#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Type.h"
#include "llvm/DerivedTypes.h"
+#include "llvm/GlobalVariable.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
PN->addIncoming(PN->getIncomingValueForBlock(ExistPred), NewPred);
}
-// CanPropagatePredecessorsForPHIs - Return true if we can fold BB, an
-// almost-empty BB ending in an unconditional branch to Succ, into succ.
-//
-// Assumption: Succ is the single successor for BB.
-//
+/// CanPropagatePredecessorsForPHIs - Return true if we can fold BB, an
+/// almost-empty BB ending in an unconditional branch to Succ, into succ.
+///
+/// Assumption: Succ is the single successor for BB.
+///
static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!");
- DOUT << "Looking to fold " << BB->getNameStart() << " into "
- << Succ->getNameStart() << "\n";
- // Shortcut, if there is only a single predecessor is must be BB and merging
+ DEBUG(errs() << "Looking to fold " << BB->getName() << " into "
+ << Succ->getName() << "\n");
+ // Shortcut, if there is only a single predecessor it must be BB and merging
// is always safe
if (Succ->getSinglePredecessor()) return true;
- typedef SmallPtrSet<Instruction*, 16> InstrSet;
- InstrSet BBPHIs;
-
- // Make a list of all phi nodes in BB
- BasicBlock::iterator BBI = BB->begin();
- while (isa<PHINode>(*BBI)) BBPHIs.insert(BBI++);
-
// Make a list of the predecessors of BB
typedef SmallPtrSet<BasicBlock*, 16> BlockSet;
BlockSet BBPreds(pred_begin(BB), pred_end(BB));
PI != PE; PI++) {
if (BBPN->getIncomingValueForBlock(*PI)
!= PN->getIncomingValueForBlock(*PI)) {
- DOUT << "Can't fold, phi node " << *PN->getNameStart() << " in "
- << Succ->getNameStart() << " is conflicting with "
- << BBPN->getNameStart() << " with regard to common predecessor "
- << (*PI)->getNameStart() << "\n";
+ DEBUG(errs() << "Can't fold, phi node " << PN->getName() << " in "
+ << Succ->getName() << " is conflicting with "
+ << BBPN->getName() << " with regard to common predecessor "
+ << (*PI)->getName() << "\n");
return false;
}
}
- // Remove this phinode from the list of phis in BB, since it has been
- // handled.
- BBPHIs.erase(BBPN);
} else {
Value* Val = PN->getIncomingValueForBlock(BB);
for (BlockSet::iterator PI = CommonPreds.begin(), PE = CommonPreds.end();
// one for BB, in which case this phi node will not prevent the merging
// of the block.
if (Val != PN->getIncomingValueForBlock(*PI)) {
- DOUT << "Can't fold, phi node " << *PN->getNameStart() << " in "
- << Succ->getNameStart() << " is conflicting with regard to common "
- << "predecessor " << (*PI)->getNameStart() << "\n";
+ DEBUG(errs() << "Can't fold, phi node " << PN->getName() << " in "
+ << Succ->getName() << " is conflicting with regard to common "
+ << "predecessor " << (*PI)->getName() << "\n");
return false;
}
}
}
}
- // If there are any other phi nodes in BB that don't have a phi node in Succ
- // to merge with, they must be moved to Succ completely. However, for any
- // predecessors of Succ, branches will be added to the phi node that just
- // point to itself. So, for any common predecessors, this must not cause
- // conflicts.
- for (InstrSet::iterator I = BBPHIs.begin(), E = BBPHIs.end();
- I != E; I++) {
- PHINode *PN = cast<PHINode>(*I);
- for (BlockSet::iterator PI = CommonPreds.begin(), PE = CommonPreds.end();
- PI != PE; PI++)
- if (PN->getIncomingValueForBlock(*PI) != PN) {
- DOUT << "Can't fold, phi node " << *PN->getNameStart() << " in "
- << BB->getNameStart() << " is conflicting with regard to common "
- << "predecessor " << (*PI)->getNameStart() << "\n";
- return false;
- }
- }
-
return true;
}
// Check to see if merging these blocks would cause conflicts for any of the
// phi nodes in BB or Succ. If not, we can safely merge.
if (!CanPropagatePredecessorsForPHIs(BB, Succ)) return false;
-
- DOUT << "Killing Trivial BB: \n" << *BB;
+
+ // Check for cases where Succ has multiple predecessors and a PHI node in BB
+ // has uses which will not disappear when the PHI nodes are merged. It is
+ // possible to handle such cases, but difficult: it requires checking whether
+ // BB dominates Succ, which is non-trivial to calculate in the case where
+ // Succ has multiple predecessors. Also, it requires checking whether
+ // constructing the necessary self-referential PHI node doesn't intoduce any
+ // conflicts; this isn't too difficult, but the previous code for doing this
+ // was incorrect.
+ //
+ // Note that if this check finds a live use, BB dominates Succ, so BB is
+ // something like a loop pre-header (or rarely, a part of an irreducible CFG);
+ // folding the branch isn't profitable in that case anyway.
+ if (!Succ->getSinglePredecessor()) {
+ BasicBlock::iterator BBI = BB->begin();
+ while (isa<PHINode>(*BBI)) {
+ for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end();
+ UI != E; ++UI) {
+ if (PHINode* PN = dyn_cast<PHINode>(*UI)) {
+ if (PN->getIncomingBlock(UI) != BB)
+ return false;
+ } else {
+ return false;
+ }
+ }
+ ++BBI;
+ }
+ }
+
+ DEBUG(errs() << "Killing Trivial BB: \n" << *BB);
if (isa<PHINode>(Succ->begin())) {
// If there is more than one pred of succ, and there are PHI nodes in
}
}
- if (isa<PHINode>(&BB->front())) {
- SmallVector<BasicBlock*, 16>
- OldSuccPreds(pred_begin(Succ), pred_end(Succ));
-
- // Move all PHI nodes in BB to Succ if they are alive, otherwise
- // delete them.
