[all-commits] [llvm/llvm-project] 465836: [ARM64EC 3/?] Mark reserved registers specific to ...

[Eli Friedman via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4658366d95d5e398baad956225cc4ba339d5b037
      https://github.com/llvm/llvm-project/commit/4658366d95d5e398baad956225cc4ba339d5b037
  Author: Eli Friedman <efriedma at quicinc.com>
  Date:   2022-09-05 (Mon, 05 Sep 2022)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
    M llvm/lib/Target/AArch64/AArch64Subtarget.h
    A llvm/test/CodeGen/AArch64/arm64ec-reservedregs.ll
    M llvm/utils/UpdateTestChecks/asm.py

  Log Message:
  -----------
  [ARM64EC 3/?] Mark reserved registers specific to ARM64EC ABI.

Part of patchset to add initial support for ARM64EC.

I'm not completely sure I understand the reason for this restriction,
but Microsoft documentation says that asynchronous signals clobber these
registers, so we can't ever use them.

As far as I know, none of these registers have any hardcoded meaning, so
reserving them shouldn't have any significant side-effects.

Differental Revision: https://reviews.llvm.org/D125413