[PING] [RFC/Windows] Remember last tlb type for re-use in windows_get_tlb_type

["Pierre Muller" <pierre.muller@ics-cnrs.unistra.fr>]

Nobody reacted to this:
http://sourceware.org/ml/gdb-patches/2010-04/msg00552.html

It helps avoid some unnecessary recomputation.

Pierre

> -----Message d'origine-----
> De : gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] De la part de Pierre Muller
> Envoyé : Monday, April 19, 2010 11:00 AM
> À : gdb-patches@sourceware.org
> Objet : [RFC/Windows] Remember last tlb type for re-use in
> windows_get_tlb_type
> 
>   Each time, you examine the convenience variable
> $_tlb on Windows executable
> the function windows_get_tlb_type is called
> and creates a new type.
> 
>   I copied this behavior from the internal variable _siginfo,
> but I think that it is a big waste of time and memory to
> regenerate it each time.
>   Nevertheless, with multi-target GDB, you can possibly create
> a type of windows-32 bit another for windows 64-bit
> or even one for windows-CE.
>   Thus I remember the last gdbarch passed
> and return the remember type only if gdbarch did not change,
> which is most of the time.
> 
>   I do not know if those kind of patches
> are regarded as useful.
> 
> Comments welcome.
> 
> 
> Pierre Muller
> 
> 2010-04-19  Pierre Muller  <muller@ics.u-strasbg.fr>
> 
> 	* windows-tdep.c (windows_get_tlb_type): Remember
> 	last GDBARCH and created type for re-use.
> 
> Index: windows-tdep.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/windows-tdep.c,v
> retrieving revision 1.6
> diff -u -p -r1.6 windows-tdep.c
> --- windows-tdep.c	16 Apr 2010 07:49:35 -0000	1.6
> +++ windows-tdep.c	19 Apr 2010 08:45:27 -0000
> @@ -97,12 +97,18 @@ static int maint_display_all_tib = 0;
>  static struct type *
>  windows_get_tlb_type (struct gdbarch *gdbarch)
>  {
> +  static struct gdbarch *last_gdbarch = NULL;
> +  static struct type *last_tlb_type = NULL;
>    struct type *dword_ptr_type, *dword32_type, *void_ptr_type;
>    struct type *peb_ldr_type, *peb_ldr_ptr_type;
>    struct type *peb_type, *peb_ptr_type, *list_type, *list_ptr_type;
>    struct type *module_list_ptr_type;
>    struct type *tib_type, *seh_type, *tib_ptr_type, *seh_ptr_type;
> 
> +  /* Do not rebuild type if same gdbarch as last time.  */
> +  if (last_tlb_type && last_gdbarch == gdbarch)
> +    return last_tlb_type;
> +
>    dword_ptr_type = arch_integer_type (gdbarch, gdbarch_ptr_bit
> (gdbarch),
>  				 1, "DWORD_PTR");
>    dword32_type = arch_integer_type (gdbarch, 32,
> @@ -210,6 +216,9 @@ windows_get_tlb_type (struct gdbarch *gd
>  			    TYPE_LENGTH (void_ptr_type), NULL);
>    TYPE_TARGET_TYPE (tib_ptr_type) = tib_type;
> 
> +  last_tlb_type = tib_ptr_type;
> +  last_gdbarch = gdbarch;
> +
>    return tib_ptr_type;
>  }
>