#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <set>
#include <map>
using namespace llvm;
+static cl::opt<unsigned>
+PHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(1),
+ cl::desc("Control the amount of phi node folding to perform (default = 1)"));
+
static cl::opt<bool>
DupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false),
cl::desc("Duplicate return instructions into unconditional branches"));
BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI,
std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases);
bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
- BasicBlock *Pred);
- bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI);
+ BasicBlock *Pred,
+ IRBuilder<> &Builder);
+ bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
+ IRBuilder<> &Builder);
- bool SimplifyReturn(ReturnInst *RI);
- bool SimplifyUnwind(UnwindInst *UI);
+ bool SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder);
+ bool SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder);
bool SimplifyUnreachable(UnreachableInst *UI);
- bool SimplifySwitch(SwitchInst *SI);
+ bool SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder);
bool SimplifyIndirectBr(IndirectBrInst *IBI);
- bool SimplifyUncondBranch(BranchInst *BI);
- bool SimplifyCondBranch(BranchInst *BI);
+ bool SimplifyUncondBranch(BranchInst *BI, IRBuilder <> &Builder);
+ bool SimplifyCondBranch(BranchInst *BI, IRBuilder <>&Builder);
public:
explicit SimplifyCFGOpt(const TargetData *td) : TD(td) {}
/// 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.
+/// see if V (which must be an instruction) and its recursive operands
+/// that do not dominate BB have a combined cost lower than CostRemaining and
+/// are non-trapping. If both are true, the instruction is inserted into the
+/// set and true is returned.
+///
+/// The cost for most non-trapping instructions is defined as 1 except for
+/// Select whose cost is 2.
+///
+/// After this function returns, CostRemaining is decreased by the cost of
+/// V plus its non-dominating operands. If that cost is greater than
+/// CostRemaining, false is returned and CostRemaining is undefined.
static bool DominatesMergePoint(Value *V, BasicBlock *BB,
- SmallPtrSet<Instruction*, 4> *AggressiveInsts) {
+ SmallPtrSet<Instruction*, 4> *AggressiveInsts,
+ unsigned &CostRemaining) {
Instruction *I = dyn_cast<Instruction>(V);
if (!I) {
// Non-instructions all dominate instructions, but not all constantexprs
// instructions in the 'if region'.
if (AggressiveInsts == 0) return false;
+ // If we have seen this instruction before, don't count it again.
+ if (AggressiveInsts->count(I)) return true;
+
// Okay, it looks like the instruction IS in the "condition". Check to
// see if it's 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;
+ unsigned Cost = 0;
+
switch (I->getOpcode()) {
default: return false; // Cannot hoist this out safely.
case Instruction::Load:
// predecessor.
if (PBB->getFirstNonPHIOrDbg() != I)
return false;
+ Cost = 1;
break;
case Instruction::GetElementPtr:
// GEPs are cheap if all indices are constant.
if (!cast<GetElementPtrInst>(I)->hasAllConstantIndices())
return false;
+ Cost = 1;
break;
case Instruction::Add:
case Instruction::Sub:
case Instruction::LShr:
case Instruction::AShr:
case Instruction::ICmp:
+ case Instruction::Trunc:
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ Cost = 1;
break; // These are all cheap and non-trapping instructions.
+
+ case Instruction::Select:
+ Cost = 2;
+ break;
}
- // Okay, we can only really hoist these out if their operands are not
- // defined in the conditional region.
+ if (Cost > CostRemaining)
+ return false;
+
+ CostRemaining -= Cost;
+
+ // Okay, we can only really hoist these out if their operands do
+ // not take us over the cost threshold.
for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
- if (!DominatesMergePoint(*i, BB, 0))
+ if (!DominatesMergePoint(*i, BB, AggressiveInsts, CostRemaining))
return false;
// Okay, it's safe to do this! Remember this instruction.
AggressiveInsts->insert(I);
/// form of jump threading.
bool SimplifyCFGOpt::
SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
- BasicBlock *Pred) {
+ BasicBlock *Pred,
+ IRBuilder<> &Builder) {
Value *PredVal = isValueEqualityComparison(Pred->getTerminator());
if (!PredVal) return false; // Not a value comparison in predecessor.
// uncond br.
assert(ThisCases.size() == 1 && "Branch can only have one case!");
// Insert the new branch.
- Instruction *NI = BranchInst::Create(ThisDef, TI);
+ Instruction *NI = Builder.CreateBr(ThisDef);
(void) NI;
// Remove PHI node entries for the dead edge.
