gdb/

	* findvar.c (value_of_register): Mark the value as unavailable, if
	the register is unavailable.
	* frame.h (frame_register_unwind): New `unavailablep' parameter.
	(frame_register): New `unavailablep' parameter.
	(frame_register_read): Update comment.
	* frame.c (frame_register_unwind): New `unavailablep' parameter.
	Set it if the register is unavailable.  If the register is
	unavailable, clear the output buffer.
	(frame_register): New `unavailablep' parameter.  Pass it down.
	(frame_unwind_register): Adjust.
	(put_frame_register): Adjust.
	(frame_register_read): Adjust.  Also return false if the register
	is not available.
	(frame_register_unwind_location): Adjust.
	* sentinel-frame.c (sentinel_frame_prev_register): If the register
	is unavailable, mark the value accordingly.
	* stack.c (frame_info): Handle unavailable registers.

	gdb/testsuite/
	* gdb.trace/unavailable.exp (fpreg, spreg, pcreg): Define.
	(test_register, test_register_unavailable): New procedures.
	(gdb_unavailable_registers_test): New procedure.
	(gdb_trace_collection_test): Call it.

1 files changed, 4 insertions, 1 deletions

diff --git a/gdb/sentinel-frame.c b/gdb/sentinel-frame.c
index f68ea1c..e6000cc 100644
--- a/gdb/sentinel-frame.c
+++ b/gdb/sentinel-frame.c
@@ -61,7 +61,10 @@ sentinel_frame_prev_register (struct frame_info *this_frame,
   /* Use the regcache_cooked_read() method so that it, on the fly,
      constructs either a raw or pseudo register from the raw
      register cache.  */
-  regcache_cooked_read (cache->regcache, regnum, value_contents_raw (value));
+  if (regcache_cooked_read (cache->regcache,
+			    regnum,
+			    value_contents_raw (value)) == REG_UNAVAILABLE)
+    mark_value_bytes_unavailable (value, 0, register_size (gdbarch, regnum));
 
   return value;
 }