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SimplifyCFG: Turn the ad-hoc std::pair that represents switch cases into an explicit struct.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157516 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2012-05-26 14:29:37 +00:00
parent 937338cf64
commit 3e933ecb74
1 changed files with 54 additions and 39 deletions
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93
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -56,12 +56,26 @@ 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<std::pair<ConstantInt*, BasicBlock*> > &Cases);
std::vector<ValueEqualityComparisonCase> &Cases);
bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
BasicBlock *Pred,
IRBuilder<> &Builder);
@ -477,21 +491,22 @@ 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<std::pair<ConstantInt*,
BasicBlock*> > &Cases) {
std::vector<ValueEqualityComparisonCase>
&Cases) {
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(std::make_pair(i.getCaseValue(),
i.getCaseSuccessor()));
Cases.push_back(ValueEqualityComparisonCase(i.getCaseValue(),
i.getCaseSuccessor()));
return SI->getDefaultDest();
}
BranchInst *BI = cast<BranchInst>(TI);
ICmpInst *ICI = cast<ICmpInst>(BI->getCondition());
Cases.push_back(std::make_pair(GetConstantInt(ICI->getOperand(1), TD),
BI->getSuccessor(ICI->getPredicate() ==
ICmpInst::ICMP_NE)));
BasicBlock *Succ = BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_NE);
Cases.push_back(ValueEqualityComparisonCase(GetConstantInt(ICI->getOperand(1),
TD),
Succ));
return BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_EQ);
}
@ -499,9 +514,9 @@ GetValueEqualityComparisonCases(TerminatorInst *TI,
/// 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<std::pair<ConstantInt*, BasicBlock*> > &Cases) {
std::vector<ValueEqualityComparisonCase> &Cases) {
for (unsigned i = 0, e = Cases.size(); i != e; ++i)
if (Cases[i].second == BB) {
if (Cases[i].Dest == BB) {
Cases.erase(Cases.begin()+i);
--i; --e;
}
@ -510,9 +525,9 @@ static void EliminateBlockCases(BasicBlock *BB,
/// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as
/// well.
static bool
ValuesOverlap(std::vector<std::pair<ConstantInt*, BasicBlock*> > &C1,
std::vector<std::pair<ConstantInt*, BasicBlock*> > &C2) {
std::vector<std::pair<ConstantInt*, BasicBlock*> > *V1 = &C1, *V2 = &C2;
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())
@ -521,9 +536,9 @@ ValuesOverlap(std::vector<std::pair<ConstantInt*, BasicBlock*> > &C1,
if (V1->size() == 0) return false;
if (V1->size() == 1) {
// Just scan V2.
ConstantInt *TheVal = (*V1)[0].first;
ConstantInt *TheVal = (*V1)[0].Value;
for (unsigned i = 0, e = V2->size(); i != e; ++i)
if (TheVal == (*V2)[i].first)
if (TheVal == (*V2)[i].Value)
return true;
}
@ -532,9 +547,9 @@ ValuesOverlap(std::vector<std::pair<ConstantInt*, BasicBlock*> > &C1,
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].first == (*V2)[i2].first)
if ((*V1)[i1].Value == (*V2)[i2].Value)
return true;
if ((*V1)[i1].first < (*V2)[i2].first)
if ((*V1)[i1].Value < (*V2)[i2].Value)
++i1;
else
++i2;
@ -560,13 +575,13 @@ 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<std::pair<ConstantInt*, BasicBlock*> > PredCases;
std::vector<ValueEqualityComparisonCase> PredCases;
BasicBlock *PredDef = GetValueEqualityComparisonCases(Pred->getTerminator(),
PredCases);
EliminateBlockCases(PredDef, PredCases); // Remove default from cases.
// Find information about how control leaves this block.
std::vector<std::pair<ConstantInt*, BasicBlock*> > ThisCases;
std::vector<ValueEqualityComparisonCase> ThisCases;
BasicBlock *ThisDef = GetValueEqualityComparisonCases(TI, ThisCases);
EliminateBlockCases(ThisDef, ThisCases); // Remove default from cases.
