[GHC] #9125: int-to-float conversion broken on ARM

[GHC]

#9125: int-to-float conversion broken on ARM
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              Reporter:  Ansible     |            Owner:
                  Type:  bug         |           Status:  infoneeded
              Priority:  highest     |        Milestone:  7.8.4
             Component:  Compiler    |          Version:  7.8.3
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  arm
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:  Incorrect   |       Blocked By:
  result at runtime                  |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Changes (by rwbarton):

 * status:  new => infoneeded


Comment:

 I think that something is reordering the assignment to R1 with the call to
 `__decodeFloat_Int`. After all, R1 is supposed to receive the value that
 ends up at `Sp[-4]`, which is set to F1 at the top of the function. Not
 sure whether GHC or LLVM is doing this incorrect reordering.

 It would be informative to

 * build the broken GHC
 * `rm rts/dist/build/PrimOps.o`
 * run `make` again and copy the command used to build
 `rts/dist/build/PrimOps.o`
 * rerun the command with `-v -keep-tmp-files -ddump-cmm -ddump-to-file`
 * find the files `rts/PrimOps.dump-cmm` and `/tmp/ghc*/ghc*.ll` and attach
 them to this ticket

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9125#comment:10>
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