LLVM: llvm::SystemZELFFrameLowering Class Reference (original) (raw)
#include "[Target/SystemZ/SystemZFrameLowering.h](SystemZFrameLowering%5F8h%5Fsource.html)"
| Public Member Functions | |
|---|---|
| SystemZELFFrameLowering (unsigned PointerSize) | |
| bool | assignCalleeSavedSpillSlots (MachineFunction &MF, const TargetRegisterInfo *TRI, std::vector< CalleeSavedInfo > &CSI) const override |
| assignCalleeSavedSpillSlots - Allows target to override spill slot assignment logic. | |
| void | determineCalleeSaves (MachineFunction &MF, BitVector &SavedRegs, RegScavenger *RS) const override |
| This method determines which of the registers reported by TargetRegisterInfo::getCalleeSavedRegs() should actually get saved. | |
| bool | spillCalleeSavedRegisters (MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, ArrayRef< CalleeSavedInfo > CSI, const TargetRegisterInfo *TRI) const override |
| spillCalleeSavedRegisters - Issues instruction(s) to spill all callee saved registers and returns true if it isn't possible / profitable to do so by issuing a series of store instructions via storeRegToStackSlot(). | |
| bool | restoreCalleeSavedRegisters (MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBII, MutableArrayRef< CalleeSavedInfo > CSI, const TargetRegisterInfo *TRI) const override |
| restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee saved registers and returns true if it isn't possible / profitable to do so by issuing a series of load instructions via loadRegToStackSlot(). | |
| void | processFunctionBeforeFrameFinalized (MachineFunction &MF, RegScavenger *RS) const override |
| processFunctionBeforeFrameFinalized - This method is called immediately before the specified function's frame layout (MF.getFrameInfo()) is finalized. | |
| void | emitPrologue (MachineFunction &MF, MachineBasicBlock &MBB) const override |
| emitProlog/emitEpilog - These methods insert prolog and epilog code into the function. | |
| void | emitEpilogue (MachineFunction &MF, MachineBasicBlock &MBB) const override |
| void | inlineStackProbe (MachineFunction &MF, MachineBasicBlock &PrologMBB) const override |
| Replace a StackProbe stub (if any) with the actual probe code inline. | |
| StackOffset | getFrameIndexReference (const MachineFunction &MF, int FI, Register &FrameReg) const override |
| getFrameIndexReference - This method should return the base register and offset used to reference a frame index location. | |
| void | orderFrameObjects (const MachineFunction &MF, SmallVectorImpl< int > &ObjectsToAllocate) const override |
| Order the symbols in the local stack frame. | |
| unsigned | getRegSpillOffset (MachineFunction &MF, Register Reg) const |
| bool | usePackedStack (MachineFunction &MF) const |
| unsigned | getBackchainOffset (MachineFunction &MF) const override |
| int | getReturnAddressOffset (MachineFunction &MF) const override |
| int | getOrCreateFramePointerSaveIndex (MachineFunction &MF) const override |
| Public Member Functions inherited from llvm::SystemZFrameLowering | |
| SystemZFrameLowering (StackDirection D, Align StackAl, int LAO, Align TransAl, bool StackReal, unsigned PointerSize) | |
| bool | allocateScavengingFrameIndexesNearIncomingSP (const MachineFunction &MF) const override |
| Control the placement of special register scavenging spill slots when allocating a stack frame. | |
| bool | hasReservedCallFrame (const MachineFunction &MF) const override |
| hasReservedCallFrame - Under normal circumstances, when a frame pointer is not required, we reserve argument space for call sites in the function immediately on entry to the current function. | |
| unsigned | getPointerSize () const |
| Public Member Functions inherited from llvm::TargetFrameLowering | |
| TargetFrameLowering (StackDirection D, Align StackAl, int LAO, Align TransAl=Align(1), bool StackReal=true) | |
| virtual | ~TargetFrameLowering () |
| StackDirection | getStackGrowthDirection () const |
| getStackGrowthDirection - Return the direction the stack grows | |
| unsigned | getStackAlignment () const |
| getStackAlignment - This method returns the number of bytes to which the stack pointer must be aligned on entry to a function. | |
| Align | getStackAlign () const |
| getStackAlignment - This method returns the number of bytes to which the stack pointer must be aligned on entry to a function. | |
