From 0ef5f678144b8ff3a1d247a992aa2e14128b82d1 Mon Sep 17 00:00:00 2001
From: Martin Liska <mliska@suse.cz>
Date: Mon, 16 May 2022 14:01:52 +0200
Subject: [PATCH] Implement LDPT_REGISTER_GET_API_VERSION.

---
 include/plugin-api.h    | 14 ++++++++++++++
 lto-plugin/lto-plugin.c | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/include/plugin-api.h b/include/plugin-api.h
index 8aebe2ff267..f01f4301fc9 100644
--- a/include/plugin-api.h
+++ b/include/plugin-api.h
@@ -483,6 +483,18 @@ enum ld_plugin_level
   LDPL_FATAL
 };
 
+/* The linker's interface for API version negotiation.  */
+
+typedef
+int (*ld_plugin_get_api_version) (char *linker_identifier, int linker_version,
+				  int preferred_linker_api,
+				  const char **compiler_identifier,
+				  int *compiler_version);
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_register_get_api_version) (ld_plugin_get_api_version handler);
+
 /* Values for the tv_tag field of the transfer vector.  */
 
 enum ld_plugin_tag
@@ -521,6 +533,7 @@ enum ld_plugin_tag
   LDPT_REGISTER_NEW_INPUT_HOOK,
   LDPT_GET_WRAP_SYMBOLS,
   LDPT_ADD_SYMBOLS_V2,
+  LDPT_REGISTER_GET_API_VERSION,
 };
 
 /* The plugin transfer vector.  */
@@ -556,6 +569,7 @@ 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_register_get_api_version tv_register_get_api_version;
   } tv_u;
 };
 
diff --git a/lto-plugin/lto-plugin.c b/lto-plugin/lto-plugin.c
index 00b760636dc..49484decd89 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.  */
@@ -166,6 +167,10 @@ static ld_plugin_add_input_file add_input_file;
 static ld_plugin_add_input_library add_input_library;
 static ld_plugin_message message;
 static ld_plugin_add_symbols add_symbols, add_symbols_v2;
+static ld_plugin_register_get_api_version register_get_api_version;
+
+/* By default, use version 1 if there is not negotiation.  */
+static int used_api_version = 1;
 
 static struct plugin_file_info *claimed_files = NULL;
 static unsigned int num_claimed_files = 0;
@@ -1407,6 +1412,29 @@ process_option (const char *option)
   verbose = verbose || debug;
 }
 
+static int
+get_api_version (char *linker_identifier, int linker_version,
+		 int preferred_linker_api,
+		 const char **compiler_identifier,
+		 int *compiler_version)
+{
+  *compiler_identifier = "GCC";
+  *compiler_version = GCC_VERSION;
+
+  if (preferred_linker_api >= 2)
+    {
+      check (get_symbols_v3, LDPL_FATAL,
+	     "get_symbols_v3 requires for API version 2");
+      check (add_symbols_v2, LDPL_FATAL,
+	     "add_symbols_v2 requires for API version 2");
+
+      /* The plug-in supports version 2.  */
+      used_api_version = 2;
+    }
+
+  return used_api_version;
+}
+
 /* Called by a linker after loading the plugin. TV is the transfer vector. */
 
 enum ld_plugin_status
@@ -1467,12 +1495,22 @@ 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_REGISTER_GET_API_VERSION:
+	  register_get_api_version = p->tv_u.tv_register_get_api_version;
+	  break;
 	default:
 	  break;
 	}
       p++;
     }
 
+  if (register_get_api_version)
+    {
+      status = register_get_api_version (get_api_version);
+      check (status == LDPS_OK, LDPL_FATAL,
+	     "could not register the get_api_version callback");
+    }
+
   check (register_claim_file, LDPL_FATAL, "register_claim_file not found");
   check (add_symbols, LDPL_FATAL, "add_symbols not found");
   status = register_claim_file (claim_file_handler);
-- 
2.36.1