llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.h

   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 hasFP(const MachineFunction &MF) const override;
  45   bool hasReservedCallFrame(const MachineFunction &MF) const override;
  46   bool isSupportedStackID(TargetStackID::Value ID) const override;
  47   DwarfFrameBase getDwarfFrameBase(const MachineFunction &MF) const override;
  48
  49   bool needsPrologForEH(const MachineFunction &MF) const;
  50
  51   /// Write SP back to __stack_pointer global.
  52   void writeSPToGlobal(unsigned SrcReg, MachineFunction &MF,
  53                        MachineBasicBlock &MBB,
  54                        MachineBasicBlock::iterator &InsertStore,
  55                        const DebugLoc &DL) const;
  56
  57   // Returns the index of the WebAssembly local to which the stack object
  58   // FrameIndex in MF should be allocated, or std::nullopt.
  59   static std::optional<unsigned> getLocalForStackObject(MachineFunction &MF,
  60                                                         int FrameIndex);
  61
  62   static unsigned getSPReg(const MachineFunction &MF);
  63   static unsigned getFPReg(const MachineFunction &MF);
  64   static unsigned getOpcConst(const MachineFunction &MF);
  65   static unsigned getOpcAdd(const MachineFunction &MF);
  66   static unsigned getOpcSub(const MachineFunction &MF);
  67   static unsigned getOpcAnd(const MachineFunction &MF);
  68   static unsigned getOpcGlobGet(const MachineFunction &MF);
  69   static unsigned getOpcGlobSet(const MachineFunction &MF);
  70
  71 private:
  72   bool hasBP(const MachineFunction &MF) const;
  73   bool needsSPForLocalFrame(const MachineFunction &MF) const;
  74   bool needsSP(const MachineFunction &MF) const;
  75   bool needsSPWriteback(const MachineFunction &MF) const;
  76 };
  77
  78 } // end namespace llvm
  79
  80 #endif