[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
  (CodeGen)                          |         Keywords:
            Resolution:              |     Architecture:  arm
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:  Incorrect   |  Related Tickets:
  result at runtime                  |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by rwbarton):

 Actually I prefer this one, since I can read x86 assembly better than ARM
 assembly :)

 The TBAA patch had the expected effect on the .ll file. But LLVM 3.0 still
 decided to carefully save the input value across the function call so that
 it can erroneously return it as the result (esi).
 {{{
 00000748 83ec1c                         sub         esp, 0x1c
 0000074b 8d45fc                         lea         eax, [ebp-4]
 0000074e 3bab1c030000                   cmp         ebp, [ebx+0x31c]
 00000754 7235                           jc          0x78b
 00000756 f30f104500                     movss       xmm0, [ebp]
 0000075b f30f11442418                   movss       [esp+0x18], xmm0
 00000761 f30f11442408                   movss       [esp+0x8], xmm0
 00000767 89442404                       mov         [esp+0x4], eax
 0000076b 892c24                         mov         [esp], ebp
 0000076e e815faffff                     call        __decodeFloat_Int
 00000773 8b45fc                         mov         eax, [ebp-4]
 00000776 894500                         mov         [ebp], eax
 00000779 8b4504                         mov         eax, [ebp+0x4]
 0000077c f30f10442418                   movss       xmm0, [esp+0x18]
 00000782 660f7ec6                       movd        esi, xmm0
 00000786 83c41c                         add         esp, 0x1c
 00000789 ffe0                           jmp         eax
 }}}
 I think this is just a bug in LLVM 3.0, particularly as you say LLVM 3.4
 has the expected behavior.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9125#comment:31>
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