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 class MachineFrameInfo;
  22
  23 class WebAssemblyFrameLowering final : public TargetFrameLowering {
  24 public:
  25   /// Size of the red zone for the user stack (leaf functions can use this much
  26   /// space below the stack pointer without writing it back to __stack_pointer
  27   /// global).
  28   // TODO: (ABI) Revisit and decide how large it should be.
  29   static const size_t RedZoneSize = 128;
  30
  31   WebAssemblyFrameLowering()
  32       : TargetFrameLowering(StackGrowsDown, /*StackAlignment=*/Align(16),
  33                             /*LocalAreaOffset=*/0,
  34                             /*TransientStackAlignment=*/Align(16),
  35                             /*StackRealignable=*/true) {}
  36
  37   MachineBasicBlock::iterator
  38   eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
  39                                 MachineBasicBlock::iterator I) const override;
  40
  41   /// These methods insert prolog and epilog code into the function.
  42   void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
  43   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
  44
  45   bool hasFP(const MachineFunction &MF) const override;
  46   bool hasReservedCallFrame(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 private:
  57   bool hasBP(const MachineFunction &MF) const;
  58   bool needsSPForLocalFrame(const MachineFunction &MF) const;
  59   bool needsSP(const MachineFunction &MF) const;
  60   bool needsSPWriteback(const MachineFunction &MF) const;
  61 };
  62
  63 } // end namespace llvm
  64
  65 #endif