| virtual uint64_t | getStackThreshold () const |
| getStackThreshold - Return the maximum stack size | |
| int | alignSPAdjust (int SPAdj) const |
| alignSPAdjust - This method aligns the stack adjustment to the correct alignment. | |
| Align | getTransientStackAlign () const |
| getTransientStackAlignment - This method returns the number of bytes to which the stack pointer must be aligned at all times, even between calls. | |
| bool | isStackRealignable () const |
| isStackRealignable - This method returns whether the stack can be realigned. | |
| virtual bool | isStackIdSafeForLocalArea (unsigned StackId) const |
| This method returns whether or not it is safe for an object with the given stack id to be bundled into the local area. | |
| int | getOffsetOfLocalArea () const |
| getOffsetOfLocalArea - This method returns the offset of the local area from the stack pointer on entrance to a function. | |
| virtual const SpillSlot * | getCalleeSavedSpillSlots (unsigned &NumEntries) const |
| getCalleeSavedSpillSlots - This method returns a pointer to an array of pairs, that contains an entry for each callee saved register that must be spilled to a particular stack location if it is spilled. | |
| virtual bool | targetHandlesStackFrameRounding () const |
| targetHandlesStackFrameRounding - Returns true if the target is responsible for rounding up the stack frame (probably at emitPrologue time). | |
| virtual bool | enableShrinkWrapping (const MachineFunction &MF) const |
| Returns true if the target will correctly handle shrink wrapping. | |
| virtual bool | enableStackSlotScavenging (const MachineFunction &MF) const |
| Returns true if the stack slot holes in the fixed and callee-save stack area should be used when allocating other stack locations to reduce stack size. | |
| virtual bool | enableCalleeSaveSkip (const MachineFunction &MF) const |
| Returns true if the target can safely skip saving callee-saved registers for noreturn nounwind functions. | |
| virtual void | emitZeroCallUsedRegs (BitVector RegsToZero, MachineBasicBlock &MBB) const |
| emitZeroCallUsedRegs - Zeros out call used registers. | |
| virtual void | emitCalleeSavedFrameMovesFullCFA (MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI) const |
| With basic block sections, emit callee saved frame moves for basic blocks that are in a different section. | |
| virtual bool | enableCFIFixup (const MachineFunction &MF) const |
| Returns true if we may need to fix the unwind information for the function. | |
| virtual bool | enableFullCFIFixup (const MachineFunction &MF) const |
| enableFullCFIFixup - Returns true if we may need to fix the unwind information such that it is accurate for every instruction in the function (e.g. | |
| virtual void | resetCFIToInitialState (MachineBasicBlock &MBB) const |
| Emit CFI instructions that recreate the state of the unwind information upon function entry. | |
| virtual bool | stackProbeFunctionModifiesSP () const |
| Does the stack probe function call return with a modified stack pointer? | |
| virtual void | adjustForSegmentedStacks (MachineFunction &MF, MachineBasicBlock &PrologueMBB) const |
| Adjust the prologue to have the function use segmented stacks. | |
| virtual void | adjustForHiPEPrologue (MachineFunction &MF, MachineBasicBlock &PrologueMBB) const |
| Adjust the prologue to add Erlang Run-Time System (ERTS) specific code in the assembly prologue to explicitly handle the stack. | |
| void | spillCalleeSavedRegister (MachineBasicBlock &SaveBlock, MachineBasicBlock::iterator MI, const CalleeSavedInfo &CS, const TargetInstrInfo *TII, const TargetRegisterInfo *TRI) const |
| spillCalleeSavedRegister - Default implementation for spilling a single callee saved register. | |
| void | restoreCalleeSavedRegister (MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, const CalleeSavedInfo &CS, const TargetInstrInfo *TII, const TargetRegisterInfo *TRI) const |
| bool | hasFP (const MachineFunction &MF) const |
| hasFP - Return true if the specified function should have a dedicated frame pointer register. | |
| virtual bool | canSimplifyCallFramePseudos (const MachineFunction &MF) const |
| canSimplifyCallFramePseudos - When possible, it's best to simplify the call frame pseudo ops before doing frame index elimination. | |
