AArch64: Migrate calls and returns to ISLE. #4788
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| (decl lower_return (Range ValueSlice) InstOutput) | ||
| (rule (lower_return (range_empty) _) (output_none)) | ||
| (rule (lower_return (range_unwrap head tail) args) | ||
| (let ((_ Unit (copy_to_regs (retval head) (value_slice_get args head)))) | ||
| (lower_return tail args))) |
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Not at all blocking, but I wonder what a better name for this would be now that it's shared between multiple backends.
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We can definitely think more about this -- it also felt a little strange to put it in prelude.isle to be honest; it seems more like we need a library of "common lowering helpers" that is separate from the language and ISLE-binding prelude proper. But, we can refine more in subsequent PRs!
| ; orr x0, xzr, #4294967295 | ||
| ; movn x0, #0 |
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The returns are going through a different path now, so the immediate handling is a little different; but this is still correct I think (movn x0, #0 generates all-ones, which for an i32 func is the same as u32::MAX in the return register).
This borrows some machinery from x64 and makes it common. The order of setup for on-stack args is reversed now, but that seems OK if it means we can share more code!