[LLVMdev] [RFC PATCH] X32 ABI support for Clang/compiler-rt

Steven Newbury steve at snewbury.org.uk
Thu Aug 22 01:04:55 CDT 2013

I'm working on bringing up complete coverage for a Gentoo x32 "desktop"
system.  I've been cooking up quite a few patches for various packages
to push upstream, but right now, the biggest blocker is the lack of
support for building with/codegen targeting x32 in llvm/clang.  Since
the x32 patches were sent last year, I see support code has landed in
LLVM, and basic handling of 32-bit pointers in Clang, but no
elf32_x86_64 codegen or support for the -mx32 switch.  I've been trying
to get x32 ABI support working in Clang and compiler-rt, I based off the
previous clang patch, bringing it up to date with the changes in trunk,
and hacked together handling of x32 "ARCH" support for compiler-rt.
(there must be a better way??)

Unfortunately, although the build succeeds as far as beginning to build
compiler-rt the resulting clang doesn't seem to respect the fact that
the target is x86_64-pc-linux-gnux32, nor that the "-mx32" opt has been
supplied.  Something is clearly missing.

Can somebody please take a look at the patches, and look to see what I'm
missing/where I've gone wrong, or otherwise point me to a working
patchset/repo if I'm duplicating effort.

Patches to follow...

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