- while (PHINode *PN = dyn_cast<PHINode>(&BB->front()))
- if (PN->use_empty()) {
- // Just remove the dead phi. This happens if Succ's PHIs were the only
- // users of the PHI nodes.
- PN->eraseFromParent();
- } else {
- // The instruction is alive, so this means that BB must dominate all
- // predecessors of Succ (Since all uses of the PN are after its
- // definition, so in Succ or a block dominated by Succ. If a predecessor
- // of Succ would not be dominated by BB, PN would violate the def before
- // use SSA demand). Therefore, we can simply move the phi node to the
- // next block.
- Succ->getInstList().splice(Succ->begin(),
- BB->getInstList(), BB->begin());
-
- // We need to add new entries for the PHI node to account for
- // predecessors of Succ that the PHI node does not take into
- // account. At this point, since we know that BB dominated succ and all
- // of its predecessors, this means that we should any newly added
- // incoming edges should use the PHI node itself as the value for these
- // edges, because they are loop back edges.
- for (unsigned i = 0, e = OldSuccPreds.size(); i != e; ++i)
- if (OldSuccPreds[i] != BB)
- PN->addIncoming(PN, OldSuccPreds[i]);
- }
+ while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
+ if (Succ->getSinglePredecessor()) {
+ // BB is the only predecessor of Succ, so Succ will end up with exactly
+ // the same predecessors BB had.
+ Succ->getInstList().splice(Succ->begin(),
+ BB->getInstList(), BB->begin());
+ } else {
+ // We explicitly check for such uses in CanPropagatePredecessorsForPHIs.
+ assert(PN->use_empty() && "There shouldn't be any uses here!");
+ PN->eraseFromParent();
+ }
}
// Everything that jumped to BB now goes to Succ.
return 0;
}
-
-// If we have a merge point of an "if condition" as accepted above, return true
-// if the specified value dominates the block. We don't handle the true
-// generality of domination here, just a special case which works well enough
-// for us.
-//
-// If AggressiveInsts is non-null, and if V does not dominate BB, we check to
-// see if V (which must be an instruction) is cheap to compute and is
-// non-trapping. If both are true, the instruction is inserted into the set and
-// true is returned.
+/// DominatesMergePoint - If we have a merge point of an "if condition" as
+/// accepted above, return true if the specified value dominates the block. We
+/// don't handle the true generality of domination here, just a special case
+/// which works well enough for us.
+///
+/// If AggressiveInsts is non-null, and if V does not dominate BB, we check to
+/// see if V (which must be an instruction) is cheap to compute and is
+/// non-trapping. If both are true, the instruction is inserted into the set
+/// and true is returned.
static bool DominatesMergePoint(Value *V, BasicBlock *BB,
std::set<Instruction*> *AggressiveInsts) {
Instruction *I = dyn_cast<Instruction>(V);
// Okay, it looks like the instruction IS in the "condition". Check to
// see if its a cheap instruction to unconditionally compute, and if it
// only uses stuff defined outside of the condition. If so, hoist it out.
+ if (!I->isSafeToSpeculativelyExecute())
+ return false;
+
switch (I->getOpcode()) {
default: return false; // Cannot hoist this out safely.
- case Instruction::Load:
- // We can hoist loads that are non-volatile and obviously cannot trap.
- if (cast<LoadInst>(I)->isVolatile())
- return false;
- // FIXME: A computation of a constant can trap!
- if (!isa<AllocaInst>(I->getOperand(0)) &&
- !isa<Constant>(I->getOperand(0)))
- return false;
-
- // Finally, we have to check to make sure there are no instructions
- // before the load in its basic block, as we are going to hoist the loop
- // out to its predecessor.
- if (PBB->begin() != BasicBlock::iterator(I))
+ case Instruction::Load: {
+ // We have to check to make sure there are no instructions before the
+ // load in its basic block, as we are going to hoist the loop out to
+ // its predecessor.
+ BasicBlock::iterator IP = PBB->begin();
+ while (isa<DbgInfoIntrinsic>(IP))
+ IP++;
+ if (IP != BasicBlock::iterator(I))
return false;
break;
+ }
case Instruction::Add:
case Instruction::Sub:
case Instruction::And:
case Instruction::LShr:
case Instruction::AShr:
case Instruction::ICmp:
- case Instruction::FCmp:
- if (I->getOperand(0)->getType()->isFPOrFPVector())
- return false; // FP arithmetic might trap.
break; // These are all cheap and non-trapping instructions.
}
return true;
}
-// GatherConstantSetEQs - Given a potentially 'or'd together collection of
-// icmp_eq instructions that compare a value against a constant, return the
-// value being compared, and stick the constant into the Values vector.
+/// GatherConstantSetEQs - Given a potentially 'or'd together collection of
+/// icmp_eq instructions that compare a value against a constant, return the
+/// value being compared, and stick the constant into the Values vector.
static Value *GatherConstantSetEQs(Value *V, std::vector<ConstantInt*> &Values){
if (Instruction *Inst = dyn_cast<Instruction>(V)) {
if (Inst->getOpcode() == Instruction::ICmp &&
return 0;
}
-// GatherConstantSetNEs - Given a potentially 'and'd together collection of
-// setne instructions that compare a value against a constant, return the value
-// being compared, and stick the constant into the Values vector.
+/// GatherConstantSetNEs - Given a potentially 'and'd together collection of
+/// setne instructions that compare a value against a constant, return the value
+/// being compared, and stick the constant into the Values vector.
static Value *GatherConstantSetNEs(Value *V, std::vector<ConstantInt*> &Values){
if (Instruction *Inst = dyn_cast<Instruction>(V)) {
if (Inst->getOpcode() == Instruction::ICmp &&
return 0;
}
-
-
/// GatherValueComparisons - If the specified Cond is an 'and' or 'or' of a
/// bunch of comparisons of one value against constants, return the value and
/// the constants being compared.
return 0;
}
-/// Given a value comparison instruction, decode all of the 'cases' that it
-/// represents and return the 'default' block.
