[LLVMdev] strace for whole-program bitcodes

[Timo Juhani Lindfors]

Tianwei <tianwei.sheng at gmail.com> writes:
> someone suggested me to use gold-plugin, I know nothing about it yet, I will
> have a try later.  Does anyone have a good solution for this problem?

Afaik gold does not help here. I tried it and managed to only generate
native code.

I'm currently investigating an alternative approach to produce
whole-program bitcodes:

1) add /tmp/wrap to PATH
2) create /tmp/wrap/gcc with the following contents

#!/bin/sh
exec llvm-gcc -specs /tmp/wrap/gcc.specs "$@"

3) llvm-gcc -dumpspecs > /tmp/wrap/gcc.specs
4) modify /tmp/wrap/gcc.specs so that it always passes -emit-llvm to cc1
5) modify /tmp/wrap/gcc.specs so that it calls llvm-ld* instead of real
   ld and does not pass any unknown flags to it.

With this approach I was able to compile and run airstrike (a 2d
dogfighting game) in bitcode form very transparently with:

$ make-bitcode fakeroot apt-get --build source airstrike
$ sudo dpkg -i airstrike*.deb
$ airstrike

If you are interested I can try to rework my scripts to a shape where
they could be used by somebody else.

(*) I am not actually calling llvm-ld directly. Instead I have an
    "llvm-ld-exe" wrapper that calls llvm-ld and then uses "anytoexe" to
    pack the resulting bitcode to a shell script that can execute itself with
    lli and use the correct -load options.