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, 12 insertions, 8 deletions

diff --git a/gdb/frame.h b/gdb/frame.h
index 252b75e..605528c 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -471,7 +471,8 @@ const char *frame_stop_reason_string (enum unwind_stop_reason);
    fetch/compute the value.  Instead just return the location of the
    value.  */
 extern void frame_register_unwind (struct frame_info *frame, int regnum,
-				   int *optimizedp, enum lval_type *lvalp,
+				   int *optimizedp, int *unavailablep,
+				   enum lval_type *lvalp,
 				   CORE_ADDR *addrp, int *realnump,
 				   gdb_byte *valuep);
 
@@ -507,7 +508,8 @@ extern ULONGEST get_frame_register_unsigned (struct frame_info *frame,
    VALUEP is NULL, the registers value is not fetched/computed.  */
 
 extern void frame_register (struct frame_info *frame, int regnum,
-			    int *optimizedp, enum lval_type *lvalp,
+			    int *optimizedp, int *unavailablep,
+			    enum lval_type *lvalp,
 			    CORE_ADDR *addrp, int *realnump,
 			    gdb_byte *valuep);
 
@@ -654,12 +656,14 @@ extern int deprecated_pc_in_call_dummy (struct gdbarch *gdbarch, CORE_ADDR pc);
 /* FIXME: cagney/2003-02-02: Should be deprecated or replaced with a
    function called get_frame_register_p().  This slightly weird (and
    older) variant of get_frame_register() returns zero (indicating the
-   register is unavailable) if either: the register isn't cached; or
-   the register has been optimized out.  Problem is, neither check is
-   exactly correct.  A register can't be optimized out (it may not
-   have been saved as part of a function call); The fact that a
-   register isn't in the register cache doesn't mean that the register
-   isn't available (it could have been fetched from memory).  */
+   register value is unavailable/invalid) if either: the register
+   isn't cached; or the register has been optimized out; or the
+   register contents are unavailable (because they haven't been
+   collected in a traceframe).  Problem is, neither check is exactly
+   correct.  A register can't be optimized out (it may not have been
+   saved as part of a function call); The fact that a register isn't
+   in the register cache doesn't mean that the register isn't
+   available (it could have been fetched from memory).  */
 
 extern int frame_register_read (struct frame_info *frame, int regnum,
 				gdb_byte *buf);