[commit: ghc] ghc-8.2: Revert "Use a deterministic map for imp_dep_mods" (6cb4271)

[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/6cb4271194364e65ce150c3323d136749444aed0/ghc

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commit 6cb4271194364e65ce150c3323d136749444aed0
Author: Bartosz Nitka <niteria at gmail.com>
Date:   Mon May 15 04:44:35 2017 -0700

    Revert "Use a deterministic map for imp_dep_mods"
    
    This reverts commit 7fea7121ce195e562a5443c0a8ef3861504ef1b3.
    It turns out that on a newly added MultiLayerModules test
    case it gets very expensive to union the transitive module
    sets while preserving determinism.
    
    Fortunately, we can just sort to restore determinism
    when converting imp_dep_mods to a list.
    
    Test Plan: ./validate
    
    Reviewers: simonmar, austin, bgamari
    
    Reviewed By: bgamari
    
    Subscribers: rwbarton, thomie
    
    Differential Revision: https://phabricator.haskell.org/D3577
    
    (cherry picked from commit 8bf50d5026f92eb5a6768eb2ac38479802da1411)


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6cb4271194364e65ce150c3323d136749444aed0
 compiler/deSugar/DsUsage.hs         |  4 ++--
 compiler/iface/MkIface.hs           |  5 ++---
 compiler/typecheck/TcRnDriver.hs    | 14 +++++++-------
 compiler/typecheck/TcRnTypes.hs     | 24 ++++++++++++++++--------
 testsuite/tests/perf/compiler/all.T |  3 ++-
 5 files changed, 29 insertions(+), 21 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 6cb4271194364e65ce150c3323d136749444aed0