[PATCH 11/10] remote_target::m_remote_state, pointer -> object (Re: [PATCH 10/10] remote: one struct remote_state per struct remote_target)

Pedro Alves
2018-05-24T15:54:05Z

On 05/22/2018 06:30 PM, Pedro Alves wrote:
> On 05/22/2018 04:37 AM, Simon Marchi wrote:

>> Is there a reason not to make the remote_state object a simple field
>> of remote_target, does it have to be a pointer? You would have to
>> shuffle things around a little bit more, but it seems to work fine.
>
> Yeah, no reason other than struct remote_state not being complete yet
> when the field is defined in struct remote_target. I was thinking the
> moving would be done as follow up, to avoid even more churn mixed in with
> changes, very much like patch #4 started with a pointer and then patch #5
> moved to objects.
Like this?

(Note this is generated with "git format-patch --patience".
The default diff algorithm produces a much less readable patch.)

From 3ab58d94cb7b3b7039f3e02b5ed72571e546f80d Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Thu, 24 May 2018 16:33:23 +0100
Subject: [PATCH] remote_target::m_remote_state, pointer -> object

The only reason remote_target::m_remote_state is a pointer is that
struct remote_state is incomplete when struct remote_target is
defined.

This commit thus moves struct remote_state (and its dependencies)
higher up and makes remote_target::m_remote_state an object instead of
a pointer.

gdb/ChangeLog:
2018-05-24 Pedro Alves <palves@redhat.com>

* remote.c (struct vCont_action_support, MAXTHREADLISTRESULTS)
(struct readahead_cache, struct packet_reg, struct
remote_arch_state, class remote_state): Move higher up in the
file.
(remote_target::m_remote_state): Now an object instead of a pointer.
(remote_target::get_remote_state): Adjust.
---
gdb/remote.c | 546 +++++++++++++++++++++++++++++------------------------------
1 file changed, 272 insertions(+), 274 deletions(-)

diff --git a/gdb/remote.c b/gdb/remote.c
index 3e4566d985..38ba7b581c 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -123,7 +123,273 @@ enum packet_result
};

