offload-defaulted: Config option to silently ignore uninstalled offload compilers

If configured with --enable-offload-defaulted, configured but not installed
offload compilers and libgomp plugins are silently ignored.  Useful for
distribution compilers where those are in separate optional packages.

2021-04-28  Jakub Jelinek  <jakub@redhat.com>
	    Tobias Burnus  <tobias@codesourcery.com>

ChangeLog:

	* configure.ac (--enable-offload-defaulted): New.
	* configure: Regenerate.

gcc/ChangeLog:

	* configure.ac (OFFLOAD_DEFAULTED): AC_DEFINE if offload-defaulted.
	* gcc.c (process_command): New variable.
	(driver::maybe_putenv_OFFLOAD_TARGETS): If OFFLOAD_DEFAULTED,
	set it if -foffload is defaulted.
	* lto-wrapper.c (OFFLOAD_TARGET_DEFAULT_ENV): Define.
	(compile_offload_image): If OFFLOAD_DEFAULTED and
	OFFLOAD_TARGET_DEFAULT is in the environment, don't fail
	if corresponding mkoffload can't be found.
	(compile_images_for_offload_targets): Likewise.  Free and clear
	offload_names if no valid offload is found.
	* config.in: Regenerate.
	* configure: Regenerate.

libgomp/ChangeLog:

	* configure.ac (OFFLOAD_DEFAULTED): AC_DEFINE if offload-defaulted.
	* target.c (gomp_load_plugin_for_device): If set and if a plugin
	can't be dlopened, silently assume it has no devices.
	* Makefile.in: Regenerate.
	* config.h.in: Regenerate.
	* configure: Regenerate.

1 files changed, 14 insertions, 0 deletions

diff --git a/configure b/configure
index 504f641..7dd1fd5 100755
--- a/configure
+++ b/configure
@@ -786,6 +786,7 @@ with_build_libsubdir
 with_system_zlib
 enable_as_accelerator_for
 enable_offload_targets
+enable_offload_defaulted
 enable_gold
 enable_ld
 enable_compressed_debug_sections
@@ -1515,6 +1516,11 @@ Optional Features:
                           enable offloading to devices from comma-separated
                           LIST of TARGET[=DIR]. Use optional path to find
                           offload target compiler during the build
+  --enable-offload-defaulted
+		If enabled, configured but not installed offload compilers and
+		libgomp plugins are silently ignored.  Useful for distribution
+		compilers where those are in separate optional packages.
+
   --enable-gold[=ARG]     build gold [ARG={default,yes,no}]
   --enable-ld[=ARG]       build ld [ARG={default,yes,no}]
   --enable-compressed-debug-sections={all,gas,gold,ld,none}
@@ -2981,6 +2987,14 @@ else
 fi
 
 
+# Check whether --enable-offload-defaulted was given.
+if test "${enable_offload_defaulted+set}" = set; then :
+  enableval=$enable_offload_defaulted; enable_offload_defaulted=$enableval
+else
+  enable_offload_defaulted=
+fi
+
+
 # Handle --enable-gold, --enable-ld.
 # --disable-gold [--enable-ld]
 #     Build only ld.  Default option.