[PATCH] LTO: fallback to -flto=N if -flto=jobserver does not work.

["Martin Liška" <mliska@suse.cz>]

When -flto=jobserver is used and we cannot detect job server, then we can
still fallbackto -flto=N mode.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Ready to be installed?
Thanks,
Martin

gcc/ChangeLog:

	* lto-wrapper.c (run_gcc): When -flto=jobserver is used, but the
	makeserver cannot be detected, then use -flto=N fallback.
---
 gcc/lto-wrapper.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
index 03a5922f8ea..0b626d7c811 100644
--- a/gcc/lto-wrapper.c
+++ b/gcc/lto-wrapper.c
@@ -1585,8 +1585,9 @@ run_gcc (unsigned argc, char *argv[])
       if (jobserver && jobserver_error != NULL)
 	{
 	  warning (0, jobserver_error);
-	  parallel = 0;
+	  /* Fall back to auto parallelism.  */
 	  jobserver = 0;
+	  auto_parallel = 1;
 	}
       else if (!jobserver && jobserver_error == NULL)
 	{
-- 
2.31.1