forked from Imagelibrary/binutils-gdb
44c04ee9bf
I am sending this as an RFC because it's far from complete and definitive, but I'd like to gather some comments and opinions before going further in this direction. The goal of this patch is to decouple the notion of the user-selected inferior/thread/frame from GDB's internally selected inferior/thread/frame. Currently, for example, the inferior_ptid variable has two jobs: - it's the user-selected thread: it's changed by the "thread" command. Other commands (continue, backtrace, etc) apply to this thread. - it's the internally-selected thread: it defines the thread GDB is currently "working" on. For example, implementations of to_xfer_partial will refer to it to know from which thread to read/write memory. Because of this dual usage, if we want to do some operations on a thread other than the currently selected one, we have to save the current inferior/thread/frame and restore them when we're done. Failing to do so would result in an unexpected selection switch for the user. To improve this, Pedro suggested in [1] to decouple the two concepts. This is essentially what this patch is trying to do. A new "user_selection" object is introduced, which contains the selected inferior/thread/frame from the point of view of the user. Before every command, we "apply" this selection to the core of GDB to make sure the internal selection matches the user selection. There is a single user selection for the whole GDB (named "global user-selection"), but as was mentioned in the linked thread, it opens the door to having different selections for different UIs. This means that each UI would have its own user-selection object, which would be applied to the core prior to executing commands from this UI. The global user-selection object only gets modified when we really intend to change it. It can be because of the thread / -thread-select / up / down / frame / inferior commands, a breakpoint hit in all-stop, an inferior exit, etc. The problem that initially prompted this effort is that the "--thread" flag of MI commands changes the user-selected thread under the user's feet. My initial attempt to fix it was to restore the selection after the MI command execution. However, some cases are hard to get right. For example: (thread 1 is currently selected) -interpreter-exec --thread 2 console "thread 3" Restoring the selected thread to thread 1 after the MI command execution wrongfully cancels the switch to thread 3. So it's hard to determine when we should or shouldn't restore. With the current patch, it works naturally: the --thread flag doesn't touch the user-selected thread, only the internal one. The "thread 3" command updates the user selection. Another difficulty is to send the right notifications to MI when the user selection changes. That means to not miss any, but not send too many either. Getting it somewhat right lead to ugly hacks (see the command_notifies_uscc_observer function) and even then it's not perfect (see the kfails in user-selected-context-sync.exp test). With the proposed method, it's easy to know when the user-selection changes and send notifications. With this patch, there are probably a few usage of make_cleanup_restore_current_thread that are not needed anymore, if they are only used to restore the user selection. I kept removing them for a later time though. In the current state, there are a few minor regressions in the testsuite (especially some follow-fork stuff I'm not sure how to handle), but the vast majority of the previously passing tests still pass. Comments are welcome! Thanks, Simon [1] https://sourceware.org/ml/gdb-patches/2016-08/msg00031.html
86 lines
2.9 KiB
C++
86 lines
2.9 KiB
C++
/* Output generating routines for GDB CLI.
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Copyright (C) 1999-2017 Free Software Foundation, Inc.
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Contributed by Cygnus Solutions.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef CLI_OUT_H
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#define CLI_OUT_H
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#include "ui-out.h"
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#include <vector>
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class cli_ui_out : public ui_out
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{
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public:
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explicit cli_ui_out (ui_file *stream, ui_out_flags flags);
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virtual ~cli_ui_out ();
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ui_file *set_stream (ui_file *stream);
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bool suppress_output ()
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{ return m_suppress_output; }
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void suppress_output (bool val)
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{ m_suppress_output = val; }
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protected:
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virtual void do_table_begin (int nbrofcols, int nr_rows,
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const char *tblid) override;
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virtual void do_table_body () override;
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virtual void do_table_end () override;
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virtual void do_table_header (int width, ui_align align,
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const std::string &col_name,
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const std::string &col_hdr) override;
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/* Note: level 0 is the top-level so LEVEL is always greater than
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zero. */
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virtual void do_begin (ui_out_type type, const char *id) override;
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virtual void do_end (ui_out_type type) override;
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virtual void do_field_int (int fldno, int width, ui_align align,
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const char *fldname, int value) override;
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virtual void do_field_skip (int fldno, int width, ui_align align,
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const char *fldname) override;
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virtual void do_field_string (int fldno, int width, ui_align align,
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const char *fldname, const char *string) override;
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virtual void do_field_fmt (int fldno, int width, ui_align align,
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const char *fldname, const char *format, va_list args)
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override ATTRIBUTE_PRINTF (6,0);
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virtual void do_spaces (int numspaces) override;
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virtual void do_text (const char *string) override;
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virtual void do_message (const char *format, va_list args) override
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ATTRIBUTE_PRINTF (2,0);
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virtual void do_wrap_hint (const char *identstring) override;
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virtual void do_flush () override;
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virtual void do_redirect (struct ui_file *outstream) override;
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private:
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void field_separator ();
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void out_field_fmt (int fldno, const char *fldname, const char *format, ...)
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ATTRIBUTE_PRINTF (4, 5);
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std::vector<ui_file *> m_streams;
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bool m_suppress_output;
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};
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extern cli_ui_out *cli_out_new (struct ui_file *stream);
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extern void cli_display_match_list (char **matches, int len, int max);
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#endif
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