CheckEdge = 0;
// Insert the new branch.
- Instruction *NI = BranchInst::Create(TheRealDest, TI);
+ Instruction *NI = Builder.CreateBr(TheRealDest);
(void) NI;
DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator()
/// 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.
-bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI) {
+bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
+ IRBuilder<> &Builder) {
BasicBlock *BB = TI->getParent();
Value *CV = isValueEqualityComparison(TI); // CondVal
assert(CV && "Not a comparison?");
for (unsigned i = 0, e = NewSuccessors.size(); i != e; ++i)
AddPredecessorToBlock(NewSuccessors[i], Pred, BB);
+ Builder.SetInsertPoint(PTI);
// Convert pointer to int before we switch.
if (CV->getType()->isPointerTy()) {
assert(TD && "Cannot switch on pointer without TargetData");
- CV = new PtrToIntInst(CV, TD->getIntPtrType(CV->getContext()),
- "magicptr", PTI);
+ CV = Builder.CreatePtrToInt(CV, TD->getIntPtrType(CV->getContext()),
+ "magicptr");
}
// Now that the successors are updated, create the new Switch instruction.
- SwitchInst *NewSI = SwitchInst::Create(CV, PredDefault,
- PredCases.size(), PTI);
+ 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].first, PredCases[i].second);
// These values do not agree. Insert a select instruction before NT
// that determines the right value.
SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)];
- if (SI == 0)
+ if (SI == 0) {
SI = SelectInst::Create(BI->getCondition(), BB1V, BB2V,
BB1V->getName()+"."+BB2V->getName(), NT);
+ SI->setDebugLoc(BI->getDebugLoc());
+ }
// Make the PHI node use the select for all incoming values for BB1/BB2
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingBlock(i) == BB1 || PN->getIncomingBlock(i) == BB2)
else
SI = SelectInst::Create(BrCond, HInst, FalseV,
HInst->getName() + "." + FalseV->getName(), BI);
+ SI->setDebugLoc(BI->getDebugLoc());
// Make the PHI node use the select for all incoming values for "then" and
// "if" blocks.
/// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry
/// PHI node, see if we can eliminate it.
-static bool FoldTwoEntryPHINode(PHINode *PN, const TargetData *TD) {
+static bool FoldTwoEntryPHINode(PHINode *PN, const TargetData *TD,
+ IRBuilder<> &Builder) {
// Ok, this is a two entry PHI node. Check to see if this is a simple "if
// statement", which has a very simple dominance structure. Basically, we
// are trying to find the condition that is being branched on, which
// instructions. While we are at it, keep track of the instructions
// that need to be moved to the dominating block.
SmallPtrSet<Instruction*, 4> AggressiveInsts;
+ unsigned MaxCostVal0 = PHINodeFoldingThreshold,
+ MaxCostVal1 = PHINodeFoldingThreshold;
for (BasicBlock::iterator II = BB->begin(); isa<PHINode>(II);) {
PHINode *PN = cast<PHINode>(II++);
continue;
}
- if (!DominatesMergePoint(PN->getIncomingValue(0), BB, &AggressiveInsts) ||
- !DominatesMergePoint(PN->getIncomingValue(1), BB, &AggressiveInsts))
+ if (!DominatesMergePoint(PN->getIncomingValue(0), BB, &AggressiveInsts,
+ MaxCostVal0) ||
+ !DominatesMergePoint(PN->getIncomingValue(1), BB, &AggressiveInsts,
+ MaxCostVal1))
return false;
}
// If we can still promote the PHI nodes after this gauntlet of tests,
// do all of the PHI's now.
Instruction *InsertPt = DomBlock->getTerminator();
+ Builder.SetInsertPoint(InsertPt);
// Move all 'aggressive' instructions, which are defined in the
// conditional parts of the if's up to the dominating block.
Value *TrueVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfFalse);
Value *FalseVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue);
- Value *NV = SelectInst::Create(IfCond, TrueVal, FalseVal, "", InsertPt);
+ SelectInst *NV =
+ cast<SelectInst>(Builder.CreateSelect(IfCond, TrueVal, FalseVal, ""));
PN->replaceAllUsesWith(NV);
NV->takeName(PN);
PN->eraseFromParent();
// has been flattened. Change DomBlock to jump directly to our new block to
// avoid other simplifycfg's kicking in on the diamond.
TerminatorInst *OldTI = DomBlock->getTerminator();
- BranchInst::Create(BB, OldTI);
+ Builder.SetInsertPoint(OldTI);
+ Builder.CreateBr(BB);
OldTI->eraseFromParent();
return true;
}
/// 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.
