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IntRange:

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- Changed isSingleNumber method behaviour. Now this flag is calculated on demand.
IntegersSubsetMapping
  - Optimized diff operation.
  - Replaced type of Items field from std::list with std::map.
  - Added new methods:
    bool isOverlapped(self &RHS)
    void add(self& RHS, SuccessorClass *S)
    void detachCase(self& NewMapping, SuccessorClass *Succ)
    void removeCase(SuccessorClass *Succ)
    SuccessorClass *findSuccessor(const IntTy& Val)
    const IntTy* getCaseSingleNumber(SuccessorClass *Succ)
IntegersSubsetTest
  - DiffTest: Added checks for successors.
SimplifyCFG
  Updated SwitchInst usage (now it is case-ragnes compatible) for
    - SimplifyEqualityComparisonWithOnlyPredecessor
    - FoldValueComparisonIntoPredecessors



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159527 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Stepan Dyatkovskiy
2012-07-02 13:02:18 +00:00
parent 4177e6fff5
commit b2833d9dcb
7 changed files with 328 additions and 210 deletions
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231
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -56,26 +56,12 @@ DupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false),
STATISTIC(NumSpeculations, "Number of speculative executed instructions");
namespace {
/// ValueEqualityComparisonCase - Represents a case of a switch.
struct ValueEqualityComparisonCase {
ConstantInt *Value;
BasicBlock *Dest;
ValueEqualityComparisonCase(ConstantInt *Value, BasicBlock *Dest)
: Value(Value), Dest(Dest) {}
bool operator<(ValueEqualityComparisonCase RHS) const {
// Comparing pointers is ok as we only rely on the order for uniquing.
return Value < RHS.Value;
}
};
class SimplifyCFGOpt {
const TargetData *const TD;
Value *isValueEqualityComparison(TerminatorInst *TI);
BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI,
std::vector<ValueEqualityComparisonCase> &Cases);
IntegersSubsetToBB &Mapping);
bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
BasicBlock *Pred,
IRBuilder<> &Builder);
@ -532,72 +518,25 @@ Value *SimplifyCFGOpt::isValueEqualityComparison(TerminatorInst *TI) {
/// decode all of the 'cases' that it represents and return the 'default' block.
BasicBlock *SimplifyCFGOpt::
GetValueEqualityComparisonCases(TerminatorInst *TI,
std::vector<ValueEqualityComparisonCase>
&Cases) {
IntegersSubsetToBB &Mapping) {
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
Cases.reserve(SI->getNumCases());
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i)
Cases.push_back(ValueEqualityComparisonCase(i.getCaseValue(),
i.getCaseSuccessor()));
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
i != e; ++i)
Mapping.add(i.getCaseValueEx(), i.getCaseSuccessor());
return SI->getDefaultDest();
}
BranchInst *BI = cast<BranchInst>(TI);
ICmpInst *ICI = cast<ICmpInst>(BI->getCondition());
BasicBlock *Succ = BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_NE);
Cases.push_back(ValueEqualityComparisonCase(GetConstantInt(ICI->getOperand(1),
TD),
Succ));
IntegersSubsetToBB Builder;
Mapping.add(
IntItem::fromConstantInt(GetConstantInt(ICI->getOperand(1), TD)),
BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_NE));
return BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_EQ);
}
/// EliminateBlockCases - Given a vector of bb/value pairs, remove any entries
/// in the list that match the specified block.
static void EliminateBlockCases(BasicBlock *BB,
std::vector<ValueEqualityComparisonCase> &Cases) {
for (unsigned i = 0, e = Cases.size(); i != e; ++i)
if (Cases[i].Dest == BB) {
Cases.erase(Cases.begin()+i);
--i; --e;
}
}
/// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as
/// well.
static bool
ValuesOverlap(std::vector<ValueEqualityComparisonCase> &C1,
std::vector<ValueEqualityComparisonCase > &C2) {
std::vector<ValueEqualityComparisonCase> *V1 = &C1, *V2 = &C2;
// Make V1 be smaller than V2.
if (V1->size() > V2->size())
std::swap(V1, V2);
if (V1->size() == 0) return false;
if (V1->size() == 1) {
// Just scan V2.
ConstantInt *TheVal = (*V1)[0].Value;
for (unsigned i = 0, e = V2->size(); i != e; ++i)
if (TheVal == (*V2)[i].Value)
return true;
}
// Otherwise, just sort both lists and compare element by element.
array_pod_sort(V1->begin(), V1->end());
array_pod_sort(V2->begin(), V2->end());
unsigned i1 = 0, i2 = 0, e1 = V1->size(), e2 = V2->size();
while (i1 != e1 && i2 != e2) {
if ((*V1)[i1].Value == (*V2)[i2].Value)
return true;
if ((*V1)[i1].Value < (*V2)[i2].Value)
++i1;
else
++i2;
}
return false;
}
/// SimplifyEqualityComparisonWithOnlyPredecessor - If TI is known to be a
/// terminator instruction and its block is known to only have a single
/// predecessor block, check to see if that predecessor is also a value
@ -616,23 +555,27 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
if (ThisVal != PredVal) return false; // Different predicates.
