[ELF] Support LDPT_GET_API_VERSION

elf/lto.cc

@@ -109,6 +109,7 @@ static std::vector<PluginSymbol> plugin_symbols;
 static ClaimFileHandler *claim_file_hook;
 static AllSymbolsReadHandler *all_symbols_read_hook;
 static CleanupHandler *cleanup_hook;
+static bool is_gcc_linker_api_v1 = false;
 
 // Event handlers
 
@@ -398,6 +399,19 @@ get_wrap_symbols(uint64_t *num_symbols, const char ***wrap_symbols) {
   return LDPS_OK;
 }
 
+static PluginLinkerAPIVersion
+get_api_version(const char *plugin_identifier,
+                unsigned plugin_version,
+                PluginLinkerAPIVersion minimal_api_supported,
+                PluginLinkerAPIVersion maximal_api_supported,
+                const char **linker_identifier,
+                unsigned *linker_version) {
+  assert(maximal_api_supported >= LAPI_V1);
+  *linker_identifier = "mold";
+  is_gcc_linker_api_v1 = true;
+  return LAPI_V1;
+}
+
 template <typename E>
 static void load_plugin(Context<E> &ctx) {
   assert(phase == 0);
@@ -458,6 +472,7 @@ static void load_plugin(Context<E> &ctx) {
   tv.emplace_back(LDPT_GET_INPUT_SECTION_SIZE, get_input_section_size);
   tv.emplace_back(LDPT_REGISTER_NEW_INPUT_HOOK, register_new_input_hook<E>);
   tv.emplace_back(LDPT_GET_WRAP_SYMBOLS, get_wrap_symbols);
+  tv.emplace_back(LDPT_GET_API_VERSION, get_api_version);
   tv.emplace_back(LDPT_NULL, 0);
 
   onload(tv.data());
@@ -524,10 +539,10 @@ static bool is_llvm(Context<E> &ctx) {
 }
 
 // Returns true if a given linker plugin supports the get_symbols_v3 API.
-// Currently, we simply assume that LLVM supports it and GCC does not.
+// Any version of LLVM and GCC 12 or newer support it.
 template <typename E>
 static bool suppots_v3_api(Context<E> &ctx) {
-  return is_llvm(ctx);
+  return is_gcc_linker_api_v1 || is_llvm(ctx);
 }
 
 template <typename E>

elf/lto.h

@@ -44,6 +44,7 @@ enum PluginTag {
   LDPT_REGISTER_NEW_INPUT_HOOK,
   LDPT_GET_WRAP_SYMBOLS,
   LDPT_ADD_SYMBOLS_V2,
+  LDPT_GET_API_VERSION,
 };
 
 enum PluginApiVersion {
@@ -141,6 +142,11 @@ enum PluginLevel {
   LDPL_FATAL,
 };
 
+enum PluginLinkerAPIVersion {
+  LAPI_UNSPECIFIED = 0,
+  LAPI_V1 = 1,
+};
+
 typedef PluginStatus OnloadFn(PluginTagValue *tv);
 typedef PluginStatus ClaimFileHandler(const PluginInputFile *, int *);
 typedef PluginStatus AllSymbolsReadHandler();

test/elf/lto-archive.sh

@@ -13,8 +13,6 @@ cd "$(dirname "$0")"/../..
 t=out/test/elf/$testname
 mkdir -p $t
 
-[ "$CC" = cc ] || { echo skipped; exit; }
-
 cat <<EOF | $CC -o $t/a.o -c -flto -xc -
 #include <stdio.h>
 void hello() {