LLVM  12.0.0git
WebAssemblyFrameLowering.h
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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 
19 
20 namespace llvm {
21 
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 
31  : TargetFrameLowering(StackGrowsDown, /*StackAlignment=*/Align(16),
32  /*LocalAreaOffset=*/0,
33  /*TransientStackAlignment=*/Align(16),
34  /*StackRealignable=*/true) {}
35 
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  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  static unsigned getSPReg(const MachineFunction &MF);
57  static unsigned getFPReg(const MachineFunction &MF);
58  static unsigned getOpcConst(const MachineFunction &MF);
59  static unsigned getOpcAdd(const MachineFunction &MF);
60  static unsigned getOpcSub(const MachineFunction &MF);
61  static unsigned getOpcAnd(const MachineFunction &MF);
62  static unsigned getOpcGlobGet(const MachineFunction &MF);
63  static unsigned getOpcGlobSet(const MachineFunction &MF);
64 
65 private:
66  bool hasBP(const MachineFunction &MF) const;
67  bool needsSPForLocalFrame(const MachineFunction &MF) const;
68  bool needsSP(const MachineFunction &MF) const;
69  bool needsSPWriteback(const MachineFunction &MF) const;
70 };
71 
72 } // end namespace llvm
73 
74 #endif
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override
These methods insert prolog and epilog code into the function.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
static unsigned getOpcAnd(const MachineFunction &MF)
A debug info location.
Definition: DebugLoc.h:33
bool hasFP(const MachineFunction &MF) const override
Return true if the specified function should have a dedicated frame pointer register.
MachineBasicBlock & MBB
MachineBasicBlock::iterator eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const override
This method is called during prolog/epilog code insertion to eliminate call frame setup and destroy p...
static unsigned getSPReg(const MachineFunction &MF)
bool needsPrologForEH(const MachineFunction &MF) const
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override
static unsigned getOpcGlobGet(const MachineFunction &MF)
static unsigned getOpcSub(const MachineFunction &MF)
static unsigned getFPReg(const MachineFunction &MF)
void writeSPToGlobal(unsigned SrcReg, MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator &InsertStore, const DebugLoc &DL) const
Write SP back to __stack_pointer global.
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:39
static unsigned getOpcConst(const MachineFunction &MF)
Information about stack frame layout on the target.
DwarfFrameBase getDwarfFrameBase(const MachineFunction &MF) const override
Return the frame base information to be encoded in the DWARF subprogram debug info.
static unsigned getOpcGlobSet(const MachineFunction &MF)
basic Basic Alias true
static const size_t RedZoneSize
Size of the red zone for the user stack (leaf functions can use this much space below the stack point...
#define I(x, y, z)
Definition: MD5.cpp:59
bool hasReservedCallFrame(const MachineFunction &MF) const override
Under normal circumstances, when a frame pointer is not required, we reserve argument space for call ...
static unsigned getOpcAdd(const MachineFunction &MF)
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL