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

[Peter Waller via Phabricator via cfe-commits]

peterwaller-arm updated this revision to Diff 442251.
peterwaller-arm added a comment.

- Cite D127209 <https://reviews.llvm.org/D127209> in the release note per tschuett comment.
- Be more specific about p0-p4, remove 'by analogy', per rsandifo-arm comment.
- Clarify 9th argument or greater, per DavidSpicket comment.

Thank you everyone for your inputs, hope this addresses everything so far, happy to receive further input.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129135/new/

https://reviews.llvm.org/D129135

Files:
  clang/docs/ReleaseNotes.rst


Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -499,6 +499,14 @@
   (e.g. ``int : 0``) no longer prevents the structure from being considered a
   homogeneous floating-point or vector aggregate. The new behavior agrees with
   the AAPCS specification, and matches the similar bug fix in GCC 12.1.
+- Targeting AArch64, since D127209 LLVM now only preserves the z8-z23
+  and p4-p15 registers across a call if the registers z0-z7 or p0-p4 are
+  used to pass data into or out of a subroutine. The new behavior
+  matches the AAPCS. Previously LLVM preserved z8-z23 and p4-p15 across
+  a call if the callee had an SVE type anywhere in its signature. This
+  would cause an incorrect use of the caller-preserved z8-z23 and p4-p15
+  ABI for example if the 9th argument or greater were the first SVE type
+  in the signature of a function.
 - All copy constructors can now be trivial if they are not user-provided,
   regardless of the type qualifiers of the argument of the defaulted constructor,
   fixing dr2171.


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