Clause *CaptureConstraints::get_avoid_branch(
const TerminatorInst *ti, unsigned i) const {
assert(ti->getNumSuccessors() > 1);
assert(isa<BranchInst>(ti) || isa<IndirectBrInst>(ti) ||
isa<InvokeInst>(ti) || isa<SwitchInst>(ti));
if (const BranchInst *bi = dyn_cast<BranchInst>(ti)) {
assert(i == 0 || i == 1);
const Value *cond = bi->getCondition();
assert(cond && cond->getType()->isIntegerTy(1));
if (!is_reachable_integer(cond))
return NULL;
// i == 0 => avoid true branch => cond is 0
// i == 1 => avoid false branch => cond is 1
if (i == 0) {
return new Clause(new BoolExpr(
CmpInst::ICMP_EQ,
new Expr(cond),
new Expr(ConstantInt::getFalse(ti->getContext()))));
} else {
return new Clause(new BoolExpr(
CmpInst::ICMP_EQ,
new Expr(cond),
new Expr(ConstantInt::getTrue(ti->getContext()))));
}
} else if (const SwitchInst *si = dyn_cast<SwitchInst>(ti)) {
/*
* switch (condition) {
* case 0:
* case 1:
* ...
* case k:
* default:
* }
*/
const Value *cond = si->getCondition();
assert(cond);
if (!is_reachable_integer(cond))
return NULL;
if (ti->getSuccessor(i) == si->getDefaultDest()) {
// The condition is equal to one of the case values.
Clause *disj = NULL;
// Case 0 is the default branch. It doesn't have a case value.
for (SwitchInst::ConstCaseIt iter = si->case_begin(); iter != si->case_end(); ++iter) {
Clause *c = new Clause(new BoolExpr(
CmpInst::ICMP_EQ, new Expr(cond), new Expr(iter.getCaseValue())));
if (!disj)
disj = c;
else
disj = new Clause(Instruction::Or, disj, c);
}
assert(disj);
return disj;
} else {
// The condition does not equal the particular case.
return new Clause(new BoolExpr(
CmpInst::ICMP_NE,
new Expr(cond),
new Expr(const_cast<SwitchInst *>(si)->findCaseDest(const_cast<BasicBlock *>(ti->getSuccessor(i))))));
}
} else if (const IndirectBrInst *ii = dyn_cast<IndirectBrInst>(ti)) {
errs() << *ii << "\n";
assert_not_supported();
} else {
return NULL;
}
}
/// WriteInstruction - Emit an instruction to the specified stream.
/// Returns true if instruction actually emitted.
static bool WriteInstruction(const Instruction &I, unsigned InstID,
NaClValueEnumerator &VE,
NaClBitstreamWriter &Stream,
SmallVector<unsigned, 64> &Vals) {
unsigned Code = 0;
unsigned AbbrevToUse = 0;
VE.setInstructionID(&I);
switch (I.getOpcode()) {
default:
if (Instruction::isCast(I.getOpcode())) {
// CAST: [opval, destty, castopc]
if (VE.IsElidedCast(&I))
return false;
Code = naclbitc::FUNC_CODE_INST_CAST;
AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
Vals.push_back(VE.getTypeID(I.getType()));
unsigned Opcode = I.getOpcode();
Vals.push_back(GetEncodedCastOpcode(Opcode, I));
if (Opcode == Instruction::PtrToInt ||
Opcode == Instruction::IntToPtr ||
(Opcode == Instruction::BitCast &&
(I.getOperand(0)->getType()->isPointerTy() ||
I.getType()->isPointerTy()))) {
ReportIllegalValue("(PNaCl ABI) pointer cast", I);
}
} else if (isa<BinaryOperator>(I)) {
// BINOP: [opval, opval, opcode]
Code = naclbitc::FUNC_CODE_INST_BINOP;
AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
pushValue(I.getOperand(1), InstID, Vals, VE, Stream);
Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode(), I));
} else {
ReportIllegalValue("instruction", I);
}
break;
case Instruction::Select:
Code = naclbitc::FUNC_CODE_INST_VSELECT;
pushValue(I.getOperand(1), InstID, Vals, VE, Stream);
pushValue(I.getOperand(2), InstID, Vals, VE, Stream);
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
break;
case Instruction::ExtractElement:
Code = naclbitc::FUNC_CODE_INST_EXTRACTELT;
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
pushValue(I.getOperand(1), InstID, Vals, VE, Stream);
break;
case Instruction::InsertElement:
Code = naclbitc::FUNC_CODE_INST_INSERTELT;
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
