void TestInstVisitor::visitSwitchInst(SwitchInst &I){
if (except){
return;
}
DynValEntry entry;
size_t n = fread(&entry, sizeof(DynValEntry), 1, dlog);
if (entry.entrytype == EXCEPTIONENTRY){
except = true;
return;
}
assert(entry.entrytype == SWITCHENTRY);
//printf("switch %d\n", entry.entry.switchstmt.cond);
IntegerType *intType = IntegerType::get(getGlobalContext(), sizeof(int)*8);
ConstantInt *caseVal =
ConstantInt::get(intType, entry.entry.switchstmt.cond);
SwitchInst::CaseIt caseIndex = I.findCaseValue(caseVal);
TFP->setNextBB(I.getSuccessor(caseIndex.getSuccessorIndex()));
}
// RewriteLoopBodyWithConditionConstant - We know either that the value LIC has
// the value specified by Val in the specified loop, or we know it does NOT have
// that value. Rewrite any uses of LIC or of properties correlated to it.
void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
Constant *Val,
bool IsEqual) {
assert(!isa<Constant>(LIC) && "Why are we unswitching on a constant?");
// FIXME: Support correlated properties, like:
// for (...)
// if (li1 < li2)
// ...
// if (li1 > li2)
// ...
// FOLD boolean conditions (X|LIC), (X&LIC). Fold conditional branches,
// selects, switches.
std::vector<User*> Users(LIC->use_begin(), LIC->use_end());
std::vector<Instruction*> Worklist;
LLVMContext &Context = Val->getContext();
// If we know that LIC == Val, or that LIC == NotVal, just replace uses of LIC
// in the loop with the appropriate one directly.
if (IsEqual || (isa<ConstantInt>(Val) &&
Val->getType()->isIntegerTy(1))) {
Value *Replacement;
if (IsEqual)
Replacement = Val;
else
Replacement = ConstantInt::get(Type::getInt1Ty(Val->getContext()),
!cast<ConstantInt>(Val)->getZExtValue());
for (unsigned i = 0, e = Users.size(); i != e; ++i)
if (Instruction *U = cast<Instruction>(Users[i])) {
if (!L->contains(U))
continue;
U->replaceUsesOfWith(LIC, Replacement);
Worklist.push_back(U);
}
SimplifyCode(Worklist, L);
return;
}
// Otherwise, we don't know the precise value of LIC, but we do know that it
// is certainly NOT "Val". As such, simplify any uses in the loop that we
// can. This case occurs when we unswitch switch statements.
for (unsigned i = 0, e = Users.size(); i != e; ++i) {
Instruction *U = cast<Instruction>(Users[i]);
if (!L->contains(U))
continue;
Worklist.push_back(U);
// TODO: We could do other simplifications, for example, turning
// 'icmp eq LIC, Val' -> false.
// If we know that LIC is not Val, use this info to simplify code.
SwitchInst *SI = dyn_cast<SwitchInst>(U);
if (SI == 0 || !isa<ConstantInt>(Val)) continue;
unsigned DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
if (DeadCase == 0) continue; // Default case is live for multiple values.
// Found a dead case value. Don't remove PHI nodes in the
// successor if they become single-entry, those PHI nodes may
// be in the Users list.
// FIXME: This is a hack. We need to keep the successor around
// and hooked up so as to preserve the loop structure, because
// trying to update it is complicated. So instead we preserve the
// loop structure and put the block on a dead code path.
BasicBlock *Switch = SI->getParent();
SplitEdge(Switch, SI->getSuccessor(DeadCase), this);
// Compute the successors instead of relying on the return value
// of SplitEdge, since it may have split the switch successor
// after PHI nodes.
BasicBlock *NewSISucc = SI->getSuccessor(DeadCase);
BasicBlock *OldSISucc = *succ_begin(NewSISucc);
// Create an "unreachable" destination.
BasicBlock *Abort = BasicBlock::Create(Context, "us-unreachable",
Switch->getParent(),
OldSISucc);
new UnreachableInst(Context, Abort);
// Force the new case destination to branch to the "unreachable"
// block while maintaining a (dead) CFG edge to the old block.
NewSISucc->getTerminator()->eraseFromParent();
BranchInst::Create(Abort, OldSISucc,
ConstantInt::getTrue(Context), NewSISucc);
// Release the PHI operands for this edge.
for (BasicBlock::iterator II = NewSISucc->begin();
PHINode *PN = dyn_cast<PHINode>(II); ++II)
PN->setIncomingValue(PN->getBasicBlockIndex(Switch),
UndefValue::get(PN->getType()));
// Tell the domtree about the new block. We don't fully update the
// domtree here -- instead we force it to do a full recomputation
// after the pass is complete -- but we do need to inform it of
// new blocks.
if (DT)
DT->addNewBlock(Abort, NewSISucc);
}
SimplifyCode(Worklist, L);
}
// Set outgoing edges alive dependent on the terminator instruction SI.
