[PATCH] Generalize -fuse-ld= to support absolute path or arbitrary ld.linker

["Fangrui Song via gcc-patches" <gcc-patches at gcc dot gnu dot org>]

	PR driver/93645
	* common.opt (-fuse-ld=): Delete -fuse-ld=[bfd|gold|lld]. Add -fuse-ld=.
	* opts.c (common_handle_option): Handle OPT_fuse_ld_.
	* gcc.c (driver_handle_option): Likewise.
	* collect2.c (main): Likewise.
---
 gcc/ChangeLog       |  8 ++++++
 gcc/collect2.c      | 67 ++++++++++++++++++++++++---------------------
 gcc/common.opt      | 14 ++--------
 gcc/doc/invoke.texi | 15 +++-------
 gcc/gcc.c           | 14 ++++------
 gcc/opts.c          |  4 +--
 6 files changed, 57 insertions(+), 65 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index feb2d066d0b..6bcec12d841 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2020-02-09  Fangrui Song  <maskray@google.com>
+
+	PR driver/93645
+	* common.opt (-fuse-ld=): Delete -fuse-ld=[bfd|gold|lld]. Add -fuse-ld=.
+	* opts.c (common_handle_option): Handle OPT_fuse_ld_.
+	* gcc.c (driver_handle_option): Likewise.
+	* collect2.c (main): Likewise.
+
 2020-02-09  Uroš Bizjak  <ubizjak@gmail.com>
 
 	* recog.c: Move pass_split_before_sched2 code in front of
diff --git a/gcc/collect2.c b/gcc/collect2.c
index 502d629141c..a3ef525a93b 100644
--- a/gcc/collect2.c
+++ b/gcc/collect2.c
@@ -859,18 +859,12 @@ main (int argc, char **argv)
     {
       USE_DEFAULT_LD,
       USE_PLUGIN_LD,
-      USE_GOLD_LD,
-      USE_BFD_LD,
-      USE_LLD_LD,
-      USE_LD_MAX
+      USE_LD
     } selected_linker = USE_DEFAULT_LD;
-  static const char *const ld_suffixes[USE_LD_MAX] =
+  static const char *const ld_suffixes[USE_LD] =
     {
       "ld",
-      PLUGIN_LD_SUFFIX,
-      "ld.gold",
-      "ld.bfd",
-      "ld.lld"
+      PLUGIN_LD_SUFFIX
     };
   static const char *const real_ld_suffix = "real-ld";
   static const char *const collect_ld_suffix = "collect-ld";
@@ -882,7 +876,7 @@ main (int argc, char **argv)
   static const char *const strip_suffix = "strip";
   static const char *const gstrip_suffix = "gstrip";
 
-  const char *full_ld_suffixes[USE_LD_MAX];
+  const char *full_ld_suffixes[USE_LD];
 #ifdef CROSS_DIRECTORY_STRUCTURE
   /* If we look for a program in the compiler directories, we just use
      the short name, since these directories are already system-specific.
@@ -924,6 +918,7 @@ main (int argc, char **argv)
   const char **ld1;
   bool use_plugin = false;
   bool use_collect_ld = false;
+  const char *use_ld = NULL;
 
   /* The kinds of symbols we will have to consider when scanning the
      outcome of a first pass link.  This is ALL to start with, then might
@@ -948,7 +943,7 @@ main (int argc, char **argv)
 #endif
   int i;
 
