[PATCH] Assert on lval_register

[Yao Qi <qiyaoltc@gmail.com>]

This patch adds asserts where the value's lval must be lval_register.
This triggers an error in frame_register_unwind because VALUE_REGNUM
is used but value's lval is not lval_register.

This also reveals a design issue in frame_register_unwind, that is
arguments addrp and realnump are mutually exclusive, we either use
addrp (for lval_memory), or use realnump (for lval_register).  This
can be done in a separate patch.

Regression tested on x86_64-linux.

gdb:

2016-11-30  Yao Qi  <yao.qi@linaro.org>

	* frame.c (frame_register_unwind): Set *realnump if *lvalp is
	lval_register.
	* value.c (deprecated_value_next_frame_id_hack): Assert
	value->lval is lval_register.
	(deprecated_value_regnum_hack): Likewise.
---
 gdb/frame.c | 3 ++-
 gdb/value.c | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdb/frame.c b/gdb/frame.c
index 5414cb3..1c388d1 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -1107,7 +1107,8 @@ frame_register_unwind (struct frame_info *frame, int regnum,
   *unavailablep = !value_entirely_available (value);
   *lvalp = VALUE_LVAL (value);
   *addrp = value_address (value);
-  *realnump = VALUE_REGNUM (value);
+  if (*lvalp == lval_register)
+    *realnump = VALUE_REGNUM (value);
 
   if (bufferp)
     {
diff --git a/gdb/value.c b/gdb/value.c
index cc291cf..022900f 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -1576,12 +1576,14 @@ deprecated_value_internalvar_hack (struct value *value)
 struct frame_id *
 deprecated_value_next_frame_id_hack (struct value *value)
 {
+  gdb_assert (value->lval == lval_register);
   return &value->location.reg.next_frame_id;
 }
 
 int *
 deprecated_value_regnum_hack (struct value *value)
 {
+  gdb_assert (value->lval == lval_register);
   return &value->location.reg.regnum;
 }
 
-- 
1.9.1