[all-commits] [llvm/llvm-project] f7f44f: [AArch64][SME] Set up a lazy-save/restore around c...

[kmclaughlin-arm via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f7f44f018f6ffbd11cd3bd2ffafbdb15725aac86
      https://github.com/llvm/llvm-project/commit/f7f44f018f6ffbd11cd3bd2ffafbdb15725aac86
  Author: Kerry McLaughlin <kerry.mclaughlin at arm.com>
  Date:   2022-10-05 (Wed, 05 Oct 2022)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
    M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    M llvm/lib/Target/AArch64/AArch64ISelLowering.h
    M llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h
    M llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
    M llvm/lib/Target/AArch64/AArch64RegisterInfo.h
    M llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td
    A llvm/test/CodeGen/AArch64/sme-lazy-save-call.ll
    M llvm/test/CodeGen/AArch64/sme-shared-za-interface.ll

  Log Message:
  -----------
  [AArch64][SME] Set up a lazy-save/restore around calls.

Setting up a lazy-save mechanism around calls is done during SelectionDAG
because calls to intrinsics may be expanded into an actual function call
(e.g. calls to @llvm.cos()), and maintaining an allowed-list in the SMEABI
pass is not feasible.

The approach for conditionally restoring the lazy-save based on the runtime
value of TPIDR2_EL0 is similar to how we handle conditional smstart/smstop.
We create a pseudo-node which gets expanded into a conditional branch and
expands to a call to __arm_tpidr2_restore(%tpidr2_object_ptr).

The lazy-save buffer and TPIDR2 block are only allocated once at the start
of the function. For each call, the TPIDR2 block is initialised, and at
the end of the call, a pseudo node (RestoreZA) is planted.

Patch by Sander de Smalen.

Differential Revision: https://reviews.llvm.org/D133900