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SomeType($value) style coercions a la new-disp
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Compared to the current implementation, we can lift out anything from
some to a lot of the work and cache + guard it. The best case is when
we have only a single argument to coerce and it is either a bare value
or in a Scalar container, in which case we can also guard on the target
type, pre-calculate the coercion type, and rewrite the call directly to
its coerce method. It is possible that further examination will find
even more direct mapping to the coercion implementation, but for now
this already avoids calcualting the coercion type and arg flattening and
slurpying, plus intermediate closure invocations, and so should be quite
a nice win.
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@jnthn
jnthn committed Sep 28, 2021
1 parent 85d4aae commit dda0ea0
Showing 1 changed file with 122 additions and 1 deletion.
123 changes: 122 additions & 1 deletion src/vm/moar/dispatchers.nqp
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Expand Up @@ -1900,6 +1900,20 @@ nqp::dispatch('boot-syscall', 'dispatcher-register', 'raku-multi-remove-proxies'
# This is where invocation bottoms out, however we reach it. By this point, we
# just have something to invoke, which is either a code object (potentially with
# wrappers) or something that hopefully has a CALL-ME.
my $late-coerce := -> $target, $val {
my $how := $target.HOW;
my $coercion-type := Perl6::Metamodel::CoercionHOW.new_type(
(nqp::istype($how, Perl6::Metamodel::ClassHOW) && $how.is_pun($target)
?? $target.HOW.pun_source($target)
!! $target.WHAT),
$val.WHAT);
$coercion-type.HOW.coerce($coercion-type, $val)
}
my $listy-coercion := -> $coercion-type, *@args {
my $list := nqp::create(List);
nqp::bindattr($list, List, '$!reified', @args);
$coercion-type.HOW.coerce($coercion-type, $list)
}
nqp::dispatch('boot-syscall', 'dispatcher-register', 'raku-invoke', -> $capture {
# Guard type and concreteness of code object. This is a no-op in the case
# that it's been determined a constant by an upper dispatcher.
Expand Down Expand Up @@ -1993,7 +2007,114 @@ nqp::dispatch('boot-syscall', 'dispatcher-register', 'raku-invoke', -> $capture
# Looks like a coercion. In the best case we just have one argument
# and things will be straightforward. Failing that, we'll have to
# form a list and take the slow-bound path.
nqp::die('Coercion NYI in new dispatcher');
if nqp::captureposelems($capture) == 2 {
# Work out what we have to coerce.
my $arg-type;
my int $could-not-guard;
my int $prim := nqp::captureposprimspec($capture, 1);
if $prim == 1 { $arg-type := Int }
elsif $prim == 2 { $arg-type := Num }
elsif $prim == 3 { $arg-type := Str }
else {
# Object argument, so type guard.
my $arg := nqp::captureposarg($capture, 1);
$arg-type := $arg.WHAT;
my $track-arg := nqp::dispatch('boot-syscall', 'dispatcher-track-arg',
$capture, 1);
nqp::dispatch('boot-syscall', 'dispatcher-guard-type', $track-arg);
if nqp::isconcrete_nd($arg) && nqp::iscont($arg) {
# Containerized. If it's a Scalar, we can deref and guard
# on that. If not, we'll have to thunk it and figure it
# out each time.
if nqp::istype_nd($arg, Scalar) {
nqp::dispatch('boot-syscall', 'dispatcher-guard-type',
nqp::dispatch('boot-syscall', 'dispatcher-track-attr',
$track-arg, Scalar, '$!value'));
}
else {
$could-not-guard := 1;
}
}
}

# Ensure there's no nameds.
if nqp::capturehasnameds($capture) {
Perl6::Metamodel::Configuration.throw_or_die(
'X::Coerce::Impossible',
"Cannot coerce to " ~ $code.HOW.name($code) ~ " with named arguments",
:target-type($code.WHAT),
:from-type($arg-type), :hint("named arguments passed")
);
}

# If we could not guard need to delegate to a late-bound
# handler.
if $could-not-guard {
my $delegate := nqp::dispatch('boot-syscall',
'dispatcher-insert-arg-literal-obj', $capture,
0, $late-coerce);
nqp::dispatch('boot-syscall', 'dispatcher-delegate',
'boot-code-constant', $delegate);
}

# Otherwise, can rewrite the callsite directly to do the
# coercion.
else {
# Form the coercion type.
my $how := $code.HOW;
my $coercion-type := Perl6::Metamodel::CoercionHOW.new_type(
(nqp::istype($how, Perl6::Metamodel::ClassHOW) && $how.is_pun($code)
?? $how.pun_source($code)
!! $code.WHAT),
$arg-type);

# Call $coercion-type.HOW.coerce($coercion-type, $val). We
# know that there was only one item, so we can drop the
# callee, prepend the coercion type, the HOW, and then the
# name and type as raku-meth-call wants.
my $coercee-only := nqp::dispatch('boot-syscall', 'dispatcher-drop-arg',
$capture, 0);
my $with-coercion-type := nqp::dispatch('boot-syscall',
'dispatcher-insert-arg-literal-obj', $coercee-only, 0, $coercion-type);
my $coerce-how := $coercion-type.HOW;
my $with-how := nqp::dispatch('boot-syscall',
'dispatcher-insert-arg-literal-obj', $with-coercion-type, 0, $coerce-how);
my $with-name := nqp::dispatch('boot-syscall',
'dispatcher-insert-arg-literal-str', $with-how, 0, 'coerce');
my $delegate := nqp::dispatch('boot-syscall',
'dispatcher-insert-arg-literal-obj', $with-name, 0, $coerce-how);
nqp::dispatch('boot-syscall', 'dispatcher-delegate', 'raku-meth-call',
$delegate);
}
}
else {
# List formation is too complex for a dispatch program, so we
# form a coercion type, prepend it, do the args that form the
# list to be coerced, and then delegate to a code object to
# do the rest of the work.
if nqp::capturehasnameds($capture) {
Perl6::Metamodel::Configuration.throw_or_die(
'X::Coerce::Impossible',
"Cannot coerce to " ~ $code.HOW.name($code) ~ " with named arguments",
:target-type($code.WHAT),
:from-type(List), :hint("named arguments passed")
);
}
my $how := $code.HOW;
my $coercion-type := Perl6::Metamodel::CoercionHOW.new_type(
(nqp::istype($how, Perl6::Metamodel::ClassHOW) && $how.is_pun($code)
?? $how.pun_source($code)
!! $code.WHAT),
List);
my $list-elems-only := nqp::dispatch('boot-syscall', 'dispatcher-drop-arg',
$capture, 0);
my $with-coercion-type := nqp::dispatch('boot-syscall',
'dispatcher-insert-arg-literal-obj', $list-elems-only, 0, $coercion-type);
my $delegate := nqp::dispatch('boot-syscall',
'dispatcher-insert-arg-literal-obj', $with-coercion-type, 0, $listy-coercion);
nqp::dispatch('boot-syscall', 'dispatcher-delegate', 'boot-code-constant',
$delegate);
}
}
else {
my $typename := $code.HOW.name($code);
Expand Down

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