Improve code comments for some ctx stuff

* in pp_return(), some comments were out of date about how
  leave_adjust_stacks() is called ;
* add a comment to all the functions that pp_return() tail-calls to the
  effect that they can be tail-called;
* make it clearer when/why OPf_SPECIAL is set on OP_LEAVE;
* CXt_LOOP_PLAIN can be a while loop as well as a plain block.

1 files changed, 2 insertions, 0 deletions

diff --git a/pp_hot.c b/pp_hot.c
index d7fa3d26da..d6cb1aa091 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -3623,6 +3623,8 @@ Perl_leave_adjust_stacks(pTHX_ SV **from_sp, SV **to_sp, U8 gimme, int pass)
 }
 
 
+/* also tail-called by pp_return */
+
 PP(pp_leavesub)
 {
     U8 gimme;