forked from OSchip/llvm-project
169 lines
5.3 KiB
C++
169 lines
5.3 KiB
C++
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//===-- BPFInstrInfo.cpp - BPF Instruction Information ----------*- 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 contains the BPF implementation of the TargetInstrInfo class.
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//
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//===----------------------------------------------------------------------===//
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#include "BPF.h"
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#include "BPFInstrInfo.h"
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#include "BPFSubtarget.h"
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#include "BPFTargetMachine.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/TargetRegistry.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallVector.h"
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#define GET_INSTRINFO_CTOR_DTOR
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#include "BPFGenInstrInfo.inc"
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using namespace llvm;
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BPFInstrInfo::BPFInstrInfo()
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: BPFGenInstrInfo(BPF::ADJCALLSTACKDOWN, BPF::ADJCALLSTACKUP) {}
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void BPFInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I, DebugLoc DL,
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unsigned DestReg, unsigned SrcReg,
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bool KillSrc) const {
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if (BPF::GPRRegClass.contains(DestReg, SrcReg))
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BuildMI(MBB, I, DL, get(BPF::MOV_rr), DestReg)
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.addReg(SrcReg, getKillRegState(KillSrc));
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else
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llvm_unreachable("Impossible reg-to-reg copy");
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}
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void BPFInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I,
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unsigned SrcReg, bool IsKill, int FI,
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const TargetRegisterClass *RC,
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const TargetRegisterInfo *TRI) const {
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DebugLoc DL;
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if (I != MBB.end())
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DL = I->getDebugLoc();
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if (RC == &BPF::GPRRegClass)
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BuildMI(MBB, I, DL, get(BPF::STD))
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.addReg(SrcReg, getKillRegState(IsKill))
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.addFrameIndex(FI)
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.addImm(0);
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else
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llvm_unreachable("Can't store this register to stack slot");
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}
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void BPFInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I,
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unsigned DestReg, int FI,
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const TargetRegisterClass *RC,
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const TargetRegisterInfo *TRI) const {
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DebugLoc DL;
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if (I != MBB.end())
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DL = I->getDebugLoc();
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if (RC == &BPF::GPRRegClass)
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BuildMI(MBB, I, DL, get(BPF::LDD), DestReg).addFrameIndex(FI).addImm(0);
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else
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llvm_unreachable("Can't load this register from stack slot");
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}
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bool BPFInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
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MachineBasicBlock *&TBB,
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MachineBasicBlock *&FBB,
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SmallVectorImpl<MachineOperand> &Cond,
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bool AllowModify) const {
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// Start from the bottom of the block and work up, examining the
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// terminator instructions.
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MachineBasicBlock::iterator I = MBB.end();
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while (I != MBB.begin()) {
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--I;
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if (I->isDebugValue())
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continue;
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// Working from the bottom, when we see a non-terminator
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// instruction, we're done.
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if (!isUnpredicatedTerminator(I))
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break;
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// A terminator that isn't a branch can't easily be handled
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// by this analysis.
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if (!I->isBranch())
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return true;
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// Handle unconditional branches.
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if (I->getOpcode() == BPF::JMP) {
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if (!AllowModify) {
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TBB = I->getOperand(0).getMBB();
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continue;
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}
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// If the block has any instructions after a J, delete them.
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while (std::next(I) != MBB.end())
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std::next(I)->eraseFromParent();
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Cond.clear();
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FBB = 0;
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// Delete the J if it's equivalent to a fall-through.
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if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
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TBB = 0;
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I->eraseFromParent();
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I = MBB.end();
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continue;
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}
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// TBB is used to indicate the unconditinal destination.
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TBB = I->getOperand(0).getMBB();
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continue;
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}
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// Cannot handle conditional branches
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return true;
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}
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return false;
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}
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unsigned BPFInstrInfo::InsertBranch(MachineBasicBlock &MBB,
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MachineBasicBlock *TBB,
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MachineBasicBlock *FBB,
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const SmallVectorImpl<MachineOperand> &Cond,
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DebugLoc DL) const {
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// Shouldn't be a fall through.
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assert(TBB && "InsertBranch must not be told to insert a fallthrough");
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if (Cond.empty()) {
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// Unconditional branch
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assert(!FBB && "Unconditional branch with multiple successors!");
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BuildMI(&MBB, DL, get(BPF::JMP)).addMBB(TBB);
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return 1;
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}
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llvm_unreachable("Unexpected conditional branch");
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}
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unsigned BPFInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
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MachineBasicBlock::iterator I = MBB.end();
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unsigned Count = 0;
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while (I != MBB.begin()) {
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--I;
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if (I->isDebugValue())
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continue;
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if (I->getOpcode() != BPF::JMP)
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break;
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// Remove the branch.
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I->eraseFromParent();
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I = MBB.end();
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++Count;
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}
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return Count;
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}
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