Support stack probing

[bjorn3]

This is used to prevent Stack Clash, where the stack grows down to the heap, corrupting values on the heap.

[bjorn3]

@sunfishcode is __cranelift_probestack compatible with __rust_probestack?

[sunfishcode]

Yes. The precise probestack convention can be controlled by the probestack_func_adjusts_sp and probestack_size_log2 settings, but the default settings are compatible with __rust_probestack.

One way to tell cranelift to use the name __rust_probestack is to pass a custom libcall_names mapping function to FaerieBuilder/SimpleJITBuilder::new.

[bjorn3]

is to pass a custom libcall_names mapping function to FaerieBuilder/SimpleJITBuilder::new.

That is exactly what I wanted to do. I just didn't want to get surprised by a hard to debug error originating from an abi incompatibility :)

[bjorn3]

I do need to find a way to avoid the inline asm version used by compiler builtins first.

[bjorn3]

Inline stack probing is enabled on x86_64 now. Cranelift 0.91 will support it on AArch64 too.