struct threads_listing_context;
-struct remote_state;
+
+/* Stub vCont actions support.
+
+ Each field is a boolean flag indicating whether the stub reports
+ support for the corresponding action. */
+
+struct vCont_action_support
+{
+ /* vCont;t */
+ bool t = false;
+
+ /* vCont;r */
+ bool r = false;
+
+ /* vCont;s */
+ bool s = false;
+
+ /* vCont;S */
+ bool S = false;
+};
+
+/* About this many threadisds fit in a packet. */
+
+#define MAXTHREADLISTRESULTS 32
+
+/* Data for the vFile:pread readahead cache. */
+
+struct readahead_cache
+{
+ /* Invalidate the readahead cache. */
+ void invalidate ();
+
+ /* Invalidate the readahead cache if it is holding data for FD. */
+ void invalidate_fd (int fd);
+
+ /* Serve pread from the readahead cache. Returns number of bytes
+ read, or 0 if the request can't be served from the cache. */
+ int pread (int fd, gdb_byte *read_buf, size_t len, ULONGEST offset);
+
+ /* The file descriptor for the file that is being cached. -1 if the
+ cache is invalid. */
+ int fd = -1;
+
+ /* The offset into the file that the cache buffer corresponds
+ to. */
+ ULONGEST offset = 0;
+
+ /* The buffer holding the cache contents. */
+ gdb_byte *buf = nullptr;
+ /* The buffer's size. We try to read as much as fits into a packet
+ at a time. */
+ size_t bufsize = 0;
+
+ /* Cache hit and miss counters. */
+ ULONGEST hit_count = 0;
+ ULONGEST miss_count = 0;
+};
+
+/* Description of the remote protocol for a given architecture. */
+
+struct packet_reg
+{
+ long offset; /* Offset into G packet. */
+ long regnum; /* GDB's internal register number. */
+ LONGEST pnum; /* Remote protocol register number. */
+ int in_g_packet; /* Always part of G packet. */
+ /* long size in bytes; == register_size (target_gdbarch (), regnum);
+ at present. */
+ /* char *name; == gdbarch_register_name (target_gdbarch (), regnum);
+ at present. */
+};
+
+struct remote_arch_state
+{
+ explicit remote_arch_state (struct gdbarch *gdbarch);
+
+ /* Description of the remote protocol registers. */
+ long sizeof_g_packet;
+
+ /* Description of the remote protocol registers indexed by REGNUM
+ (making an array gdbarch_num_regs in size). */
+ std::unique_ptr<packet_reg[]> regs;
+
+ /* This is the size (in chars) of the first response to the ``g''
+ packet. It is used as a heuristic when determining the maximum
+ size of memory-read and memory-write packets. A target will
+ typically only reserve a buffer large enough to hold the ``g''
+ packet. The size does not include packet overhead (headers and
+ trailers). */
+ long actual_register_packet_size;
+
+ /* This is the maximum size (in chars) of a non read/write packet.
+ It is also used as a cap on the size of read/write packets. */
+ long remote_packet_size;
+};
+
+/* Description of the remote protocol state for the currently
+ connected target. This is per-target state, and independent of the
+ selected architecture. */
+
+class remote_state
+{
+public:
+
+ remote_state ();
+ ~remote_state ();
+
+ /* Get the remote arch state for GDBARCH. */
+ struct remote_arch_state *get_remote_arch_state (struct gdbarch *gdbarch);
+
+public: /* data */
+
+ /* A buffer to use for incoming packets, and its current size. The
+ buffer is grown dynamically for larger incoming packets.
+ Outgoing packets may also be constructed in this buffer.
+ BUF_SIZE is always at least REMOTE_PACKET_SIZE;
+ REMOTE_PACKET_SIZE should be used to limit the length of outgoing
+ packets. */
+ char *buf;
+ long buf_size;
+
+ /* True if we're going through initial connection setup (finding out
+ about the remote side's threads, relocating symbols, etc.). */
+ bool starting_up = false;
+
+ /* If we negotiated packet size explicitly (and thus can bypass
+ heuristics for the largest packet size that will not overflow
+ a buffer in the stub), this will be set to that packet size.
+ Otherwise zero, meaning to use the guessed size. */
+ long explicit_packet_size = 0;
+
+ /* remote_wait is normally called when the target is running and
+ waits for a stop reply packet. But sometimes we need to call it
+ when the target is already stopped. We can send a "?" packet
+ and have remote_wait read the response. Or, if we already have
+ the response, we can stash it in BUF and tell remote_wait to
+ skip calling getpkt. This flag is set when BUF contains a
+ stop reply packet and the target is not waiting. */
+ int cached_wait_status = 0;
+
+ /* True, if in no ack mode. That is, neither GDB nor the stub will
+ expect acks from each other. The connection is assumed to be
+ reliable. */
+ bool noack_mode = false;
+
+ /* True if we're connected in extended remote mode. */
+ bool extended = false;
+
+ /* True if we resumed the target and we're waiting for the target to
+ stop. In the mean time, we can't start another command/query.
+ The remote server wouldn't be ready to process it, so we'd
