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Provide optimized form of assigning Nil
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So that the spesh plugin can return that, instead of falling back on the
fully general case that cannot be inlined.
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@jnthn
jnthn committed Aug 19, 2019
1 parent e5d2933 commit c7056f2
Showing 1 changed file with 14 additions and 2 deletions.
16 changes: 14 additions & 2 deletions src/vm/moar/spesh-plugins.nqp
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Expand Up @@ -305,6 +305,11 @@ sub assign-fallback($cont, $value) {
sub assign-scalar-no-whence-no-typecheck($cont, $value) {
nqp::bindattr($cont, Scalar, '$!value', $value);
}
sub assign-scalar-nil-no-whence($cont, $value) {
my $desc := nqp::getattr($cont, Scalar, '$!descriptor');
nqp::bindattr($cont, Scalar, '$!value',
nqp::getattr($desc, ContainerDescriptor, '$!default'))
}
sub assign-scalar-no-whence($cont, $value) {
my $desc := nqp::getattr($cont, Scalar, '$!descriptor');
my $type := nqp::getattr($desc, ContainerDescriptor, '$!of');
Expand Down Expand Up @@ -357,13 +362,20 @@ nqp::speshreg('perl6', 'assign', sub ($cont, $value) {
my $desc := nqp::speshguardgetattr($cont, Scalar, '$!descriptor');
if nqp::eqaddr($desc.WHAT, ContainerDescriptor) && nqp::isconcrete($desc) {
# Simple assignment, no whence. But is Nil being assigned?
my $of := $desc.of;
if nqp::eqaddr($value, Nil) {
# Yes; NYI.
# Yes; just copy in the default, provided we've a simple type.
if $of.HOW.archetypes.nominal {
nqp::speshguardtype($desc, $desc.WHAT);
nqp::speshguardconcrete($desc);
my $of := nqp::speshguardgetattr($desc, ContainerDescriptor, '$!of');
nqp::speshguardobj($of);
return &assign-scalar-nil-no-whence;
}
}
else {
# No whence, no Nil. Is it a nominal type? If yes, we can check
# it here.
my $of := $desc.of;
unless $of.HOW.archetypes.nominal {
nqp::speshguardobj($desc);
return &assign-scalar-no-whence;
Expand Down

3 comments on commit c7056f2

@salortiz
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@jnthn
This commit broke a test in DBIish.
Coincidentally I was removing a 'diag' in it and travis CI detect the problem.
Reverting my build to the previous one (e5d2933) the test succeeds.
The path broken seem to be https://github.com/perl6/DBIish/blob/master/lib/DBDish/ErrorHandling.pm6#L26

@salortiz
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The case golfed:

$ perl6 -v
This is Rakudo version 2019.07.1-174-ge5d2933b3 built on MoarVM version 2019.07.1-72-g352ae27e4
$ perl6 -e 'class F { has Exception $!e; method set($a){$!e=$a}; method check() {say so $!e}}; my $f = F.new(); $f.set(Nil);  $f.set(X::AdHoc.new()); $f.check()'
True

vs

$ perl6 -v
This is Rakudo version 2019.07.1-176-g207b825ea built on MoarVM version 2019.07.1-72-g352ae27e4
implementing Perl 6.d.
$ perl6 -e 'class F { has Exception $!e; method set($a){$!e=$a}; method check() {say so $!e}}; my $f = F.new(); $f.set(Nil);  $f.set(X::AdHoc.new()); $f.check()'
False

Seems that with your commit, the second assignment to $!e, (after setting to Nil) isn't preserved.

@jnthn
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@jnthn jnthn commented on c7056f2 Aug 19, 2019

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@salortiz Excellent golf (and will make a nice spectest!) I suspect a missing guard; I'll look at it in the morning. :)

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