[LLVMdev] Architecture Dependency of LLVM bitcode

Christian Plessl
Tue, 30 Sep 2008 19:02:51 -0000

Thanks to anyone for these helpful answers. At least to me the causes
for architecture dependencies in LLVM IR are much clearer now.

On 29.09.2008, at 23:19, Chris Lattner wrote:

>>> Is this worth a FAQ entry?
>> I would definitely appreciate such a FAQ entry.
> Patches welcome :)

>
> Many things are target independent, but the most significant is that
> LLVM allows unrestricted pointer casting.  An example that allows the
> programmer to "see" the underlying endianness of the target is C
code
> like this:
>
> int X = ...
> char C = *(char*)&X


I don't feel sufficiently confident with the matter to write such a
FAQ entry myself.

But wouldn't it make sense to move the notes on target independency
from the Kaleidoscope tutorial
(http://llvm.org/docs/tutorial/LangImpl8.html#targetindep
) to the FAQ page? In my opinion, these explanations and the
additional endianness example you gave, explain the issues with target
dependencies quite well.

Best regards,
  Christian