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

[Christopher Faylor <cgf-use-the-mailinglist-please@sourceware.org>]

On Fri, Apr 30, 2010 at 12:24:26AM +0200, Pierre Muller wrote:
>Nobody reacted to this:
>http://sourceware.org/ml/gdb-patches/2010-04/msg00552.html
>
>It helps avoid some unnecessary recomputation.

Looks ok but is this computation really so onerous that we need to add
the extra code?

cgf
>Pierre
>
>> -----Message d'origine-----
>> De?: gdb-patches-owner@sourceware.org [mailto:gdb-patches-
>> owner@sourceware.org] De la part de Pierre Muller
>> Envoy??: Monday, April 19, 2010 11:00 AM
>> ??: 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;
>>  }
>> 
>
>
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