Re: How to recognize registers after reload ?.

[Jeff Law <law@redhat.com>]

On 10/22/20 2:02 AM, Henri Cloetens wrote:
> Hello all,
>
> I have an issue with my custom compiler back-end after reload.
>
> 1. The machine has move-instructions that can do following:
>    a. From register file to (register indirect offset) or to register
> file.
>    b. From (register indirect offset), register file, immediate to
> register file
>
> 2. I have now 3 patterns to emit moves in the .md-file:
>
>     1. movesi_internal_fromreg (from register file to memory or
> register file)
>     2. movesi_internal_toreg (from memory , immediate, register file
> to register file)
>     3. movesi : define_expand. It has C-code that analyses the
> operands and selects 1,2 or both.
>
> Motivation for the split was problems with the "combine" step. Suppose
> following code:
>     *a = 10.
>     Even if my front_end (define_expand) splits this in
>     r100 = 10
>    *r101 = r100
>    the combine step, if these is only one movesi_internal, willl group
> it again, to then find out
>    there is no instruction pattern.

This is an indication the insn's condition or operand's predicate or
operand constraints are wrong.

Jeff