[PATCH v10 18/28] record-btrace, frame: supply target-specific unwinder

Markus Metzger
2014-01-14T08:04:48Z

Supply a target-specific frame unwinder for the record-btrace target that does
not allow unwinding while replaying.

2013-02-11 Jan Kratochvil <jan.kratochvil@redhat.com>
Markus Metzger <markus.t.metzger@intel.com>

gdb/
* record-btrace.c: Include frame-unwind.h.
(record_btrace_frame_unwind_stop_reason)
(record_btrace_frame_this_id, record_btrace_frame_prev_register)
(record_btrace_frame_sniffer, record_btrace_frame_unwind):
New.
(init_record_btrace_ops): Install it.

---
gdb/record-btrace.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 64 insertions(+)

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 44ce754..870ad7d 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -33,6 +33,7 @@
#include "symtab.h"
#include "filenames.h"
#include "regcache.h"
+#include "frame-unwind.h"

/* The target_ops of record-btrace. */
static struct target_ops record_btrace_ops;
@@ -840,6 +841,68 @@ record_btrace_prepare_to_store (struct target_ops *ops,
}
}

+/* Implement stop_reason method for record_btrace_frame_unwind. */
+
+static enum unwind_stop_reason
+record_btrace_frame_unwind_stop_reason (struct frame_info *this_frame,
+ void **this_cache)
+{
+ return UNWIND_UNAVAILABLE;
+}
+
+/* Implement this_id method for record_btrace_frame_unwind. */
+
+static void
+record_btrace_frame_this_id (struct frame_info *this_frame, void **this_cache,
+ struct frame_id *this_id)
+{
+ /* Leave there the outer_frame_id value. */
+}
+
+/* Implement prev_register method for record_btrace_frame_unwind. */
+
+static struct value *
+record_btrace_frame_prev_register (struct frame_info *this_frame,
+ void **this_cache,
+ int regnum)
+{
+ throw_error (NOT_AVAILABLE_ERROR,
+ _("Registers are not available in btrace record history"));
+}
+
+/* Implement sniffer method for record_btrace_frame_unwind. */
+
+static int
+record_btrace_frame_sniffer (const struct frame_unwind *self,
+ struct frame_info *this_frame,
+ void **this_cache)
+{
+ struct thread_info *tp;
+ struct btrace_thread_info *btinfo;
+ struct btrace_insn_iterator *replay;
+
+ /* THIS_FRAME does not contain a reference to its thread. */
+ tp = find_thread_ptid (inferior_ptid);
+ gdb_assert (tp != NULL);
+
+ return btrace_is_replaying (tp);
+}
+
+/* btrace recording does not store previous memory content, neither the stack
+ frames content. Any unwinding would return errorneous results as the stack
+ contents no longer matches the changed PC value restored from history.
+ Therefore this unwinder reports any possibly unwound registers as
+ <unavailable>. */
+
+static const struct frame_unwind record_btrace_frame_unwind =
+{
+ NORMAL_FRAME,
+ record_btrace_frame_unwind_stop_reason,
+ record_btrace_frame_this_id,
+ record_btrace_frame_prev_register,
+ NULL,
+ record_btrace_frame_sniffer
+};
/* Initialize the record-btrace target ops. */

static void
@@ -870,6 +933,7 @@ init_record_btrace_ops (void)
ops->to_fetch_registers = record_btrace_fetch_registers;
ops->to_store_registers = record_btrace_store_registers;
ops->to_prepare_to_store = record_btrace_prepare_to_store;
+ ops->to_get_unwinder = &record_btrace_frame_unwind;
ops->to_stratum = record_stratum;
ops->to_magic = OPS_MAGIC;
}
--
1.8.3.1