+/// GetValueEqualityComparisonCases - Given a value comparison instruction,
+/// decode all of the 'cases' that it represents and return the 'default' block.
static BasicBlock *
GetValueEqualityComparisonCases(TerminatorInst *TI,
std::vector<std::pair<ConstantInt*,
}
-// EliminateBlockCases - Given a vector of bb/value pairs, remove any entries
-// in the list that match the specified block.
+/// 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) {
for (unsigned i = 0, e = Cases.size(); i != e; ++i)
}
}
-// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as
-// well.
+/// 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) {
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
-// comparison with the same value, and if that comparison determines the outcome
-// of this comparison. If so, simplify TI. This does a very limited form of
-// jump threading.
+/// 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
+/// comparison with the same value, and if that comparison determines the
+/// outcome of this comparison. If so, simplify TI. This does a very limited
+/// form of jump threading.
static bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
BasicBlock *Pred) {
Value *PredVal = isValueEqualityComparison(Pred->getTerminator());
assert(ThisCases.size() == 1 && "Branch can only have one case!");
// Insert the new branch.
Instruction *NI = BranchInst::Create(ThisDef, TI);
+ (void) NI;
// Remove PHI node entries for the dead edge.
ThisCases[0].second->removePredecessor(TI->getParent());
- DOUT << "Threading pred instr: " << *Pred->getTerminator()
- << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n";
+ DEBUG(errs() << "Threading pred instr: " << *Pred->getTerminator()
+ << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n");
EraseTerminatorInstAndDCECond(TI);
return true;
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
DeadCases.insert(PredCases[i].first);
- DOUT << "Threading pred instr: " << *Pred->getTerminator()
- << "Through successor TI: " << *TI;
+ DEBUG(errs() << "Threading pred instr: " << *Pred->getTerminator()
+ << "Through successor TI: " << *TI);
for (unsigned i = SI->getNumCases()-1; i != 0; --i)
if (DeadCases.count(SI->getCaseValue(i))) {
SI->removeCase(i);
}
- DOUT << "Leaving: " << *TI << "\n";
+ DEBUG(errs() << "Leaving: " << *TI << "\n");
return true;
}
}
// Insert the new branch.
Instruction *NI = BranchInst::Create(TheRealDest, TI);
+ (void) NI;
- DOUT << "Threading pred instr: " << *Pred->getTerminator()
- << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n";
+ DEBUG(errs() << "Threading pred instr: " << *Pred->getTerminator()
+ << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n");
EraseTerminatorInstAndDCECond(TI);
return true;
return false;
}
-// FoldValueComparisonIntoPredecessors - The specified terminator is a value
-// equality comparison instruction (either a switch or a branch on "X == c").
-// See if any of the predecessors of the terminator block are value comparisons
-// on the same value. If so, and if safe to do so, fold them together.
+namespace {
+ /// ConstantIntOrdering - This class implements a stable ordering of constant
+ /// integers that does not depend on their address. This is important for
+ /// applications that sort ConstantInt's to ensure uniqueness.
+ struct ConstantIntOrdering {
+ bool operator()(const ConstantInt *LHS, const ConstantInt *RHS) const {
+ return LHS->getValue().ult(RHS->getValue());
+ }
+ };
+}
+
+/// FoldValueComparisonIntoPredecessors - The specified terminator is a value
+/// equality comparison instruction (either a switch or a branch on "X == c").
+/// See if any of the predecessors of the terminator block are value comparisons
+/// on the same value. If so, and if safe to do so, fold them together.
static bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI) {
BasicBlock *BB = TI->getParent();
Value *CV = isValueEqualityComparison(TI); // CondVal
SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB));
while (!Preds.empty()) {
- BasicBlock *Pred = Preds.back();
- Preds.pop_back();
+ BasicBlock *Pred = Preds.pop_back_val();
// See if the predecessor is a comparison with the same value.
TerminatorInst *PTI = Pred->getTerminator();
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*> PTIHandled;
+ 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 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*> PTIHandled;
+ 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 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*>::iterator I = PTIHandled.begin(),
+ for (std::set<ConstantInt*, ConstantIntOrdering>::iterator I =
+ PTIHandled.begin(),
E = PTIHandled.end(); I != E; ++I) {
PredCases.push_back(std::make_pair(*I, BBDefault));
NewSuccessors.push_back(BBDefault);
if (InfLoopBlock == 0) {
// Insert it at the end of the function, because it's either code,
// or it won't matter if it's hot. :)
- InfLoopBlock = BasicBlock::Create("infloop", BB->getParent());
+ InfLoopBlock = BasicBlock::Create(BB->getContext(),
+ "infloop", BB->getParent());
BranchInst::Create(InfLoopBlock, InfLoopBlock);
}
NewSI->setSuccessor(i, InfLoopBlock);
return Changed;
}
+// isSafeToHoistInvoke - If we would need to insert a select that uses the
+// value of this invoke (comments in HoistThenElseCodeToIf explain why we
+// would need to do this), we can't hoist the invoke, as there is nowhere
+// to put the select in this case.
+static bool isSafeToHoistInvoke(BasicBlock *BB1, BasicBlock *BB2,
+ Instruction *I1, Instruction *I2) {
+ for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) {
+ PHINode *PN;
+ for (BasicBlock::iterator BBI = SI->begin();
+ (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
+ Value *BB1V = PN->getIncomingValueForBlock(BB1);
+ Value *BB2V = PN->getIncomingValueForBlock(BB2);
+ if (BB1V != BB2V && (BB1V==I1 || BB2V==I2)) {
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
/// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and
/// BB2, hoist any common code in the two blocks up into the branch block. The
/// caller of this function guarantees that BI's block dominates BB1 and BB2.