pushValue(I.getOperand(1), InstID, Vals, VE, Stream);
pushValue(I.getOperand(2), InstID, Vals, VE, Stream);
break;
case Instruction::ICmp:
case Instruction::FCmp:
// compare returning Int1Ty or vector of Int1Ty
Code = naclbitc::FUNC_CODE_INST_CMP2;
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
pushValue(I.getOperand(1), InstID, Vals, VE, Stream);
Vals.push_back(GetEncodedCmpPredicate(cast<CmpInst>(I)));
break;
case Instruction::Ret:
{
Code = naclbitc::FUNC_CODE_INST_RET;
unsigned NumOperands = I.getNumOperands();
if (NumOperands == 0)
AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
else if (NumOperands == 1) {
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
} else {
for (unsigned i = 0, e = NumOperands; i != e; ++i)
pushValue(I.getOperand(i), InstID, Vals, VE, Stream);
}
}
break;
case Instruction::Br:
{
Code = naclbitc::FUNC_CODE_INST_BR;
const BranchInst &II = cast<BranchInst>(I);
Vals.push_back(VE.getValueID(II.getSuccessor(0)));
if (II.isConditional()) {
Vals.push_back(VE.getValueID(II.getSuccessor(1)));
pushValue(II.getCondition(), InstID, Vals, VE, Stream);
}
}
break;
case Instruction::Switch:
{
// Redefine Vals, since here we need to use 64 bit values
// explicitly to store large APInt numbers.
SmallVector<uint64_t, 128> Vals64;
Code = naclbitc::FUNC_CODE_INST_SWITCH;
const SwitchInst &SI = cast<SwitchInst>(I);
Vals64.push_back(VE.getTypeID(SI.getCondition()->getType()));
pushValue64(SI.getCondition(), InstID, Vals64, VE, Stream);
Vals64.push_back(VE.getValueID(SI.getDefaultDest()));
Vals64.push_back(SI.getNumCases());
for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
i != e; ++i) {
// The PNaCl bitcode format has vestigial support for case
// ranges, but we no longer support reading or writing them,
// so the next two fields always have the same values.
// See https://code.google.com/p/nativeclient/issues/detail?id=3758
Vals64.push_back(1/*NumItems = 1*/);
Vals64.push_back(true/*IsSingleNumber = true*/);
emitSignedInt64(Vals64, i.getCaseValue()->getSExtValue());
Vals64.push_back(VE.getValueID(i.getCaseSuccessor()));
}
Stream.EmitRecord(Code, Vals64, AbbrevToUse);
// Also do expected action - clear external Vals collection:
Vals.clear();
return true;
}
break;
case Instruction::Unreachable:
Code = naclbitc::FUNC_CODE_INST_UNREACHABLE;
AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
break;
case Instruction::PHI: {
const PHINode &PN = cast<PHINode>(I);
Code = naclbitc::FUNC_CODE_INST_PHI;
// With the newer instruction encoding, forward references could give
// negative valued IDs. This is most common for PHIs, so we use
// signed VBRs.
SmallVector<uint64_t, 128> Vals64;
Vals64.push_back(VE.getTypeID(PN.getType()));
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE, Stream);
Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
}
// Emit a Vals64 vector and exit.
Stream.EmitRecord(Code, Vals64, AbbrevToUse);
Vals64.clear();
return true;
}
case Instruction::Alloca:
if (!cast<AllocaInst>(&I)->getAllocatedType()->isIntegerTy(8))
report_fatal_error("Type of alloca instruction is not i8");
Code = naclbitc::FUNC_CODE_INST_ALLOCA;
pushValue(I.getOperand(0), InstID, Vals, VE, Stream); // size.
Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
break;
case Instruction::Load:
// LOAD: [op, align, ty]
Code = naclbitc::FUNC_CODE_INST_LOAD;
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
Vals.push_back(VE.getTypeID(I.getType()));
break;
case Instruction::Store:
// STORE: [ptr, val, align]
Code = naclbitc::FUNC_CODE_INST_STORE;
AbbrevToUse = FUNCTION_INST_STORE_ABBREV;
pushValue(I.getOperand(1), InstID, Vals, VE, Stream);
pushValue(I.getOperand(0), InstID, Vals, VE, Stream);
Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
break;
case Instruction::Call: {
// CALL: [cc, fnid, args...]
