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Re: PATCH for m68k.md


You are right. The manual for the 5200 has three pages of documentation
for the move and movea instructions.  Most of the information is on the
first two pages, which I read.  Unfortunately, the third page has the
table that describes the legal combinations of source and destinations,
which I didn't see.  Back to the drawing board.

-Will

Jeffrey A Law wrote:
> 
>   In message <3A96E35E.AF51B00C@redhat.com>you write:
>   > When building the compiler for the m68k (actually, the m5200 target). I
>   > found that the the template for the movqi was missing the memory operand
>   > in the constraints. This causes the compiler to fail in some when
>   > compiling cp-demangle.c in libiberty with the "-m5200" option.  The
>   > following insn pattern cannot be converted:
>   >
>   > (insn 1203 995 996 (set (reg:QI 8 %a0)
>   >         (mem/f:QI (plus:SI (reg:SI 14 %a6)
>   >                 (const_int -5 [0xfffffffb])) 0)) 37 {*m68k.md:1060}
>   > (nil)
>   >     (nil))
>   >
>   > The attached patch fixes this problem The change log is below:
>   >
>   > 2001-02-23  Will Cohen  <wcohen@redhat.com>
>   >
>   >     * config/m68k/m68k.md: Update movqi pattern for TARGET_5200.
>   >
>   > Is it okay to apply this patch?
> I'm pretty sure this is wrong -- if I recall properly the 5200 can't actually
> do byte sized moves into address registers.
> 
> You can probably look in the gcc list archives and find the discussion behind
> this patch:
> 
> Sat Sep  5 03:23:05 1998  Jeffrey A Law  (law@cygnus.com)
> 
>         * m68k.md (5200 movqi): Do not allow byte sized memory references
>         using address regs.
>         * m68k.c (output_move_qimode): Do not use byte sized operations on
>         address registers.
> 
> jeff


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