3be667ae5a
Without frame pointers, the locations of variables on the stack are emitted relative to the stack pointer (via the stack pointer being the value of DW_AT_frame_base on the subprogram). If a call modifies the stack pointer this results in the locations being wrong and the debugger displaying the wrong values for variables. By using DW_OP_call_frame_cfa in these situations the emitted location for the variable will automatically handle changes in the stack pointer (provided LLVM is emitting the correct CFI directives elsewhere, of course). The CFA needs to be adjusted for the size of the stack frame (including the return address) to allow the variable locations themselves to remain unchanged by this patch. Certain LLDB features cannot cope with DW_OP_call_frame_cfa, so this change is heuristically limited to the cases where it's necessary for correctness to minimize the fallout there. Reviewed By: #debug-info, scott.linder, jryans, jmorse Differential Revision: https://reviews.llvm.org/D143463
275 lines
12 KiB
C++
275 lines
12 KiB
C++
//===-- X86TargetFrameLowering.h - Define frame lowering for X86 -*- C++ -*-==//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This class implements X86-specific bits of TargetFrameLowering class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_X86_X86FRAMELOWERING_H
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#define LLVM_LIB_TARGET_X86_X86FRAMELOWERING_H
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/TargetFrameLowering.h"
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#include "llvm/Support/TypeSize.h"
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namespace llvm {
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class MachineInstrBuilder;
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class MCCFIInstruction;
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class X86InstrInfo;
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class X86Subtarget;
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class X86RegisterInfo;
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class X86FrameLowering : public TargetFrameLowering {
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public:
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X86FrameLowering(const X86Subtarget &STI, MaybeAlign StackAlignOverride);
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// Cached subtarget predicates.
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const X86Subtarget &STI;
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const X86InstrInfo &TII;
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const X86RegisterInfo *TRI;
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unsigned SlotSize;
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/// Is64Bit implies that x86_64 instructions are available.
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bool Is64Bit;
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bool IsLP64;
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/// True if the 64-bit frame or stack pointer should be used. True for most
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/// 64-bit targets with the exception of x32. If this is false, 32-bit
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/// instruction operands should be used to manipulate StackPtr and FramePtr.
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bool Uses64BitFramePtr;
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unsigned StackPtr;
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/// Emit target stack probe code. This is required for all
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/// large stack allocations on Windows. The caller is required to materialize
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/// the number of bytes to probe in RAX/EAX.
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/// \p InstrNum optionally contains a debug-info instruction number for the
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/// new stack pointer.
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void emitStackProbe(MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
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bool InProlog,
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std::optional<MachineFunction::DebugInstrOperandPair>
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InstrNum = std::nullopt) const;
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bool stackProbeFunctionModifiesSP() const override;
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/// Replace a StackProbe inline-stub with the actual probe code inline.
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void inlineStackProbe(MachineFunction &MF,
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MachineBasicBlock &PrologMBB) const override;
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void emitCalleeSavedFrameMovesFullCFA(
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MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI) const override;
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void emitCalleeSavedFrameMoves(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL, bool IsPrologue) const;
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/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
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/// 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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void adjustForSegmentedStacks(MachineFunction &MF,
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MachineBasicBlock &PrologueMBB) const override;
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void adjustForHiPEPrologue(MachineFunction &MF,
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MachineBasicBlock &PrologueMBB) const override;
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void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
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RegScavenger *RS = nullptr) const override;
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bool
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assignCalleeSavedSpillSlots(MachineFunction &MF,
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const TargetRegisterInfo *TRI,
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std::vector<CalleeSavedInfo> &CSI) const override;
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bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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ArrayRef<CalleeSavedInfo> CSI,
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const TargetRegisterInfo *TRI) const override;
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bool
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restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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MutableArrayRef<CalleeSavedInfo> CSI,
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const TargetRegisterInfo *TRI) 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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bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override;
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bool needsFrameIndexResolution(const MachineFunction &MF) const override;
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StackOffset getFrameIndexReference(const MachineFunction &MF, int FI,
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Register &FrameReg) const override;
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int getWin64EHFrameIndexRef(const MachineFunction &MF, int FI,
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Register &SPReg) const;
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StackOffset getFrameIndexReferenceSP(const MachineFunction &MF, int FI,
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Register &SPReg, int Adjustment) const;
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StackOffset
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getFrameIndexReferencePreferSP(const MachineFunction &MF, int FI,
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Register &FrameReg,
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bool IgnoreSPUpdates) const override;
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MachineBasicBlock::iterator
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eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI) const override;
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unsigned getWinEHParentFrameOffset(const MachineFunction &MF) const override;
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void processFunctionBeforeFrameFinalized(MachineFunction &MF,
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RegScavenger *RS) const override;
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void
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processFunctionBeforeFrameIndicesReplaced(MachineFunction &MF,
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RegScavenger *RS) const override;
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/// Check the instruction before/after the passed instruction. If
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/// it is an ADD/SUB/LEA instruction it is deleted argument and the
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/// stack adjustment is returned as a positive value for ADD/LEA and
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/// a negative for SUB.
