Make indirect type lookup 3x as fast

Should have a positive effect on bare startup time, since we do at
least 5 of these every time we start.

src/core/operators.pm

@@ -536,34 +536,60 @@ sub prefix:<let>(\cont) is raw {
     cont
 }
 
-# not sure where this should go
 # this implements the ::() indirect lookup
 sub INDIRECT_NAME_LOOKUP($root, *@chunks) is raw {
-    # note that each part of @chunks itself can
-    # contain double colons. That's why joining and
-    # re-splitting is necessary
-    my Str $name = @chunks.join('::');
-    my @parts    = $name.split('::');
-    my $first    = @parts.shift;
-    if @parts && '$@%&'.index(substr($first,0, 1)).defined {
-        # move sigil from first to last chunk, because
-        # $Foo::Bar::baz is actually stored as Foo::Bar::$baz
-        my $last_idx      = @parts.end;
-        @parts[$last_idx] = substr($first,0, 1) ~ @parts[$last_idx];
-        $first            = substr($first,1);
-        if $first eq '' {
-            $first = @parts.shift;
-            $name = @chunks.join('::');
-        }
-    }
-    my Mu $thing := $root.EXISTS-KEY($first) ?? $root{$first} !!
-                    GLOBAL::.EXISTS-KEY($first) ?? GLOBAL::{$first} !!
-                    X::NoSuchSymbol.new(symbol => $name).fail;
-    for @parts {
-        X::NoSuchSymbol.new(symbol => $name).fail unless $thing.WHO.EXISTS-KEY($_);
-        $thing := $thing.WHO{$_};
-    }
-    $thing;
+    nqp::if(
+      # Note that each part of @chunks itself can contain double colons.
+      # That's why joining and re-splitting is necessary
+      nqp::elems(my $parts :=
+        nqp::split('::',my str $name = @chunks.join('::'))),
+      nqp::stmts(
+        (my str $first = nqp::shift($parts)),
+        nqp::if(
+          nqp::elems($parts),
+          nqp::stmts(
+            (my str $sigil = nqp::substr($first,0,1)),
+            nqp::if(
+              nqp::iseq_s($sigil,'$')
+                || nqp::iseq_s($sigil,'@')
+                || nqp::iseq_s($sigil,'%')
+                || nqp::iseq_s($sigil,'&'),
+              nqp::stmts(
+                nqp::push($parts,
+                  nqp::concat($sigil,nqp::unbox_s(nqp::pop($parts)))),
+                ($first = nqp::substr($first,1))
+              )
+            ),
+            nqp::unless(
+              $first,
+              nqp::stmts(
+                ($first = nqp::shift($parts)),
+                ($name  = nqp::join("::",$parts)),
+              )
+            )
+          )
+        ),
+        (my Mu $thing := nqp::if(
+          $root.EXISTS-KEY($first),
+          $root.AT-KEY($first),
+          nqp::if(
+            GLOBAL::.EXISTS-KEY($first),
+            GLOBAL::.AT-KEY($first),
+            X::NoSuchSymbol.new(symbol => $name).fail
+          )
+        )),
+        nqp::while(
+          nqp::elems($parts),
+          nqp::if(
+            $thing.WHO.EXISTS-KEY(my $part := nqp::shift($parts)),
+            ($thing := $thing.WHO.AT-KEY($part)),
+            X::NoSuchSymbol.new(symbol => $name).fail
+          )
+        ),
+        $thing
+      ),
+      X::NoSuchSymbol.new(symbol => $name).fail
+    )
 }
 
 sub REQUIRE_IMPORT($compunit, *@syms) {