llvm-6502/lib/CodeGen/MachineBasicBlock.cpp
2009-07-21 21:12:58 +00:00

373 lines
12 KiB
C++

//===-- llvm/CodeGen/MachineBasicBlock.cpp ----------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Collect the sequence of machine instructions for a basic block.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/BasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetInstrDesc.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/LeakDetector.h"
#include <algorithm>
using namespace llvm;
MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb)
: BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false) {
Insts.Parent = this;
}
MachineBasicBlock::~MachineBasicBlock() {
LeakDetector::removeGarbageObject(this);
}
std::ostream& llvm::operator<<(std::ostream &OS, const MachineBasicBlock &MBB) {
MBB.print(OS);
return OS;
}
/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the
/// parent pointer of the MBB, the MBB numbering, and any instructions in the
/// MBB to be on the right operand list for registers.
///
/// MBBs start out as #-1. When a MBB is added to a MachineFunction, it
/// gets the next available unique MBB number. If it is removed from a
/// MachineFunction, it goes back to being #-1.
void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock* N) {
MachineFunction &MF = *N->getParent();
N->Number = MF.addToMBBNumbering(N);
// Make sure the instructions have their operands in the reginfo lists.
MachineRegisterInfo &RegInfo = MF.getRegInfo();
for (MachineBasicBlock::iterator I = N->begin(), E = N->end(); I != E; ++I)
I->AddRegOperandsToUseLists(RegInfo);
LeakDetector::removeGarbageObject(N);
}
void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock* N) {
N->getParent()->removeFromMBBNumbering(N->Number);
N->Number = -1;
LeakDetector::addGarbageObject(N);
}
/// addNodeToList (MI) - When we add an instruction to a basic block
/// list, we update its parent pointer and add its operands from reg use/def
/// lists if appropriate.
void ilist_traits<MachineInstr>::addNodeToList(MachineInstr* N) {
assert(N->getParent() == 0 && "machine instruction already in a basic block");
N->setParent(Parent);
// Add the instruction's register operands to their corresponding
// use/def lists.
MachineFunction *MF = Parent->getParent();
N->AddRegOperandsToUseLists(MF->getRegInfo());
LeakDetector::removeGarbageObject(N);
}
/// removeNodeFromList (MI) - When we remove an instruction from a basic block
/// list, we update its parent pointer and remove its operands from reg use/def
/// lists if appropriate.
void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr* N) {
assert(N->getParent() != 0 && "machine instruction not in a basic block");
// Remove from the use/def lists.
N->RemoveRegOperandsFromUseLists();
N->setParent(0);
LeakDetector::addGarbageObject(N);
}
/// transferNodesFromList (MI) - When moving a range of instructions from one
/// MBB list to another, we need to update the parent pointers and the use/def
/// lists.
void ilist_traits<MachineInstr>::transferNodesFromList(
ilist_traits<MachineInstr>& fromList,
MachineBasicBlock::iterator first,
MachineBasicBlock::iterator last) {
assert(Parent->getParent() == fromList.Parent->getParent() &&
"MachineInstr parent mismatch!");
// Splice within the same MBB -> no change.
if (Parent == fromList.Parent) return;
// If splicing between two blocks within the same function, just update the
// parent pointers.
for (; first != last; ++first)
first->setParent(Parent);
}
void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) {
assert(!MI->getParent() && "MI is still in a block!");
Parent->getParent()->DeleteMachineInstr(MI);
}
MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
iterator I = end();
while (I != begin() && (--I)->getDesc().isTerminator())
; /*noop */
if (I != end() && !I->getDesc().isTerminator()) ++I;
return I;
}
bool
MachineBasicBlock::isOnlyReachableByFallthrough() const {
return !isLandingPad() &&
!pred_empty() &&
next(pred_begin()) == pred_end() &&
(*pred_begin())->isLayoutSuccessor(this) &&
((*pred_begin())->empty() ||
!(*pred_begin())->back().getDesc().isBarrier());
}
void MachineBasicBlock::dump() const {
print(*cerr.stream());
}
static inline void OutputReg(std::ostream &os, unsigned RegNo,
const TargetRegisterInfo *TRI = 0) {
if (!RegNo || TargetRegisterInfo::isPhysicalRegister(RegNo)) {
if (TRI)
os << " %" << TRI->get(RegNo).Name;
else
os << " %mreg(" << RegNo << ")";
} else
os << " %reg" << RegNo;
}
void MachineBasicBlock::print(std::ostream &OS) const {
const MachineFunction *MF = getParent();
if(!MF) {
OS << "Can't print out MachineBasicBlock because parent MachineFunction"
<< " is null\n";
return;
}
const BasicBlock *LBB = getBasicBlock();
OS << "\n";
if (LBB) OS << LBB->getName() << ": ";
OS << (const void*)this
<< ", LLVM BB @" << (const void*) LBB << ", ID#" << getNumber();
if (Alignment) OS << ", Alignment " << Alignment;
if (isLandingPad()) OS << ", EH LANDING PAD";
OS << ":\n";
const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
if (!livein_empty()) {
OS << "Live Ins:";
for (const_livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
OutputReg(OS, *I, TRI);
OS << "\n";
}
// Print the preds of this block according to the CFG.
