[LLVMdev] customized output of double load/store on ppc32

[Scott Graham]

On Wed, Jul 23, 2008 at 4:46 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
> On Wed, Jul 23, 2008 at 4:23 PM, Scott Graham <scott.llvm at h4ck3r.net> wrote:
>> I'm using the PPC backend's output as the "bytecode" for an interpreter
>> that I would like to be able to run on both little- and big-endian
>> platforms. The split stw's mean that i32s of the f64 are swapped in
>> memory on little-endian (thus foiling native-code interop).
>
> It's fundamentally impossible to correctly interpret using the wrong
> endianness, at least for general C code.  Have you considered making
> your interpreter map memory backwards on opposite-endian platforms?

Hi

The front-end is not C code, and doesn't do bit-level operations (if
that's what you mean). My first attempt was indeed to just leave
memory in big endian and swap during loads/stores. But, I'd like to
support an FFI to native code (which of course doesn't have any
knowledge of having to swap memory), so that isn't too practical.

thanks,
scott