+ /* Don't frame_debug print legacy_get_prev_frame() here, just
+ confuses the output. */
+
+ /* Allocate the new frame.
+
+ There is no reason to worry about memory leaks, should the
+ remainder of the function fail. The allocated memory will be
+ quickly reclaimed when the frame cache is flushed, and the `we've
+ been here before' check, in get_prev_frame will stop repeated
+ memory allocation calls. */
+ prev = FRAME_OBSTACK_ZALLOC (struct frame_info);
+ prev->level = this_frame->level + 1;
+
+ /* Do not completly wire it in to the frame chain. Some (bad) code
+ in INIT_FRAME_EXTRA_INFO tries to look along frame->prev to pull
+ some fancy tricks (of course such code is, by definition,
+ recursive).
+
+ On the other hand, methods, such as get_frame_pc() and
+ get_frame_base() rely on being able to walk along the frame
+ chain. Make certain that at least they work by providing that
+ link. Of course things manipulating prev can't go back. */
+ prev->next = this_frame;
+
+ /* NOTE: cagney/2002-11-18: Should have been correctly setting the
+ frame's type here, before anything else, and not last, at the
+ bottom of this function. The various
+ DEPRECATED_INIT_EXTRA_FRAME_INFO, DEPRECATED_INIT_FRAME_PC,
+ DEPRECATED_INIT_FRAME_PC_FIRST and
+ DEPRECATED_FRAME_INIT_SAVED_REGS methods are full of work-arounds
+ that handle the frame not being correctly set from the start.
+ Unfortunatly those same work-arounds rely on the type defaulting
+ to NORMAL_FRAME. Ulgh! The new frame code does not have this
+ problem. */
+ prev->type = UNKNOWN_FRAME;
+
+ /* A legacy frame's ID is always computed here. Mark it as valid. */
+ prev->this_id.p = 1;
+
+ /* Handle sentinel frame unwind as a special case. */
+ if (this_frame->level < 0)
+ {
+ /* Try to unwind the PC. If that doesn't work, assume we've reached
+ the oldest frame and simply return. Is there a better sentinal
+ value? The unwound PC value is then used to initialize the new
+ previous frame's type.
+
+ Note that the pc-unwind is intentionally performed before the
+ frame chain. This is ok since, for old targets, both
+ frame_pc_unwind (nee, DEPRECATED_FRAME_SAVED_PC) and
+ DEPRECATED_FRAME_CHAIN()) assume THIS_FRAME's data structures
+ have already been initialized (using
+ DEPRECATED_INIT_EXTRA_FRAME_INFO) and hence the call order
+ doesn't matter.
+
+ By unwinding the PC first, it becomes possible to, in the case of
+ a dummy frame, avoid also unwinding the frame ID. This is
+ because (well ignoring the PPC) a dummy frame can be located
+ using THIS_FRAME's frame ID. */
+
+ deprecated_update_frame_pc_hack (prev, frame_pc_unwind (this_frame));
+ if (get_frame_pc (prev) == 0)
+ {
+ /* The allocated PREV_FRAME will be reclaimed when the frame
+ obstack is next purged. */
+ if (frame_debug)
+ {
+ fprintf_unfiltered (gdb_stdlog, "-> ");
+ fprint_frame (gdb_stdlog, NULL);
+ fprintf_unfiltered (gdb_stdlog,
+ " // unwound legacy PC zero }\n");
+ }
+ return NULL;
+ }
+
+ /* Set the unwind functions based on that identified PC. Ditto
+ for the "type" but strongly prefer the unwinder's frame type. */
+ prev->unwind = frame_unwind_find_by_pc (current_gdbarch,
+ get_frame_pc (prev));
+ if (prev->unwind->type == UNKNOWN_FRAME)
+ prev->type = frame_type_from_pc (get_frame_pc (prev));
+ else
+ prev->type = prev->unwind->type;
+
+ /* Find the prev's frame's ID. */
+ if (prev->type == DUMMY_FRAME
+ && gdbarch_unwind_dummy_id_p (current_gdbarch))
+ {
+ /* When unwinding a normal frame, the stack structure is
+ determined by analyzing the frame's function's code (be
+ it using brute force prologue analysis, or the dwarf2
+ CFI). In the case of a dummy frame, that simply isn't
+ possible. The The PC is either the program entry point,
+ or some random address on the stack. Trying to use that
+ PC to apply standard frame ID unwind techniques is just
+ asking for trouble. */
+ /* Assume call_function_by_hand(), via SAVE_DUMMY_FRAME_TOS,
+ previously saved the dummy frame's ID. Things only work
+ if the two return the same value. */
+ gdb_assert (SAVE_DUMMY_FRAME_TOS_P ());
+ /* Use an architecture specific method to extract the prev's
+ dummy ID from the next frame. Note that this method uses
+ frame_register_unwind to obtain the register values
+ needed to determine the dummy frame's ID. */
+ prev->this_id.value = gdbarch_unwind_dummy_id (current_gdbarch,
+ this_frame);
+ }
+ else
+ {
+ /* We're unwinding a sentinel frame, the PC of which is
+ pointing at a stack dummy. Fake up the dummy frame's ID
+ using the same sequence as is found a traditional
+ unwinder. Once all architectures supply the
+ unwind_dummy_id method, this code can go away. */
+ prev->this_id.value = frame_id_build (deprecated_read_fp (),
+ read_pc ());
+ }
+
+ /* Check that the unwound ID is valid. */
+ if (!frame_id_p (prev->this_id.value))
+ {
+ if (frame_debug)
+ {
+ fprintf_unfiltered (gdb_stdlog, "-> ");
+ fprint_frame (gdb_stdlog, NULL);
+ fprintf_unfiltered (gdb_stdlog,
+ " // unwound legacy ID invalid }\n");
+ }
+ return NULL;
+ }
+
+ /* Check that the new frame isn't inner to (younger, below,
+ next) the old frame. If that happens the frame unwind is
+ going backwards. */
+ /* FIXME: cagney/2003-02-25: Ignore the sentinel frame since
+ that doesn't have a valid frame ID. Should instead set the
+ sentinel frame's frame ID to a `sentinel'. Leave it until
+ after the switch to storing the frame ID, instead of the
+ frame base, in the frame object. */
+
+ /* Link it in. */
+ this_frame->prev = prev;
+
+ /* FIXME: cagney/2002-01-19: This call will go away. Instead of
+ initializing extra info, all frames will use the frame_cache
+ (passed to the unwind functions) to store additional frame
+ info. Unfortunatly legacy targets can't use
+ legacy_get_prev_frame() to unwind the sentinel frame and,
+ consequently, are forced to take this code path and rely on
+ the below call to DEPRECATED_INIT_EXTRA_FRAME_INFO to
+ initialize the inner-most frame. */
+ if (DEPRECATED_INIT_EXTRA_FRAME_INFO_P ())
+ {
+ DEPRECATED_INIT_EXTRA_FRAME_INFO (0, prev);
+ }
+
+ if (prev->type == NORMAL_FRAME)
+ prev->this_id.value.code_addr
+ = get_pc_function_start (prev->this_id.value.code_addr);
+
+ if (frame_debug)
+ {
+ fprintf_unfiltered (gdb_stdlog, "-> ");
+ fprint_frame (gdb_stdlog, prev);
+ fprintf_unfiltered (gdb_stdlog, " } // legacy innermost frame\n");
+ }
+ return prev;
+ }
+