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// WebAssemblyFrameLowering.h - TargetFrameLowering for WebAssembly -*- C++ -*-/
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This class implements WebAssembly-specific bits of
/// TargetFrameLowering class.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYFRAMELOWERING_H
#define LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYFRAMELOWERING_H
#include "llvm/CodeGen/TargetFrameLowering.h"
namespace llvm {
class WebAssemblyFrameLowering final : public TargetFrameLowering {
public:
/// Size of the red zone for the user stack (leaf functions can use this much
/// space below the stack pointer without writing it back to __stack_pointer
/// global).
// TODO: (ABI) Revisit and decide how large it should be.
static const size_t RedZoneSize = 128;
WebAssemblyFrameLowering()
: TargetFrameLowering(StackGrowsDown, /*StackAlignment=*/Align(16),
/*LocalAreaOffset=*/0,
/*TransientStackAlignment=*/Align(16),
/*StackRealignable=*/true) {}
MachineBasicBlock::iterator
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const override;
/// These methods insert prolog and epilog code into the function.
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool hasFP(const MachineFunction &MF) const override;
bool hasReservedCallFrame(const MachineFunction &MF) const override;
bool isSupportedStackID(TargetStackID::Value ID) const override;
DwarfFrameBase getDwarfFrameBase(const MachineFunction &MF) const override;
bool needsPrologForEH(const MachineFunction &MF) const;
/// Write SP back to __stack_pointer global.
void writeSPToGlobal(unsigned SrcReg, MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator &InsertStore,
const DebugLoc &DL) const;
// Returns the index of the WebAssembly local to which the stack object
// FrameIndex in MF should be allocated, or std::nullopt.
static std::optional<unsigned> getLocalForStackObject(MachineFunction &MF,
int FrameIndex);
static unsigned getSPReg(const MachineFunction &MF);
static unsigned getFPReg(const MachineFunction &MF);
static unsigned getOpcConst(const MachineFunction &MF);
static unsigned getOpcAdd(const MachineFunction &MF);
static unsigned getOpcSub(const MachineFunction &MF);
static unsigned getOpcAnd(const MachineFunction &MF);
static unsigned getOpcGlobGet(const MachineFunction &MF);
static unsigned getOpcGlobSet(const MachineFunction &MF);
private:
bool hasBP(const MachineFunction &MF) const;
bool needsSPForLocalFrame(const MachineFunction &MF) const;
bool needsSP(const MachineFunction &MF) const;
bool needsSPWriteback(const MachineFunction &MF) const;
};
} // end namespace llvm
#endif
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