[lld] e3ecc6a - [ELF] Make symAux[0] a sentinel

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2022-09-29T00:50:19-07:00
New Revision: e3ecc6a91241affd1d93615e0c9569794b016a00

URL: https://github.com/llvm/llvm-project/commit/e3ecc6a91241affd1d93615e0c9569794b016a00
DIFF: https://github.com/llvm/llvm-project/commit/e3ecc6a91241affd1d93615e0c9569794b016a00.diff

LOG: [ELF] Make symAux[0] a sentinel

And default auxIdx to 0.

Added: 
    

Modified: 
    lld/ELF/Driver.cpp
    lld/ELF/InputFiles.cpp
    lld/ELF/Relocations.cpp
    lld/ELF/SymbolTable.cpp
    lld/ELF/Symbols.h
    lld/ELF/SyntheticSections.cpp

Removed: 
    


################################################################################
diff  --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 74b16e016791a..d5e9e8f017d25 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -118,6 +118,8 @@ bool elf::link(ArrayRef<const char *> args, llvm::raw_ostream &stdoutOS,
   script = std::make_unique<LinkerScript>();
   symtab = std::make_unique<SymbolTable>();
 
+  symAux.emplace_back();
+
   partitions.clear();
   partitions.emplace_back();
 

diff  --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index 2f2d40ba800dc..d5faefe64fde6 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -1131,7 +1131,6 @@ void ObjFile<ELFT>::initSectionsAndLocalSyms(bool ignoreComdats) {
                                eSym.st_value, eSym.st_size, sec);
     symbols[i]->partition = 1;
     symbols[i]->isUsedInRegularObj = true;
-    symbols[i]->auxIdx = -1;
   }
 }
 

diff  --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index 6590d9184802a..e2e7a5ee79eb8 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -1748,7 +1748,7 @@ void elf::postScanRelocations() {
           {R_ADDEND, target->symbolicRel, in.got->getTlsIndexOff(), 1, &dummy});
   }
 
-  assert(symAux.empty());
+  assert(symAux.size() == 1);
   for (Symbol *sym : symtab->getSymbols())
     fn(*sym);
 

diff  --git a/lld/ELF/SymbolTable.cpp b/lld/ELF/SymbolTable.cpp
index baa085c9c7133..7852127c895da 100644
--- a/lld/ELF/SymbolTable.cpp
+++ b/lld/ELF/SymbolTable.cpp
@@ -91,7 +91,6 @@ Symbol *SymbolTable::insert(StringRef name) {
   memset(sym, 0, sizeof(Symbol));
   sym->setName(name);
   sym->partition = 1;
-  sym->auxIdx = -1;
   sym->verdefIndex = -1;
   sym->versionId = VER_NDX_GLOBAL;
   if (pos != StringRef::npos)

diff  --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h
index 6e8f0a0414e36..5ef08a6fa6808 100644
--- a/lld/ELF/Symbols.h
+++ b/lld/ELF/Symbols.h
@@ -201,18 +201,10 @@ class Symbol {
   // truncated by Symbol::parseSymbolVersion().
   const char *getVersionSuffix() const { return nameData + nameSize; }
 
-  uint32_t getGotIdx() const {
-    return auxIdx == uint32_t(-1) ? uint32_t(-1) : symAux[auxIdx].gotIdx;
-  }
-  uint32_t getPltIdx() const {
-    return auxIdx == uint32_t(-1) ? uint32_t(-1) : symAux[auxIdx].pltIdx;
-  }
-  uint32_t getTlsDescIdx() const {
-    return auxIdx == uint32_t(-1) ? uint32_t(-1) : symAux[auxIdx].tlsDescIdx;
-  }
-  uint32_t getTlsGdIdx() const {
-    return auxIdx == uint32_t(-1) ? uint32_t(-1) : symAux[auxIdx].tlsGdIdx;
-  }
+  uint32_t getGotIdx() const { return symAux[auxIdx].gotIdx; }
+  uint32_t getPltIdx() const { return symAux[auxIdx].pltIdx; }
+  uint32_t getTlsDescIdx() const { return symAux[auxIdx].tlsDescIdx; }
+  uint32_t getTlsGdIdx() const { return symAux[auxIdx].tlsGdIdx; }
 
   bool isInGot() const { return getGotIdx() != uint32_t(-1); }
   bool isInPlt() const { return getPltIdx() != uint32_t(-1); }
@@ -328,7 +320,7 @@ class Symbol {
             NEEDS_TLSGD_TO_IE | NEEDS_GOT_DTPREL | NEEDS_TLSIE);
   }
   void allocateAux() {
-    assert(auxIdx == uint32_t(-1));
+    assert(auxIdx == 0);
     auxIdx = symAux.size();
     symAux.emplace_back();
   }
@@ -548,7 +540,6 @@ template <typename... T> Defined *makeDefined(T &&...args) {
   auto *sym = getSpecificAllocSingleton<SymbolUnion>().Allocate();
   memset(sym, 0, sizeof(Symbol));
   auto &s = *new (reinterpret_cast<Defined *>(sym)) Defined(std::forward<T>(args)...);
-  s.auxIdx = -1;
   return &s;
 }
 

diff  --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index eb70c1d5504f1..24336fd50b51a 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -960,12 +960,12 @@ void MipsGotSection::build() {
   // Update SymbolAux::gotIdx field to use this
   // value later in the `sortMipsSymbols` function.
   for (auto &p : primGot->global) {
-    if (p.first->auxIdx == uint32_t(-1))
+    if (p.first->auxIdx == 0)
       p.first->allocateAux();
     symAux.back().gotIdx = p.second;
   }
   for (auto &p : primGot->relocs) {
-    if (p.first->auxIdx == uint32_t(-1))
+    if (p.first->auxIdx == 0)
       p.first->allocateAux();
     symAux.back().gotIdx = p.second;
   }