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To support spilling/filling of scalable vectors we need a more generic
representation of a stack offset than simply 'int'.
For this we introduce the StackOffset struct, which comprises multiple
offsets sized by their respective MVTs. Byte-offsets will thus be a simple
tuple such as { offset, MVT::i8 }. Adding two byte-offsets will result in a
byte offset { offsetA + offsetB, MVT::i8 }. When two offsets have different
types, we can canonicalise them to use the same MVT, as long as their
runtime sizes are guaranteed to have the same size-ratio as they would have
at compile-time.
When we have both scalable- and fixed-size objects on the stack, we can
create an offset that is:
({ offset_fixed, MVT::i8 } + { offset_scalable, MVT::nxv1i8 })
The struct also contains a getForFrameOffset() method that is specific to
AArch64 and decomposes the frame-offset to be used directly in instructions
that operate on the stack or index into the stack.
Note: This patch adds StackOffset as an AArch64-only concept, but we would
like to make this a generic concept/struct that is supported by all
interfaces that take or return stack offsets (currently as 'int'). Since
that would be a bigger change that is currently pending on D32530 landing,
we thought it makes sense to first show/prove the concept in the AArch64
target before proposing to roll this out further.
Reviewers: thegameg, rovka, t.p.northover, efriedma, greened
Reviewed By: rovka, greened
Differential Revision: https://reviews.llvm.org/D61435
llvm-svn: 368024
98 lines
4.1 KiB
C++
98 lines
4.1 KiB
C++
//==-- AArch64FrameLowering.h - TargetFrameLowering for AArch64 --*- 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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//
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_AARCH64_AARCH64FRAMELOWERING_H
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#define LLVM_LIB_TARGET_AARCH64_AARCH64FRAMELOWERING_H
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#include "AArch64StackOffset.h"
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#include "llvm/CodeGen/TargetFrameLowering.h"
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namespace llvm {
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class AArch64FrameLowering : public TargetFrameLowering {
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public:
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explicit AArch64FrameLowering()
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: TargetFrameLowering(StackGrowsDown, 16, 0, 16,
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true /*StackRealignable*/) {}
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void emitCalleeSavedFrameMoves(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI) const;
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MachineBasicBlock::iterator
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eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I) const override;
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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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bool canUseAsPrologue(const MachineBasicBlock &MBB) const override;
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int getFrameIndexReference(const MachineFunction &MF, int FI,
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unsigned &FrameReg) const override;
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StackOffset resolveFrameIndexReference(const MachineFunction &MF, int FI,
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unsigned &FrameReg, bool PreferFP,
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bool ForSimm) const;
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StackOffset resolveFrameOffsetReference(const MachineFunction &MF,
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int ObjectOffset, bool isFixed,
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unsigned &FrameReg, bool PreferFP,
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bool ForSimm) const;
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bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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const std::vector<CalleeSavedInfo> &CSI,
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const TargetRegisterInfo *TRI) const override;
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bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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std::vector<CalleeSavedInfo> &CSI,
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const TargetRegisterInfo *TRI) const override;
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/// Can this function use the red zone for local allocations.
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bool canUseRedZone(const MachineFunction &MF) const;
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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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void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
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RegScavenger *RS) 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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return true;
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}
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bool enableStackSlotScavenging(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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unsigned getWinEHParentFrameOffset(const MachineFunction &MF) const override;
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unsigned getWinEHFuncletFrameSize(const MachineFunction &MF) const;
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int getFrameIndexReferencePreferSP(const MachineFunction &MF, int FI,
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unsigned &FrameReg,
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bool IgnoreSPUpdates) const override;
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int getNonLocalFrameIndexReference(const MachineFunction &MF,
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int FI) const override;
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int getSEHFrameIndexOffset(const MachineFunction &MF, int FI) const;
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private:
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bool shouldCombineCSRLocalStackBump(MachineFunction &MF,
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unsigned StackBumpBytes) const;
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};
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} // End llvm namespace
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#endif
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