if (!pred_empty()) {
OS << " Predecessors according to CFG:";
for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
OS << " " << *PI << " (#" << (*PI)->getNumber() << ")";
OS << "\n";
}
for (const_iterator I = begin(); I != end(); ++I) {
OS << "\t";
I->print(OS, &getParent()->getTarget());
}
// Print the successors of this block according to the CFG.
if (!succ_empty()) {
OS << " Successors according to CFG:";
for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI)
OS << " " << *SI << " (#" << (*SI)->getNumber() << ")";
OS << "\n";
}
}
void MachineBasicBlock::removeLiveIn(unsigned Reg) {
livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
assert(I != livein_end() && "Not a live in!");
LiveIns.erase(I);
}
bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
const_livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
return I != livein_end();
}
void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) {
getParent()->splice(NewAfter, this);
}
void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
MachineFunction::iterator BBI = NewBefore;
getParent()->splice(++BBI, this);
}
void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) {
Successors.push_back(succ);
succ->addPredecessor(this);
}
void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
succ->removePredecessor(this);
succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
assert(I != Successors.end() && "Not a current successor!");
Successors.erase(I);
}
MachineBasicBlock::succ_iterator
MachineBasicBlock::removeSuccessor(succ_iterator I) {
assert(I != Successors.end() && "Not a current successor!");
(*I)->removePredecessor(this);
return Successors.erase(I);
}
void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
Predecessors.push_back(pred);
}
void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
std::vector<MachineBasicBlock *>::iterator I =
std::find(Predecessors.begin(), Predecessors.end(), pred);
assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
Predecessors.erase(I);
}
void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB)
{
if (this == fromMBB)
return;
for(MachineBasicBlock::succ_iterator iter = fromMBB->succ_begin(),
end = fromMBB->succ_end(); iter != end; ++iter) {
addSuccessor(*iter);
}
while(!fromMBB->succ_empty())
fromMBB->removeSuccessor(fromMBB->succ_begin());
}
bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
std::vector<MachineBasicBlock *>::const_iterator I =
std::find(Successors.begin(), Successors.end(), MBB);
return I != Successors.end();
}
bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
MachineFunction::const_iterator I(this);
return next(I) == MachineFunction::const_iterator(MBB);
}
/// removeFromParent - This method unlinks 'this' from the containing function,
/// and returns it, but does not delete it.
MachineBasicBlock *MachineBasicBlock::removeFromParent() {
assert(getParent() && "Not embedded in a function!");
getParent()->remove(this);
return this;
}
/// eraseFromParent - This method unlinks 'this' from the containing function,
/// and deletes it.
void MachineBasicBlock::eraseFromParent() {
assert(getParent() && "Not embedded in a function!");
getParent()->erase(this);
}
/// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
/// 'Old', change the code and CFG so that it branches to 'New' instead.
void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
MachineBasicBlock *New) {
assert(Old != New && "Cannot replace self with self!");
MachineBasicBlock::iterator I = end();
while (I != begin()) {
--I;
if (!I->getDesc().isTerminator()) break;
// Scan the operands of this machine instruction, replacing any uses of Old
// with New.
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
if (I->getOperand(i).isMBB() &&
I->getOperand(i).getMBB() == Old)
I->getOperand(i).setMBB(New);
}
// Update the successor information.
removeSuccessor(Old);
addSuccessor(New);
}
/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
/// CFG to be inserted. If we have proven that MBB can only branch to DestA and
/// DestB, remove any other MBB successors from the CFG. DestA and DestB can
/// be null.
/// Besides DestA and DestB, retain other edges leading to LandingPads
/// (currently there can be only one; we don't check or require that here).
/// Note it is possible that DestA and/or DestB are LandingPads.
bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA,
MachineBasicBlock *DestB,
bool isCond) {
bool MadeChange = false;
bool AddedFallThrough = false;
MachineFunction::iterator FallThru = next(MachineFunction::iterator(this));
// If this block ends with a conditional branch that falls through to its
// successor, set DestB as the successor.
if (isCond) {
if (DestB == 0 && FallThru != getParent()->end()) {
DestB = FallThru;
AddedFallThrough = true;
}
} else {
// If this is an unconditional branch with no explicit dest, it must just be
// a fallthrough into DestB.
if (DestA == 0 && FallThru != getParent()->end()) {
DestA = FallThru;
AddedFallThrough = true;
}
}
MachineBasicBlock::succ_iterator SI = succ_begin();
MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB;
while (SI != succ_end()) {
if (*SI == DestA && DestA == DestB) {
DestA = DestB = 0;
++SI;
} else if (*SI == DestA) {
DestA = 0;
++SI;
} else if (*SI == DestB) {
DestB = 0;
++SI;
} else if ((*SI)->isLandingPad() &&
*SI!=OrigDestA && *SI!=OrigDestB) {
++SI;
} else {
// Otherwise, this is a superfluous edge, remove it.
SI = removeSuccessor(SI);
MadeChange = true;
}
}
if (!AddedFallThrough) {
assert(DestA == 0 && DestB == 0 &&
"MachineCFG is missing edges!");
} else if (isCond) {
assert(DestA == 0 && "MachineCFG is missing edges!");
}
return MadeChange;
}