From 1fea80498891db3fef831bd65f231603951e5f14 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Tue, 19 May 2020 12:21:26 -0700
Subject: [PATCH] Add -fuse-ld= to specify an arbitrary executable as the
 linker

The value can be either a relative path (relative to a COMPILER_PATH
directory or a PATH directory) or an absolute path.  Unlike
-fuse-ld={bfd,gold,lld}, -fuse-ld= does not add a prefix `ld.`

	PR driver/93645
	* common.opt (-fuse-ld=): Add -fuse-ld=.
	* opts.c (common_handle_option): Handle OPT_fuse_ld_.
	* gcc.c (driver_handle_option): Likewise.
	* collect2.c (main): Likewise.
	* doc/invoke.texi: Document -fuse-ld=.
---
 gcc/collect2.c      | 32 ++++++++++++++++++++++++--------
 gcc/common.opt      |  4 ++++
 gcc/doc/invoke.texi |  4 ++++
 gcc/opts.c          |  1 +
 4 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/gcc/collect2.c b/gcc/collect2.c
index f8a5ce45994..cc57a20e08b 100644
--- a/gcc/collect2.c
+++ b/gcc/collect2.c
@@ -844,6 +844,7 @@ 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
@@ -967,6 +968,11 @@ main (int argc, char **argv)
 	  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_MAX;
+	  }
 	else if (strncmp (argv[i], "-o", 2) == 0)
 	  {
 	    /* Parse the output filename if it's given so that we can make
@@ -1117,14 +1123,24 @@ 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_MAX)
+    {
+      ld_file_name = find_a_file (&cpath, use_ld, X_OK);
+      if (ld_file_name == 0)
+	ld_file_name = find_a_file (&path, use_ld, X_OK);
+    }
+  else
+    {
+      /* 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);
+    }
 
 #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 4464049fc1f..6408d042d8c 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2908,6 +2908,10 @@ fuse-ld=lld
 Common Driver Negative(fuse-ld=lld)
 Use the lld LLVM linker instead of the default linker.
 
+fuse-ld=
+Common Driver Joined
+Use the specified executable instead of the default linker.
+
 fuse-linker-plugin
 Common Undocumented Var(flag_use_linker_plugin)
 
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7217e27151d..30a2fc4fa53 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -14304,6 +14304,10 @@ Use the @command{gold} linker instead of the default linker.
 @opindex fuse-ld=lld
 Use the LLVM @command{lld} linker instead of the default linker.
 
+@item -fuse-ld=@var{linker}
+@opindex fuse-ld=linker
+Use the specified executable named @var{linker} instead of the default linker.
+
 @cindex Libraries
 @item -l@var{library}
 @itemx -l @var{library}
diff --git a/gcc/opts.c b/gcc/opts.c
index ec3ca0720f9..522a196ab0f 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -2785,6 +2785,7 @@ common_handle_option (struct gcc_options *opts,
     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;
-- 
2.27.0.rc0.183.gde8f92d652-goog