On Fri, Oct 17, 2008 at 01:26:20PM -0400, Michael Meissner wrote:
> Why do you need new syntax? The current constraints file already supports
> target specific constraints. For example, from the i386:
>
> (define_register_constraint "x" "TARGET_SSE ? SSE_REGS : NO_REGS"
> "Any SSE register.")
>
> I could imagine that you could have more complex cases than just something or
> NO_REGS.
As one alternative, I want something that is not regarded as a register
class by reload, yet which matches the members of a register class as
an EXTRA_CONSTRAINT.
I.e.:
(define_register_constraint "Rcq"
"(TARGET_2ADDR
? (TARGET_ARC700 ? CHEAP_CORE_REGS : WRITABLE_CORE_REGS)
: NO_REGS"
"@internal
'w' constraint variant for use in early alternatives with matching
constraint")
(define_constraint "Rcq"
"@internal
Cryptic w - for use in early alternatives with matching constraint"
(and (match_code "REG")
(match_test "TEST_HARD_REG_BIT (reg_class_contents[WRITABLE_CORE_REGS],
REGNO (op))")))
