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Date: Thu, 05 Jan 2012 12:56:16 -0200 From: Luis Machado<luis_gustavo@mentor.com>
This machinery works by marking locations modified through the "condition_changed" field. Conditions change whenever we create a new location, use the "condition" command or delete an old duplicate location. Furthermore, if a location at addr 0xdeadbeef had its condition modified, all duplicate locations at 0xdeadbeef are marked modified as well.
The modification detection takes place inside update_global_location_list (...). By calling force_breakpoint_reinsertion (...), we mark every location at address 0xdeadbeef as modified. When consolidating the final updated list of locations, we detect these locations and mark the non-duplicate location at 0xdeafbeef as "needs_update".
The "needs_update" field is used during breakpoint insertion. It forces insertion of breakpoints even if they are marked as inserted already.
Now that we have information about locations that we should reinsert in the target, we proceed to build a list of hex-encoded agent expressions.
At this point, if any conditional expressions fail to parse to a valid agent expression, we assume that the conditions will be evaluated on GDB's side. Thus we don't send the conditions to the stub. Otherwise, we proceed to insert the breakpoints and the remote code now attaches the hex-encoded expressions to the z0/z1 packet.
Regarding always-inserted mode, if it is "on" we must send condition changes right away, or else the target will potentially miss breakpoint hits. If always-inserted is "off", this isn't too critical, so we just wait for the insertion call to send all the conditions to the stub. We will remove them when stopping anyway.WIBNI these details were somewhere in the source comments or (gasp!) in gdbint.texinfo?
+/* Shows the current mode of breakpoint condition evaluation. Explicitly shows + what "auto" is translating to. */ + +static void +show_condition_evaluation_mode (struct ui_file *file, int from_tty, + struct cmd_list_element *c, const char *value) +{ + if (condition_evaluation_mode == condition_evaluation_auto) + fprintf_filtered (file, + _("Breakpoint condition evaluation " + "mode is %s (currently %s).\n"), + value, + breakpoint_condition_evaluation_mode ()); + else + fprintf_filtered (file, _("Breakpoint condition evaluation mode is %s.\n"), + value); +} +Is it a good idea to show "gdb" or "stub" rather than "auto"? After all, as you explained elsewhere, the translation is not 100% accurate, depending on the specifics of each individual condition.
Sounds good. I'll make that change.+ /* Print whether the remote stub is doing the breakpoint's condition + evaluation. If GDB is doing the evaluation, don't print anything. */ + if (loc&& is_breakpoint (b)&& loc->cond_bytecode + && breakpoint_condition_evaluation_mode () + != condition_evaluation_gdb) + { + ui_out_text (uiout, " ("); + ui_out_field_string (uiout, "condeval", + breakpoint_condition_evaluation_mode ());I suggest "cond.eval." instead of "condeval". Better yet, how about "evaluated by"?
Btw, what happens if I set the mode to "stub" and the sub does not support this? Do I get any feedback, and if so, at what time?
1 - Target supports it (via ConditionalBreakpoints feature). 2 - breakpoint condition-evaluation is "auto" or "stub".
-- Luis lgustavo@codesourcery.com
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