BasicBlock *BB1 = BI->getSuccessor(0); // The true destination.
BasicBlock *BB2 = BI->getSuccessor(1); // The false destination
- Instruction *I1 = BB1->begin(), *I2 = BB2->begin();
- if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) ||
- isa<InvokeInst>(I1) || !I1->isIdenticalTo(I2))
+ BasicBlock::iterator BB1_Itr = BB1->begin();
+ BasicBlock::iterator BB2_Itr = BB2->begin();
+
+ Instruction *I1 = BB1_Itr++, *I2 = BB2_Itr++;
+ while (isa<DbgInfoIntrinsic>(I1))
+ I1 = BB1_Itr++;
+ while (isa<DbgInfoIntrinsic>(I2))
+ I2 = BB2_Itr++;
+ if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) ||
+ !I1->isIdenticalToWhenDefined(I2) ||
+ (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)))
return false;
// If we get here, we can hoist at least one instruction.
BIParent->getInstList().splice(BI, BB1->getInstList(), I1);
if (!I2->use_empty())
I2->replaceAllUsesWith(I1);
+ I1->intersectOptionalDataWith(I2);
BB2->getInstList().erase(I2);
- I1 = BB1->begin();
- I2 = BB2->begin();
- } while (I1->getOpcode() == I2->getOpcode() && I1->isIdenticalTo(I2));
+ I1 = BB1_Itr++;
+ while (isa<DbgInfoIntrinsic>(I1))
+ I1 = BB1_Itr++;
+ I2 = BB2_Itr++;
+ while (isa<DbgInfoIntrinsic>(I2))
+ I2 = BB2_Itr++;
+ } while (I1->getOpcode() == I2->getOpcode() &&
+ I1->isIdenticalToWhenDefined(I2));
return true;
HoistTerminator:
+ // It may not be possible to hoist an invoke.
+ if (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2))
+ return true;
+
// Okay, it is safe to hoist the terminator.
Instruction *NT = I1->clone();
BIParent->getInstList().insert(BI, NT);
- if (NT->getType() != Type::VoidTy) {
+ if (NT->getType() != Type::getVoidTy(BB1->getContext())) {
I1->replaceAllUsesWith(NT);
I2->replaceAllUsesWith(NT);
NT->takeName(I1);
static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) {
// Only speculatively execution a single instruction (not counting the
// terminator) for now.
- BasicBlock::iterator BBI = BB1->begin();
- ++BBI; // must have at least a terminator
- if (BBI == BB1->end()) return false; // only one inst
- ++BBI;
- if (BBI != BB1->end()) return false; // more than 2 insts.
+ Instruction *HInst = NULL;
+ Instruction *Term = BB1->getTerminator();
+ for (BasicBlock::iterator BBI = BB1->begin(), BBE = BB1->end();
+ BBI != BBE; ++BBI) {
+ Instruction *I = BBI;
+ // Skip debug info.
+ if (isa<DbgInfoIntrinsic>(I)) continue;
+ if (I == Term) break;
+
+ if (!HInst)
+ HInst = I;
+ else
+ return false;
+ }
+ if (!HInst)
+ return false;
// Be conservative for now. FP select instruction can often be expensive.
Value *BrCond = BI->getCondition();
// %t1 = icmp
// %t4 = add %t2, c
// %t3 = select i1 %t1, %t2, %t3
- Instruction *I = BB1->begin();
- switch (I->getOpcode()) {
+ switch (HInst->getOpcode()) {
default: return false; // Not safe / profitable to hoist.
case Instruction::Add:
case Instruction::Sub:
- // FP arithmetic might trap. Not worth doing for vector ops.
- if (I->getType()->isFloatingPoint() || isa<VectorType>(I->getType()))
+ // Not worth doing for vector ops.
+ if (isa<VectorType>(HInst->getType()))
return false;
break;
case Instruction::And:
case Instruction::LShr:
case Instruction::AShr:
// Don't mess with vector operations.
- if (isa<VectorType>(I->getType()))
+ if (isa<VectorType>(HInst->getType()))
return false;
break; // These are all cheap and non-trapping instructions.
}
// If the instruction is obviously dead, don't try to predicate it.
- if (I->use_empty()) {
- I->eraseFromParent();
+ if (HInst->use_empty()) {
+ HInst->eraseFromParent();
return true;
}
Value *FalseV = NULL;
BasicBlock *BB2 = BB1->getTerminator()->getSuccessor(0);
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
+ for (Value::use_iterator UI = HInst->use_begin(), E = HInst->use_end();
UI != E; ++UI) {
// Ignore any user that is not a PHI node in BB2. These can only occur in
// unreachable blocks, because they would not be dominated by the instr.
// Do not hoist the instruction if any of its operands are defined but not
// used in this BB. The transformation will prevent the operand from
// being sunk into the use block.
- for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) {
+ for (User::op_iterator i = HInst->op_begin(), e = HInst->op_end();
+ i != e; ++i) {
Instruction *OpI = dyn_cast<Instruction>(*i);
if (OpI && OpI->getParent() == BIParent &&
!OpI->isUsedInBasicBlock(BIParent))
}
// If we get here, we can hoist the instruction. Try to place it
- // before the icmp instruction preceeding the conditional branch.
+ // before the icmp instruction preceding the conditional branch.
BasicBlock::iterator InsertPos = BI;
- if (InsertPos != BIParent->begin())
+ if (InsertPos != BIParent->begin())
+ --InsertPos;
+ // Skip debug info between condition and branch.
