Skip to content
  • Simon Marlow's avatar
    Optimise the %.hi : %.o rule · 0fb9ad3a
    Simon Marlow authored
    Previously this rule had a sanity check for the existence of the .o
    file.  However, the sanity check is expensive, especially on Windows,
    because it requires spawning a shell.  So now we use an empty command
    here.
    
    This change reduced the time to do 'make' in an up-to-date tree on
    Windows from 33s to 16s for me.  (the actual saving depends on how
    much rebuilding you've been doing, and how many .hi files are older
    than their .o files).
    
    The comments in this file now describe various versions of the rule
    that don't work.
    0fb9ad3a