Re: [PATCH] Check endianess detection.

[Richard Biener <richard.guenther@gmail.com>]

On Mon, Mar 23, 2020 at 4:07 PM Martin Liška <mliska@suse.cz> wrote:
>
> Hi.
>
> There's a patch draft that will do the proper versioning of API.

Would sth like this be preferred on the binutils side or would
splitting up the 'def' field via shift&masking better?

@@ -87,25 +87,30 @@ struct ld_plugin_symbol
 {
   char *name;
   char *version;
-  /* This is for compatibility with older ABIs.  The older ABI defined
-     only 'def' field.  */
-#ifdef __BIG_ENDIAN__
-  char unused;
...
+  int def;
   int visibility;
   uint64_t size;
   char *comdat_key;
   int resolution;
 };

+/* A symbol belonging to an input file managed by the plugin library
+   (version 2).  */
+
+struct ld_plugin_symbol_v2
+{
+  char *name;
+  char *version;
+  int def;
+  int visibility;
+  uint64_t size;
+  char *comdat_key;
+  int resolution;
+  char symbol_type;
+  char section_kind;
+  uint16_t unused;
+};

I think for ease of use you should do

struct ld_plugin_symbol_v2
{
  ld_plugin_symbol v1_data;
  char symbol_type;
  char section_kind;
  uint16_t unused;
}

also please avoid 'char', either use uint8_t or
at least unsigned char.  I guess since you're extending
the type anyway using two plain 'int' would better follow
the rest of the data structure.

> It's a subject for discussion.

-       status = add_symbols_v2 (file->handle, lto_file.symtab.nsyms,
-                                lto_file.symtab.syms);
+       {
+         /* Merge symtab::syms and symtab::syms_v2 data.  */
+         for (unsigned int i = 0; i < lto_file.symtab.nsyms; i++)
+           {

I think lto-plugin should internally always parse into the "full" format,
using defaults for entries not in IL files.  Only the interfacing with
the linker should then decide.

>
> Martin