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AAPCS ABI is accepted for x86 target #57182
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Compiling
extern "aapcs"on aarch64 will explode in LLVM withLLVM ERROR: Unsupported calling convention..I ran into these same issues in #65443 .
One thing that I mentioned there, that is not mentioned here, is that because these errors can happen on stable safe Rust code, this is actually a soundness bug (safe Rust code has UB). Note also that for some ABIs, like
stdcall, we don't error on tier-1 targets.I feel that to avoid this issue in the future we should rather prefer a whitelist of ABIs, rather than a blacklist, and by default put no ABIs, so that the compilation fails until the ABI list is properly populated for the target.
I agree. There are some ABIs that the reference says are available on all targets (e.g.
"C","system","Rust", etc.) but except for those, each target should have a white-list that explicitly allows using an ABI on the target.- added a commit that references this issue
on Jul 6, 2021
Currently the following code compiles fine when targetting x86_64.
This code is non-sensical because AAPCS calling convention is only defined for ARM. An example of non-sensical ABI being disallowed is
when compiling with
--target=armv7-unknown-linux-gnueabihfwhich fails with:Targets should be reviewed for such nonsensical ABIs and their blacklists updated. I feel that to avoid this issue in the future we should rather prefer a whitelist of ABIs, rather than a blacklist, and by default put no ABIs, so that the compilation fails until the ABI list is properly populated for the target.