[lld][WebAssembly] Move linker global state in to context object. NFC (llvm#78629)

See lld/ELF/Config.h

Author: sbc100

lld/wasm/Config.h

@@ -71,6 +71,11 @@ struct Configuration {
   uint64_t initialHeap;
   uint64_t initialMemory;
   uint64_t maxMemory;
+  // The table offset at which to place function addresses.  We reserve zero
+  // for the null function pointer.  This gets set to 1 for executables and 0
+  // for shared libraries (since they always added to a dynamic offset at
+  // runtime).
+  uint64_t tableBase;
   uint64_t zStackSize;
   unsigned ltoPartitions;
   unsigned ltoo;
@@ -96,24 +101,20 @@ struct Configuration {
   std::optional<std::vector<std::string>> features;
   std::optional<std::vector<std::string>> extraFeatures;
   llvm::SmallVector<uint8_t, 0> buildIdVector;
+};
 
-  // The following config options do not directly correspond to any
-  // particular command line options, and should probably be moved to separate
-  // Ctx struct as in ELF/Config.h
+// The only instance of Configuration struct.
+extern Configuration *config;
 
+// The Ctx object hold all other (non-configuration) global state.
+struct Ctx {
   // True if we are creating position-independent code.
   bool isPic;
 
   // True if we have an MVP input that uses __indirect_function_table and which
   // requires it to be allocated to table number 0.
   bool legacyFunctionTable = false;
 
-  // The table offset at which to place function addresses.  We reserve zero
-  // for the null function pointer.  This gets set to 1 for executables and 0
-  // for shared libraries (since they always added to a dynamic offset at
-  // runtime).
-  uint32_t tableBase = 0;
-
   // Will be set to true if bss data segments should be emitted. In most cases
   // this is not necessary.
   bool emitBssSegments = false;
@@ -124,8 +125,7 @@ struct Configuration {
       whyExtractRecords;
 };
 
-// The only instance of Configuration struct.
-extern Configuration *config;
+extern Ctx ctx;
 
 } // namespace lld::wasm
 

lld/wasm/Driver.cpp

@@ -45,6 +45,7 @@ using namespace llvm::wasm;
 
 namespace lld::wasm {
 Configuration *config;
+Ctx ctx;
 
 namespace {
 
@@ -308,7 +309,7 @@ static std::optional<std::string> searchLibraryBaseName(StringRef name) {
   for (StringRef dir : config->searchPaths) {
     // Currently we don't enable dynamic linking at all unless -shared or -pie
     // are used, so don't even look for .so files in that case..
-    if (config->isPic && !config->isStatic)
+    if (ctx.isPic && !config->isStatic)
       if (std::optional<std::string> s = findFile(dir, "lib" + name + ".so"))
         return s;
     if (std::optional<std::string> s = findFile(dir, "lib" + name + ".a"))
@@ -571,9 +572,9 @@ static void readConfigs(opt::InputArgList &args) {
 // This function initialize such members. See Config.h for the details
 // of these values.
 static void setConfigs() {
-  config->isPic = config->pie || config->shared;
+  ctx.isPic = config->pie || config->shared;
 
-  if (config->isPic) {
+  if (ctx.isPic) {
     if (config->exportTable)
       error("-shared/-pie is incompatible with --export-table");
     config->importTable = true;
@@ -680,7 +681,7 @@ static void checkOptions(opt::InputArgList &args) {
     warn("-Bsymbolic is only meaningful when combined with -shared");
   }
 
-  if (config->isPic) {
+  if (ctx.isPic) {
     if (config->globalBase)
       error("--global-base may not be used with -shared/-pie");
     if (config->tableBase)
@@ -707,7 +708,7 @@ static Symbol *handleUndefined(StringRef name, const char *option) {
   if (auto *lazySym = dyn_cast<LazySymbol>(sym)) {
     lazySym->extract();
     if (!config->whyExtract.empty())
-      config->whyExtractRecords.emplace_back(option, sym->getFile(), *sym);
+      ctx.whyExtractRecords.emplace_back(option, sym->getFile(), *sym);
   }
 
   return sym;
@@ -722,8 +723,7 @@ static void handleLibcall(StringRef name) {
     MemoryBufferRef mb = lazySym->getMemberBuffer();
     if (isBitcode(mb)) {
       if (!config->whyExtract.empty())
-        config->whyExtractRecords.emplace_back("<libcall>", sym->getFile(),
-                                               *sym);
+        ctx.whyExtractRecords.emplace_back("<libcall>", sym->getFile(), *sym);
       lazySym->extract();
     }
   }
@@ -742,7 +742,7 @@ static void writeWhyExtract() {
   }
 
   os << "reference\textracted\tsymbol\n";
-  for (auto &entry : config->whyExtractRecords) {
+  for (auto &entry : ctx.whyExtractRecords) {
     os << std::get<0>(entry) << '\t' << toString(std::get<1>(entry)) << '\t'
        << toString(std::get<2>(entry)) << '\n';
   }
@@ -811,7 +811,7 @@ static void createSyntheticSymbols() {
 
   bool is64 = config->is64.value_or(false);
 
