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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34700 91177308-0d34-0410-b5e6-96231b3b80d8
110 lines
3.4 KiB
C++
110 lines
3.4 KiB
C++
//===-- RegisterScavenging.h - Machine register scavenging ------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the Evan Cheng and is distributed under the
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// University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares the machine register scavenger class. It can provide
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// information such as unused register at any point in a machine basic block.
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// It also provides a mechanism to make registers availbale by evicting them
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// to spill slots.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_REGISTER_SCAVENGING_H
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#define LLVM_CODEGEN_REGISTER_SCAVENGING_H
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/ADT/BitVector.h"
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namespace llvm {
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class TargetRegisterClass;
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class RegScavenger {
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MachineBasicBlock *MBB;
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MachineBasicBlock::iterator MBBI;
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unsigned NumPhysRegs;
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/// Tracking - True if RegScavenger is currently tracking the liveness of
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/// registers.
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bool Tracking;
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/// RegStates - The current state of all the physical registers immediately
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/// before MBBI. One bit per physical register. If bit is set that means it's
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/// available, unset means the register is currently being used.
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BitVector RegStates;
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public:
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RegScavenger()
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: MBB(NULL), NumPhysRegs(0), Tracking(false) {};
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RegScavenger(MachineBasicBlock *mbb)
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: MBB(mbb), NumPhysRegs(0), Tracking(false) {};
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/// Init - Initialize the states.
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///
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void init(MachineBasicBlock *mbb);
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/// Reset - Discard previous states and re-initialize the states given for
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/// the specific basic block.
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void reset(MachineBasicBlock *mbb) {
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clear();
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init(mbb);
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}
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/// forward / backward - Move the internal MBB iterator and update register
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/// states.
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void forward();
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void backward();
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/// forward / backward - Move the internal MBB iterator and update register
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/// states until it has reached but not processed the specific iterator.
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void forward(MachineBasicBlock::iterator I) {
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while (MBBI != I) forward();
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}
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void backward(MachineBasicBlock::iterator I) {
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while (MBBI != I) backward();
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}
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/// isReserved - Returns true if a register is reserved. It is never "unused".
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bool isReserved(unsigned Reg) const { return ReservedRegs[Reg]; }
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/// isUsed / isUsed - Test if a register is currently being used.
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///
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bool isUsed(unsigned Reg) const { return !RegStates[Reg]; }
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bool isUnused(unsigned Reg) const { return RegStates[Reg]; }
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/// setUsed / setUnused - Mark the state of one or a number of registers.
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///
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void setUsed(unsigned Reg) { RegStates.reset(Reg); }
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void setUsed(BitVector Regs) { RegStates &= ~Regs; }
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void setUnused(unsigned Reg) { RegStates.set(Reg); }
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void setUnused(BitVector Regs) { RegStates |= Regs; }
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/// FindUnusedReg - Find a unused register of the specified register class.
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/// Exclude callee saved registers if directed. It return 0 is none is found.
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unsigned FindUnusedReg(const TargetRegisterClass *RegClass,
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bool ExCalleeSaved = false) const;
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private:
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/// clear - Clear states.
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///
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void clear();
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/// CalleeSavedrRegs - A bitvector of callee saved registers for the target.
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///
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BitVector CalleeSavedRegs;
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/// ReservedRegs - A bitvector of reserved registers.
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///
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BitVector ReservedRegs;
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};
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} // End llvm namespace
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#endif
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