[GHC] #7794: GHCi "Prelude.undefined" exceptions on ARM; ByteCodeItbls.mkJumpToAddr unimplemented

[GHC]

#7794: GHCi "Prelude.undefined" exceptions on ARM; ByteCodeItbls.mkJumpToAddr
unimplemented
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        Reporter:  cjwatson    |            Owner:
            Type:  bug         |           Status:  new
        Priority:  normal      |        Milestone:  7.8.1
       Component:  GHCi        |          Version:  7.6.2
      Resolution:              |         Keywords:
Operating System:  Linux       |     Architecture:  arm
 Type of failure:  GHCi crash  |       Difficulty:  Unknown
       Test Case:              |       Blocked By:
        Blocking:              |  Related Tickets:
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Comment (by RoboTux):

 Replying to [comment:4 RoboTux]:
 > Inlining the call of the cacheflush system call (the call behind
 {{{__clear_cache}}}) should work but it means the cache would be flush
 every time mkJumpToAddr is called. I don't know enough the context of the
 code generation but if that function is called several time after 1 code
 generation then it's suboptimal. The patch then become:
 >
 >
 > {{{
 > +#elif arm_TARGET_ARCH
 > +type ItblCode = Word32
 > +mkJumpToAddr a
 > +    = [ 0xe92d0080      -- push    {r7}
 > +      , 0xe3a0780f      -- mov     r7, #983040     ; 0xf0000
 > +      , 0xe2877002      -- add     r7, r7, #2
 > +      , 0xe3a02000      -- mov     r2, #0
 > +      , 0xef000000      -- swi     0x0
 > +      , 0xe8bd0080      -- pop     {r7}
 > +      , 0xe51ff004      -- ldr pc, [pc, #-4]    # pc reads as <current
 insn>+8
 > +      , fromIntegral (ptrToInt a) ]
 > }}}

 I tried the patch on a Debian arm porterbox and it seems to work as no
 exception was raised with it while an exception was raised without it.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7794#comment:5>
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