-  if (config->isPic) {
+  if (ctx.isPic) {
     WasmSym::stackPointer =
         createUndefinedGlobal("__stack_pointer", config->is64.value_or(false)
                                                      ? &mutableGlobalTypeI64
@@ -850,7 +850,7 @@ static void createSyntheticSymbols() {
             "__wasm_init_tls"));
   }
 
-  if (config->isPic ||
+  if (ctx.isPic ||
       config->unresolvedSymbols == UnresolvedPolicy::ImportDynamic) {
     // For PIC code, or when dynamically importing addresses, we create
     // synthetic functions that apply relocations.  These get called from
@@ -871,7 +871,7 @@ static void createOptionalSymbols() {
   if (!config->shared)
     WasmSym::dataEnd = symtab->addOptionalDataSymbol("__data_end");
 
-  if (!config->isPic) {
+  if (!ctx.isPic) {
     WasmSym::stackLow = symtab->addOptionalDataSymbol("__stack_low");
     WasmSym::stackHigh = symtab->addOptionalDataSymbol("__stack_high");
     WasmSym::globalBase = symtab->addOptionalDataSymbol("__global_base");
@@ -967,8 +967,8 @@ static void processStubLibraries() {
               depsAdded = true;
               lazy->extract();
               if (!config->whyExtract.empty())
-                config->whyExtractRecords.emplace_back(stub_file->getName(),
-                                                       sym->getFile(), *sym);
+                ctx.whyExtractRecords.emplace_back(stub_file->getName(),
+                                                   sym->getFile(), *sym);
             }
           }
         }
@@ -1305,7 +1305,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
       sym->forceExport = true;
   }
 
-  if (!config->relocatable && !config->isPic) {
+  if (!config->relocatable && !ctx.isPic) {
     // Add synthetic dummies for weak undefined functions.  Must happen
     // after LTO otherwise functions may not yet have signatures.
     symtab->handleWeakUndefines();

lld/wasm/InputChunks.cpp

@@ -378,7 +378,7 @@ void InputChunk::generateRelocationCode(raw_ostream &os) const {
     uint64_t offset = getVA(rel.Offset) - getInputSectionOffset();
 
     Symbol *sym = file->getSymbol(rel);
-    if (!config->isPic && sym->isDefined())
+    if (!ctx.isPic && sym->isDefined())
       continue;
 
     LLVM_DEBUG(dbgs() << "gen reloc: type=" << relocTypeToString(rel.Type)
@@ -390,7 +390,7 @@ void InputChunk::generateRelocationCode(raw_ostream &os) const {
     writeSleb128(os, offset, "offset");
 
     // In PIC mode we need to add the __memory_base
-    if (config->isPic) {
+    if (ctx.isPic) {
       writeU8(os, WASM_OPCODE_GLOBAL_GET, "GLOBAL_GET");
       if (isTLS())
         writeUleb128(os, WasmSym::tlsBase->getGlobalIndex(), "tls_base");
@@ -417,7 +417,7 @@ void InputChunk::generateRelocationCode(raw_ostream &os) const {
         writeU8(os, opcode_reloc_add, "ADD");
       }
     } else {
-      assert(config->isPic);
+      assert(ctx.isPic);
       const GlobalSymbol* baseSymbol = WasmSym::memoryBase;
       if (rel.Type == R_WASM_TABLE_INDEX_I32 ||
           rel.Type == R_WASM_TABLE_INDEX_I64)

lld/wasm/InputFiles.cpp

@@ -351,7 +351,7 @@ void ObjFile::addLegacyIndirectFunctionTableIfNeeded(
 
   // We assume that this compilation unit has unrelocatable references to
   // this table.
-  config->legacyFunctionTable = true;
+  ctx.legacyFunctionTable = true;
 }
 
