On May 28, 2014, at 7:27 AM, Richard Earnshaw <rearn...@arm.com> wrote:
>
> Speed of implementation. We're gradually replacing these with proper
> builtins, but that takes a lot more work.
As an owner of a port with more builtins that yours, I can offer a
technological solution to reduce the cost of builtins to:
(define_builtin “my_stop"
[
(define_outputs [(void_operand 0)])
(define_rtl_pattern “my_stop" [])
]
)
(define_insn “my_stop"
[(unspec_volatile [(const_int 0)]
UNSPECV_STOP)]
""
“stop”)
for example. This creates the builtins, allows overloading, allows
input/output parameters, can reorder operands, allows for complex types, allows
memory reference parameters, allows pure markings, does vectors, conditional
availability, generates documentation, creates test suites and more. If you
wire up a speaker it even sings.
Someone would have have to step forward with a need and some time to port their
port over to the new scheme and help with the reason for why the technology
should go in. It is mostly contained in 5600 lines of self contained python
code, and is built to solve the problem generally. It adds about 800 lines to
builtins.c. It has a macro system that is more powerful than the macro system
.md files use, so one gets to share and collapse builtins rather nicely. It is
known to work for C and C++. Other languages may need extending; C for example
cost is around 250 lines to support.
One promise, you will never have to create an argument list, or a type, for
example here is a two output, type input functional instruction with some doc
content:
(define_mode_iterator MYTYPE
[V8QI V4HI V2SI DI ...])
(define_builtin “my_foo” "my_foo2_<type>"
[
(define_desc “Doc string for operation")
(define_outputs [(var_operand:T_MYTYPE 0)
(var_operand:T_MYTYPE 1)])
(define_inputs [(var_operand:T_MYTYPE 2)
(var_operand:T_MYTYPE 3)])
(define_rtl_pattern “my_foo2_<mode>" [0 2 1 3])
(attributes [pure])
]
)
I stripped it so you can’t know what the instruction was, but you get a flavor
of multiple outputs, doc bits, pure, overloading, arguments and argument
rearranging.
Let me know if you’re interested.