// Find out information about when control will move from Pred to TI's block.
std::vector<ValueEqualityComparisonCase> PredCases;
IntegersSubsetToBB PredCases;
BasicBlock *PredDef = GetValueEqualityComparisonCases(Pred->getTerminator(),
PredCases);
EliminateBlockCases(PredDef, PredCases); // Remove default from cases.
// Remove default from cases.
PredCases.removeCase(PredDef);
// Find information about how control leaves this block.
std::vector<ValueEqualityComparisonCase> ThisCases;
IntegersSubsetToBB ThisCases;
BasicBlock *ThisDef = GetValueEqualityComparisonCases(TI, ThisCases);
EliminateBlockCases(ThisDef, ThisCases); // Remove default from cases.
// Remove default from cases.
ThisCases.removeCase(ThisDef);
// If TI's block is the default block from Pred's comparison, potentially
// simplify TI based on this knowledge.
if (PredDef == TI->getParent()) {
// If we are here, we know that the value is none of those cases listed in
// PredCases. If there are any cases in ThisCases that are in PredCases, we
// can simplify TI.
if (!ValuesOverlap(PredCases, ThisCases))
if (!PredCases.isOverlapped(ThisCases))
return false;
if (isa<BranchInst>(TI)) {
@ -644,7 +587,7 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
(void) NI;
// Remove PHI node entries for the dead edge.
ThisCases[0].Dest->removePredecessor(TI->getParent());
ThisCases.begin()->second->removePredecessor(TI->getParent());
DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator()
<< "Through successor TI: " << *TI << "Leaving: " << *NI << "\n");
@ -655,45 +598,45 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
SwitchInst *SI = cast<SwitchInst>(TI);
// Okay, TI has cases that are statically dead, prune them away.
SmallPtrSet<Constant*, 16> DeadCases;
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
DeadCases.insert(PredCases[i].Value);
IRBuilder<> CodeBuilder(SI);
CodeBuilder.SetCurrentDebugLocation(SI->getDebugLoc());
DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator()
<< "Through successor TI: " << *TI);
for (SwitchInst::CaseIt i = SI->case_end(), e = SI->case_begin(); i != e;) {
--i;
if (DeadCases.count(i.getCaseValue())) {
i.getCaseSuccessor()->removePredecessor(TI->getParent());
SI->removeCase(i);
}
}
DEBUG(dbgs() << "Leaving: " << *TI << "\n");
// Okay, TI has cases that are statically dead, prune them away.
IntegersSubsetToBB NewThisCases;
IntegersSubsetToBB WastedCases;
ThisCases.diff(&NewThisCases, &WastedCases, 0, PredCases);
IntegersSubsetToBB::Cases Cases;
NewThisCases.getCases(Cases, true/*temporary prevent complex cases*/);
SwitchInst *NewSI =
CodeBuilder.CreateSwitch(ThisVal, SI->getDefaultDest(), Cases.size());
for (IntegersSubsetToBB::RangeIterator i = WastedCases.begin(),
e = WastedCases.end(); i != e; ++i)
i->second->removePredecessor(TI->getParent());
for (IntegersSubsetToBB::CasesIt i = Cases.begin(), e = Cases.end();
i != e; ++i)
NewSI->addCase(i->second, i->first);
EraseTerminatorInstAndDCECond(SI);
DEBUG(dbgs() << "Leaving: " << *NewSI << "\n");
return true;
}
// Otherwise, TI's block must correspond to some matched value. Find out
// which value (or set of values) this is.
ConstantInt *TIV = 0;
BasicBlock *TIBB = TI->getParent();
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
if (PredCases[i].Dest == TIBB) {
if (TIV != 0)
return false; // Cannot handle multiple values coming to this block.
TIV = PredCases[i].Value;
}
assert(TIV && "No edge from pred to succ?");
const IntItem* TIVIntITem = PredCases.getCaseSingleNumber(TIBB);
assert(TIVIntITem && "No edge from pred to succ?");
// Okay, we found the one constant that our value can be if we get into TI's
// BB. Find out which successor will unconditionally be branched to.
