Use simplifier to optimize simple &postcircumfix calls

lib/SAFE.setting

@@ -780,6 +780,15 @@ my class Pair is Enum {
 }
 # }}}
 # List utilities {{{
+sub _at_pos(\&container, $index) {
+    $container.defined
+        ?? $container.at-pos($index)
+        !! Any!Any::butWHENCE(sub (\$var) {
+            $container.defined && die("Autovivification collision");
+            $container = Array.new;
+            $container!Array::extend($index, $var);
+        });
+}
 sub postcircumfix:<[ ]>(\$container, $index) { # TODO: is rwtrans
     $container.defined
         ?? $container.at-pos($index)
@@ -802,6 +811,22 @@ sub postcircumfix:<{ }>(\$container, $key, :$exists, :$delete) {
         });
 }
 
+sub _exists_key(\$container, $key) {
+    $container.defined ?? $container.exists-key($key) !! False
+}
+sub _delete_key(\$container, $key) {
+    $container.defined ?? $container.delete-key($key) !! Any
+}
+sub _at_key(\$container, $key) {
+    $container.defined
+        ?? $container.at-key($key)
+        !! Any!Any::butWHENCE(sub (\$var) {
+            $container.defined && die("Autovivification collision");
+            $container = Hash.new;
+            $container!Hash::extend($key, $var);
+        });
+}
+
 my class GatherIterator is IterCursor {
     has $!frame;
     has $!reify;

perf/hashmark.pl

@@ -0,0 +1,20 @@
+# vim: ft=perl6
+sub _exists_key(\$container, $key) {
+    $container.defined ?? $container.exists-key($key) !! False
+}
+sub _delete_key(\$container, $key) {
+    $container.defined ?? $container.delete-key($key) !! Any
+}
+sub _at_key(\$container, $key) {
+    $container.defined
+        ?? $container.at-key($key)
+        !! Any!Any::butWHENCE(sub (\$var) {
+            $container.defined && die("Autovivification collision");
+            $container = Hash.new;
+            $container!Hash::extend($key, $var);
+        });
+}
+
+my $i = 0;
+my %hash;
+%hash{$i} = $i until ($i++) == 100000;

src/Optimizer/Simplifier.pm

@@ -41,6 +41,8 @@ our %funcs = (
     '&infix:<=>' => \&do_assign,
     '&infix:<==>' => \&do_numeq,
     '&postfix:<++>' => \&do_postinc,
+    '&postcircumfix:<{ }>' => \&do_atkey,
+    '&postcircumfix:<[ ]>' => \&do_atpos,
 );
 
 sub do_assign {
@@ -75,6 +77,21 @@ sub do_numeq {
     return Op::Builtin->new(name => 'numeq', args => $args);
 }
 
+# TODO: similar conversion for :delete and :exists
+sub do_atkey {
+    my ($body, $nv, $invname, $args) = @_;
+    return unless @$args == 2;
+    return Op::CallSub->new(invocant => Op::Lexical->new(name => '&_at_key'),
+        positionals => $args);
+}
+
+sub do_atpos {
+    my ($body, $nv, $invname, $args) = @_;
+    return unless @$args == 2;
+    return Op::CallSub->new(invocant => Op::Lexical->new(name => '&_at_pos'),
+        positionals => $args);
+}
+
 sub run_optree {
     my ($body, $op, $nv) = @_;
     Carp::confess "WTF" if !defined $nv;