[nvptx] Use TARGET_SET_CURRENT_FUNCTION

Implement TARGET_SET_CURRENT_FUNCTION for nvptx.  This gives us a place to
add initialization or reset actions that need to be executed on a per-function
basis.

Build and reg-tested on x86_64 with nvptx accelerator.

2018-12-19  Tom de Vries  <tdevries@suse.de>

	* config/nvptx/nvptx.c (nvptx_previous_fndecl): Declare.
	(nvptx_set_current_function): New function.
	(TARGET_SET_CURRENT_FUNCTION): Define.

From-SVN: r267256

gcc/ChangeLog

+2018-12-19  Tom de Vries  <tdevries@suse.de>
+
+	* config/nvptx/nvptx.c (nvptx_previous_fndecl): Declare.
+	(nvptx_set_current_function): New function.
+	(TARGET_SET_CURRENT_FUNCTION): Define.
+
 2018-12-19  Shaokun Zhang  <zhangshaokun@hisilicon.com>
 
 	* config/aarch64/aarch64-cores.def (tsv110): Fix architecture.  This

gcc/config/nvptx/nvptx.c

@@ -5980,6 +5980,17 @@ nvptx_can_change_mode_class (machine_mode, machine_mode, reg_class_t)
   return false;
 }
 
+static GTY(()) tree nvptx_previous_fndecl;
+
+static void
+nvptx_set_current_function (tree fndecl)
+{
+  if (!fndecl || fndecl == nvptx_previous_fndecl)
+    return;
+
+  nvptx_previous_fndecl = fndecl;
+}
+
 #undef TARGET_OPTION_OVERRIDE
 #define TARGET_OPTION_OVERRIDE nvptx_option_override
 
@@ -6116,6 +6127,9 @@ nvptx_can_change_mode_class (machine_mode, machine_mode, reg_class_t)
 #undef TARGET_HAVE_SPECULATION_SAFE_VALUE
 #define TARGET_HAVE_SPECULATION_SAFE_VALUE speculation_safe_value_not_needed
 
+#undef TARGET_SET_CURRENT_FUNCTION
+#define TARGET_SET_CURRENT_FUNCTION nvptx_set_current_function
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-nvptx.h"