[PATCH] D30224: [ELF] Insert linkerscript symbols directly into symbol table

[Petr Hosek via Phabricator via llvm-commits]

phosek created this revision.
phosek added a project: lld.

This change exposes the symbol table insert method and uses it to  insert the linkerscript defined symbols directly into the symbol table to avoid unnecessarily pulling the object out of an archive.

This change addresses PR32026.


Repository:
  rL LLVM

https://reviews.llvm.org/D30224

Files:
  ELF/LinkerScript.cpp
  ELF/SymbolTable.h
  test/ELF/linkerscript/Inputs/lazy-symbols.s
  test/ELF/linkerscript/lazy-symbols.s


Index: test/ELF/linkerscript/lazy-symbols.s
===================================================================
--- /dev/null
+++ test/ELF/linkerscript/lazy-symbols.s
@@ -0,0 +1,10 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %S/Inputs/lazy-symbols.s -o %t1
+# RUN: llvm-ar rcs %tar %t1
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t2
+# RUN: echo "foo = 1;" > %t.script
+# RUN: ld.lld %t2 %tar --script %t.script -o %tout
+# RUN: llvm-readobj -symbols %tout | FileCheck %s
+
+# CHECK: Name: foo
+# CHECK-NEXT: Value: 0x1
Index: test/ELF/linkerscript/Inputs/lazy-symbols.s
===================================================================
--- /dev/null
+++ test/ELF/linkerscript/Inputs/lazy-symbols.s
@@ -0,0 +1,7 @@
+.globl foo
+foo:
+ .long .Linfo_string
+
+.section .debug_str,"MS", at progbits,1
+.Linfo_string:
+  .asciz "foo"
Index: ELF/SymbolTable.h
===================================================================
--- ELF/SymbolTable.h
+++ ELF/SymbolTable.h
@@ -77,6 +77,11 @@
                     uint8_t Binding, uint8_t StOther, uint8_t Type,
                     InputFile *File);
 
+  std::pair<Symbol *, bool> insert(StringRef Name);
+  std::pair<Symbol *, bool> insert(StringRef Name, uint8_t Type,
+                                   uint8_t Visibility, bool CanOmitFromDynSym,
+                                   InputFile *File);
+
   void scanUndefinedFlags();
   void scanShlibUndefined();
   void scanVersionScript();
@@ -90,11 +95,6 @@
   std::vector<InputSectionBase<ELFT> *> Sections;
 
 private:
-  std::pair<Symbol *, bool> insert(StringRef Name);
-  std::pair<Symbol *, bool> insert(StringRef Name, uint8_t Type,
-                                   uint8_t Visibility, bool CanOmitFromDynSym,
-                                   InputFile *File);
-
   std::vector<SymbolBody *> findByVersion(SymbolVersion Ver);
   std::vector<SymbolBody *> findAllByVersion(SymbolVersion Ver);
 
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -57,27 +57,27 @@
 ScriptConfiguration *elf::ScriptConfig;
 
 template <class ELFT> static SymbolBody *addRegular(SymbolAssignment *Cmd) {
+  Symbol *Sym;
   uint8_t Visibility = Cmd->Hidden ? STV_HIDDEN : STV_DEFAULT;
-  Symbol *Sym = Symtab<ELFT>::X->addUndefined(
-      Cmd->Name, /*IsLocal=*/false, STB_GLOBAL, Visibility,
-      /*Type*/ 0,
-      /*CanOmitFromDynSym*/ false, /*File*/ nullptr);
-
+  std::tie(Sym, std::ignore) = Symtab<ELFT>::X->insert(
+      Cmd->Name, /*Type*/ 0, Visibility, /*CanOmitFromDynSym*/ false,
+      /*File*/ nullptr);
+  Sym->Binding = STB_GLOBAL;
   replaceBody<DefinedRegular<ELFT>>(Sym, Cmd->Name, /*IsLocal=*/false,
                                     Visibility, STT_NOTYPE, 0, 0, nullptr,
                                     nullptr);
   return Sym->body();
 }
 
 template <class ELFT> static SymbolBody *addSynthetic(SymbolAssignment *Cmd) {
+  Symbol *Sym;
   uint8_t Visibility = Cmd->Hidden ? STV_HIDDEN : STV_DEFAULT;
   const OutputSectionBase *Sec =
       ScriptConfig->HasSections ? nullptr : Cmd->Expression.Section();
-  Symbol *Sym = Symtab<ELFT>::X->addUndefined(
-      Cmd->Name, /*IsLocal=*/false, STB_GLOBAL, Visibility,
-      /*Type*/ 0,
-      /*CanOmitFromDynSym*/ false, /*File*/ nullptr);
-
+  std::tie(Sym, std::ignore) = Symtab<ELFT>::X->insert(
+      Cmd->Name, /*Type*/ 0, Visibility, /*CanOmitFromDynSym*/ false,
+      /*File*/ nullptr);
+  Sym->Binding = STB_GLOBAL;
   replaceBody<DefinedSynthetic>(Sym, Cmd->Name, 0, Sec);
   return Sym->body();
 }


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