[commit: ghc] ghc-8.2: StgCse: Do not re-use trivial case scrutinees (687e79f)

[git at git.haskell.org]

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

On branch  : ghc-8.2
Link       : http://ghc.haskell.org/trac/ghc/changeset/687e79fdf3d192cdc16bccb8b28eaec60ebb8abb/ghc

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commit 687e79fdf3d192cdc16bccb8b28eaec60ebb8abb
Author: Joachim Breitner <mail at joachim-breitner.de>
Date:   Sun Apr 9 19:40:02 2017 -0400

    StgCse: Do not re-use trivial case scrutinees
    
    as they might be marked as one-shot, and suddenly we’d evaluate them
    multiple times. This came up in #13536 (test cases included).
    
    The solution was layed out by SPJ in ticket:13536#comment:12.
    
    Differential Revision: https://phabricator.haskell.org/D3437
    
    (cherry picked from commit b55f310d06b8d3988d40aaccc0ff13601ee52b84)


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687e79fdf3d192cdc16bccb8b28eaec60ebb8abb
 compiler/simplStg/StgCse.hs                       | 108 +++++++++++-----------
 testsuite/tests/simplStg/should_run/T13536.hs     |  17 ++++
 testsuite/tests/simplStg/should_run/T13536.stderr |   1 +
 testsuite/tests/simplStg/should_run/T13536.stdout |   1 +
 testsuite/tests/simplStg/should_run/all.T         |   1 +
 5 files changed, 75 insertions(+), 53 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 687e79fdf3d192cdc16bccb8b28eaec60ebb8abb