BasicBlock *TheRealDest = 0;
for (unsigned i = 0, e = ThisCases.size(); i != e; ++i)
if (ThisCases[i].Value == TIV) {
TheRealDest = ThisCases[i].Dest;
break;
}
BasicBlock *TheRealDest = ThisCases.findSuccessor(*TIVIntITem);
// If not handled by any explicit cases, it is handled by the default case.
if (TheRealDest == 0) TheRealDest = ThisDef;
@ -759,10 +702,10 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
if (PCV == CV && SafeToMergeTerminators(TI, PTI)) {
// Figure out which 'cases' to copy from SI to PSI.
std::vector<ValueEqualityComparisonCase> BBCases;
IntegersSubsetToBB BBCases;
BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases);
std::vector<ValueEqualityComparisonCase> PredCases;
IntegersSubsetToBB PredCases;
BasicBlock *PredDefault = GetValueEqualityComparisonCases(PTI, PredCases);
// Based on whether the default edge from PTI goes to BB or not, fill in
@ -773,61 +716,51 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
if (PredDefault == BB) {
// If this is the default destination from PTI, only the edges in TI
// that don't occur in PTI, or that branch to BB will be activated.
std::set<ConstantInt*, ConstantIntOrdering> PTIHandled;
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
if (PredCases[i].Dest != BB)
PTIHandled.insert(PredCases[i].Value);
else {
// The default destination is BB, we don't need explicit targets.
std::swap(PredCases[i], PredCases.back());
PredCases.pop_back();
--i; --e;
}
PredCases.removeCase(BB);
IntegersSubsetToBB NewBBCases;
BBCases.diff(&NewBBCases, 0, 0, PredCases);
PredCases.add(NewBBCases);
for (IntegersSubsetToBB::RangeIterator i = NewBBCases.begin(),
e = NewBBCases.end(); i != e; ++i)
NewSuccessors.push_back(i->second);
// Reconstruct the new switch statement we will be building.
// Replace the default if needed.
if (PredDefault != BBDefault) {
PredDefault->removePredecessor(Pred);
PredDefault = BBDefault;
NewSuccessors.push_back(BBDefault);
}
for (unsigned i = 0, e = BBCases.size(); i != e; ++i)
if (!PTIHandled.count(BBCases[i].Value) &&
BBCases[i].Dest != BBDefault) {
PredCases.push_back(BBCases[i]);
NewSuccessors.push_back(BBCases[i].Dest);
}
} else {
// If this is not the default destination from PSI, only the edges
// in SI that occur in PSI with a destination of BB will be
// activated.
std::set<ConstantInt*, ConstantIntOrdering> PTIHandled;
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
if (PredCases[i].Dest == BB) {
PTIHandled.insert(PredCases[i].Value);
std::swap(PredCases[i], PredCases.back());
PredCases.pop_back();
--i; --e;
}
IntegersSubsetToBB BBPredCase;
PredCases.detachCase(BBPredCase, BB);
IntegersSubsetToBB CasesWithBBDef;
IntegersSubsetToBB InharitedCases;
// Okay, now we know which constants were sent to BB from the
// predecessor. Figure out where they will all go now.
for (unsigned i = 0, e = BBCases.size(); i != e; ++i)
if (PTIHandled.count(BBCases[i].Value)) {
// If this is one we are capable of getting...
PredCases.push_back(BBCases[i]);
NewSuccessors.push_back(BBCases[i].Dest);
PTIHandled.erase(BBCases[i].Value);// This constant is taken care of
}
if (!BBPredCase.empty()) {
BBCases.diff(
0, // LHS excl RHS
&InharitedCases, // intersection
&CasesWithBBDef, // RHS excl LHS
BBPredCase); // RHS.
}
PredCases.add(InharitedCases);
for (IntegersSubsetToBB::RangeIterator i = InharitedCases.begin(),
e = InharitedCases.end();
i != e; ++i)
NewSuccessors.push_back(i->second);
// If there are any constants vectored to BB that TI doesn't handle,
// they must go to the default destination of TI.
for (std::set<ConstantInt*, ConstantIntOrdering>::iterator I =
PTIHandled.begin(),
E = PTIHandled.end(); I != E; ++I) {
PredCases.push_back(ValueEqualityComparisonCase(*I, BBDefault));
PredCases.add(CasesWithBBDef, BBDefault);
for (unsigned i = 0, e = CasesWithBBDef.size(); i != e; ++i)
NewSuccessors.push_back(BBDefault);
}
}
// Okay, at this point, we know which new successor Pred will get. Make
@ -848,8 +781,12 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
SwitchInst *NewSI = Builder.CreateSwitch(CV, PredDefault,
PredCases.size());
NewSI->setDebugLoc(PTI->getDebugLoc());
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
NewSI->addCase(PredCases[i].Value, PredCases[i].Dest);
IntegersSubsetToBB::Cases Cases;
PredCases.getCases(Cases, true/*temporary prevent complex case*/);
for (IntegersSubsetToBB::CasesIt i = Cases.begin(), e = Cases.end();
i != e; ++i)
NewSI->addCase(i->second, i->first);
EraseTerminatorInstAndDCECond(PTI);