+ while (InsertPos != BIParent->begin() && isa<DbgInfoIntrinsic>(InsertPos))
--InsertPos;
if (InsertPos == BrCond && !isa<PHINode>(BrCond)) {
SmallPtrSet<Instruction *, 4> BB1Insns;
}
} else
InsertPos = BI;
- BIParent->getInstList().splice(InsertPos, BB1->getInstList(), I);
+ BIParent->getInstList().splice(InsertPos, BB1->getInstList(), HInst);
// Create a select whose true value is the speculatively executed value and
// false value is the previously determined FalseV.
SelectInst *SI;
if (Invert)
- SI = SelectInst::Create(BrCond, FalseV, I,
- FalseV->getName() + "." + I->getName(), BI);
+ SI = SelectInst::Create(BrCond, FalseV, HInst,
+ FalseV->getName() + "." + HInst->getName(), BI);
else
- SI = SelectInst::Create(BrCond, I, FalseV,
- I->getName() + "." + FalseV->getName(), BI);
+ SI = SelectInst::Create(BrCond, HInst, FalseV,
+ HInst->getName() + "." + FalseV->getName(), BI);
// Make the PHI node use the select for all incoming values for "then" and
// "if" blocks.
BranchInst *BI = cast<BranchInst>(BB->getTerminator());
unsigned Size = 0;
- // If this basic block contains anything other than a PHI (which controls the
- // branch) and branch itself, bail out. FIXME: improve this in the future.
- for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI, ++Size) {
+ for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) {
+ if (isa<DbgInfoIntrinsic>(BBI))
+ continue;
if (Size > 10) return false; // Don't clone large BB's.
+ ++Size;
- // We can only support instructions that are do not define values that are
+ // We can only support instructions that do not define values that are
// live outside of the current basic block.
for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end();
UI != E; ++UI) {
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
ConstantInt *CB;
if ((CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i))) &&
- CB->getType() == Type::Int1Ty) {
+ CB->getType() == Type::getInt1Ty(BB->getContext())) {
// Okay, we now know that all edges from PredBB should be revectored to
// branch to RealDest.
BasicBlock *PredBB = PN->getIncomingBlock(i);
// difficult cases. Instead of being smart about this, just insert a new
// block that jumps to the destination block, effectively splitting
// the edge we are about to create.
- BasicBlock *EdgeBB = BasicBlock::Create(RealDest->getName()+".critedge",
+ BasicBlock *EdgeBB = BasicBlock::Create(BB->getContext(),
+ RealDest->getName()+".critedge",
RealDest->getParent(), RealDest);
BranchInst::Create(RealDest, EdgeBB);
PHINode *PN;
}
// Check for trivial simplification.
- if (Constant *C = ConstantFoldInstruction(N)) {
+ if (Constant *C = ConstantFoldInstruction(N, BB->getContext())) {
TranslateMap[BBI] = C;
delete N; // Constant folded away, don't need actual inst
} else {
if (NumPhis > 2)
return false;
- DOUT << "FOUND IF CONDITION! " << *IfCond << " T: "
- << IfTrue->getName() << " F: " << IfFalse->getName() << "\n";
+ DEBUG(errs() << "FOUND IF CONDITION! " << *IfCond << " T: "
+ << IfTrue->getName() << " F: " << IfFalse->getName() << "\n");
// Loop over the PHI's seeing if we can promote them all to select
// instructions. While we are at it, keep track of the instructions
DomBlock = *pred_begin(Pred);
for (BasicBlock::iterator I = Pred->begin();
!isa<TerminatorInst>(I); ++I)
- if (!AggressiveInsts.count(I)) {
+ if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) {
// This is not an aggressive instruction that we can promote.
// Because of this, we won't be able to get rid of the control
// flow, so the xform is not worth it.
DomBlock = *pred_begin(Pred);
for (BasicBlock::iterator I = Pred->begin();
!isa<TerminatorInst>(I); ++I)
- if (!AggressiveInsts.count(I)) {
+ if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) {
// This is not an aggressive instruction that we can promote.
// Because of this, we won't be able to get rid of the control
// flow, so the xform is not worth it.
return true;
}
+/// isTerminatorFirstRelevantInsn - Return true if Term is very first
+/// instruction ignoring Phi nodes and dbg intrinsics.
+static bool isTerminatorFirstRelevantInsn(BasicBlock *BB, Instruction *Term) {
+ BasicBlock::iterator BBI = Term;
+ while (BBI != BB->begin()) {
+ --BBI;
+ if (!isa<DbgInfoIntrinsic>(BBI))
+ break;
+ }
+
+ if (isa<PHINode>(BBI) || &*BBI == Term || isa<DbgInfoIntrinsic>(BBI))
+ return true;
+ return false;
+}
+
/// SimplifyCondBranchToTwoReturns - If we found a conditional branch that goes
/// to two returning blocks, try to merge them together into one return,
/// introducing a select if the return values disagree.
// Check to ensure both blocks are empty (just a return) or optionally empty
// with PHI nodes. If there are other instructions, merging would cause extra
// computation on one path or the other.
- BasicBlock::iterator BBI = TrueRet;
- if (BBI != TrueSucc->begin() && !isa<PHINode>(--BBI))
- return false; // Not empty with optional phi nodes.
- BBI = FalseRet;
- if (BBI != FalseSucc->begin() && !isa<PHINode>(--BBI))
- return false; // Not empty with optional phi nodes.
+ if (!isTerminatorFirstRelevantInsn(TrueSucc, TrueRet))
+ return false;
+ if (!isTerminatorFirstRelevantInsn(FalseSucc, FalseRet))
+ return false;
// Okay, we found a branch that is going to two return nodes. If
// there is no return value for this function, just change the
if (FalseRet->getNumOperands() == 0) {
TrueSucc->removePredecessor(BI->getParent());
FalseSucc->removePredecessor(BI->getParent());
- ReturnInst::Create(0, BI);
+ ReturnInst::Create(BI->getContext(), 0, BI);
EraseTerminatorInstAndDCECond(BI);
return true;
}
}
Value *RI = !TrueValue ?