| virtual bool | needsFrameIndexResolution (const MachineFunction &MF) const |
| virtual StackOffset | getFrameIndexReferencePreferSP (const MachineFunction &MF, int FI, Register &FrameReg, bool IgnoreSPUpdates) const |
| Same as getFrameIndexReference, except that the stack pointer (as opposed to the frame pointer) will be the preferred value for FrameReg. | |
| virtual StackOffset | getNonLocalFrameIndexReference (const MachineFunction &MF, int FI) const |
| getNonLocalFrameIndexReference - This method returns the offset used to reference a frame index location. | |
| virtual StackOffset | getFrameIndexReferenceFromSP (const MachineFunction &MF, int FI) const |
| getFrameIndexReferenceFromSP - This method returns the offset from the stack pointer to the slot of the specified index. | |
| virtual void | getCalleeSaves (const MachineFunction &MF, BitVector &SavedRegs) const |
| Returns the callee-saved registers as computed by determineCalleeSaves in the BitVector SavedRegs. | |
| virtual void | processFunctionBeforeFrameIndicesReplaced (MachineFunction &MF, RegScavenger *RS=nullptr) const |
| processFunctionBeforeFrameIndicesReplaced - This method is called immediately before MO_FrameIndex operands are eliminated, but after the frame is finalized. | |
| virtual unsigned | getWinEHParentFrameOffset (const MachineFunction &MF) const |
| virtual MachineBasicBlock::iterator | eliminateCallFramePseudoInstr (MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator MI) const |
| This method is called during prolog/epilog code insertion to eliminate call frame setup and destroy pseudo instructions (but only if the Target is using them). | |
| virtual bool | canUseAsPrologue (const MachineBasicBlock &MBB) const |
| Check whether or not the given MBB can be used as a prologue for the target. | |
| virtual bool | canUseAsEpilogue (const MachineBasicBlock &MBB) const |
| Check whether or not the given MBB can be used as a epilogue for the target. | |
| virtual TargetStackID::Value | getStackIDForScalableVectors () const |
| Returns the StackID that scalable vectors should be associated with. | |
| virtual bool | isSupportedStackID (TargetStackID::Value ID) const |
| virtual bool | isProfitableForNoCSROpt (const Function &F) const |
| Check if the no-CSR optimisation is profitable for the given function. | |
| virtual int | getInitialCFAOffset (const MachineFunction &MF) const |
| Return initial CFA offset value i.e. | |
| virtual Register | getInitialCFARegister (const MachineFunction &MF) const |
| Return initial CFA register value i.e. | |
| virtual DwarfFrameBase | getDwarfFrameBase (const MachineFunction &MF) const |
| Return the frame base information to be encoded in the DWARF subprogram debug info. | |
| virtual void | spillFPBP (MachineFunction &MF) const |
| If frame pointer or base pointer is clobbered by an instruction, we should spill/restore it around that instruction. | |
| virtual void | emitRemarks (const MachineFunction &MF, MachineOptimizationRemarkEmitter *ORE) const |
| This method is called at the end of prolog/epilog code insertion, so targets can emit remarks based on the final frame layout. |
| Additional Inherited Members | |
|---|---|
| Public Types inherited from llvm::TargetFrameLowering | |
| enum | StackDirection { StackGrowsUp, StackGrowsDown } |
| Static Public Member Functions inherited from llvm::SystemZFrameLowering | |
| static std::unique_ptr< SystemZFrameLowering > | create (const SystemZSubtarget &STI) |
| Static Public Member Functions inherited from llvm::TargetFrameLowering | |
| static bool | isSafeForNoCSROpt (const Function &F) |
| Check if given function is safe for not having callee saved registers. |
Definition at line 61 of file SystemZFrameLowering.h.
| SystemZELFFrameLowering::SystemZELFFrameLowering | ( | unsigned | PointerSize | ) |
|---|
◆ assignCalleeSavedSpillSlots()
assignCalleeSavedSpillSlots - Allows target to override spill slot assignment logic.
If implemented, assignCalleeSavedSpillSlots() should assign frame slots to all CSI entries and return true. If this method returns false, spill slots will be assigned using generic implementation. assignCalleeSavedSpillSlots() may add, delete or rearrange elements of CSI.
