本文整理汇总了C++中UseVector::clear方法的典型用法代码示例。如果您正苦于以下问题:C++ UseVector::clear方法的具体用法?C++ UseVector::clear怎么用?C++ UseVector::clear使用的例子?那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类UseVector
的用法示例。
在下文中一共展示了UseVector::clear方法的2个代码示例,这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞,您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: SurveyFunction
//.........这里部分代码省略.........
!= F.getFunctionType()->getReturnType()) {
// We don't support old style multiple return values.
MarkLive(F);
return;
}
if (!F.hasLocalLinkage() && (!ShouldHackArguments() || F.isIntrinsic())) {
MarkLive(F);
return;
}
DEBUG(dbgs() << "DAE - Inspecting callers for fn: " << F.getName() << "\n");
// Keep track of the number of live retvals, so we can skip checks once all
// of them turn out to be live.
unsigned NumLiveRetVals = 0;
// Loop all uses of the function.
for (const Use &U : F.uses()) {
// If the function is PASSED IN as an argument, its address has been
// taken.
ImmutableCallSite CS(U.getUser());
if (!CS || !CS.isCallee(&U)) {
MarkLive(F);
return;
}
// If this use is anything other than a call site, the function is alive.
const Instruction *TheCall = CS.getInstruction();
if (!TheCall) { // Not a direct call site?
MarkLive(F);
return;
}
// If we end up here, we are looking at a direct call to our function.
// Now, check how our return value(s) is/are used in this caller. Don't
// bother checking return values if all of them are live already.
if (NumLiveRetVals == RetCount)
continue;
// Check all uses of the return value.
for (const Use &U : TheCall->uses()) {
if (ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(U.getUser())) {
// This use uses a part of our return value, survey the uses of
// that part and store the results for this index only.
unsigned Idx = *Ext->idx_begin();
if (RetValLiveness[Idx] != Live) {
RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]);
if (RetValLiveness[Idx] == Live)
NumLiveRetVals++;
}
} else {
// Used by something else than extractvalue. Survey, but assume that the
// result applies to all sub-values.
UseVector MaybeLiveAggregateUses;
if (SurveyUse(&U, MaybeLiveAggregateUses) == Live) {
NumLiveRetVals = RetCount;
RetValLiveness.assign(RetCount, Live);
break;
} else {
for (unsigned i = 0; i != RetCount; ++i) {
if (RetValLiveness[i] != Live)
MaybeLiveRetUses[i].append(MaybeLiveAggregateUses.begin(),
MaybeLiveAggregateUses.end());
}
}
}
}
}
// Now we've inspected all callers, record the liveness of our return values.
for (unsigned i = 0; i != RetCount; ++i)
MarkValue(CreateRet(&F, i), RetValLiveness[i], MaybeLiveRetUses[i]);
DEBUG(dbgs() << "DAE - Inspecting args for fn: " << F.getName() << "\n");
// Now, check all of our arguments.
unsigned i = 0;
UseVector MaybeLiveArgUses;
for (Function::const_arg_iterator AI = F.arg_begin(),
E = F.arg_end(); AI != E; ++AI, ++i) {
Liveness Result;
if (F.getFunctionType()->isVarArg()) {
// Variadic functions will already have a va_arg function expanded inside
// them, making them potentially very sensitive to ABI changes resulting
// from removing arguments entirely, so don't. For example AArch64 handles
// register and stack HFAs very differently, and this is reflected in the
// IR which has already been generated.
Result = Live;
} else {
// See what the effect of this use is (recording any uses that cause
// MaybeLive in MaybeLiveArgUses).
Result = SurveyUses(&*AI, MaybeLiveArgUses);
}
// Mark the result.
MarkValue(CreateArg(&F, i), Result, MaybeLiveArgUses);
// Clear the vector again for the next iteration.
MaybeLiveArgUses.clear();
}
}
示例2: SurveyFunction
//.........这里部分代码省略.........
typedef SmallVector<UseVector, 5> RetUses;
// These vectors map each return value to the uses that make it MaybeLive, so
// we can add those to the Uses map if the return value really turns out to be
// MaybeLive. Initialized to a list of RetCount empty lists.
RetUses MaybeLiveRetUses(RetCount);
for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
if (const ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
if (RI->getNumOperands() != 0 && RI->getOperand(0)->getType()
!= F.getFunctionType()->getReturnType()) {
// We don't support old style multiple return values.
MarkLive(F);
return;
}
if (!F.hasLocalLinkage() && (!ShouldHackArguments() || F.isIntrinsic())) {
MarkLive(F);
return;
}
DEBUG(dbgs() << "DAE - Inspecting callers for fn: " << F.getName() << "\n");
// Keep track of the number of live retvals, so we can skip checks once all
// of them turn out to be live.
unsigned NumLiveRetVals = 0;
Type *STy = dyn_cast<StructType>(F.getReturnType());
// Loop all uses of the function.
for (Value::const_use_iterator I = F.use_begin(), E = F.use_end();
I != E; ++I) {
// If the function is PASSED IN as an argument, its address has been
// taken.
ImmutableCallSite CS(*I);
if (!CS || !CS.isCallee(I)) {
MarkLive(F);
return;
}
// If this use is anything other than a call site, the function is alive.
const Instruction *TheCall = CS.getInstruction();
if (!TheCall) { // Not a direct call site?
MarkLive(F);
return;
}
// If we end up here, we are looking at a direct call to our function.
// Now, check how our return value(s) is/are used in this caller. Don't
// bother checking return values if all of them are live already.
if (NumLiveRetVals != RetCount) {
if (STy) {
// Check all uses of the return value.
for (Value::const_use_iterator I = TheCall->use_begin(),
E = TheCall->use_end(); I != E; ++I) {
const ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(*I);
if (Ext && Ext->hasIndices()) {
// This use uses a part of our return value, survey the uses of
// that part and store the results for this index only.
unsigned Idx = *Ext->idx_begin();
if (RetValLiveness[Idx] != Live) {
RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]);
if (RetValLiveness[Idx] == Live)
NumLiveRetVals++;
}
} else {
// Used by something else than extractvalue. Mark all return
// values as live.
for (unsigned i = 0; i != RetCount; ++i )
RetValLiveness[i] = Live;
NumLiveRetVals = RetCount;
break;
}
}
} else {
// Single return value
RetValLiveness[0] = SurveyUses(TheCall, MaybeLiveRetUses[0]);
if (RetValLiveness[0] == Live)
NumLiveRetVals = RetCount;
}
}
}
// Now we've inspected all callers, record the liveness of our return values.
for (unsigned i = 0; i != RetCount; ++i)
MarkValue(CreateRet(&F, i), RetValLiveness[i], MaybeLiveRetUses[i]);
DEBUG(dbgs() << "DAE - Inspecting args for fn: " << F.getName() << "\n");
// Now, check all of our arguments.
unsigned i = 0;
UseVector MaybeLiveArgUses;
for (Function::const_arg_iterator AI = F.arg_begin(),
E = F.arg_end(); AI != E; ++AI, ++i) {
// See what the effect of this use is (recording any uses that cause
// MaybeLive in MaybeLiveArgUses).
Liveness Result = SurveyUses(AI, MaybeLiveArgUses);
// Mark the result.
MarkValue(CreateArg(&F, i), Result, MaybeLiveArgUses);
// Clear the vector again for the next iteration.
MaybeLiveArgUses.clear();
}
}