[PATCH] D92445: [PowerPC] Add powerpcle target.

Tue Dec 1 20:57:53 PST 2020

Bdragon28 added a comment.

Regarding things like Altivec and VSX:
Altivec should be just fine to run in 32-bit LE.
I am undecided as to whether VSX should be banned or not. However that goes, it should be identical in powerpc64 -m32 and powerpc64le -m32.

Regarding codegen:
CPU capabilities are a property of the selected CPU, not whether it is 32-bit/64-bit code, or LE/BE. (With the exception of certain instructions that are banned in LE, and certain instructions that are banned in 32-bit IIRC)

Regarding Book-III support for powerpcle:
I see zero value in using powerpcle for any Book-III activities. Modern LE kernels will always be powerpc64, and oldschool LE kernels were A) proprietary, and B) ancient history.
Since bridge mode is gone on modern TRUELE processors, it's pointless anyway, as you can't run a 32-bit kernel in either endian.

Regarding cpu support for powerpcle:
I see zero value in supporting non-TRUELE processors such as PPC74xx. Limiting it to POWER7 and above (or even POWER8 and above) seems sane to me. That is, I think it is a valid assumption
that powerpcle will not be being used in a "true" 32-bit environment where the 64-bit options are not implemented on the processor.

Regarding hosted use:
TBD. We don't have plans in FreeBSD for building a powerpcle compat32 userland. Linux userlands are experimental. There may be some open ABI questions. I'm fine with putting that off for now.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D92445/new/

https://reviews.llvm.org/D92445