+ timeout waiting for a reply that would never come and eventually
+ we'd close the connection. This can happen in asynchronous mode
+ because we allow GDB commands while the target is running. */
+ bool waiting_for_stop_reply = false;
+
+ /* The status of the stub support for the various vCont actions. */
+ vCont_action_support supports_vCont;
+
+ /* True if the user has pressed Ctrl-C, but the target hasn't
+ responded to that. */
+ bool ctrlc_pending_p = false;
+
+ /* True if we saw a Ctrl-C while reading or writing from/to the
+ remote descriptor. At that point it is not safe to send a remote
+ interrupt packet, so we instead remember we saw the Ctrl-C and
+ process it once we're done with sending/receiving the current
+ packet, which should be shortly. If however that takes too long,
+ and the user presses Ctrl-C again, we offer to disconnect. */
+ bool got_ctrlc_during_io = false;
+
+ /* Descriptor for I/O to remote machine. Initialize it to NULL so that
+ remote_open knows that we don't have a file open when the program
+ starts. */
+ struct serial *remote_desc = nullptr;
+
+ /* These are the threads which we last sent to the remote system. The
+ TID member will be -1 for all or -2 for not sent yet. */
+ ptid_t general_thread = null_ptid;
+ ptid_t continue_thread = null_ptid;
+
+ /* This is the traceframe which we last selected on the remote system.
+ It will be -1 if no traceframe is selected. */
+ int remote_traceframe_number = -1;
+
+ char *last_pass_packet = nullptr;
+
+ /* The last QProgramSignals packet sent to the target. We bypass
+ sending a new program signals list down to the target if the new
+ packet is exactly the same as the last we sent. IOW, we only let
+ the target know about program signals list changes. */
+ char *last_program_signals_packet = nullptr;
+
+ gdb_signal last_sent_signal = GDB_SIGNAL_0;
+
+ bool last_sent_step = false;
+
+ /* The execution direction of the last resume we got. */
+ exec_direction_kind last_resume_exec_dir = EXEC_FORWARD;
+
+ char *finished_object = nullptr;
+ char *finished_annex = nullptr;
+ ULONGEST finished_offset = 0;
+
+ /* Should we try the 'ThreadInfo' query packet?
+
+ This variable (NOT available to the user: auto-detect only!)
+ determines whether GDB will use the new, simpler "ThreadInfo"
+ query or the older, more complex syntax for thread queries.
+ This is an auto-detect variable (set to true at each connect,
+ and set to false when the target fails to recognize it). */
+ bool use_threadinfo_query = false;
+ bool use_threadextra_query = false;
+
+ threadref echo_nextthread {};
+ threadref nextthread {};
+ threadref resultthreadlist[MAXTHREADLISTRESULTS] {};
+
+ /* The state of remote notification. */
+ struct remote_notif_state *notif_state = nullptr;
+
+ /* The branch trace configuration. */
+ struct btrace_config btrace_config {};
+
+ /* The argument to the last "vFile:setfs:" packet we sent, used
+ to avoid sending repeated unnecessary "vFile:setfs:" packets.
+ Initialized to -1 to indicate that no "vFile:setfs:" packet
+ has yet been sent. */
+ int fs_pid = -1;
+
+ /* A readahead cache for vFile:pread. Often, reading a binary
+ involves a sequence of small reads. E.g., when parsing an ELF
+ file. A readahead cache helps mostly the case of remote
+ debugging on a connection with higher latency, due to the
+ request/reply nature of the RSP. We only cache data for a single
+ file descriptor at a time. */
+ struct readahead_cache readahead_cache;
+
+ /* The list of already fetched and acknowledged stop events. This
+ queue is used for notification Stop, and other notifications
+ don't need queue for their events, because the notification
+ events of Stop can't be consumed immediately, so that events
+ should be queued first, and be consumed by remote_wait_{ns,as}
+ one per time. Other notifications can consume their events
+ immediately, so queue is not needed for them. */
+ QUEUE (stop_reply_p) *stop_reply_queue;
+
+ /* Asynchronous signal handle registered as event loop source for
+ when we have pending events ready to be passed to the core. */
+ struct async_event_handler *remote_async_inferior_event_token = nullptr;
+
+ /* FIXME: cagney/1999-09-23: Even though getpkt was called with
+ ``forever'' still use the normal timeout mechanism. This is
+ currently used by the ASYNC code to guarentee that target reads
+ during the initial connect always time-out. Once getpkt has been
+ modified to return a timeout indication and, in turn
+ remote_wait()/wait_for_inferior() have gained a timeout parameter
+ this can go away. */
+ int wait_forever_enabled_p = 1;
+
+private:
+ /* Mapping of remote protocol data for each gdbarch. Usually there
+ is only one entry here, though we may see more with stubs that
+ support multi-process. */
+ std::unordered_map<struct gdbarch *, remote_arch_state>
+ m_arch_states;
+};

