From 3835aa0eb90292d652dd6b200f302f3cac7e643f Mon Sep 17 00:00:00 2001
From: Martin Liska <mliska@suse.cz>
Date: Wed, 12 May 2021 11:59:17 +0200
Subject: [PATCH] LTO: merge -flto=arg from object files.

gcc/ChangeLog:

	* lto-wrapper.c (merge_and_complain): Merge -flto=arg options.
	(run_gcc): Use -flto argument detection for merged
	fdecoded_options.
---
 gcc/lto-wrapper.c | 77 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 57 insertions(+), 20 deletions(-)

diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
index 7931ae3fada..a71d6147152 100644
--- a/gcc/lto-wrapper.c
+++ b/gcc/lto-wrapper.c
@@ -425,6 +425,31 @@ merge_and_complain (vec<cl_decoded_option> decoded_options,
 	case OPT_foffload_:
 	  decoded_options.safe_push (*foption);
 	  break;
+
+	case OPT_flto_:
+	  if (existing_opt == -1)
+	    decoded_options.safe_push (*foption);
+	  else
+	    {
+	      if (strcmp (foption->arg, decoded_options[existing_opt].arg) != 0)
+		{
+		  /* -flto=auto is preferred.  */
+		  if (strcmp (decoded_options[existing_opt].arg, "auto") == 0)
+		    ;
+		  else if (strcmp (foption->arg, "auto") == 0
+			   || strcmp (foption->arg, "jobserver") == 0)
+		    decoded_options[existing_opt].arg = foption->arg;
+		  else if (strcmp (decoded_options[existing_opt].arg,
+				   "jobserver") != 0)
+		    {
+		      int n = atoi (foption->arg);
+		      int original_n = atoi (decoded_options[existing_opt].arg);
+		      if (n > original_n)
+			decoded_options[existing_opt].arg = foption->arg;
+		    }
+		}
+	    }
+	  break;
 	}
     }
 
@@ -1490,6 +1515,37 @@ run_gcc (unsigned argc, char *argv[])
   append_compiler_options (&argv_obstack, fdecoded_options);
   append_linker_options (&argv_obstack, decoded_options);
 
+  /* Process LTO-related options on merged options.  */
+  for (j = 1; j < fdecoded_options.length (); ++j)
+    {
+      cl_decoded_option *option = &fdecoded_options[j];
+      switch (option->opt_index)
+	{
+	case OPT_flto_:
+	  if (strcmp (option->arg, "jobserver") == 0)
+	    {
+	      parallel = 1;
+	      jobserver = 1;
+	    }
+	  else if (strcmp (option->arg, "auto") == 0)
+	    {
+	      parallel = 1;
+	      auto_parallel = 1;
+	    }
+	  else
+	    {
+	      parallel = atoi (option->arg);
+	      if (parallel <= 1)
+		parallel = 0;
+	    }
+	  /* Fallthru.  */
+
+	case OPT_flto:
+	  lto_mode = LTO_MODE_WHOPR;
+	  break;
+	}
+    }
+
   /* Scan linker driver arguments for things that are of relevance to us.  */
   for (j = 1; j < decoded_options.length (); ++j)
     {
@@ -1519,26 +1575,7 @@ run_gcc (unsigned argc, char *argv[])
 
 	case OPT_flto_:
 	  if (strcmp (option->arg, "jobserver") == 0)
-	    {
-	      parallel = 1;
-	      jobserver = 1;
-	      jobserver_requested = true;
-	    }
-	  else if (strcmp (option->arg, "auto") == 0)
-	    {
-	      parallel = 1;
-	      auto_parallel = 1;
-	    }
-	  else
-	    {
-	      parallel = atoi (option->arg);
-	      if (parallel <= 1)
-		parallel = 0;
-	    }
-	  /* Fallthru.  */
-
-	case OPT_flto:
-	  lto_mode = LTO_MODE_WHOPR;
+	    jobserver_requested = true;
 	  break;
 
 	case OPT_flinker_output_: