Add a script which sorts the expr templates by oplist order

This script parses the expression templates and orders it based on the
oplist order. It attaches any text between two template definitions
(i.e. comments) with the following op so that comments are preserved.
Any text before the first template is pinned to the top of the output
file. Before writing over the previous expression template file it makes
sure the output is the same number of graphemes as the input (minus
newlines).

tools/sort-expr-templates-by-oplist-order.p6

@@ -0,0 +1,79 @@
+#!/usr/bin/env perl6
+# This script
+my Str:D $file = slurp 'src/jit/core_templates.expr';
+my @spots;
+my @newlines;
+sub peek (Int $i) {
+    $file.substr: $i, 20;
+}
+loop (my Int $i = 0; $i < $file.chars; $i++) {
+    my $char = $file.substr: $i, 1;
+    if $char eq '#' && ($i == 0 || $file.substr($i-1, 1) eq "\n") {
+        #say "found # at $i";
+        while $file.substr($i, 1) ne "\n" {
+            $i++;
+        }
+        #say "found newline after # at $i";
+        push @newlines, $i;
+        die if $file.substr($i, 1) ne "\n";
+    }
+    else {
+        use nqp;
+        if nqp::eqat($file, "(template:", $i) {
+            #say "found template start at $i";
+            my @stack = $file.substr: $i, 1;
+            my $start = $i;
+            $i++;
+            while @stack {
+                my $char = $file.substr: $i, 1;
+                #print $char;
+                if $char eq '(' {
+                    #say "open at $i", "stack is ", @stack.Int;
+                    #say peek $i;
+                    @stack.push: $char;
+                }
+                elsif $char eq ')' {
+                    my $rtrn = @stack.pop;
+                    die "unmatching number of () at char $i" if $rtrn ne '(';
+                }
+                $i++;
+            }
+            $i--;
+            my $end = $i;
+            @spots.push: [$start, $end];
+        }
+    }
+}
+my %parts;
+my $last = -1;
+my $prefix;
+sub oplistorder {
+     qx{./tools/compare-oplist-interp-order.sh get_oplist_order}.lines
+}
+loop ($i = 0; $i < @spots; $i++) {
+    my $prev-start = $last + 1;
+    my $prev-end   = @spots[$i][0] - 1;
+    my $prev = $file.substr: $prev-start, $prev-end - $prev-start +1;
+    my $current = $file.substr: @spots[$i][0], @spots[$i][1] - @spots[$i][0] + 1;
+    $current ~~ /'(template:' \s+ (<[_a..zA..Z0..9]>+)'!'?\s/;
+    my $opname =  $0.Str;
+    die "Couldn't find opname. Likely the regex needs to be adjusted: $current"
+        if !$opname;
+    #say $opname;
+    my $total;
+    if $last == -1 {
+        $total = $current;
+        $prefix = $prev;
+    }
+    else {
+        $total = $prev ~ $current;
+    }
+    %parts{$opname} = $total;
+    $last = @spots[$i][1];
+}
+my @out = $prefix;
+for oplistorder() -> $op {
+    @out.push: %parts{$op} if %parts{$op}:exists;
+}
+die "seems like we lost some characters not counting newlines" if @out.join.lines.join.chars != $file.lines.join.chars;
+"src/jit/core_templates.expr".IO.spurt: @out.join.chomp ~ "\n"