static const target_info remote_target_info = {
"remote",
@@ -671,7 +937,9 @@ public: /* Remote specific methods. */

private: /* data fields */

- std::unique_ptr<struct remote_state> m_remote_state;
+ /* The remote state. Don't reference this directly. Use the
+ get_remote_state method instead. */
+ remote_state m_remote_state;
};

static const target_info extended_remote_target_info = {
@@ -775,282 +1043,15 @@ static struct cmd_list_element *remote_cmdlist;
static struct cmd_list_element *remote_set_cmdlist;
static struct cmd_list_element *remote_show_cmdlist;

-/* Stub vCont actions support.
-
- Each field is a boolean flag indicating whether the stub reports
- support for the corresponding action. */
-
-struct vCont_action_support
-{
- /* vCont;t */
- bool t = false;
-
- /* vCont;r */
- bool r = false;
-
- /* vCont;s */
- bool s = false;
-
- /* vCont;S */
- bool S = false;
-};
-
/* Controls whether GDB is willing to use range stepping. */

static int use_range_stepping = 1;

-/* About this many threadisds fit in a packet. */
-
-#define MAXTHREADLISTRESULTS 32
-
/* The max number of chars in debug output. The rest of chars are
omitted. */

#define REMOTE_DEBUG_MAX_CHAR 512

-/* Data for the vFile:pread readahead cache. */
-
-struct readahead_cache
-{
- /* Invalidate the readahead cache. */
- void invalidate ();
-
- /* Invalidate the readahead cache if it is holding data for FD. */
- void invalidate_fd (int fd);
-
- /* Serve pread from the readahead cache. Returns number of bytes
- read, or 0 if the request can't be served from the cache. */
- int pread (int fd, gdb_byte *read_buf, size_t len, ULONGEST offset);
-
- /* The file descriptor for the file that is being cached. -1 if the
- cache is invalid. */
- int fd = -1;
-
- /* The offset into the file that the cache buffer corresponds
- to. */
- ULONGEST offset = 0;
-
- /* The buffer holding the cache contents. */
- gdb_byte *buf = nullptr;
- /* The buffer's size. We try to read as much as fits into a packet
- at a time. */
- size_t bufsize = 0;
-
- /* Cache hit and miss counters. */
- ULONGEST hit_count = 0;
- ULONGEST miss_count = 0;
-};
-
-/* Description of the remote protocol for a given architecture. */
-
-struct packet_reg
-{
- long offset; /* Offset into G packet. */
- long regnum; /* GDB's internal register number. */
- LONGEST pnum; /* Remote protocol register number. */
- int in_g_packet; /* Always part of G packet. */
- /* long size in bytes; == register_size (target_gdbarch (), regnum);
- at present. */
- /* char *name; == gdbarch_register_name (target_gdbarch (), regnum);
- at present. */
-};
-
-struct remote_arch_state
-{
- explicit remote_arch_state (struct gdbarch *gdbarch);
-
- /* Description of the remote protocol registers. */
- long sizeof_g_packet;
-
- /* Description of the remote protocol registers indexed by REGNUM
- (making an array gdbarch_num_regs in size). */
- std::unique_ptr<packet_reg[]> regs;
-
- /* This is the size (in chars) of the first response to the ``g''
- packet. It is used as a heuristic when determining the maximum
- size of memory-read and memory-write packets. A target will
- typically only reserve a buffer large enough to hold the ``g''
- packet. The size does not include packet overhead (headers and
- trailers). */
- long actual_register_packet_size;
-
- /* This is the maximum size (in chars) of a non read/write packet.
- It is also used as a cap on the size of read/write packets. */
- long remote_packet_size;
-};
-
-/* Description of the remote protocol state for the currently
- connected target. This is per-target state, and independent of the
- selected architecture. */
-
-class remote_state
-{
-public:
-
- remote_state ();
- ~remote_state ();
-
- /* Get the remote arch state for GDBARCH. */
