Generate better code for NQP's prefix:<!>.

Author: jnthn

src/NQP/Grammar.pm

@@ -702,7 +702,7 @@ grammar NQP::Grammar is HLL::Grammar {
     token prefix:sym<~>   { <sym>  <O('%symbolic_unary, :op<stringify>')> }
     token prefix:sym<->   { <sym>  <![>]> <!number> <O('%symbolic_unary, :op<neg_n>')> }
     token prefix:sym<?>   { <sym>  <O('%symbolic_unary, :op<istrue>')> }
-    token prefix:sym<!>   { <sym>  <O('%symbolic_unary, :op<isfalse>')> }
+    token prefix:sym<!>   { <sym>  <O('%symbolic_unary, :op<falsey>')> }
     token prefix:sym<|>   { <sym>  <O('%symbolic_unary')> }
 
     token infix:sym<*>    { <sym>  <O('%multiplicative, :op<mul_n>')> }

src/NQP/Ops.pm

@@ -95,3 +95,19 @@ $ops.add_hll_op('nqp', 'eqaddr', -> $qastcomp, $op {
         QAST::Op.new( :op('where'), $op[1] )
     ))
 });
+
+$ops.add_hll_op('nqp', 'falsey', -> $qastcomp, $op {
+    my $res := $*REGALLOC.fresh_i();
+    my $ops := PIRT::Ops.new(:result($res));
+    my $arg_post := $qastcomp.as_post($op[0]);
+    if nqp::lc($qastcomp.infer_type($arg_post.result)) eq 'i' {
+        $ops.push($arg_post);
+        $ops.push_pirop('not', $res, $arg_post);
+    }
+    else {
+        $arg_post := $qastcomp.coerce($arg_post, 'P');
+        $ops.push($arg_post);
+        $ops.push_pirop('isfalse', $res, $arg_post);
+    }
+    $ops
+});