[PATCH] LTO plugin: add ld_plugin_version callback.

[Martin Liška]

Hi.

This in a new plug-in function that helps identifying compiler
by a linker. Will be used in mold linker.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Ready to be installed?
Thanks,
Martin

include/ChangeLog:

        * plugin-api.h (enum ld_plugin_compiler): New enum.
        (enum ld_plugin_version): New typedef.
        (struct ld_plugin_tv): Add new field.

lto-plugin/ChangeLog:

        * lto-plugin.c (onload): Call ld_plugin_version.
---
 include/plugin-api.h    | 18 +++++++++++++++++-
 lto-plugin/lto-plugin.c |  4 ++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/include/plugin-api.h b/include/plugin-api.h
index 4e12c0320d6..4d0989028cc 100644
--- a/include/plugin-api.h
+++ b/include/plugin-api.h
@@ -211,6 +211,13 @@ enum ld_plugin_symbol_section_kind
   LDSSK_BSS
 };
 
+enum ld_plugin_compiler
+{
+  LDPC_UNKNOWN,
+  LDPC_GCC,
+  LDPC_LLVM
+};
+
 /* How a symbol is resolved.  */
 
 enum ld_plugin_symbol_resolution
@@ -475,6 +482,13 @@ enum ld_plugin_status
 (*ld_plugin_get_wrap_symbols) (uint64_t *num_symbols,
                                const char ***wrap_symbol_list);
 
+/* The linker's interface for registering the "plugin_version" handler.
+   This handler is called directly after onload and provides compiler
+   and its number version (MAJOR * 1000 + MINOR).  */
+
+typedef
+void (*ld_plugin_version) (enum ld_plugin_compiler compiler, int version);
+
 enum ld_plugin_level
 {
   LDPL_INFO,
@@ -520,7 +534,8 @@ enum ld_plugin_tag
   LDPT_GET_INPUT_SECTION_SIZE = 30,
   LDPT_REGISTER_NEW_INPUT_HOOK = 31,
   LDPT_GET_WRAP_SYMBOLS = 32,
-  LDPT_ADD_SYMBOLS_V2 = 33
+  LDPT_ADD_SYMBOLS_V2 = 33,
+  LDPT_PLUGIN_VERSION = 34,
 };
 
 /* The plugin transfer vector.  */
@@ -556,6 +571,7 @@ struct ld_plugin_tv
     ld_plugin_get_input_section_size tv_get_input_section_size;
     ld_plugin_register_new_input tv_register_new_input;
     ld_plugin_get_wrap_symbols tv_get_wrap_symbols;
+    ld_plugin_version tv_plugin_version;
   } tv_u;
 };
 
diff --git a/lto-plugin/lto-plugin.c b/lto-plugin/lto-plugin.c
index 7a1c77812f6..698a0617ca7 100644
--- a/lto-plugin/lto-plugin.c
+++ b/lto-plugin/lto-plugin.c
@@ -69,6 +69,7 @@ along with this program; see the file COPYING3.  If not see
 #include "../gcc/lto/common.h"
 #include "simple-object.h"
 #include "plugin-api.h"
+#include "ansidecl.h"
 
 /* We need to use I64 instead of ll width-specifier on native Windows.
    The reason for this is that older MS-runtimes don't support the ll.  */
@@ -1466,6 +1467,9 @@ onload (struct ld_plugin_tv *tv)
          /* We only use this to make user-friendly temp file names.  */
          link_output_name = p->tv_u.tv_string;
          break;
+       case LDPT_PLUGIN_VERSION:
+         p->tv_u.tv_plugin_version (LDPC_GCC, GCC_VERSION);
+         break;
        default:
          break;
        }
-- 
2.36.0