71768bb6cf
This PR updates the AArch64 ABI implementation so that it (i) properly respects that v8-v15 inclusive have callee-save lower halves, and caller-save upper halves, by conservatively approximating (to full registers) in the appropriate directions when generating prologue caller-saves and when informing the regalloc of clobbered regs across callsites. In order to prevent saving all of these vector registers in the prologue of every non-leaf function due to the above approximation, this also makes use of a new regalloc.rs feature to exclude call instructions' writes from the clobber set returned by register allocation. This is safe whenever the caller and callee have the same ABI (because anything the callee could clobber, the caller is allowed to clobber as well without saving it in the prologue). Fixes #2254.
This crate contains the core Cranelift code generator. It translates code from an intermediate representation into executable machine code.