Reimplemented from llvm::TargetFrameLowering.
Definition at line 164 of file SystemZFrameLowering.cpp.
References assert(), contains(), llvm::SystemZ::ELFArgGPRs, llvm::SystemZMC::ELFCallFrameSize, llvm::SystemZ::ELFNumArgGPRs, llvm::MachineFunction::getFrameInfo(), llvm::MachineFunction::getFunction(), llvm::MachineFunction::getInfo(), llvm::SystemZFrameLowering::getPointerSize(), getRegSpillOffset(), llvm::SystemZMachineFunctionInfo::getVarArgsFirstGPR(), llvm::Function::isVarArg(), llvm::Offset, llvm::SystemZMachineFunctionInfo::setRestoreGPRRegs(), llvm::SystemZMachineFunctionInfo::setSpillGPRRegs(), Size, TRI, and usePackedStack().
◆ determineCalleeSaves()
This method determines which of the registers reported by TargetRegisterInfo::getCalleeSavedRegs() should actually get saved.
The default implementation checks populates the SavedRegs bitset with all registers which are modified in the function, targets may override this function to save additional registers. This method also sets up the register scavenger ensuring there is a free register or a frameindex available. This method should not be called by any passes outside of PEI, because it may change state passed in by MF and RS. The preferred interface outside PEI is getCalleeSaves.
Reimplemented from llvm::TargetFrameLowering.
Definition at line 231 of file SystemZFrameLowering.cpp.
References contains(), llvm::TargetFrameLowering::determineCalleeSaves(), llvm::SystemZ::ELFArgGPRs, llvm::SystemZ::ELFNumArgGPRs, llvm::MachineFunction::getFrameInfo(), llvm::MachineFunction::getFunction(), llvm::MachineFunction::getInfo(), llvm::MachineFunction::getLandingPads(), llvm::TargetSubtargetInfo::getRegisterInfo(), llvm::MachineFunction::getSubtarget(), llvm::SystemZMachineFunctionInfo::getVarArgsFirstGPR(), llvm::MachineFrameInfo::hasCalls(), llvm::TargetFrameLowering::hasFP(), I, llvm::Function::isVarArg(), llvm::BitVector::set(), llvm::BitVector::test(), and TRI.
◆ emitEpilogue()
Implements llvm::TargetFrameLowering.
Definition at line 719 of file SystemZFrameLowering.cpp.
References assert(), DL, emitIncrement(), llvm::Function::getCallingConv(), llvm::MachineFunction::getFrameInfo(), llvm::MachineFunction::getFunction(), llvm::MachineFunction::getInfo(), llvm::SystemZMachineFunctionInfo::getRestoreGPRRegs(), llvm::MachineFunction::getSubtarget(), llvm::CallingConv::GHC, llvm_unreachable, llvm::SystemZ::GPRRegs::LowGPR, MBB, MBBI, and llvm::Offset.
◆ emitPrologue()
emitProlog/emitEpilog - These methods insert prolog and epilog code into the function.
Implements llvm::TargetFrameLowering.
Definition at line 529 of file SystemZFrameLowering.cpp.
