Re: RFA: Fix compile time warning in gdb/mips-tdep.c

[Andrew Cagney <ac131313 at cygnus dot com>]

Nick Clifton wrote:
> 
> Hi Guys,
> 
>   Whilst working on something else I noticed a warning from gcc about
>   a variable in unpack_mips16() which was being used before it was
>   initialised.  Looking at the code concerned it was obvious that it
>   was wrong ('extension' is used without being initialised), but it
>   was not obvious what the programmer actually intended.  Below is a
>   patch that represent my best guess as to what should actually be
>   happening.
> 
>   Is the patch right ?  Can I apply it ?

I'm not sure - I don't have the correct manual handy.  For the moment,
I'll simply disable this code.  As you note it is clearly wrong yet no
one has noticed.

	Andrew

> Cheers
>         Nick
> 
> 2000-08-07  Nick Clifton  <nickc@cygnus.com>
> 
>         * mips-tdep.c (unpack_mips16): Fix the initialisation of
>         'extension' and 'extended'.
> 
> Index: gdb/mips-tdep.c
> ===================================================================
> RCS file: /cvs/src//src/gdb/mips-tdep.c,v
> retrieving revision 1.29
> diff -p -r1.29 mips-tdep.c
> *** mips-tdep.c 2000/07/30 01:48:26     1.29
> --- mips-tdep.c 2000/08/07 23:53:03
> *************** unpack_mips16 (CORE_ADDR pc,
> *** 915,928 ****
>     CORE_ADDR extpc;
>     unsigned long extension;
>     int extended;
> !   extpc = (pc - 4) & ~0x01;   /* Extensions are 32 bit instructions */
> !   /* Decrement to previous address and loose the 16bit mode flag */
> !   /* return if the instruction was extendable, but not actually extended */
>     extended = ((mips32_op (extension) == 30) ? 1 : 0);
> !   if (extended)
> !     {
> !       extension = mips_fetch_instruction (extpc);
> !     }
>     switch (upk->fmt)
>       {
>       case itype:
> --- 915,927 ----
>     CORE_ADDR extpc;
>     unsigned long extension;
>     int extended;
> !
> !   /* Decrement to previous address and loose the 16bit mode flag.  */
> !   extpc = (pc - 4) & ~0x01;
> !   /* Extensions are 32 bit instructions.  */
> !   extension = mips_fetch_instruction (extpc);
>     extended = ((mips32_op (extension) == 30) ? 1 : 0);
> !
>     switch (upk->fmt)
>       {
>       case itype: