lto-plugin - support -save-temps, -v, --version.

This patch makes the lto-plugin follow the same approach
to save-temps as collect2. 

-save-temps causes the temp file to be named meaningfully,
and for the relevant input files to be saved in CWD.

-v, —version causes the save actions to be output to stderr.

one can get this to happen by just putting -save-temps, -v on
the regular link line or (for compatibility with the way the
 -debug flag works) by appending -plugin-opt=-save-temps, etc.

lto-plugin/

2019-05-15  Iain Sandoe  <iain@sandoe.co.uk>

	* lto-plugin.c (exec_lto_wrapper): Make the wrapper
	arguments filename more user-friendly.
	(file_exists, maybe_unlink): New.
	(cleanup_handler): Use maybe unlink to handle the
	case when temps should be saved.
	(process_option): Look for -v, —-version, -save-temps.
	(onload): Record the linker output file name.
	Check for -v, —-version, -save-temps in the GCC collect
	options environment.

From-SVN: r271202

lto-plugin/ChangeLog

+2019-05-15  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* lto-plugin.c (exec_lto_wrapper): Make the wrapper
+	arguments filename more user-friendly.
+	(file_exists, maybe_unlink): New.
+	(cleanup_handler): Use maybe unlink to handle the
+	case when temps should be saved.
+	(process_option): Look for -v, —-version, -save-temps.
+	(onload): Record the linker output file name.
+	Check for -v, —-version, -save-temps in the GCC collect
+	options environment.
+
 2019-02-26  Martin Liska  <mliska@suse.cz>
 
 	* lto-symtab.c: Remove.

lto-plugin/lto-plugin.c

@@ -41,6 +41,7 @@ along with this program; see the file COPYING3.  If not see
 #if HAVE_STDINT_H
 #include <stdint.h>
 #endif
+#include <stdbool.h>
 #include <assert.h>
 #include <errno.h>
 #include <string.h>
@@ -184,12 +185,15 @@ static int lto_wrapper_num_args;
 static char **pass_through_items = NULL;
 static unsigned int num_pass_through_items;
 
-static char debug;
+static bool debug;
+static bool save_temps;
+static bool verbose;
 static char nop;
 static char *resolution_file = NULL;
 static enum ld_plugin_output_file_type linker_output;
 static int linker_output_set;
 static int linker_output_known;
+static const char *link_output_name = NULL;
 
 /* The version of gold being used, or -1 if not gold.  The number is
    MAJOR * 100 + MINOR.  */
@@ -560,8 +564,17 @@ exec_lto_wrapper (char *argv[])
   struct pex_obj *pex;
   const char *errmsg;
 
-  /* Write argv to a file to avoid a command line that is too long. */
-  arguments_file_name = make_temp_file ("");
+  /* Write argv to a file to avoid a command line that is too long
+     Save the file locally on save-temps.  */
+  if (save_temps && link_output_name)
+    {
+      arguments_file_name = (char *) xmalloc (strlen (link_output_name)
+				  + sizeof (".lto_wrapper_args") + 1);
+      strcpy (arguments_file_name, link_output_name);
+      strcat (arguments_file_name, ".lto_wrapper_args");
+    }
+  else
+     arguments_file_name = make_temp_file (".lto_wrapper_args");
   check (arguments_file_name, LDPL_FATAL,
          "Failed to generate a temorary file name");
 
@@ -579,15 +592,21 @@ exec_lto_wrapper (char *argv[])
   for (i = 1; argv[i]; i++)
     {
       char *a = argv[i];
+      /* Check the input argument list for a verbose marker too.  */
       if (a[0] == '-' && a[1] == 'v' && a[2] == '\0')
 	{
-	  for (i = 0; argv[i]; i++)
-	    fprintf (stderr, "%s ", argv[i]);
-	  fprintf (stderr, "\n");
+	  verbose = true;
 	  break;
 	}
     }
 
+  if (verbose)
+    {
+      for (i = 0; argv[i]; i++)
+	fprintf (stderr, "%s ", argv[i]);
+      fprintf (stderr, "\n");
+    }
+
   new_argv[0] = argv[0];
   new_argv[1] = at_args;
   new_argv[2] = NULL;
@@ -599,7 +618,6 @@ exec_lto_wrapper (char *argv[])
       fprintf (stderr, "\n");
     }
 
