[GHC] #10953: Switch to LLVM 3.7

[GHC]

#10953: Switch to LLVM 3.7
-------------------------------------+-------------------------------------
        Reporter:  erikd             |                Owner:  erikd
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler (LLVM)   |              Version:  7.11
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1320
-------------------------------------+-------------------------------------

Comment (by Erik de Castro Lopo <erikd@…>):

 In [changeset:"29310b622801733e1b29a9a61988406872db13ca/ghc"
 29310b62/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="29310b622801733e1b29a9a61988406872db13ca"
 Switch to LLVM version 3.7

 Before this commit, GHC only supported LLVM 3.6. Now it only supports
 LLVM 3.7 which was released in August 2015. LLVM version 3.6 and earlier
 do not work on AArch64/Arm64, but 3.7 does.

 Also:
 * Add CC_Ghc constructor to LlvmCallConvention.
 * Replace `maxSupportLlvmVersion`/`minSupportLlvmVersion` with
   a single `supportedLlvmVersion` variable.
 * Get `supportedLlvmVersion` from version specified in configure.ac.
 * Drop llvmVersion field from DynFlags (no longer needed because only
   one version is supported).

 Test Plan: Validate on x86_64 and arm

 Reviewers: bgamari, austin

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D1320

 GHC Trac Issues: #10953
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10953#comment:2>
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