[llvm] [AArch64][SME] Implement the SME ABI (ZA state management) in Machine IR (PR #149062)

[via llvm-commits]

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+//===- MachineSMEABIPass.cpp ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass implements the SME ABI requirements for ZA state. This includes
+// implementing the lazy ZA state save schemes around calls.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AArch64InstrInfo.h"
+#include "AArch64MachineFunctionInfo.h"
+#include "AArch64Subtarget.h"
+#include "MCTargetDesc/AArch64AddressingModes.h"
+#include "llvm/ADT/BitmaskEnum.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/CodeGen/EdgeBundles.h"
+#include "llvm/CodeGen/LivePhysRegs.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/TargetRegisterInfo.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "aarch64-machine-sme-abi"
+
+namespace {
+
+enum ZAState {
+  // Any/unknown state (not valid)
+  ANY = 0,
+
+  // ZA is in use and active (i.e. within the accumulator)
+  ACTIVE,
+
+  // A ZA save has been set up or committed (i.e. ZA is dormant or off)
+  LOCAL_SAVED,
+
+  // ZA is off or a lazy save has been set up by the caller
+  CALLER_DORMANT,
+
+  // ZA is off
+  OFF,
+
+  // The number of ZA states (not a valid state)
+  NUM_ZA_STATE
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padipiee wrote:

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https://github.com/llvm/llvm-project/pull/149062