[PATCH 3/3] lto-plugin: implement LDPT_GET_API_VERSION

Alexander Monakov amonakov@ispras.ru
Mon Jul 11 16:35:58 GMT 2022


On Mon, 11 Jul 2022, Martin Liška wrote:

> I've clarified that linker should return a value that is in range
> [minimal_api_supported, maximal_api_supported] and added an abort
> if it's not the case.

I noticed that we are placing a trap for C++ consumers such as mold
by passing min/max_api_supported as enum values. Unlike C, C++ disallows
out-of-range enum values, so when mold does

enum PluginLinkerAPIVersion {
  LAPI_V0 = 0,
  LAPI_V1,
};

get_api_version(const char *plugin_identifier,
                unsigned plugin_version,
                PluginLinkerAPIVersion minimal_api_supported,
                PluginLinkerAPIVersion maximal_api_supported,
                const char **linker_identifier,
                const char **linker_version) {

checks such as 'min_api_supported > LAPI_V1' can be optimized out. Also,
if a future tool passes LAPI_V2, it will trigger Clang's UBSan (GCC
-fsanitize-undefined=enum instruments loads but not retrieval of function
arguments).

I'd suggest to fix this on both sides by changing the arguments to plain
integer types.

Alexander


More information about the Gcc-patches mailing list