Re: [PATCH 02/26] gdbserver: convert new_register_cache into a regcache constructor

[Simon Marchi <simark@simark.ca>]

On 2/28/23 06:28, Tankut Baris Aktemur via Gdb-patches wrote:
> Convert the `new_register_cache` function into a constructor of the
> regcache struct.  Also define a default ctor because it is used in
> other places, in particular, tracepoint.cc.
> ---
>  gdbserver/regcache.cc | 11 +++--------
>  gdbserver/regcache.h  |  8 ++++----
>  gdbserver/server.cc   |  2 +-
>  3 files changed, 8 insertions(+), 13 deletions(-)
> 
> diff --git a/gdbserver/regcache.cc b/gdbserver/regcache.cc
> index 7987c406ab4..1410dd96551 100644
> --- a/gdbserver/regcache.cc
> +++ b/gdbserver/regcache.cc
> @@ -43,7 +43,7 @@ get_thread_regcache (struct thread_info *thread, int fetch)
>  
>        gdb_assert (proc->tdesc != NULL);
>  
> -      regcache = new_register_cache (proc->tdesc);
> +      regcache = new struct regcache (proc->tdesc);
>        set_thread_regcache_data (thread, regcache);
>      }
>  
> @@ -151,15 +151,10 @@ regcache::initialize (const target_desc *tdesc,
>  
>  #ifndef IN_PROCESS_AGENT
>  
> -struct regcache *
> -new_register_cache (const struct target_desc *tdesc)
> +regcache::regcache (const target_desc *tdesc)
>  {
> -  struct regcache *regcache = new struct regcache;
> -
>    gdb_assert (tdesc->registers_size != 0);
> -  regcache->initialize (tdesc, nullptr);
> -
> -  return regcache;
> +  initialize (tdesc, nullptr);
>  }
>  
>  void
> diff --git a/gdbserver/regcache.h b/gdbserver/regcache.h
> index 15b7e2b4dff..0002726ed00 100644
> --- a/gdbserver/regcache.h
> +++ b/gdbserver/regcache.h
> @@ -44,6 +44,10 @@ struct regcache : public reg_buffer_common
>  #ifndef IN_PROCESS_AGENT
>    /* One of REG_UNAVAILABLE or REG_VALID.  */
>    unsigned char *register_status = nullptr;
> +
> +  /* Constructors.  */
> +  regcache () = default;
> +  regcache (const target_desc *tdesc);

Ok, so with this patch I understood better the two modes regcache can
operate, it can allocate its own memory or use a buffer passed to the
initialize method.  I think my previous suggestion still stands.  You
could have:

  regcache (const target_desc *tdesc,  unsigned char *regbuf);
  regcache (const target_desc *tdesc);

... former using the passed-in buffer and the latter allocating its own
buffer.  I don't think we would need a default constructor then (and we
should use DISALLOW_COPY_AND_ASSIGN).

Simon