[GHC] #11295: Figure out what LLVM passes are fruitful

[GHC]

#11295: Figure out what LLVM passes are fruitful
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        Reporter:  bgamari           |                Owner:  kavon
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler (LLVM)   |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:  14528             |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"a4ae199cf810a63444a4ef24a44b33329023cd93/ghc" a4ae199/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a4ae199cf810a63444a4ef24a44b33329023cd93"
 Extract hard-coded LLVM opt flags into a file

 To resolve ticket #11295, I think it makes sense to stop hard-coding
 the pass sequences used by GHC when compiling with LLVM into the
 compiler
 itself.

 This patchset introduces a companion to the existing `llvm-targets` file
 called `llvm-passes`. The passes file is a simple association list that
 holds the default LLVM `opt` pass sequence used by GHC. This allows end
 users to easily save their favorite optimization flags when compiling
 with LLVM.

 The main benefit for ticket #11295 is that when adding a custom pass
 sequence, it tends to be an extremely long string that would be
 unsightly in the code.

 This is essentially part 1 of 2 for ticket #11295.

 Test Plan: ./validate

 Reviewers: bgamari, angerman

 Reviewed By: angerman

 Subscribers: rwbarton, thomie, carter

 Differential Revision: https://phabricator.haskell.org/D4695
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11295#comment:19>
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