Hello Rask,
On Friday 02 June 2006 09:24, Rask Ingemann Lambertsen wrote:
> There may be a faster way of seeing if the modification is going to
> work for the DS at all. I noticed from the output template
> "swp%?b\\t%1, %1, [%M0]" that "swp" takes three operands. I don't
> know ARM assembler, but you may be able to choose to always clobber a
> specific register. Make it a fixed register (see FIXED_REGISTERS),
> refer to this register directly in the output template and don't add
> a clobber to the movqi patterns. IMHO, that's an acceptable hack at
> an experimental stage. If the resulting code runs correctly on the
> DS, you can then undo the FIXED_REGISTERS change and add the clobber
> statements.
I have tried this. No luck. Problem is the lack of addressing modes for
the swp instruction. Only a simple pointer in a register (no offset, no
auto-increment is allowed).
After reading most of the gcc rtl documentation (and forgetting way too
much..) I came up to the following conclusion:
Splitting the insn
(define_insn "*arm_movqi_insn"
[(set (match_operand:QI 0 "nonimmediate_operand" "=r,r,r,m")
(match_operand:QI 1 "general_operand" "rI,K,m,r"))]
into 4 different insns:
(define_insn "*arm_movqi_insn"
[(set (match_operand:QI 0 "register_operand" "")
(match_operand:QI 1 "register_operand" ""))]
(define_insn "*arm_movnqi_insn"
[(set (match_operand:QI 0 "register_operand" "")
(match_operand:QI 1 "constant_operand" ""))]
(define_insn "*arm_loadqi_insn"
[(set (match_operand:QI 0 "register_operand" "")
(match_operand:QI 1 "memory_operand" ""))]
(define_insn "*arm_storeqi_insn"
[(set (match_operand:QI 0 "memory_operand" "")
(match_operand:QI 1 "register_operand" ""))]
This should give the same function as before, but I then I can do
(define_insn "*arm_storeqi_insn"
[(set (match_operand:QI 0 "simple_memory_operand" "")
(match_operand:QI 1 "register_operand" ""))]
etc
to limit the addressing modes of the store insn to the limits of the
swpb instruction.
And then I can recode the
(define_expand "movqi"
[(set (match_operand:QI 0 "general_operand" "")
(match_operand:QI 1 "general_operand" ""))]
to cope with the movqi requirements defined in the gcc manual.
Hmmm... wondering who all these xxx_operand functions are defined, and
where they are documented...
Is this the right way to go?
regards
Wolfgang
--
We're back to the times when men were men
and wrote their own device drivers.
(Linus Torvalds)
