contrib/perl5/ext/B/ramblings/reg.alloc

   1 while ($i--) {
   2     foo();
   3 }
   4 exit
   5
   6     PP code                     if i an int register    if i an int but not a
   7                                 (i.e. can't be          register (i.e. can be
   8                                 implicitly invalidated) implicitly invalidated)
   9     nextstate
  10     enterloop
  11
  12
  13   loop:
  14     gvsv  GV (0xe6078) *i       validates i             validates i
  15     postdec                     invalidates $i          invalidates $i
  16     and if_false goto out;
  17                                 i valid; $i invalid     i valid; $i invalid
  18
  19                                 i valid; $i invalid     i valid; $i invalid
  20     nextstate
  21     pushmark
  22     gv  GV (0xe600c) *foo
  23     entersub                                            validates $i; invals i
  24
  25     unstack
  26     goto loop:
  27
  28                                 i valid; $i invalid
  29   out:
  30     leaveloop
  31     nextstate
  32     exit