References llvm::MachineInstrBuilder::addCFIIndex(), llvm::MachineInstrBuilder::addExternalSymbol(), llvm::MachineFunction::addFrameInst(), llvm::MachineInstrBuilder::addImm(), llvm::MachineInstrBuilder::addReg(), llvm::MachineInstrBuilder::addRegMask(), llvm::CallingConv::AnyReg, assert(), buildCFAOffs(), buildDefCFAReg(), llvm::BuildMI(), contains(), llvm::MCCFIInstruction::createOffset(), llvm::RegState::Define, DL, llvm::drop_begin(), llvm::SystemZMC::ELFCallFrameSize, llvm::SystemZMC::ELFCFAOffsetFromInitialSP, emitIncrement(), llvm::MachineFunction::front(), getBackchainOffset(), llvm::MachineFrameInfo::getCalleeSavedInfo(), llvm::Function::getCallingConv(), llvm::MachineFunction::getContext(), llvm::StackOffset::getFixed(), llvm::Function::getFnAttribute(), getFrameIndexReference(), llvm::MachineFunction::getFrameInfo(), llvm::MachineFunction::getFunction(), llvm::MachineFunction::getInfo(), llvm::SystemZSubtarget::getInstrInfo(), llvm::MachineFrameInfo::getObjectIndexEnd(), llvm::MachineFrameInfo::getObjectOffset(), llvm::MCContext::getRegisterInfo(), llvm::SystemZMachineFunctionInfo::getSpillGPRRegs(), llvm::MachineFrameInfo::getStackSize(), llvm::MachineFunction::getSubtarget(), llvm::SystemZSubtarget::getTargetLowering(), llvm::TargetSubtargetInfo::getTargetLowering(), llvm::Attribute::getValueAsString(), llvm::CallingConv::GHC, llvm::SystemZ::GPRRegs::GPROffset, llvm::MachineFrameInfo::hasCalls(), llvm::TargetFrameLowering::hasFP(), llvm::TargetLoweringBase::hasInlineStackProbe(), llvm::MachineFrameInfo::isDeadObjectIndex(), llvm::RegState::Kill, llvm_unreachable, llvm::SystemZ::GPRRegs::LowGPR, MBB, MBBI, MRI, llvm::Offset, llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::report_fatal_error(), and llvm::MachineFrameInfo::setStackSize().
◆ getBackchainOffset()
◆ getFrameIndexReference()
◆ getOrCreateFramePointerSaveIndex()
| int SystemZELFFrameLowering::getOrCreateFramePointerSaveIndex ( MachineFunction & MF) const | overridevirtual |
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◆ getRegSpillOffset()
◆ getReturnAddressOffset()
| int llvm::SystemZELFFrameLowering::getReturnAddressOffset ( MachineFunction & MF) const | inlineoverridevirtual |
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◆ hasFPImpl()
◆ inlineStackProbe()
Replace a StackProbe stub (if any) with the actual probe code inline.
Reimplemented from llvm::TargetFrameLowering.
Definition at line 765 of file SystemZFrameLowering.cpp.
References llvm::MachineInstrBuilder::addImm(), llvm::MachineInstrBuilder::addMBB(), llvm::MachineInstrBuilder::addMemOperand(), llvm::MachineInstrBuilder::addReg(), llvm::MachineBasicBlock::addSuccessor(), llvm::MachineBasicBlock::begin(), buildCFAOffs(), buildDefCFAReg(), llvm::BuildMI(), llvm::SystemZ::CCMASK_CMP_GT, llvm::SystemZ::CCMASK_ICMP, llvm::RegState::Define, DL, llvm::SystemZMC::ELFCallFrameSize, llvm::SystemZMC::ELFCFAOffsetFromInitialSP, llvm::SystemZ::emitBlockAfter(), emitIncrement(), llvm::MachineInstr::eraseFromParent(), llvm::fullyRecomputeLiveIns(), getBackchainOffset(), llvm::MachineInstr::getDebugLoc(), llvm::MachineOperand::getImm(), llvm::MachineFunction::getMachineMemOperand(), llvm::MachineInstr::getOperand(), llvm::MachineFunction::getSubtarget(), llvm::SystemZSubtarget::getTargetLowering(), llvm::RegState::Kill, MBB, MBBI, MI, llvm::MachineMemOperand::MOLoad, llvm::MachineMemOperand::MOVolatile, Size, llvm::SystemZ::splitBlockBefore(), and llvm::RegState::Undef.
◆ orderFrameObjects()
Order the symbols in the local stack frame.
The list of objects that we want to order is in objectsToAllocate as indices into the MachineFrameInfo. The array can be reordered in any way upon return. The contents of the array, however, may not be modified (i.e. only their order may be changed). By default, just maintain the original order.
Reimplemented from llvm::TargetFrameLowering.
Definition at line 85 of file SystemZFrameLowering.cpp.
References A(), B(), llvm::MachineFunction::getFrameInfo(), llvm::MachineOperand::getIndex(), llvm::MachineFrameInfo::getObjectIndexEnd(), llvm::MachineFrameInfo::getObjectSize(), llvm::MachineFunction::getSubtarget(), llvm::SystemZII::Has20BitOffset, I, llvm::MachineOperand::isFI(), MBB, MI, llvm::SmallVectorTemplateCommon< T, typename >::size(), llvm::stable_sort(), and TII.