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int mergeSPUpdates(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
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bool doMergeWithPrevious) const;
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/// Emit a series of instructions to increment / decrement the stack
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/// pointer by a constant value.
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void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
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const DebugLoc &DL, int64_t NumBytes, bool InEpilogue) const;
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/// Check that LEA can be used on SP in an epilogue sequence for \p MF.
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bool canUseLEAForSPInEpilogue(const MachineFunction &MF) const;
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/// Check whether or not the given \p MBB can be used as a prologue
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/// for the target.
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/// The prologue will be inserted first in this basic block.
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/// This method is used by the shrink-wrapping pass to decide if
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/// \p MBB will be correctly handled by the target.
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/// As soon as the target enable shrink-wrapping without overriding
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/// this method, we assume that each basic block is a valid
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/// prologue.
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bool canUseAsPrologue(const MachineBasicBlock &MBB) const override;
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/// Check whether or not the given \p MBB can be used as a epilogue
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/// for the target.
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/// The epilogue will be inserted before the first terminator of that block.
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/// This method is used by the shrink-wrapping pass to decide if
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/// \p MBB will be correctly handled by the target.
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bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
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/// Returns true if the target will correctly handle shrink wrapping.
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bool enableShrinkWrapping(const MachineFunction &MF) const override;
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/// Order the symbols in the local stack.
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/// We want to place the local stack objects in some sort of sensible order.
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/// The heuristic we use is to try and pack them according to static number
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/// of uses and size in order to minimize code size.
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void orderFrameObjects(const MachineFunction &MF,
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SmallVectorImpl<int> &ObjectsToAllocate) const override;
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/// Wraps up getting a CFI index and building a MachineInstr for it.
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void BuildCFI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL, const MCCFIInstruction &CFIInst,
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MachineInstr::MIFlag Flag = MachineInstr::NoFlags) const;
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/// Sets up EBP and optionally ESI based on the incoming EBP value. Only
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/// needed for 32-bit. Used in funclet prologues and at catchret destinations.
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MachineBasicBlock::iterator
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restoreWin32EHStackPointers(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL, bool RestoreSP = false) const;
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void restoreWinEHStackPointersInParent(MachineFunction &MF) const;
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int getInitialCFAOffset(const MachineFunction &MF) const override;
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Register getInitialCFARegister(const MachineFunction &MF) const override;
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DwarfFrameBase getDwarfFrameBase(const MachineFunction &MF) const override;
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/// Return true if the function has a redzone (accessible bytes past the
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/// frame of the top of stack function) as part of it's ABI.
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bool has128ByteRedZone(const MachineFunction& MF) const;
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private:
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bool isWin64Prologue(const MachineFunction &MF) const;
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bool needsDwarfCFI(const MachineFunction &MF) const;
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uint64_t calculateMaxStackAlign(const MachineFunction &MF) const;
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/// Emit target stack probe as a call to a helper function
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void emitStackProbeCall(
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MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI, const DebugLoc &DL, bool InProlog,
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std::optional<MachineFunction::DebugInstrOperandPair> InstrNum) const;
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/// Emit target stack probe as an inline sequence.
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void emitStackProbeInline(MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL, bool InProlog) const;
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void emitStackProbeInlineWindowsCoreCLR64(MachineFunction &MF,
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MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL,
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bool InProlog) const;
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void emitStackProbeInlineGeneric(MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL, bool InProlog) const;
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void emitStackProbeInlineGenericBlock(MachineFunction &MF,
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MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL, uint64_t Offset,
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uint64_t Align) const;
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void emitStackProbeInlineGenericLoop(MachineFunction &MF,
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MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL, uint64_t Offset,
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uint64_t Align) const;
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/// Emit target zero call-used regs.
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void emitZeroCallUsedRegs(BitVector RegsToZero,
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MachineBasicBlock &MBB) const override;
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void adjustFrameForMsvcCxxEh(MachineFunction &MF) const;
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/// Aligns the stack pointer by ANDing it with -MaxAlign.
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void BuildStackAlignAND(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
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unsigned Reg, uint64_t MaxAlign) const;
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/// Make small positive stack adjustments using POPs.
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bool adjustStackWithPops(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
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int Offset) const;
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/// Adjusts the stack pointer using LEA, SUB, or ADD.
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MachineInstrBuilder BuildStackAdjustment(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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const DebugLoc &DL, int64_t Offset,
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bool InEpilogue) const;
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unsigned getPSPSlotOffsetFromSP(const MachineFunction &MF) const;
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unsigned getWinEHFuncletFrameSize(const MachineFunction &MF) const;
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/// Materialize the catchret target MBB in RAX.
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void emitCatchRetReturnValue(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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MachineInstr *CatchRet) const;
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};
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} // End llvm namespace
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#endif
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