[PATCH] Assert on lval_register
Yao Qi
qiyaoltc@gmail.com
Tue Dec 6 10:15:00 GMT 2016
On 16-11-30 22:16:37, Ulrich Weigand wrote:
> > 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.
>
> I think we should simply get rid of frame_register_unwind. Callers
> should be changed to use frame_unwind_register_value directly, and
> just operate on the value.
>
Yeah, that is what I was trying to do, but we should be careful on
the value management in the end of frame_register_unwind,
/* Dispose of the new value. This prevents watchpoints from
trying to watch the saved frame pointer. */
release_value (value);
value_free (value);
> > *lvalp = VALUE_LVAL (value);
> > *addrp = value_address (value);
> > - *realnump = VALUE_REGNUM (value);
> > + if (*lvalp == lval_register)
> > + *realnump = VALUE_REGNUM (value);
>
> But as long as the above change is not done yet, maybe we ought to
> at least provide a defined value (e.g. -1), to avoid callers maybe
> making use of uninitialized variables?
>
OK, how about the patch below?
--
Yao (é½å°§)
>From 581e1b80ea631d5bcfb5fc64b07a36fd71f5d55e Mon Sep 17 00:00:00 2001
From: Yao Qi <yao.qi@linaro.org>
Date: Thu, 24 Nov 2016 09:08:00 +0000
Subject: [PATCH] Assert on lval_register
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.
gdb:
2016-12-06 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.
diff --git a/gdb/frame.c b/gdb/frame.c
index 5414cb3..00001bc 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -1107,7 +1107,10 @@ 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);
+ else
+ *realnump = -1;
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;
}
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