[GHC] #9315: Weird change in allocation numbers of T9203

[GHC]

#9315: Weird change in allocation numbers of T9203
-------------------------------------+-------------------------------------
              Reporter:  nomeata     |             Owner:  simonmar
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:
             Component:  Runtime     |           Version:  7.9
  System                             |          Keywords:
            Resolution:              |  Operating System:  Unknown/Multiple
Differential Revisions:              |   Type of failure:  None/Unknown
          Architecture:              |         Test Case:
  Unknown/Multiple                   |          Blocking:
            Difficulty:  Unknown     |
            Blocked By:              |
       Related Tickets:              |
-------------------------------------+-------------------------------------

Comment (by nomeata):

 I just timed two plain `./validate` runs. The first with the current
 settings (`-O`):
 {{{
 $ cat /tmp/validate-O.txt
 Command exited with non-zero status 1
 3573.46user 204.47system 36:13.68elapsed 173%CPU (0avgtext+0avgdata
 1534340maxresident)k
 76944inputs+17408472outputs (255major+249188896minor)pagefaults 0swaps
 }}}
 The second one with `GhcLibHcOpts    += -O2 -dcore-lint` in `k/validate-
 settings.mk`:
 {{{
 Command exited with non-zero status 1
 3675.64user 209.70system 37:10.83elapsed 174%CPU (0avgtext+0avgdata
 1535452maxresident)k
 1048inputs+18010496outputs (18major+249644503minor)pagefaults 0swaps
 }}}

 Yes, it does take longer. But hardly significantly.

 Hence I’m in favour of setting `GhcLibHcOpts += -O2` for validate runs,
 bringing our validation closer to what we release, and also making a `make
 -C testsuite` in non-validate non-customized tree to yield the same
 performance numbers (at least for non-compiler-performance-tests).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9315#comment:15>
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