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