Error building ghc on raspberry pi.

[Ben Gamari]

roconnor at theorem.ca writes:

> What version of GHC did you build?
>
This was building from the ghc-7.4 branch. That being said, after this
build finished I noticed that the resulting stage 2 compiler wasn't
invoking llc with the correct parameters, resulting in the same linker
error when doing builds.

This might have been due to the fact that I changed `build.mk` several
times mid-build. I'm currently waiting for a clean rebuild. However, I'm
now using a more specific configuration as passing `-optlc-float-abi=hard`
in `HC_SRC_OPTS` caused the stage 0 build to fail with,

    ...
    *** LLVM Compiler:
    'llc-3.0' '-O1' '-relocation-model=static' '/tmp/ghc25792_0/ghc25792_0.bc' '-o' '/tmp/ghc25792_0/ghc25792_0.lm_s' '-float-abi=hard' '-mcpu=cortex-a9' '-mattr=+v7,+vfp3,+d16' '-float-abi=hard'
    llc-3.0: for the -float-abi option: may only occur zero or one times!

I'm not really sure where this second `-float-abi=hard` is coming from,
but using the following in `build.mk` works around the issue,

    SRC_HC_OPTS        = -H64m -Rghc-timing
    GhcStage1HcOpts    = -O -fvia-C
    GhcStage2HcOpts    = -O0 -fllvm -keep-llvm-files -debug -DDEBUG -optc-mfloat-abi=hard -optc-mcpu=cortex-a9 -optlc-float-abi=hard -optlc-mcpu=cortex-a9
    GhcLibHcOpts       = -O -fllvm -optc-mfloat-abi=hard -optc-mcpu=cortex-a9 -optlc-float-abi=hard -optlc-mcpu=cortex-a9

The build is still in stage 1 so it is unclear whether this will fix the
original linker error.

Cheers,

- Ben