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This will become necessary in a subsequent change to make this method merge adjacent stack adjustments, i.e. it might erase the previous and/or next instruction. It also greatly simplifies the calls to this function from Prolog- EpilogInserter. Previously, that had a bunch of logic to resume iteration after the call; now it just continues with the returned iterator. Note that this changes the behaviour of PEI a little. Previously, it attempted to re-visit the new instruction created by eliminateCallFramePseudoInstr(). That code was added in r36625, but I can't see any reason for it: the new instructions will obviously not be pseudo instructions, they will not have FrameIndex operands, and we have already accounted for the stack adjustment. Differential Revision: http://reviews.llvm.org/D18627 llvm-svn: 265036
57 lines
2.1 KiB
C++
57 lines
2.1 KiB
C++
// WebAssemblyFrameLowering.h - TargetFrameLowering for WebAssembly -*- C++ -*-/
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// \brief This class implements WebAssembly-specific bits of
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/// TargetFrameLowering class.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYFRAMELOWERING_H
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#define LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYFRAMELOWERING_H
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#include "llvm/Target/TargetFrameLowering.h"
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namespace llvm {
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class MachineFrameInfo;
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class WebAssemblyFrameLowering final : public TargetFrameLowering {
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public:
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/// Size of the red zone for the user stack (leaf functions can use this much
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/// space below the stack pointer without writing it back to memory).
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// TODO: (ABI) Revisit and decide how large it should be.
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static const size_t RedZoneSize = 128;
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WebAssemblyFrameLowering()
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: TargetFrameLowering(StackGrowsDown, /*StackAlignment=*/16,
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/*LocalAreaOffset=*/0,
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/*TransientStackAlignment=*/16,
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/*StackRealignable=*/true) {}
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MachineBasicBlock::iterator eliminateCallFramePseudoInstr(
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MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I) const override;
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/// These methods insert prolog and epilog code into the function.
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void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
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void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
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bool hasFP(const MachineFunction &MF) const override;
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bool hasReservedCallFrame(const MachineFunction &MF) const override;
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private:
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bool needsSP(const MachineFunction &MF, const MachineFrameInfo &MFI) const;
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bool needsSPWriteback(const MachineFunction &MF,
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const MachineFrameInfo &MFI) const;
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};
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} // end namespace llvm
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#endif
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