-  for (i = 0; i < USE_LD_MAX; i++)
+  for (i = 0; i < USE_LD; i++)
     full_ld_suffixes[i]
 #ifdef CROSS_DIRECTORY_STRUCTURE
       = concat (target_machine, "-", ld_suffixes[i], NULL);
@@ -1041,12 +1036,11 @@ main (int argc, char **argv)
 	    if (selected_linker == USE_DEFAULT_LD)
 	      selected_linker = USE_PLUGIN_LD;
 	  }
-	else if (strcmp (argv[i], "-fuse-ld=bfd") == 0)
-	  selected_linker = USE_BFD_LD;
-	else if (strcmp (argv[i], "-fuse-ld=gold") == 0)
-	  selected_linker = USE_GOLD_LD;
-	else if (strcmp (argv[i], "-fuse-ld=lld") == 0)
-	  selected_linker = USE_LLD_LD;
+	else if (!strncmp (argv[i], "-fuse-ld=", 9))
+	  {
+	    use_ld = argv[i] + 9;
+	    selected_linker = USE_LD;
+	  }
 	else if (strncmp (argv[i], "-o", 2) == 0)
 	  {
 	    /* Parse the output filename if it's given so that we can make
@@ -1152,8 +1146,7 @@ main (int argc, char **argv)
   /* Maybe we know the right file to use (if not cross).  */
   ld_file_name = 0;
 #ifdef DEFAULT_LINKER
-  if (selected_linker == USE_BFD_LD || selected_linker == USE_GOLD_LD ||
-      selected_linker == USE_LLD_LD)
+  if (!ld_file_name && selected_linker == USE_LD)
     {
       char *linker_name;
 # ifdef HOST_EXECUTABLE_SUFFIX
@@ -1168,15 +1161,13 @@ main (int argc, char **argv)
 	  if (! strcmp (&default_linker[len], HOST_EXECUTABLE_SUFFIX))
 	    {
 	      default_linker[len] = '\0';
-	      linker_name = concat (default_linker,
-				    &ld_suffixes[selected_linker][2],
+	      linker_name = concat (default_linker, ".", use_ld,
 				    HOST_EXECUTABLE_SUFFIX, NULL);
 	    }
 	}
       if (linker_name == NULL)
 # endif
-      linker_name = concat (DEFAULT_LINKER,
-			    &ld_suffixes[selected_linker][2],
+      linker_name = concat (DEFAULT_LINKER, ".", use_ld,
 			    NULL);
       if (access (linker_name, X_OK) == 0)
 	ld_file_name = linker_name;
@@ -1197,14 +1188,28 @@ main (int argc, char **argv)
       ld_file_name = find_a_file (&cpath, collect_ld_suffix, X_OK);
       use_collect_ld = ld_file_name != 0;
     }
-  /* Search the compiler directories for `ld'.  We have protection against
-     recursive calls in find_a_file.  */
-  if (ld_file_name == 0)
-    ld_file_name = find_a_file (&cpath, ld_suffixes[selected_linker], X_OK);
-  /* Search the ordinary system bin directories
-     for `ld' (if native linking) or `TARGET-ld' (if cross).  */
-  if (ld_file_name == 0)
-    ld_file_name = find_a_file (&path, full_ld_suffixes[selected_linker], X_OK);
+  if (selected_linker != USE_LD) {
+    /* Search the compiler directories for `ld'.  We have protection against
+       recursive calls in find_a_file.  */
+    if (!ld_file_name)
+      ld_file_name = find_a_file(&cpath, ld_suffixes[selected_linker], X_OK);
+    /* Search the ordinary system bin directories
+       for `ld' (if native linking) or `TARGET-ld' (if cross).  */
+    if (!ld_file_name)
+      ld_file_name = find_a_file(&path, full_ld_suffixes[selected_linker], X_OK);
+  } else if (IS_ABSOLUTE_PATH(use_ld) && access(use_ld, X_OK) == 0) {
+    ld_file_name = use_ld;
+  } else {
+    const char *linker_name = concat("ld.", use_ld, NULL);
+    if (!ld_file_name)
+      ld_file_name = find_a_file(&cpath, linker_name, X_OK);
+    if (!ld_file_name) {
+#ifdef CROSS_DIRECTORY_STRUCTURE
+	linker_name = concat(target_machine, "-", linker_name, NULL);
+#endif
+	ld_file_name = find_a_file(&path, linker_name, X_OK);
+    }
+  }
 
 #ifdef REAL_NM_FILE_NAME
   nm_file_name = find_a_file (&path, REAL_NM_FILE_NAME, X_OK);
diff --git a/gcc/common.opt b/gcc/common.opt
index 5692cd04374..a76ed6434bb 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2859,17 +2859,9 @@ funwind-tables
 Common Report Var(flag_unwind_tables) Optimization
 Just generate unwind tables for exception handling.
 
