[commit: ghc] master: Scrutinee Constant Folding (d3b546b)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/d3b546b1a6058f26d5659c7f2000a7b25b7ea2ba/ghc

>---------------------------------------------------------------

commit d3b546b1a6058f26d5659c7f2000a7b25b7ea2ba
Author: Sylvain Henry <sylvain at haskus.fr>
Date:   Fri Dec 9 10:26:34 2016 -0500

    Scrutinee Constant Folding
    
    This patch introduces new rules to perform constant folding through
    case-expressions.
    
    E.g.,
    ```
    case t -# 10# of _ {  ===> case t of _ {
             5#      -> e1              15#     -> e1
             8#      -> e2              18#     -> e2
             DEFAULT -> e               DEFAULT -> e
    ```
    
    The initial motivation is that it allows "Merge Nested Cases"
    optimization to kick in and to further simplify the code
    (see Trac #12877).
    
    Currently we recognize the following operations for Word# and Int#: Add,
    Sub, Xor, Not and Negate (for Int# only).
    
    Test Plan: validate
    
    Reviewers: simonpj, austin, bgamari
    
    Reviewed By: simonpj, bgamari
    
    Subscribers: thomie
    
    Differential Revision: https://phabricator.haskell.org/D2762
    
    GHC Trac Issues: #12877


>---------------------------------------------------------------

d3b546b1a6058f26d5659c7f2000a7b25b7ea2ba
 compiler/basicTypes/Literal.hs                 |  41 +++++++--
 compiler/main/DynFlags.hs                      |   3 +
 compiler/prelude/PrelRules.hs                  |  57 +++++++++++-
 compiler/simplCore/SimplUtils.hs               |  76 +++++++++++++++-
 docs/users_guide/using-optimisation.rst        |  21 ++++-
 testsuite/tests/perf/compiler/T12877.hs        | 117 +++++++++++++++++++++++++
 testsuite/tests/perf/compiler/T12877.stdout    |   1 +
 testsuite/tests/perf/compiler/all.T            |  13 +++
 utils/mkUserGuidePart/Options/Optimizations.hs |   5 ++
 9 files changed, 322 insertions(+), 12 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 d3b546b1a6058f26d5659c7f2000a7b25b7ea2ba