- ReturnInst::Create(BI) :
- ReturnInst::Create(TrueValue, BI);
+ ReturnInst::Create(BI->getContext(), BI) :
+ ReturnInst::Create(BI->getContext(), TrueValue, BI);
+ (void) RI;
- DOUT << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:"
- << "\n " << *BI << "NewRet = " << *RI
- << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc;
+ DEBUG(errs() << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:"
+ << "\n " << *BI << "NewRet = " << *RI
+ << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc);
EraseTerminatorInstAndDCECond(BI);
/// and if a predecessor branches to us and one of our successors, fold the
/// setcc into the predecessor and use logical operations to pick the right
/// destination.
-static bool FoldBranchToCommonDest(BranchInst *BI) {
+bool llvm::FoldBranchToCommonDest(BranchInst *BI) {
BasicBlock *BB = BI->getParent();
Instruction *Cond = dyn_cast<Instruction>(BI->getCondition());
if (Cond == 0) return false;
// Only allow this if the condition is a simple instruction that can be
// executed unconditionally. It must be in the same block as the branch, and
// must be at the front of the block.
+ BasicBlock::iterator FrontIt = BB->front();
+ // Ignore dbg intrinsics.
+ while(isa<DbgInfoIntrinsic>(FrontIt))
+ ++FrontIt;
if ((!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond)) ||
- Cond->getParent() != BB || &BB->front() != Cond || !Cond->hasOneUse())
+ Cond->getParent() != BB || &*FrontIt != Cond || !Cond->hasOneUse()) {
return false;
-
+ }
+
// Make sure the instruction after the condition is the cond branch.
BasicBlock::iterator CondIt = Cond; ++CondIt;
- if (&*CondIt != BI)
+ // Ingore dbg intrinsics.
+ while(isa<DbgInfoIntrinsic>(CondIt))
+ ++CondIt;
+ if (&*CondIt != BI) {
+ assert (!isa<DbgInfoIntrinsic>(CondIt) && "Hey do not forget debug info!");
return false;
+ }
+
+ // Cond is known to be a compare or binary operator. Check to make sure that
+ // neither operand is a potentially-trapping constant expression.
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(0)))
+ if (CE->canTrap())
+ return false;
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(1)))
+ if (CE->canTrap())
+ return false;
+
// Finally, don't infinitely unroll conditional loops.
BasicBlock *TrueDest = BI->getSuccessor(0);
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
BasicBlock *PredBlock = *PI;
BranchInst *PBI = dyn_cast<BranchInst>(PredBlock->getTerminator());
+
// Check that we have two conditional branches. If there is a PHI node in
// the common successor, verify that the same value flows in from both
// blocks.
else
continue;
+ DEBUG(errs() << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB);
+
// If we need to invert the condition in the pred block to match, do so now.
if (InvertPredCond) {
Value *NewCond =
static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) {
assert(PBI->isConditional() && BI->isConditional());
BasicBlock *BB = BI->getParent();
-
+
// If this block ends with a branch instruction, and if there is a
// predecessor that ends on a branch of the same condition, make
// this conditional branch redundant.
if (BB->getSinglePredecessor()) {
// Turn this into a branch on constant.
bool CondIsTrue = PBI->getSuccessor(0) == BB;
- BI->setCondition(ConstantInt::get(Type::Int1Ty, CondIsTrue));
+ BI->setCondition(ConstantInt::get(Type::getInt1Ty(BB->getContext()),
+ CondIsTrue));
return true; // Nuke the branch on constant.
}
// in the constant and simplify the block result. Subsequent passes of
// simplifycfg will thread the block.
if (BlockIsSimpleEnoughToThreadThrough(BB)) {
- PHINode *NewPN = PHINode::Create(Type::Int1Ty,
+ PHINode *NewPN = PHINode::Create(Type::getInt1Ty(BB->getContext()),
BI->getCondition()->getName() + ".pr",
BB->begin());
// Okay, we're going to insert the PHI node. Since PBI is not the only
PBI->getCondition() == BI->getCondition() &&
PBI->getSuccessor(0) != PBI->getSuccessor(1)) {
bool CondIsTrue = PBI->getSuccessor(0) == BB;
- NewPN->addIncoming(ConstantInt::get(Type::Int1Ty,
+ NewPN->addIncoming(ConstantInt::get(Type::getInt1Ty(BB->getContext()),
CondIsTrue), *PI);
} else {
NewPN->addIncoming(BI->getCondition(), *PI);
// If this is a conditional branch in an empty block, and if any
// predecessors is a conditional branch to one of our destinations,
// fold the conditions into logical ops and one cond br.
- if (&BB->front() != BI)
+ BasicBlock::iterator BBI = BB->begin();
+ // Ignore dbg intrinsics.
+ while (isa<DbgInfoIntrinsic>(BBI))
+ ++BBI;
+ if (&*BBI != BI)
return false;
+
+
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(BI->getCondition()))
+ if (CE->canTrap())
+ return false;
int PBIOp, BIOp;
if (PBI->getSuccessor(0) == BI->getSuccessor(0))
// Finally, if everything is ok, fold the branches to logical ops.
BasicBlock *OtherDest = BI->getSuccessor(BIOp ^ 1);
- DOUT << "FOLDING BRs:" << *PBI->getParent()
- << "AND: " << *BI->getParent();
+ DEBUG(errs() << "FOLDING BRs:" << *PBI->getParent()
+ << "AND: " << *BI->getParent());
// If OtherDest *is* BB, then BB is a basic block with a single conditional
if (OtherDest == BB) {
// Insert it at the end of the function, because it's either code,
// or it won't matter if it's hot. :)
- BasicBlock *InfLoopBlock = BasicBlock::Create("infloop", BB->getParent());
+ BasicBlock *InfLoopBlock = BasicBlock::Create(BB->getContext(),
+ "infloop", BB->getParent());
BranchInst::Create(InfLoopBlock, InfLoopBlock);
OtherDest = InfLoopBlock;
}
- DOUT << *PBI->getParent()->getParent();
+ DEBUG(errs() << *PBI->getParent()->getParent());
// BI may have other predecessors. Because of this, we leave
// it alone, but modify PBI.