- struct remote_arch_state *get_remote_arch_state (struct gdbarch *gdbarch);
-
-public: /* data */
-
- /* A buffer to use for incoming packets, and its current size. The
- buffer is grown dynamically for larger incoming packets.
- Outgoing packets may also be constructed in this buffer.
- BUF_SIZE is always at least REMOTE_PACKET_SIZE;
- REMOTE_PACKET_SIZE should be used to limit the length of outgoing
- packets. */
- char *buf;
- long buf_size;
-
- /* True if we're going through initial connection setup (finding out
- about the remote side's threads, relocating symbols, etc.). */
- bool starting_up = false;
-
- /* If we negotiated packet size explicitly (and thus can bypass
- heuristics for the largest packet size that will not overflow
- a buffer in the stub), this will be set to that packet size.
- Otherwise zero, meaning to use the guessed size. */
- long explicit_packet_size = 0;
-
- /* remote_wait is normally called when the target is running and
- waits for a stop reply packet. But sometimes we need to call it
- when the target is already stopped. We can send a "?" packet
- and have remote_wait read the response. Or, if we already have
- the response, we can stash it in BUF and tell remote_wait to
- skip calling getpkt. This flag is set when BUF contains a
- stop reply packet and the target is not waiting. */
- int cached_wait_status = 0;
-
- /* True, if in no ack mode. That is, neither GDB nor the stub will
- expect acks from each other. The connection is assumed to be
- reliable. */
- bool noack_mode = false;
-
- /* True if we're connected in extended remote mode. */
- bool extended = false;
-
- /* True if we resumed the target and we're waiting for the target to
- stop. In the mean time, we can't start another command/query.
- The remote server wouldn't be ready to process it, so we'd
- timeout waiting for a reply that would never come and eventually
- we'd close the connection. This can happen in asynchronous mode
- because we allow GDB commands while the target is running. */
- bool waiting_for_stop_reply = false;
-
- /* The status of the stub support for the various vCont actions. */
- vCont_action_support supports_vCont;
-
- /* True if the user has pressed Ctrl-C, but the target hasn't
- responded to that. */
- bool ctrlc_pending_p = false;
-
- /* True if we saw a Ctrl-C while reading or writing from/to the
- remote descriptor. At that point it is not safe to send a remote
- interrupt packet, so we instead remember we saw the Ctrl-C and
- process it once we're done with sending/receiving the current
- packet, which should be shortly. If however that takes too long,
- and the user presses Ctrl-C again, we offer to disconnect. */
- bool got_ctrlc_during_io = false;
-
- /* Descriptor for I/O to remote machine. Initialize it to NULL so that
- remote_open knows that we don't have a file open when the program
- starts. */
- struct serial *remote_desc = nullptr;
-
- /* These are the threads which we last sent to the remote system. The
- TID member will be -1 for all or -2 for not sent yet. */
- ptid_t general_thread = null_ptid;
- ptid_t continue_thread = null_ptid;
-
- /* This is the traceframe which we last selected on the remote system.
- It will be -1 if no traceframe is selected. */
- int remote_traceframe_number = -1;
-
- char *last_pass_packet = nullptr;
-
- /* The last QProgramSignals packet sent to the target. We bypass
- sending a new program signals list down to the target if the new
- packet is exactly the same as the last we sent. IOW, we only let
- the target know about program signals list changes. */
- char *last_program_signals_packet = nullptr;
-
- gdb_signal last_sent_signal = GDB_SIGNAL_0;
-
- bool last_sent_step = false;
-
- /* The execution direction of the last resume we got. */
