[LLD][COFF][NFC] Create import thunks in ImportFile::parse. (#107929)

Author: cjacek

lld/COFF/InputFiles.cpp

@@ -1009,6 +1009,20 @@ MachineTypes ImportFile::getMachineType() const {
   return MachineTypes(machine);
 }
 
+ImportThunkChunk *ImportFile::makeImportThunk() {
+  switch (hdr->Machine) {
+  case AMD64:
+    return make<ImportThunkChunkX64>(ctx, impSym);
+  case I386:
+    return make<ImportThunkChunkX86>(ctx, impSym);
+  case ARM64:
+    return make<ImportThunkChunkARM64>(ctx, impSym);
+  case ARMNT:
+    return make<ImportThunkChunkARM>(ctx, impSym);
+  }
+  llvm_unreachable("unknown machine type");
+}
+
 void ImportFile::parse() {
   const auto *hdr =
       reinterpret_cast<const coff_import_header *>(mb.getBufferStart());
@@ -1069,9 +1083,10 @@ void ImportFile::parse() {
   // DLL functions just like regular non-DLL functions.)
   if (hdr->getType() == llvm::COFF::IMPORT_CODE) {
     if (ctx.config.machine != ARM64EC) {
-      thunkSym = ctx.symtab.addImportThunk(name, impSym, hdr->Machine);
+      thunkSym = ctx.symtab.addImportThunk(name, impSym, makeImportThunk());
     } else {
-      thunkSym = ctx.symtab.addImportThunk(name, impSym, AMD64);
+      thunkSym = ctx.symtab.addImportThunk(
+          name, impSym, make<ImportThunkChunkX64>(ctx, impSym));
       // FIXME: Add aux IAT symbols.
     }
   }

lld/COFF/InputFiles.h

@@ -55,6 +55,7 @@ class Defined;
 class DefinedImportData;
 class DefinedImportThunk;
 class DefinedRegular;
+class ImportThunkChunk;
 class SectionChunk;
 class Symbol;
 class Undefined;
@@ -352,6 +353,7 @@ class ImportFile : public InputFile {
 
 private:
   void parse() override;
+  ImportThunkChunk *makeImportThunk();
 
 public:
   StringRef externalName;

lld/COFF/SymbolTable.cpp

@@ -784,11 +784,11 @@ DefinedImportData *SymbolTable::addImportData(StringRef n, ImportFile *f) {
 }
 
 Symbol *SymbolTable::addImportThunk(StringRef name, DefinedImportData *id,
-                                    uint16_t machine) {
+                                    ImportThunkChunk *chunk) {
   auto [s, wasInserted] = insert(name, nullptr);
   s->isUsedInRegularObj = true;
   if (wasInserted || isa<Undefined>(s) || s->isLazy()) {
-    replaceSymbol<DefinedImportThunk>(s, ctx, name, id, machine);
+    replaceSymbol<DefinedImportThunk>(s, ctx, name, id, chunk);
     return s;
   }
 

lld/COFF/SymbolTable.h

@@ -28,6 +28,7 @@ class COFFLinkerContext;
 class Defined;
 class DefinedAbsolute;
 class DefinedRegular;
+class ImportThunkChunk;
 class LazyArchive;
 class SectionChunk;
 class Symbol;
@@ -104,7 +105,7 @@ class SymbolTable {
                     CommonChunk *c = nullptr);
   DefinedImportData *addImportData(StringRef n, ImportFile *f);
   Symbol *addImportThunk(StringRef name, DefinedImportData *s,
-                         uint16_t machine);
+                         ImportThunkChunk *chunk);
   void addLibcall(StringRef name);
   void addEntryThunk(Symbol *from, Symbol *to);
   void initializeEntryThunks();

lld/COFF/Symbols.cpp

@@ -107,22 +107,10 @@ COFFSymbolRef DefinedCOFF::getCOFFSymbol() {
 
 uint64_t DefinedAbsolute::getRVA() { return va - ctx.config.imageBase; }
 
-static Chunk *makeImportThunk(COFFLinkerContext &ctx, DefinedImportData *s,
-                              uint16_t machine) {
-  if (machine == AMD64)
-    return make<ImportThunkChunkX64>(ctx, s);
-  if (machine == I386)
-    return make<ImportThunkChunkX86>(ctx, s);
-  if (machine == ARM64)
-    return make<ImportThunkChunkARM64>(ctx, s);
-  assert(machine == ARMNT);
-  return make<ImportThunkChunkARM>(ctx, s);
-}
-
 DefinedImportThunk::DefinedImportThunk(COFFLinkerContext &ctx, StringRef name,
-                                       DefinedImportData *s, uint16_t machine)
-    : Defined(DefinedImportThunkKind, name), wrappedSym(s),
-      data(makeImportThunk(ctx, s, machine)) {}
+                                       DefinedImportData *s,
+                                       ImportThunkChunk *chunk)
+    : Defined(DefinedImportThunkKind, name), wrappedSym(s), data(chunk) {}
 
 Defined *Undefined::getWeakAlias() {
   // A weak alias may be a weak alias to another symbol, so check recursively.

lld/COFF/Symbols.h

@@ -388,7 +388,7 @@ class DefinedImportData : public Defined {
 class DefinedImportThunk : public Defined {
 public:
   DefinedImportThunk(COFFLinkerContext &ctx, StringRef name,
-                     DefinedImportData *s, uint16_t machine);
+                     DefinedImportData *s, ImportThunkChunk *chunk);
 
   static bool classof(const Symbol *s) {
     return s->kind() == DefinedImportThunkKind;