// CALL_INDIRECT: [cc, fnid, fnty, args...]
const CallInst &Call = cast<CallInst>(I);
const Value* Callee = Call.getCalledValue();
Vals.push_back((GetEncodedCallingConv(Call.getCallingConv()) << 1)
| unsigned(Call.isTailCall()));
pushValue(Callee, InstID, Vals, VE, Stream);
if (Callee == VE.ElideCasts(Callee)) {
// Since the call pointer has not been elided, we know that
// the call pointer has the type signature of the called
// function. This implies that the reader can use the type
// signature of the callee to figure out how to add casts to
// the arguments.
Code = naclbitc::FUNC_CODE_INST_CALL;
} else {
// If the cast was elided, a pointer conversion to a pointer
// was applied, meaning that this is an indirect call. For the
// reader, this implies that we can't use the type signature
// of the callee to resolve elided call arguments, since it is
// not known. Hence, we must send the type signature to the
// reader.
Code = naclbitc::FUNC_CODE_INST_CALL_INDIRECT;
Vals.push_back(VE.getTypeID(I.getType()));
}
for (unsigned I = 0, E = Call.getNumArgOperands(); I < E; ++I) {
pushValue(Call.getArgOperand(I), InstID, Vals, VE, Stream);
}
break;
}
}
Stream.EmitRecord(Code, Vals, AbbrevToUse);
Vals.clear();
return true;
}
/// The specified block is found to be reachable, clone it and
/// anything that it can reach.
void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
BasicBlock::const_iterator StartingInst,
std::vector<const BasicBlock*> &ToClone){
WeakVH &BBEntry = VMap[BB];
// Have we already cloned this block?
if (BBEntry) return;
// Nope, clone it now.
BasicBlock *NewBB;
BBEntry = NewBB = BasicBlock::Create(BB->getContext());
if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
// It is only legal to clone a function if a block address within that
// function is never referenced outside of the function. Given that, we
// want to map block addresses from the old function to block addresses in
// the clone. (This is different from the generic ValueMapper
// implementation, which generates an invalid blockaddress when
// cloning a function.)
//
// Note that we don't need to fix the mapping for unreachable blocks;
// the default mapping there is safe.
if (BB->hasAddressTaken()) {
Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
const_cast<BasicBlock*>(BB));
VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
}
bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
// Loop over all instructions, and copy them over, DCE'ing as we go. This
// loop doesn't include the terminator.
for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end();
II != IE; ++II) {
Instruction *NewInst = II->clone();
// Eagerly remap operands to the newly cloned instruction, except for PHI
// nodes for which we defer processing until we update the CFG.
if (!isa<PHINode>(NewInst)) {
RemapInstruction(NewInst, VMap,
ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
// If we can simplify this instruction to some other value, simply add
// a mapping to that value rather than inserting a new instruction into
// the basic block.
if (Value *V =
SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) {
// On the off-chance that this simplifies to an instruction in the old
// function, map it back into the new function.
if (Value *MappedV = VMap.lookup(V))
V = MappedV;
VMap[&*II] = V;
delete NewInst;
continue;
}
}
if (II->hasName())
NewInst->setName(II->getName()+NameSuffix);
VMap[&*II] = NewInst; // Add instruction map to value.
NewBB->getInstList().push_back(NewInst);
hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
if (CodeInfo)
if (auto CS = ImmutableCallSite(&*II))
if (CS.hasOperandBundles())
CodeInfo->OperandBundleCallSites.push_back(NewInst);
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (isa<ConstantInt>(AI->getArraySize()))
hasStaticAllocas = true;
else
hasDynamicAllocas = true;
}
}
// Finally, clone over the terminator.
const TerminatorInst *OldTI = BB->getTerminator();
bool TerminatorDone = false;
if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
if (BI->isConditional()) {
// If the condition was a known constant in the callee...
ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
// Or is a known constant in the caller...
if (!Cond) {
Value *V = VMap[BI->getCondition()];
Cond = dyn_cast_or_null<ConstantInt>(V);
}
// Constant fold to uncond branch!
if (Cond) {
BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
VMap[OldTI] = BranchInst::Create(Dest, NewBB);
ToClone.push_back(Dest);
TerminatorDone = true;
}
}
} else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
// If switching on a value known constant in the caller.
ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
if (!Cond) { // Or known constant after constant prop in the callee...
Value *V = VMap[SI->getCondition()];
Cond = dyn_cast_or_null<ConstantInt>(V);
}
if (Cond) { // Constant fold to uncond branch!
SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
VMap[OldTI] = BranchInst::Create(Dest, NewBB);
ToClone.push_back(Dest);
TerminatorDone = true;
}
}
if (!TerminatorDone) {
Instruction *NewInst = OldTI->clone();
if (OldTI->hasName())
NewInst->setName(OldTI->getName()+NameSuffix);
NewBB->getInstList().push_back(NewInst);
VMap[OldTI] = NewInst; // Add instruction map to value.
if (CodeInfo)
if (auto CS = ImmutableCallSite(OldTI))
if (CS.hasOperandBundles())
CodeInfo->OperandBundleCallSites.push_back(NewInst);
// Recursively clone any reachable successor blocks.
const TerminatorInst *TI = BB->getTerminator();
for (const BasicBlock *Succ : TI->successors())
ToClone.push_back(Succ);
}
if (CodeInfo) {
CodeInfo->ContainsCalls |= hasCalls;
CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
BB != &BB->getParent()->front();
}
}
/// CloneBlock - The specified block is found to be reachable, clone it and
/// anything that it can reach.
void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
std::vector<const BasicBlock*> &ToClone) {
TrackingVH<Value> &BBEntry = VMap[BB];
// Have we already cloned this block?
if (BBEntry) return;
// Nope, clone it now.
BasicBlock *NewBB;
BBEntry = NewBB = BasicBlock::Create(BB->getContext());
if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
// It is only legal to clone a function if a block address within that
// function is never referenced outside of the function. Given that, we
// want to map block addresses from the old function to block addresses in
// the clone. (This is different from the generic ValueMapper
// implementation, which generates an invalid blockaddress when
// cloning a function.)
//
// Note that we don't need to fix the mapping for unreachable blocks;
// the default mapping there is safe.
if (BB->hasAddressTaken()) {
Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
const_cast<BasicBlock*>(BB));
VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
}
bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
// Loop over all instructions, and copy them over, DCE'ing as we go. This
// loop doesn't include the terminator.
for (BasicBlock::const_iterator II = BB->begin(), IE = --BB->end();
II != IE; ++II) {
// If this instruction constant folds, don't bother cloning the instruction,
// instead, just add the constant to the value map.
if (Constant *C = ConstantFoldMappedInstruction(II)) {
VMap[II] = C;
continue;
}
Instruction *NewInst = II->clone();
if (II->hasName())
NewInst->setName(II->getName()+NameSuffix);
NewBB->getInstList().push_back(NewInst);
VMap[II] = NewInst; // Add instruction map to value.
hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (isa<ConstantInt>(AI->getArraySize()))
hasStaticAllocas = true;
else
hasDynamicAllocas = true;
}
}
// Finally, clone over the terminator.
const TerminatorInst *OldTI = BB->getTerminator();
bool TerminatorDone = false;
if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
if (BI->isConditional()) {
// If the condition was a known constant in the callee...
ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
// Or is a known constant in the caller...
if (Cond == 0) {
Value *V = VMap[BI->getCondition()];
Cond = dyn_cast_or_null<ConstantInt>(V);
}
// Constant fold to uncond branch!
if (Cond) {
BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
VMap[OldTI] = BranchInst::Create(Dest, NewBB);
ToClone.push_back(Dest);
TerminatorDone = true;
}
}
} else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
// If switching on a value known constant in the caller.
ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
if (Cond == 0) { // Or known constant after constant prop in the callee...
Value *V = VMap[SI->getCondition()];
Cond = dyn_cast_or_null<ConstantInt>(V);
}
if (Cond) { // Constant fold to uncond branch!
SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
VMap[OldTI] = BranchInst::Create(Dest, NewBB);
ToClone.push_back(Dest);
TerminatorDone = true;
}
}
if (!TerminatorDone) {
Instruction *NewInst = OldTI->clone();
if (OldTI->hasName())
NewInst->setName(OldTI->getName()+NameSuffix);
NewBB->getInstList().push_back(NewInst);
VMap[OldTI] = NewInst; // Add instruction map to value.
// Recursively clone any reachable successor blocks.
const TerminatorInst *TI = BB->getTerminator();
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
ToClone.push_back(TI->getSuccessor(i));
}
if (CodeInfo) {
CodeInfo->ContainsCalls |= hasCalls;
CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
BB != &BB->getParent()->front();
}
if (ReturnInst *RI = dyn_cast<ReturnInst>(NewBB->getTerminator()))
Returns.push_back(RI);
}