 static bool shouldMerge(const WasmSection &sec) {

lld/wasm/LTO.cpp

@@ -55,7 +55,7 @@ static std::unique_ptr<lto::LTO> createLTO() {
 
   if (config->relocatable)
     c.RelocModel = std::nullopt;
-  else if (config->isPic)
+  else if (ctx.isPic)
     c.RelocModel = Reloc::PIC_;
   else
     c.RelocModel = Reloc::Static;

lld/wasm/MarkLive.cpp

@@ -187,7 +187,7 @@ bool MarkLive::isCallCtorsLive() {
 
   // In Emscripten-style PIC, we call `__wasm_call_ctors` which calls
   // `__wasm_apply_data_relocs`.
-  if (config->isPic)
+  if (ctx.isPic)
     return true;
 
   // If there are any init functions, mark `__wasm_call_ctors` live so that

lld/wasm/OutputSections.cpp

@@ -107,7 +107,7 @@ void DataSection::finalizeContents() {
   });
 #endif
 
-  assert((config->sharedMemory || !config->isPic || config->extendedConst ||
+  assert((config->sharedMemory || !ctx.isPic || config->extendedConst ||
           activeCount <= 1) &&
          "output segments should have been combined by now");
 
@@ -124,7 +124,7 @@ void DataSection::finalizeContents() {
     if (segment->initFlags & WASM_DATA_SEGMENT_HAS_MEMINDEX)
       writeUleb128(os, 0, "memory index");
     if ((segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
-      if (config->isPic && config->extendedConst) {
+      if (ctx.isPic && config->extendedConst) {
         writeU8(os, WASM_OPCODE_GLOBAL_GET, "global get");
         writeUleb128(os, WasmSym::memoryBase->getGlobalIndex(),
                      "literal (global index)");
@@ -136,7 +136,7 @@ void DataSection::finalizeContents() {
       } else {
         WasmInitExpr initExpr;
         initExpr.Extended = false;
-        if (config->isPic) {
+        if (ctx.isPic) {
           assert(segment->startVA == 0);
           initExpr.Inst.Opcode = WASM_OPCODE_GLOBAL_GET;
           initExpr.Inst.Value.Global = WasmSym::memoryBase->getGlobalIndex();

lld/wasm/OutputSegment.h

@@ -27,7 +27,7 @@ class OutputSegment {
   // to the output binary.  However if the memory is imported, and
   // we can't use memory.fill during startup (due to lack of bulk
   // memory feature) then we include BSS segments verbatim.
-  bool requiredInBinary() const { return !isBss || config->emitBssSegments; }
+  bool requiredInBinary() const { return !isBss || ctx.emitBssSegments; }
 
   bool isTLS() const { return name == ".tdata"; }
 

lld/wasm/Relocations.cpp

@@ -19,7 +19,7 @@ using namespace llvm::wasm;
 namespace lld::wasm {
 
 static bool requiresGOTAccess(const Symbol *sym) {
-  if (!config->isPic &&
+  if (!ctx.isPic &&
       config->unresolvedSymbols != UnresolvedPolicy::ImportDynamic)
     return false;
   if (sym->isHidden() || sym->isLocal())
@@ -141,7 +141,7 @@ void scanRelocations(InputChunk *chunk) {
       break;
     }
 
-    if (config->isPic ||
+    if (ctx.isPic ||
         (sym->isUndefined() &&
          config->unresolvedSymbols == UnresolvedPolicy::ImportDynamic)) {
       switch (reloc.Type) {

lld/wasm/SymbolTable.cpp

@@ -535,8 +535,7 @@ Symbol *SymbolTable::addUndefinedFunction(StringRef name,
     } else {
       lazy->extract();
       if (!config->whyExtract.empty())
-        config->whyExtractRecords.emplace_back(toString(file), s->getFile(),
-                                               *s);
+        ctx.whyExtractRecords.emplace_back(toString(file), s->getFile(), *s);
     }
   } else {
     auto existingFunction = dyn_cast<FunctionSymbol>(s);
@@ -774,7 +773,7 @@ void SymbolTable::addLazy(ArchiveFile *file, const Archive::Symbol *sym) {
   const InputFile *oldFile = s->getFile();
   file->addMember(sym);
   if (!config->whyExtract.empty())
-    config->whyExtractRecords.emplace_back(toString(oldFile), s->getFile(), *s);
+    ctx.whyExtractRecords.emplace_back(toString(oldFile), s->getFile(), *s);
 }
 
 bool SymbolTable::addComdat(StringRef name) {