Re: [PATCH 05/10] remote: remote_arch_state pointers -> remote_arch_state objects

Pedro Alves
2018-05-21T16:04:08Z

On 05/18/2018 10:09 PM, Simon Marchi wrote:

> Oops, spoke a bit too soon. It fails to build with g++ 5.4.0 (Ubuntu 16.04).
> It doesn't like the "this->m_arch_states.emplace (gdbarch, gdbarch)". With
> g++ 7.1.0 it builds fine.
>
> /home/emaisin/src/binutils-gdb/gdb/remote.c:962:61: required from here
> /usr/include/c++/5/ext/new_allocator.h:120:4: error: no matching function for call to ‘std::pair<gdbarch* const, remote_arch_state>::pair(gdbarch*&, gdbarch*&)’
> { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
> ^

Bah. I tried with gcc 4.8 now, and it trips on the same issue.
Using a different emplace overload works.

From aecfc376df9b718c9f86898db925031151d16774 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Mon, 21 May 2018 16:47:03 +0100
Subject: [PATCH] remote: remote_arch_state pointers -> remote_arch_state
objects

The previous patch made the map store pointers to remote_arch_state
instead of objects directly, simply because struct remote_arch_state
is still incomplete where struct remote_state is declared. This patch
thus moves the remote_arch_state declaration higher up in the file,
and makes the map store remote_arch_state objects directly instead of
pointers to objects.

gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>

* remote.c (struct packet_reg, struct remote_arch_state):
Move higher up in the file.
(remote_state) <m_arch_states>: Store remote_arch_state values
instead of remote_arch_state pointers.
(remote_state::get_remote_arch_state): Adjust.
---
gdb/remote.c | 95 ++++++++++++++++++++++++++++++++----------------------------
1 file changed, 51 insertions(+), 44 deletions(-)

diff --git a/gdb/remote.c b/gdb/remote.c
index ba054f5061..1d1819bac1 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -603,6 +603,44 @@ struct readahead_cache
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. */
@@ -749,8 +787,7 @@ 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 *,
- std::unique_ptr<struct remote_arch_state>>
+ std::unordered_map<struct gdbarch *, remote_arch_state>
m_arch_states;
};

@@ -820,44 +857,6 @@ get_remote_state_raw (void)
return remote_state;
}

-/* 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;
-};
-
/* Utility: generate error from an incoming stub packet. */
static void
trace_error (char *buf)
@@ -958,10 +957,15 @@ remote_get_noisy_reply ()
struct remote_arch_state *
remote_state::get_remote_arch_state (struct gdbarch *gdbarch)
{
- auto &rsa = this->m_arch_states[gdbarch];
- if (rsa == nullptr)
+ remote_arch_state *rsa;
+
+ auto it = this->m_arch_states.find (gdbarch);
+ if (it == this->m_arch_states.end ())
{
- rsa.reset (new remote_arch_state (gdbarch));
+ auto p = this->m_arch_states.emplace (std::piecewise_construct,
+ std::forward_as_tuple (gdbarch),
+ std::forward_as_tuple (gdbarch));
+ rsa = &p.first->second;

/* Make sure that the packet buffer is plenty big enough for
this architecture. */
@@ -971,7 +975,10 @@ remote_state::get_remote_arch_state (struct gdbarch *gdbarch)
this->buf = (char *) xrealloc (this->buf, this->buf_size);
}
}
- return rsa.get ();
+ else
+ rsa = &it->second;
+
+ return rsa;
}

/* Fetch the global remote target state. */
--
2.14.3