-
   pex = pex_init (PEX_USE_PIPES, "lto-wrapper", NULL);
   check (pex != NULL, LDPL_FATAL, "could not pex_init lto-wrapper");
 
@@ -759,6 +777,29 @@ all_symbols_read_handler (void)
   return LDPS_OK;
 }
 
+/* Helper, as used in collect2.  */
+static int
+file_exists (const char *name)
+{
+  return access (name, R_OK) == 0;
+}
+
+/* Unlink FILE unless we have save-temps set.
+   Note that we're saving files if verbose output is set. */
+
+static void
+maybe_unlink (const char *file)
+{
+  if (save_temps && file_exists (file))
+    {
+      if (verbose)
+	fprintf (stderr, "[Leaving %s]\n", file);
+      return;
+    }
+
+  unlink_if_ordinary (file);
+}
+
 /* Remove temporary files at the end of the link. */
 
 static enum ld_plugin_status
@@ -771,16 +812,10 @@ cleanup_handler (void)
     return LDPS_OK;
 
   if (arguments_file_name)
-    {
-      t = unlink (arguments_file_name);
-      check (t == 0, LDPL_FATAL, "could not unlink arguments file");
-    }
+    maybe_unlink (arguments_file_name);
 
   for (i = 0; i < num_output_files; i++)
-    {
-      t = unlink (output_files[i]);
-      check (t == 0, LDPL_FATAL, "could not unlink output file");
-    }
+    maybe_unlink (output_files[i]);
 
   free_2 ();
   return LDPS_OK;
@@ -1143,7 +1178,12 @@ process_option (const char *option)
   if (strcmp (option, "-linker-output-known") == 0)
     linker_output_known = 1;
   if (strcmp (option, "-debug") == 0)
-    debug = 1;
+    debug = true;
+  else if ((strcmp (option, "-v") == 0)
+           || (strcmp (option, "--verbose") == 0))
+    verbose = true;
+  else if (strcmp (option, "-save-temps") == 0)
+    save_temps = true;
   else if (strcmp (option, "-nop") == 0)
     nop = 1;
   else if (!strncmp (option, "-pass-through=", strlen("-pass-through=")))
@@ -1180,6 +1220,8 @@ process_option (const char *option)
       if (strncmp (option, "-fresolution=", sizeof ("-fresolution=") - 1) == 0)
 	resolution_file = opt + sizeof ("-fresolution=") - 1;
     }
+  save_temps = save_temps || debug;
+  verbose = verbose || debug;
 }
 
 /* Called by gold after loading the plugin. TV is the transfer vector. */
@@ -1232,6 +1274,10 @@ onload (struct ld_plugin_tv *tv)
 	  linker_output = (enum ld_plugin_output_file_type) p->tv_u.tv_val;
 	  linker_output_set = 1;
 	  break;
+	case LDPT_OUTPUT_NAME:
+	  /* We only use this to make user-friendly temp file names.  */
+	  link_output_name = p->tv_u.tv_string;
+	  break;
 	default:
 	  break;
 	}
@@ -1259,12 +1305,21 @@ onload (struct ld_plugin_tv *tv)
 	     "could not register the all_symbols_read callback");
     }
 
-  /* Support -fno-use-linker-plugin by failing to load the plugin
-     for the case where it is auto-loaded by BFD.  */
   char *collect_gcc_options = getenv ("COLLECT_GCC_OPTIONS");
-  if (collect_gcc_options
-      && strstr (collect_gcc_options, "'-fno-use-linker-plugin'"))
-    return LDPS_ERR;
+  if (collect_gcc_options)
+    {
+      /* Support -fno-use-linker-plugin by failing to load the plugin
+	 for the case where it is auto-loaded by BFD.  */
+      if (strstr (collect_gcc_options, "'-fno-use-linker-plugin'"))
+	return LDPS_ERR;
+
+      if ( strstr (collect_gcc_options, "'-save-temps'"))
+	save_temps = true;
+
+      if (strstr (collect_gcc_options, "'-v'")
+          || strstr (collect_gcc_options, "'--verbose'"))
+	verbose = true;
+    }
 
   return LDPS_OK;
 }