◆ processFunctionBeforeFrameFinalized()
processFunctionBeforeFrameFinalized - This method is called immediately before the specified function's frame layout (MF.getFrameInfo()) is finalized.
Once the frame is finalized, MO_FrameIndex operands are replaced with direct constants. This method is optional.
Reimplemented from llvm::TargetFrameLowering.
Definition at line 431 of file SystemZFrameLowering.cpp.
References llvm::MachineFrameInfo::CreateSpillStackObject(), llvm::SystemZMC::ELFCallFrameSize, llvm::MachineFrameInfo::estimateStackSize(), llvm::MachineFunction::front(), llvm::MachineFunction::getFrameInfo(), llvm::MachineFunction::getInfo(), llvm::MachineFrameInfo::getObjectIndexBegin(), llvm::MachineFrameInfo::getObjectOffset(), llvm::MachineFrameInfo::getObjectSize(), getOrCreateFramePointerSaveIndex(), llvm::SystemZFrameLowering::getPointerSize(), llvm::MachineFunction::getRegInfo(), llvm::SystemZMachineFunctionInfo::getRestoreGPRRegs(), llvm::MachineFunction::getSubtarget(), I, llvm::MachineBasicBlock::isLiveIn(), llvm::isUInt(), llvm::SystemZ::GPRRegs::LowGPR, MRI, and usePackedStack().
◆ restoreCalleeSavedRegisters()
restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee saved registers and returns true if it isn't possible / profitable to do so by issuing a series of load instructions via loadRegToStackSlot().
If it returns true, and any of the registers in CSI is not restored, it sets the corresponding Restored flag in CSI to false. Returns false otherwise.
Reimplemented from llvm::TargetFrameLowering.
Definition at line 375 of file SystemZFrameLowering.cpp.
References llvm::MachineInstrBuilder::addImm(), llvm::MachineInstrBuilder::addReg(), assert(), llvm::BuildMI(), contains(), llvm::dwarf_linker::DebugLoc, llvm::RegState::Define, DL, llvm::ArrayRef< T >::empty(), llvm::MachineFunction::getInfo(), llvm::TargetSubtargetInfo::getInstrInfo(), llvm::SystemZMachineFunctionInfo::getRestoreGPRRegs(), llvm::MachineFunction::getSubtarget(), llvm::SystemZ::GPRRegs::GPROffset, llvm::TargetFrameLowering::hasFP(), llvm::SystemZ::GPRRegs::HighGPR, I, llvm::RegState::ImplicitDefine, llvm::SystemZ::GPRRegs::LowGPR, MBB, MBBI, TII, and TRI.
◆ spillCalleeSavedRegisters()
spillCalleeSavedRegisters - Issues instruction(s) to spill all callee saved registers and returns true if it isn't possible / profitable to do so by issuing a series of store instructions via storeRegToStackSlot().
Returns false otherwise.
Reimplemented from llvm::TargetFrameLowering.
Definition at line 315 of file SystemZFrameLowering.cpp.
References llvm::MachineInstrBuilder::addImm(), llvm::MachineInstrBuilder::addReg(), addSavedGPR(), assert(), llvm::BuildMI(), contains(), DL, llvm::SystemZ::ELFArgGPRs, llvm::SystemZ::ELFNumArgGPRs, llvm::ArrayRef< T >::empty(), llvm::MachineFunction::getFunction(), llvm::MachineFunction::getInfo(), llvm::TargetSubtargetInfo::getInstrInfo(), llvm::SystemZMachineFunctionInfo::getSpillGPRRegs(), llvm::MachineFunction::getSubtarget(), llvm::SystemZMachineFunctionInfo::getVarArgsFirstGPR(), llvm::SystemZ::GPRRegs::GPROffset, llvm::SystemZ::GPRRegs::HighGPR, I, llvm::Function::isVarArg(), llvm::SystemZ::GPRRegs::LowGPR, MBB, MBBI, TII, and TRI.
◆ usePackedStack()
The documentation for this class was generated from the following files:
- lib/Target/SystemZ/SystemZFrameLowering.h
- lib/Target/SystemZ/SystemZFrameLowering.cpp