[PATCH] D129135: [doc][ReleaseNotes] Document AArch64 SVE ABI fix from D127209

Tue Jul 5 02:44:54 PDT 2022

DavidSpickett added a comment.

>From reading the release note my understanding is that before this fix the caller of a function would store `z0-z7` in situations where it did not need to. Which seems low impact unless you were doing something that read the previous stack frame (but nevertheless a difference from the AAPCS).

If that's what you were trying to get across then great!

> This affects functions where the first SVE parameter appears in the 9th or later arguments

I'm reading https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#642parameter-passing-rules. Wouldn't the type of the preceding 8 arguments also be relevant?

Though I was surprised to see that "NSRN" covers floating point and SVE registers, so I'm hardly an expert here.

> and the function does not return an SVE type.

This is because the function would return in `z0` therefore the caller must preserve at least `z0` and the ABI tells you to preserve `z0-z7` to do that?

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https://reviews.llvm.org/D129135