[commit: ghc] master: Careful tweaking to exprOkForSpeculation (f334d20)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/f334d20e00e3f4bd217e49216b7e9d9c8779db10/ghc

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commit f334d20e00e3f4bd217e49216b7e9d9c8779db10
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Fri Dec 7 12:56:08 2018 +0000

    Careful tweaking to exprOkForSpeculation
    
    This patch does several things:
    
    * Make exprOkForSpeculation ignore evaluatedness of variables
      See the Note [exprOkForSpeculation and evaluated variables]
      This means that the binder-swap transformation no longer
      invaliates the let/app invariant.
    
    * Make exprOkForSpeculation return False for
         DataToTagOp and SeqOp.
      See Note [exprOkForSpeculation and SeqOp/DataToTagOp]
    
    * Remove the 'can_fail' property from dataToTag#; it was
      always a hack (described in the old Note [dataToTag#] in
      primops.txt.pp), and now its not necessary because of the
      fixes above.
    
    * Make SetLevels use exprIsHNF, /not/ exprOkForSpeculation,
      when floating single-alternative cases.  See SetLevels
      Note [Floating single-alternative cases]
    
    * Fix a buglet in FloatIn; probably never bites in practice
      See Note [Dead bindings]
    
    Collectively, these changes finally fix Trac #15696.


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f334d20e00e3f4bd217e49216b7e9d9c8779db10
 compiler/coreSyn/CoreUtils.hs   | 125 ++++++++++++++++++++++++++--------------
 compiler/coreSyn/MkCore.hs      |   2 +-
 compiler/prelude/PrelRules.hs   |  33 ++++++++++-
 compiler/prelude/primops.txt.pp |  55 +-----------------
 compiler/simplCore/FloatIn.hs   |  13 ++++-
 compiler/simplCore/SetLevels.hs |  32 +++++++---
 6 files changed, 149 insertions(+), 111 deletions(-)

Diff suppressed because of size. To see it, use:

    git diff-tree --root --patch-with-stat --no-color --find-copies-harder --ignore-space-at-eol --cc f334d20e00e3f4bd217e49216b7e9d9c8779db10