@ -588,7 +603,7 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
(void) NI;
// Remove PHI node entries for the dead edge.
ThisCases[0].second->removePredecessor(TI->getParent());
ThisCases[0].Dest->removePredecessor(TI->getParent());
DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator()
<< "Through successor TI: " << *TI << "Leaving: " << *NI << "\n");
@ -601,7 +616,7 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *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].first);
DeadCases.insert(PredCases[i].Value);
DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator()
<< "Through successor TI: " << *TI);
@ -623,10 +638,10 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
ConstantInt *TIV = 0;
BasicBlock *TIBB = TI->getParent();
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
if (PredCases[i].second == TIBB) {
if (PredCases[i].Dest == TIBB) {
if (TIV != 0)
return false; // Cannot handle multiple values coming to this block.
TIV = PredCases[i].first;
TIV = PredCases[i].Value;
}
assert(TIV && "No edge from pred to succ?");
@ -634,8 +649,8 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
// 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].first == TIV) {
TheRealDest = ThisCases[i].second;
if (ThisCases[i].Value == TIV) {
TheRealDest = ThisCases[i].Dest;
break;
}
@ -703,10 +718,10 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
if (PCV == CV && SafeToMergeTerminators(TI, PTI)) {
// Figure out which 'cases' to copy from SI to PSI.
std::vector<std::pair<ConstantInt*, BasicBlock*> > BBCases;
std::vector<ValueEqualityComparisonCase> BBCases;
BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases);
std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases;
std::vector<ValueEqualityComparisonCase> PredCases;
BasicBlock *PredDefault = GetValueEqualityComparisonCases(PTI, PredCases);
// Based on whether the default edge from PTI goes to BB or not, fill in
@ -719,8 +734,8 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *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].second != BB)
PTIHandled.insert(PredCases[i].first);
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());
@ -735,10 +750,10 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
NewSuccessors.push_back(BBDefault);
}
for (unsigned i = 0, e = BBCases.size(); i != e; ++i)
if (!PTIHandled.count(BBCases[i].first) &&
BBCases[i].second != BBDefault) {
if (!PTIHandled.count(BBCases[i].Value) &&
BBCases[i].Dest != BBDefault) {
PredCases.push_back(BBCases[i]);
NewSuccessors.push_back(BBCases[i].second);
NewSuccessors.push_back(BBCases[i].Dest);
}
} else {
@ -747,8 +762,8 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
// activated.
std::set<ConstantInt*, ConstantIntOrdering> PTIHandled;
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
if (PredCases[i].second == BB) {
PTIHandled.insert(PredCases[i].first);
if (PredCases[i].Dest == BB) {
PTIHandled.insert(PredCases[i].Value);
std::swap(PredCases[i], PredCases.back());
PredCases.pop_back();
--i; --e;
@ -757,11 +772,11 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
// 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].first)) {
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].second);
PTIHandled.erase(BBCases[i].first);// This constant is taken care of
NewSuccessors.push_back(BBCases[i].Dest);
PTIHandled.erase(BBCases[i].Value);// This constant is taken care of
}
// If there are any constants vectored to BB that TI doesn't handle,
@ -769,7 +784,7 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
for (std::set<ConstantInt*, ConstantIntOrdering>::iterator I =
PTIHandled.begin(),
E = PTIHandled.end(); I != E; ++I) {
PredCases.push_back(std::make_pair(*I, BBDefault));
PredCases.push_back(ValueEqualityComparisonCase(*I, BBDefault));
NewSuccessors.push_back(BBDefault);
}
}
@ -793,7 +808,7 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
PredCases.size());
NewSI->setDebugLoc(PTI->getDebugLoc());
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
NewSI->addCase(PredCases[i].first, PredCases[i].second);
NewSI->addCase(PredCases[i].Value, PredCases[i].Dest);
EraseTerminatorInstAndDCECond(PTI);