}
}
- DOUT << "INTO: " << *PBI->getParent();
-
- DOUT << *PBI->getParent()->getParent();
+ DEBUG(errs() << "INTO: " << *PBI->getParent());
+ DEBUG(errs() << *PBI->getParent()->getParent());
// This basic block is probably dead. We know it has at least
// one fewer predecessor.
return true;
}
-
-namespace {
- /// ConstantIntOrdering - This class implements a stable ordering of constant
- /// integers that does not depend on their address. This is important for
- /// applications that sort ConstantInt's to ensure uniqueness.
- struct ConstantIntOrdering {
- bool operator()(const ConstantInt *LHS, const ConstantInt *RHS) const {
- return LHS->getValue().ult(RHS->getValue());
+/// EliminateDuplicatePHINodes - Check for and eliminate duplicate PHI
+/// nodes in this block. This doesn't try to be clever about PHI nodes
+/// which differ only in the order of the incoming values, but instcombine
+/// orders them so it usually won't matter.
+///
+static bool EliminateDuplicatePHINodes(BasicBlock *BB) {
+ bool Changed = false;
+
+ // This implementation doesn't currently consider undef operands
+ // specially. Theroetically, two phis which are identical except for
+ // one having an undef where the other doesn't could be collapsed.
+
+ // Map from PHI hash values to PHI nodes. If multiple PHIs have
+ // the same hash value, the element is the first PHI in the
+ // linked list in CollisionMap.
+ DenseMap<uintptr_t, PHINode *> HashMap;
+
+ // Maintain linked lists of PHI nodes with common hash values.
+ DenseMap<PHINode *, PHINode *> CollisionMap;
+
+ // Examine each PHI.
+ for (BasicBlock::iterator I = BB->begin();
+ PHINode *PN = dyn_cast<PHINode>(I++); ) {
+ // Compute a hash value on the operands. Instcombine will likely have sorted
+ // them, which helps expose duplicates, but we have to check all the
+ // operands to be safe in case instcombine hasn't run.
+ uintptr_t Hash = 0;
+ for (User::op_iterator I = PN->op_begin(), E = PN->op_end(); I != E; ++I) {
+ // This hash algorithm is quite weak as hash functions go, but it seems
+ // to do a good enough job for this particular purpose, and is very quick.
+ Hash ^= reinterpret_cast<uintptr_t>(static_cast<Value *>(*I));
+ Hash = (Hash << 7) | (Hash >> (sizeof(uintptr_t) * CHAR_BIT - 7));
}
- };
+ // If we've never seen this hash value before, it's a unique PHI.
+ std::pair<DenseMap<uintptr_t, PHINode *>::iterator, bool> Pair =
+ HashMap.insert(std::make_pair(Hash, PN));
+ if (Pair.second) continue;
+ // Otherwise it's either a duplicate or a hash collision.
+ for (PHINode *OtherPN = Pair.first->second; ; ) {
+ if (OtherPN->isIdenticalTo(PN)) {
+ // A duplicate. Replace this PHI with its duplicate.
+ PN->replaceAllUsesWith(OtherPN);
+ PN->eraseFromParent();
+ Changed = true;
+ break;
+ }
+ // A non-duplicate hash collision.
+ DenseMap<PHINode *, PHINode *>::iterator I = CollisionMap.find(OtherPN);
+ if (I == CollisionMap.end()) {
+ // Set this PHI to be the head of the linked list of colliding PHIs.
+ PHINode *Old = Pair.first->second;
+ Pair.first->second = PN;
+ CollisionMap[PN] = Old;
+ break;
+ }
+ // Procede to the next PHI in the list.
+ OtherPN = I->second;
+ }
+ }
+
+ return Changed;
}
-// SimplifyCFG - This function is used to do simplification of a CFG. For
-// example, it adjusts branches to branches to eliminate the extra hop, it
-// eliminates unreachable basic blocks, and does other "peephole" optimization
-// of the CFG. It returns true if a modification was made.
-//
-// WARNING: The entry node of a function may not be simplified.
-//
+/// SimplifyCFG - This function is used to do simplification of a CFG. For
+/// example, it adjusts branches to branches to eliminate the extra hop, it
+/// eliminates unreachable basic blocks, and does other "peephole" optimization
+/// of the CFG. It returns true if a modification was made.
+///
+/// WARNING: The entry node of a function may not be simplified.
+///
bool llvm::SimplifyCFG(BasicBlock *BB) {
bool Changed = false;
Function *M = BB->getParent();
// Remove basic blocks that have no predecessors... or that just have themself
// as a predecessor. These are unreachable.
if (pred_begin(BB) == pred_end(BB) || BB->getSinglePredecessor() == BB) {
- DOUT << "Removing BB: \n" << *BB;
+ DEBUG(errs() << "Removing BB: \n" << *BB);
DeleteDeadBlock(BB);
return true;
}
// away...
Changed |= ConstantFoldTerminator(BB);
+ // Check for and eliminate duplicate PHI nodes in this block.
+ Changed |= EliminateDuplicatePHINodes(BB);
+
// If there is a trivial two-entry PHI node in this basic block, and we can
// eliminate it, do so now.
if (PHINode *PN = dyn_cast<PHINode>(BB->begin()))
// different return values, fold the replace the branch/return with a select
// and return.
if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
- BasicBlock::iterator BBI = BB->getTerminator();
- if (BBI == BB->begin() || isa<PHINode>(--BBI)) {
+ if (isTerminatorFirstRelevantInsn(BB, BB->getTerminator())) {
// Find predecessors that end with branches.
