[GHC] #11123: Arm: checkProddableBlock: invalid fixup in runtime linker

[GHC]

#11123: Arm: checkProddableBlock: invalid fixup in runtime linker
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        Reporter:  erikd                |                Owner:
            Type:  bug                  |               Status:  new
        Priority:  normal               |            Milestone:  8.0.1
       Component:  Compiler             |              Version:  7.11
      Resolution:                       |             Keywords:
Operating System:  Unknown/Multiple     |         Architecture:  arm
 Type of failure:  Building GHC failed  |            Test Case:
      Blocked By:                       |             Blocking:
 Related Tickets:                       |  Differential Rev(s):
       Wiki Page:                       |
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Comment (by erikd):

 Disassembling libm using `objdump -D /lib/arm-linux-
 gnueabihf/libm-2.19.so` shows that the `sin` function is indeed Thumb code
 (indicated by instruction offsets that are not a multiple of 2):

 {{{
 00015850 <sin>:
    15850:       b570            push    {r4, r5, r6, lr}
    15852:       ed2d 8b0e       vpush   {d8-d14}
    15856:       b08a            sub     sp, #40 ; 0x28
    15858:       eeb0 8b40       vmov.f64        d8, d0
    1585c:       ac01            add     r4, sp, #4
    1585e:       4620            mov     r0, r4
    15860:       f7f0 fd48       bl      62f4 <feholdexcept>
    ...
 }}}

 This problem is encountered when ghci loads a Haskell module which calls
 maths functions in `libm`.

 {{{
 Loading package ghc-prim-0.5.0.0 ... linking ... ghc-stage2:
 Symbol `__aeabi_idiv' requires Thumb linkage which is not currently
 supported.
 }}}

 However on IRC, @rwbarton suggests:

 {{{
 .... the rts linker should use its own copy of sin to satisfy a use in a
 .o file
 }}}

 so maybe this is still a bug in Phab:D1470.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11123#comment:6>
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