- exec_direction_kind last_resume_exec_dir = EXEC_FORWARD;
-
- char *finished_object = nullptr;
- char *finished_annex = nullptr;
- ULONGEST finished_offset = 0;
-
- /* Should we try the 'ThreadInfo' query packet?
-
- This variable (NOT available to the user: auto-detect only!)
- determines whether GDB will use the new, simpler "ThreadInfo"
- query or the older, more complex syntax for thread queries.
- This is an auto-detect variable (set to true at each connect,
- and set to false when the target fails to recognize it). */
- bool use_threadinfo_query = false;
- bool use_threadextra_query = false;
-
- threadref echo_nextthread {};
- threadref nextthread {};
- threadref resultthreadlist[MAXTHREADLISTRESULTS] {};
-
- /* The state of remote notification. */
- struct remote_notif_state *notif_state = nullptr;
-
- /* The branch trace configuration. */
- struct btrace_config btrace_config {};
-
- /* The argument to the last "vFile:setfs:" packet we sent, used
- to avoid sending repeated unnecessary "vFile:setfs:" packets.
- Initialized to -1 to indicate that no "vFile:setfs:" packet
- has yet been sent. */
- int fs_pid = -1;
-
- /* A readahead cache for vFile:pread. Often, reading a binary
- involves a sequence of small reads. E.g., when parsing an ELF
- file. A readahead cache helps mostly the case of remote
- debugging on a connection with higher latency, due to the
- request/reply nature of the RSP. We only cache data for a single
- file descriptor at a time. */
- struct readahead_cache readahead_cache;
-
- /* The list of already fetched and acknowledged stop events. This
- queue is used for notification Stop, and other notifications
- don't need queue for their events, because the notification
- events of Stop can't be consumed immediately, so that events
- should be queued first, and be consumed by remote_wait_{ns,as}
- one per time. Other notifications can consume their events
- immediately, so queue is not needed for them. */
- QUEUE (stop_reply_p) *stop_reply_queue;
-
- /* Asynchronous signal handle registered as event loop source for
- when we have pending events ready to be passed to the core. */
- struct async_event_handler *remote_async_inferior_event_token = nullptr;
-
- /* FIXME: cagney/1999-09-23: Even though getpkt was called with
- ``forever'' still use the normal timeout mechanism. This is
- currently used by the ASYNC code to guarentee that target reads
- during the initial connect always time-out. Once getpkt has been
- modified to return a timeout indication and, in turn
- remote_wait()/wait_for_inferior() have gained a timeout parameter
- this can go away. */
- int wait_forever_enabled_p = 1;
-
-private:
- /* Mapping of remote protocol data for each gdbarch. Usually there
- is only one entry here, though we may see more with stubs that
- support multi-process. */
- std::unordered_map<struct gdbarch *, remote_arch_state>
- m_arch_states;
-};
-
/* Private data that we'll store in (struct thread_info)->priv. */
struct remote_thread_info : public private_thread_info
{
@@ -1237,17 +1238,14 @@ remote_state::get_remote_arch_state (struct gdbarch *gdbarch)
remote_state *
remote_target::get_remote_state ()
{
- if (m_remote_state == nullptr)
- m_remote_state.reset (new remote_state ());
-
/* Make sure that the remote architecture state has been
initialized, because doing so might reallocate rs->buf. Any
function which calls getpkt also needs to be mindful of changes
to rs->buf, but this call limits the number of places which run
into trouble. */
- m_remote_state->get_remote_arch_state (target_gdbarch ());
+ m_remote_state.get_remote_arch_state (target_gdbarch ());

- return m_remote_state.get ();
+ return &m_remote_state;
}

/* Cleanup routine for the remote module's pspace data. */
--
2.14.3