[GHC] #9303: O2: (GHC version 7.8.3 for x86_64-unknown-linux): allocateRegsAndSpill: Cannot read from uninitialized register %vI_s1Mp

[GHC]

#9303: O2: (GHC version 7.8.3 for x86_64-unknown-linux): allocateRegsAndSpill:
Cannot read from uninitialized register %vI_s1Mp
-------------------------------------+-------------------------------------
              Reporter:  slyfox      |            Owner:  simonmar
                  Type:  bug         |           Status:  new
              Priority:  highest     |        Milestone:  7.8.4
             Component:  Compiler    |          Version:  7.8.3
  (NCG)                              |         Keywords:
            Resolution:              |     Architecture:  x86_64 (amd64)
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:  Compile-    |  Related Tickets:
  time crash                         |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------

Comment (by Simon Marlow <marlowsd@…>):

 In [changeset:"da70f9ef49a545707dc32db9662441b9c8845fba/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="da70f9ef49a545707dc32db9662441b9c8845fba"
 Allow multiple entry points when allocating recursive groups (#9303)

 Summary:
 In this example we ended up with some code that was only reachable via
 an info table, because a branch had been optimised away by the native
 code generator.  The register allocator then got confused because it
 was only considering the first block of the proc to be an entry point,
 when actually any of the info tables are entry points.

 Test Plan: validate

 Reviewers: simonpj, austin

 Subscribers: simonmar, relrod, carter

 Differential Revision: https://phabricator.haskell.org/D88
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9303#comment:5>
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