer<ELFT>:
     return;
 
   addPredefinedSections();
-  removeUnusedSyntheticSections(OutputSections, HasGotBaseSym);
+  removeUnusedSyntheticSections(OutputSections);
 
   clearOutputSections();
   sortSections();