-fuse-ld=bfd
-Common Driver Negative(fuse-ld=gold)
-Use the bfd linker instead of the default linker.
-
-fuse-ld=gold
-Common Driver Negative(fuse-ld=bfd)
-Use the gold linker instead of the default linker.
-
-fuse-ld=lld
-Common Driver Negative(fuse-ld=lld)
-Use the lld LLVM linker instead of the default linker.
+fuse-ld=
+Common Driver Joined
+-fuse-ld=[bfd|gold|lld|<absolute path>]	Use the specified linker.
 
 fuse-linker-plugin
 Common Undocumented Var(flag_use_linker_plugin)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 35b341e759f..c2dd410c88f 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -14128,17 +14128,10 @@ uses @samp{nolto-rel}. To maintain whole program optimization, it is
 recommended to link such objects into static library instead. Alternatively it
 is possible to use H.J. Lu's binutils with support for mixed objects.
 
-@item -fuse-ld=bfd
-@opindex fuse-ld=bfd
-Use the @command{bfd} linker instead of the default linker.
-
-@item -fuse-ld=gold
-@opindex fuse-ld=gold
-Use the @command{gold} linker instead of the default linker.
-
-@item -fuse-ld=lld
-@opindex fuse-ld=lld
-Use the LLVM @command{lld} linker instead of the default linker.
+@item -fuse-ld=@var{linker}
+@opindex fuse-ld=linker
+If @var{linker} is an absolute path, use it instead of the default linker;
+otherwise use @command{ld.@var{linker}}.
 
 @cindex Libraries
 @item -l@var{library}
diff --git a/gcc/gcc.c b/gcc/gcc.c
index effc384f3ef..f9a6f10502d 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -3989,12 +3989,8 @@ driver_handle_option (struct gcc_options *opts,
       do_save = false;
       break;
 
-    case OPT_fuse_ld_bfd:
-       use_ld = ".bfd";
-       break;
-
-    case OPT_fuse_ld_gold:
-       use_ld = ".gold";
+    case OPT_fuse_ld_:
+       use_ld = arg;
        break;
 
     case OPT_fcompare_debug_second:
@@ -7903,20 +7899,20 @@ driver::maybe_print_and_exit () const
 	      if (! strcmp (&default_linker[len], HOST_EXECUTABLE_SUFFIX))
 		{
 		  default_linker[len] = '\0';
-		  ld = concat (default_linker, use_ld,
+		  ld = concat (default_linker, ".", use_ld,
 			       HOST_EXECUTABLE_SUFFIX, NULL);
 		}
 	    }
 	  if (ld == NULL)
 # endif
-	  ld = concat (DEFAULT_LINKER, use_ld, NULL);
+	  ld = concat (DEFAULT_LINKER, ".", use_ld, NULL);
 	  if (access (ld, X_OK) == 0)
 	    {
 	      printf ("%s\n", ld);
 	      return (0);
 	    }
 #endif
-	  print_prog_name = concat (print_prog_name, use_ld, NULL);
+	  print_prog_name = concat (print_prog_name, ".", use_ld, NULL);
 	}
       char *newname = find_a_file (&exec_prefixes, print_prog_name, X_OK, 0);
       printf ("%s\n", (newname ? newname : print_prog_name));
diff --git a/gcc/opts.c b/gcc/opts.c
index 7affeb41a96..f50d365d517 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -2763,9 +2763,7 @@ common_handle_option (struct gcc_options *opts,
       dc->max_errors = value;
       break;
 
-    case OPT_fuse_ld_bfd:
-    case OPT_fuse_ld_gold:
-    case OPT_fuse_ld_lld:
+    case OPT_fuse_ld_:
     case OPT_fuse_linker_plugin:
       /* No-op. Used by the driver and passed to us because it starts with f.*/
       break;
-- 
2.25.0