RE: Modifying ARM code generator for elimination of 8bit writes - need help

["Dave Korn" <dave dot korn at artimi dot com>]

On 20 July 2006 07:03, Wolfgang Mües wrote:

> Hello Rask,
> 
> On Wednesday 19 July 2006 13:24, Rask Ingemann Lambertsen wrote:
>> I've spotted a function named emit_set_insn() in arm.c. It might be
>> the problem, because it uses gen_rtx_SET() directly.
> 
> But it's not the only function which uses gen_rtx_SET. There are also
> much places with
> 
>>     emit_constant_insn (cond,
>> 	gen_rtx_SET (VOIDmode, target, source));
> 
> Isn't it better to replace gen_rtx_SET?
> 

  Is there any generic advice available as to when and why one should use
emit_insn (gen_rtx_SET (....)) as opposed to emit_move_insn (...)?

  (There are other similar pairs of functions with seemingly overlapping
functionality that I find equally confusing.  For instance, I *think* that you
should only use gen_rtx_REG when you want to create a new pseudo, and that in
the general case of wanting an rtx that refers to an existing pseudo or a hard
reg you're supposed to use gen_reg_rtx which takes care of sharing and
everything for you... but I haven't seen any solid documentation that backs up
my hypothesis.)


    cheers,
      DaveK
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