1 // WebAssemblyFrameLowering.h - TargetFrameLowering for WebAssembly -*- C++ -*-/ 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 /// 9 /// \file 10 /// This class implements WebAssembly-specific bits of 11 /// TargetFrameLowering class. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYFRAMELOWERING_H 16 #define LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYFRAMELOWERING_H 17 18 #include "llvm/CodeGen/TargetFrameLowering.h" 19 20 namespace llvm { 21 22 class WebAssemblyFrameLowering final : public TargetFrameLowering { 23 public: 24 /// Size of the red zone for the user stack (leaf functions can use this much 25 /// space below the stack pointer without writing it back to __stack_pointer 26 /// global). 27 // TODO: (ABI) Revisit and decide how large it should be. 28 static const size_t RedZoneSize = 128; 29 30 WebAssemblyFrameLowering() 31 : TargetFrameLowering(StackGrowsDown, /*StackAlignment=*/Align(16), 32 /*LocalAreaOffset=*/0, 33 /*TransientStackAlignment=*/Align(16), 34 /*StackRealignable=*/true) {} 35 36 MachineBasicBlock::iterator 37 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, 38 MachineBasicBlock::iterator I) const override; 39 40 /// These methods insert prolog and epilog code into the function. 41 void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override; 42 void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override; 43 44 bool hasReservedCallFrame(const MachineFunction &MF) const override; 45 bool isSupportedStackID(TargetStackID::Value ID) const override; 46 DwarfFrameBase getDwarfFrameBase(const MachineFunction &MF) const override; 47 48 bool needsPrologForEH(const MachineFunction &MF) const; 49 50 /// Write SP back to __stack_pointer global. 51 void writeSPToGlobal(unsigned SrcReg, MachineFunction &MF, 52 MachineBasicBlock &MBB, 53 MachineBasicBlock::iterator &InsertStore, 54 const DebugLoc &DL) const; 55 56 // Returns the index of the WebAssembly local to which the stack object 57 // FrameIndex in MF should be allocated, or std::nullopt. 58 static std::optional<unsigned> getLocalForStackObject(MachineFunction &MF, 59 int FrameIndex); 60 61 static unsigned getSPReg(const MachineFunction &MF); 62 static unsigned getFPReg(const MachineFunction &MF); 63 static unsigned getOpcConst(const MachineFunction &MF); 64 static unsigned getOpcAdd(const MachineFunction &MF); 65 static unsigned getOpcSub(const MachineFunction &MF); 66 static unsigned getOpcAnd(const MachineFunction &MF); 67 static unsigned getOpcGlobGet(const MachineFunction &MF); 68 static unsigned getOpcGlobSet(const MachineFunction &MF); 69 70 protected: 71 bool hasFPImpl(const MachineFunction &MF) const override; 72 73 private: 74 bool hasBP(const MachineFunction &MF) const; 75 bool needsSPForLocalFrame(const MachineFunction &MF) const; 76 bool needsSP(const MachineFunction &MF) const; 77 bool needsSPWriteback(const MachineFunction &MF) const; 78 }; 79 80 } // end namespace llvm 81 82 #endif 83