// If the terminator is an Invoke instruction, the call has already been run.
// Return true if anything changed.
bool IntegrationAttempt::checkBlockOutgoingEdges(ShadowInstruction* SI) {
// TOCHECK: I think this only returns false if the block ends with an Unreachable inst?
switch(SI->invar->I->getOpcode()) {
case Instruction::Br:
case Instruction::Switch:
case Instruction::Invoke:
case Instruction::Resume:
break;
default:
return false;
}
if(inst_is<InvokeInst>(SI)) {
InlineAttempt* IA = getInlineAttempt(SI);
bool changed = false;
// !localStore indicates the invoke instruction doesn't return normally
if(SI->parent->localStore) {
changed |= !SI->parent->succsAlive[0];
SI->parent->succsAlive[0] = true;
}
// I mark the exceptional edge reachable here if the call is disabled, even though
// we might have proved it isn't feasible. This could be improved by converting the
// invoke into a call in the final program.
if((!IA) || (!IA->isEnabled()) || IA->mayUnwind) {
changed |= !SI->parent->succsAlive[1];
SI->parent->succsAlive[1] = true;
}
return changed;
}
else if(inst_is<ResumeInst>(SI)) {
bool changed = !mayUnwind;
mayUnwind = true;
return changed;
}
else if(BranchInst* BI = dyn_cast_inst<BranchInst>(SI)) {
if(BI->isUnconditional()) {
bool changed = !SI->parent->succsAlive[0];
SI->parent->succsAlive[0] = true;
return changed;
}
}
// Both switches and conditional branches use operand 0 for the condition.
ShadowValue Condition = SI->getOperand(0);
bool changed = false;
ConstantInt* ConstCondition = dyn_cast_or_null<ConstantInt>(getConstReplacement(Condition));
if(!ConstCondition) {
if(Condition.t == SHADOWVAL_INST || Condition.t == SHADOWVAL_ARG) {
// Switch statements can operate on a ptrtoint operand, of which only ptrtoint(null) is useful:
if(ImprovedValSetSingle* IVS = dyn_cast_or_null<ImprovedValSetSingle>(getIVSRef(Condition))) {
if(IVS->onlyContainsNulls()) {
ConstCondition = cast<ConstantInt>(Constant::getNullValue(SI->invar->I->getOperand(0)->getType()));
}
}
}
}
if(!ConstCondition) {
std::pair<ValSetType, ImprovedVal> PathVal;
if(tryGetPathValue(Condition, SI->parent, PathVal))
ConstCondition = dyn_cast_val<ConstantInt>(PathVal.second.V);
}
TerminatorInst* TI = cast_inst<TerminatorInst>(SI);
const unsigned NumSucc = TI->getNumSuccessors();
if(ConstCondition) {
BasicBlock* takenTarget = 0;
if(BranchInst* BI = dyn_cast_inst<BranchInst>(SI)) {
// This ought to be a boolean.
if(ConstCondition->isZero())
takenTarget = BI->getSuccessor(1);
else
takenTarget = BI->getSuccessor(0);
}
else {
SwitchInst* SwI = cast_inst<SwitchInst>(SI);
SwitchInst::CaseIt targetidx = SwI->findCaseValue(ConstCondition);
takenTarget = targetidx.getCaseSuccessor();
}
if(takenTarget) {
// We know where the instruction is going -- remove this block as a predecessor for its other targets.
LPDEBUG("Branch or switch instruction given known target: " << takenTarget->getName() << "\n");
return setEdgeAlive(TI, SI->parent, takenTarget);
}
// Else fall through to set all alive.
}
SwitchInst* Switch;
ImprovedValSetSingle* IVS;
if((Switch = dyn_cast_inst<SwitchInst>(SI)) &&
(IVS = dyn_cast<ImprovedValSetSingle>(getIVSRef(Condition))) &&
IVS->SetType == ValSetTypeScalar &&
!IVS->Values.empty()) {
// A set of values feeding a switch. Set each corresponding edge alive.
bool changed = false;
for (unsigned i = 0, ilim = IVS->Values.size(); i != ilim; ++i) {
SwitchInst::CaseIt targetit = Switch->findCaseValue(cast<ConstantInt>(getConstReplacement(IVS->Values[i].V)));
BasicBlock* target = targetit.getCaseSuccessor();
changed |= setEdgeAlive(TI, SI->parent, target);
}
return changed;
}
// Condition unknown -- set all successors alive.
for (unsigned I = 0; I != NumSucc; ++I) {
// Mark outgoing edge alive
if(!SI->parent->succsAlive[I])
changed = true;
SI->parent->succsAlive[I] = true;
}
return changed;
}