SmallVector<BasicBlock*, 8> UncondBranchPreds;
SmallVector<BranchInst*, 8> CondBranchPreds;
// If we found some, do the transformation!
if (!UncondBranchPreds.empty()) {
while (!UncondBranchPreds.empty()) {
- BasicBlock *Pred = UncondBranchPreds.back();
- DOUT << "FOLDING: " << *BB
- << "INTO UNCOND BRANCH PRED: " << *Pred;
- UncondBranchPreds.pop_back();
+ BasicBlock *Pred = UncondBranchPreds.pop_back_val();
+ DEBUG(errs() << "FOLDING: " << *BB
+ << "INTO UNCOND BRANCH PRED: " << *Pred);
Instruction *UncondBranch = Pred->getTerminator();
// Clone the return and add it to the end of the predecessor.
Instruction *NewRet = RI->clone();
Pred->getInstList().push_back(NewRet);
+ BasicBlock::iterator BBI = RI;
+ if (BBI != BB->begin()) {
+ // Move region end info into the predecessor.
+ if (DbgRegionEndInst *DREI = dyn_cast<DbgRegionEndInst>(--BBI))
+ DREI->moveBefore(NewRet);
+ }
+
// If the return instruction returns a value, and if the value was a
// PHI node in "BB", propagate the right value into the return.
for (User::op_iterator i = NewRet->op_begin(), e = NewRet->op_end();
// instruction. If any of them just select between returns, change the
// branch itself into a select/return pair.
while (!CondBranchPreds.empty()) {
- BranchInst *BI = CondBranchPreds.back();
- CondBranchPreds.pop_back();
+ BranchInst *BI = CondBranchPreds.pop_back_val();
// Check to see if the non-BB successor is also a return block.
if (isa<ReturnInst>(BI->getSuccessor(0)->getTerminator()) &&
} else if (isa<UnwindInst>(BB->begin())) {
// Check to see if the first instruction in this block is just an unwind.
// If so, replace any invoke instructions which use this as an exception
- // destination with call instructions, and any unconditional branch
- // predecessor with an unwind.
+ // destination with call instructions.
//
SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB));
while (!Preds.empty()) {
BasicBlock *Pred = Preds.back();
- if (BranchInst *BI = dyn_cast<BranchInst>(Pred->getTerminator())) {
- if (BI->isUnconditional()) {
- Pred->getInstList().pop_back(); // nuke uncond branch
- new UnwindInst(Pred); // Use unwind.
- Changed = true;
- }
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()))
+ if (InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()))
if (II->getUnwindDest() == BB) {
// Insert a new branch instruction before the invoke, because this
- // is now a fall through...
+ // is now a fall through.
BranchInst *BI = BranchInst::Create(II->getNormalDest(), II);
Pred->getInstList().remove(II); // Take out of symbol table
- // Insert the call now...
+ // Insert the call now.
SmallVector<Value*,8> Args(II->op_begin()+3, II->op_end());
CallInst *CI = CallInst::Create(II->getCalledValue(),
Args.begin(), Args.end(),
II->getName(), BI);
CI->setCallingConv(II->getCallingConv());
CI->setAttributes(II->getAttributes());
- // If the invoke produced a value, the Call now does instead
+ // If the invoke produced a value, the Call now does instead.
II->replaceAllUsesWith(CI);
delete II;
Changed = true;
// If the block only contains the switch, see if we can fold the block
// away into any preds.
- if (SI == &BB->front())
+ BasicBlock::iterator BBI = BB->begin();
+ // Ignore dbg intrinsics.
+ while (isa<DbgInfoIntrinsic>(BBI))
+ ++BBI;
+ if (SI == &*BBI)
if (FoldValueComparisonIntoPredecessors(SI))
return SimplifyCFG(BB) || 1;
}
BasicBlock::iterator BBI = BB->getFirstNonPHI();
BasicBlock *Succ = BI->getSuccessor(0);
+ // Ignore dbg intrinsics.
+ while (isa<DbgInfoIntrinsic>(BBI))
+ ++BBI;
if (BBI->isTerminator() && // Terminator is the only non-phi instruction!
Succ != BB) // Don't hurt infinite loops!
if (TryToSimplifyUncondBranchFromEmptyBlock(BB, Succ))
return SimplifyCFG(BB) || 1;
// This block must be empty, except for the setcond inst, if it exists.
+ // Ignore dbg intrinsics.
BasicBlock::iterator I = BB->begin();
- if (&*I == BI ||
- (&*I == cast<Instruction>(BI->getCondition()) &&
- &*++I == BI))
+ // Ignore dbg intrinsics.
+ while (isa<DbgInfoIntrinsic>(I))
+ ++I;
+ if (&*I == BI) {
if (FoldValueComparisonIntoPredecessors(BI))
return SimplifyCFG(BB) | true;
+ } else if (&*I == cast<Instruction>(BI->getCondition())){
+ ++I;
+ // Ignore dbg intrinsics.
+ while (isa<DbgInfoIntrinsic>(I))
+ ++I;
+ if(&*I == BI) {
+ if (FoldValueComparisonIntoPredecessors(BI))
+ return SimplifyCFG(BB) | true;
+ }
+ }
}
-
+
// If this is a branch on a phi node in the current block, thread control
// through this block if any PHI node entries are constants.
if (PHINode *PN = dyn_cast<PHINode>(BI->getCondition()))
--BBI;
// Do not delete instructions that can have side effects, like calls
// (which may never return) and volatile loads and stores.
- if (isa<CallInst>(BBI)) break;
+ if (isa<CallInst>(BBI) && !isa<DbgInfoIntrinsic>(BBI)) break;
if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
if (SI->isVolatile())
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
if (BI->isUnconditional()) {
if (BI->getSuccessor(0) == BB) {
- new UnreachableInst(TI);
+ new UnreachableInst(TI->getContext(), TI);
TI->eraseFromParent();
Changed = true;
}