llvm/llvm/lib/Target/AArch64/SMEABIPass.cpp

//===--------- SMEABI - SME  ABI-------------------------------------------===//
//
// 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 parts of the the SME ABI, such as:
// * Using the lazy-save mechanism before enabling the use of ZA.
// * Setting up the lazy-save mechanism around invokes.
//
//===----------------------------------------------------------------------===//

#include "AArch64.h"
#include "Utils/AArch64BaseInfo.h"
#include "Utils/AArch64SMEAttributes.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/IntrinsicsAArch64.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Utils/Cloning.h"

usingnamespacellvm;

#define DEBUG_TYPE …

namespace {
struct SMEABI : public FunctionPass { … };
} // end anonymous namespace

char SMEABI::ID = …;
static const char *name = …;
INITIALIZE_PASS_BEGIN(SMEABI, DEBUG_TYPE, name, false, false)
INITIALIZE_PASS_END(SMEABI, DEBUG_TYPE, name, false, false)

FunctionPass *llvm::createSMEABIPass() { … }

//===----------------------------------------------------------------------===//
// Utility functions
//===----------------------------------------------------------------------===//

// Utility function to emit a call to __arm_tpidr2_save and clear TPIDR2_EL0.
void emitTPIDR2Save(Module *M, IRBuilder<> &Builder) { … }

/// This function generates code at the beginning and end of a function marked
/// with either `aarch64_new_za` or `aarch64_new_zt0`.
/// At the beginning of the function, the following code is generated:
///  - Commit lazy-save if active   [Private-ZA Interface*]
///  - Enable PSTATE.ZA             [Private-ZA Interface]
///  - Zero ZA                      [Has New ZA State]
///  - Zero ZT0                     [Has New ZT0 State]
///
/// * A function with new ZT0 state will not change ZA, so committing the
/// lazy-save is not strictly necessary. However, the lazy-save mechanism
/// may be active on entry to the function, with PSTATE.ZA set to 1. If
/// the new ZT0 function calls a function that does not share ZT0, we will
/// need to conditionally SMSTOP ZA before the call, setting PSTATE.ZA to 0.
/// For this reason, it's easier to always commit the lazy-save at the
/// beginning of the function regardless of whether it has ZA state.
///
/// At the end of the function, PSTATE.ZA is disabled if the function has a
/// Private-ZA Interface. A function is considered to have a Private-ZA
/// interface if it does not share ZA or ZT0.
///
bool SMEABI::updateNewStateFunctions(Module *M, Function *F,
                                     IRBuilder<> &Builder, SMEAttrs FnAttrs) { … }

bool SMEABI::runOnFunction(Function &F) { … }