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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155795 91177308-0d34-0410-b5e6-96231b3b80d8
176 lines
6.4 KiB
C++
176 lines
6.4 KiB
C++
//===-- RegisterPressure.h - Dynamic Register Pressure -*- 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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// This file defines the RegisterPressure class which can be used to track
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// MachineInstr level register pressure.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_REGISTERPRESSURE_H
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#define LLVM_CODEGEN_REGISTERPRESSURE_H
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#include "llvm/CodeGen/SlotIndexes.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/ADT/SparseSet.h"
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namespace llvm {
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class LiveIntervals;
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class RegisterClassInfo;
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/// Base class for register pressure results.
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struct RegisterPressure {
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/// Map of max reg pressure indexed by pressure set ID, not class ID.
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std::vector<unsigned> MaxSetPressure;
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/// List of live in registers.
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SmallVector<unsigned,8> LiveInRegs;
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SmallVector<unsigned,8> LiveOutRegs;
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/// Increase register pressure for each pressure set impacted by this register
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/// class. Normally called by RegPressureTracker, but may be called manually
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/// to account for live through (global liveness).
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void increase(const TargetRegisterClass *RC, const TargetRegisterInfo *TRI);
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/// Decrease register pressure for each pressure set impacted by this register
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/// class. This is only useful to account for spilling or rematerialization.
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void decrease(const TargetRegisterClass *RC, const TargetRegisterInfo *TRI);
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};
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/// RegisterPressure computed within a region of instructions delimited by
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/// TopIdx and BottomIdx. During pressure computation, the maximum pressure per
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/// register pressure set is increased. Once pressure within a region is fully
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/// computed, the live-in and live-out sets are recorded.
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///
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/// This is preferable to RegionPressure when LiveIntervals are available,
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/// because delimiting regions by SlotIndex is more robust and convenient than
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/// holding block iterators. The block contents can change without invalidating
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/// the pressure result.
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struct IntervalPressure : RegisterPressure {
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/// Record the boundary of the region being tracked.
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SlotIndex TopIdx;
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SlotIndex BottomIdx;
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void reset();
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void openTop(SlotIndex NextTop);
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void openBottom(SlotIndex PrevBottom);
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};
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/// RegisterPressure computed within a region of instructions delimited by
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/// TopPos and BottomPos. This is a less precise version of IntervalPressure for
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/// use when LiveIntervals are unavailable.
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struct RegionPressure : RegisterPressure {
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/// Record the boundary of the region being tracked.
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MachineBasicBlock::const_iterator TopPos;
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MachineBasicBlock::const_iterator BottomPos;
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void reset();
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void openTop(MachineBasicBlock::const_iterator PrevTop);
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void openBottom(MachineBasicBlock::const_iterator PrevBottom);
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};
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/// Track the current register pressure at some position in the instruction
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/// stream, and remember the high water mark within the region traversed. This
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/// does not automatically consider live-through ranges. The client may
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/// independently adjust for global liveness.
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///
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/// Each RegPressureTracker only works within a MachineBasicBlock. Pressure can
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/// be tracked across a larger region by storing a RegisterPressure result at
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/// each block boundary and explicitly adjusting pressure to account for block
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/// live-in and live-out register sets.
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///
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/// RegPressureTracker holds a reference to a RegisterPressure result that it
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/// computes incrementally. During downward tracking, P.BottomIdx or P.BottomPos
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/// is invalid until it reaches the end of the block or closeRegion() is
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/// explicitly called. Similarly, P.TopIdx is invalid during upward
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/// tracking. Changing direction has the side effect of closing region, and
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/// traversing past TopIdx or BottomIdx reopens it.
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class RegPressureTracker {
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const MachineFunction *MF;
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const TargetRegisterInfo *TRI;
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const RegisterClassInfo *RCI;
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const MachineRegisterInfo *MRI;
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const LiveIntervals *LIS;
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/// We currently only allow pressure tracking within a block.
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const MachineBasicBlock *MBB;
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/// Track the max pressure within the region traversed so far.
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RegisterPressure &P;
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/// Run in two modes dependending on whether constructed with IntervalPressure
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/// or RegisterPressure. If requireIntervals is false, LIS are ignored.
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bool RequireIntervals;
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/// Register pressure corresponds to liveness before this instruction
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/// iterator. It may point to the end of the block rather than an instruction.
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MachineBasicBlock::const_iterator CurrPos;
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/// Pressure map indexed by pressure set ID, not class ID.
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std::vector<unsigned> CurrSetPressure;
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/// List of live registers.
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SparseSet<unsigned> LivePhysRegs;
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SparseSet<unsigned, VirtReg2IndexFunctor> LiveVirtRegs;
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public:
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RegPressureTracker(IntervalPressure &rp) :
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MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(true) {}
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RegPressureTracker(RegionPressure &rp) :
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MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(false) {}
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void init(const MachineFunction *mf, const RegisterClassInfo *rci,
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const LiveIntervals *lis, const MachineBasicBlock *mbb,
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MachineBasicBlock::const_iterator pos);
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// Get the MI position corresponding to this register pressure.
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MachineBasicBlock::const_iterator getPos() const { return CurrPos; }
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/// Recede across the previous instruction.
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bool recede();
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/// Advance across the current instruction.
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bool advance();
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/// Finalize the region boundaries and recored live ins and live outs.
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void closeRegion();
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/// Get the resulting register pressure over the traversed region.
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/// This result is complete if either advance() or recede() has returned true,
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/// or if closeRegion() was explicitly invoked.
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RegisterPressure &getPressure() { return P; }
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protected:
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bool isTopClosed() const;
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bool isBottomClosed() const;
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void closeTop();
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void closeBottom();
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void increasePhysRegPressure(ArrayRef<unsigned> Regs);
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void decreasePhysRegPressure(ArrayRef<unsigned> Regs);
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void increaseVirtRegPressure(ArrayRef<unsigned> Regs);
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void decreaseVirtRegPressure(ArrayRef<unsigned> Regs);
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void discoverPhysLiveIn(unsigned Reg);
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void discoverPhysLiveOut(unsigned Reg);
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void discoverVirtLiveIn(unsigned Reg);
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void discoverVirtLiveOut(unsigned Reg);
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};
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} // end namespace llvm
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#endif
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