-static bool SimplifyCondBranchToTwoReturns(BranchInst *BI) {
+static bool SimplifyCondBranchToTwoReturns(BranchInst *BI,
+ IRBuilder<> &Builder) {
assert(BI->isConditional() && "Must be a conditional branch");
BasicBlock *TrueSucc = BI->getSuccessor(0);
BasicBlock *FalseSucc = BI->getSuccessor(1);
if (!FalseSucc->getFirstNonPHIOrDbg()->isTerminator())
return false;
+ Builder.SetInsertPoint(BI);
// Okay, we found a branch that is going to two return nodes. If
// there is no return value for this function, just change the
// branch into a return.
if (FalseRet->getNumOperands() == 0) {
TrueSucc->removePredecessor(BI->getParent());
FalseSucc->removePredecessor(BI->getParent());
- ReturnInst::Create(BI->getContext(), 0, BI);
+ Builder.CreateRetVoid();
EraseTerminatorInstAndDCECond(BI);
return true;
}
} else if (isa<UndefValue>(TrueValue)) {
TrueValue = FalseValue;
} else {
- TrueValue = SelectInst::Create(BrCond, TrueValue,
- FalseValue, "retval", BI);
+ TrueValue = Builder.CreateSelect(BrCond, TrueValue,
+ FalseValue, "retval");
}
}
- Value *RI = !TrueValue ?
- ReturnInst::Create(BI->getContext(), BI) :
- ReturnInst::Create(BI->getContext(), TrueValue, BI);
+ Value *RI = !TrueValue ?
+ Builder.CreateRetVoid() : Builder.CreateRet(TrueValue);
+
(void) RI;
DEBUG(dbgs() << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:"
return true;
}
-/// FoldBranchToCommonDest - If this basic block is ONLY a setcc and a branch,
-/// 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.
+/// FoldBranchToCommonDest - If this basic block is simple enough, and if a
+/// predecessor branches to us and one of our successors, fold the block into
+/// the predecessor and use logical operations to pick the right destination.
bool llvm::FoldBranchToCommonDest(BranchInst *BI) {
BasicBlock *BB = BI->getParent();
Instruction *Cond = dyn_cast<Instruction>(BI->getCondition());
Cond->getParent() != BB || !Cond->hasOneUse())
return false;
- SmallVector<DbgInfoIntrinsic *, 8> DbgValues;
// 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 (DbgInfoIntrinsic *DBI = dyn_cast<DbgInfoIntrinsic>(FrontIt)) {
- DbgValues.push_back(DBI);
- ++FrontIt;
- }
+ while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt;
// Allow a single instruction to be hoisted in addition to the compare
// that feeds the branch. We later ensure that any values that _it_ uses
FrontIt->isSafeToSpeculativelyExecute()) {
BonusInst = &*FrontIt;
++FrontIt;
- }
-
- // Ignore dbg intrinsics.
- while (DbgInfoIntrinsic *DBI = dyn_cast<DbgInfoIntrinsic>(FrontIt)) {
- DbgValues.push_back(DBI);
- ++FrontIt;
+
+ // Ignore dbg intrinsics.
+ while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt;
}
// Only a single bonus inst is allowed.
// Make sure the instruction after the condition is the cond branch.
BasicBlock::iterator CondIt = Cond; ++CondIt;
+
// Ingore dbg intrinsics.
- while(DbgInfoIntrinsic *DBI = dyn_cast<DbgInfoIntrinsic>(CondIt)) {
- DbgValues.push_back(DBI);
- ++CondIt;
- }
- if (&*CondIt != BI) {
- assert (!isa<DbgInfoIntrinsic>(CondIt) && "Hey do not forget debug info!");
+ while (isa<DbgInfoIntrinsic>(CondIt)) ++CondIt;
+
+ if (&*CondIt != BI)
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 (CE->canTrap())
return false;
-
// Finally, don't infinitely unroll conditional loops.
BasicBlock *TrueDest = BI->getSuccessor(0);
BasicBlock *FalseDest = BI->getSuccessor(1);
// 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.
- if (PBI == 0 || PBI->isUnconditional() ||
- !SafeToMergeTerminators(BI, PBI))
+ if (PBI == 0 || PBI->isUnconditional() || !SafeToMergeTerminators(BI, PBI))
continue;
+ // Determine if the two branches share a common destination.
+ Instruction::BinaryOps Opc;
+ bool InvertPredCond = false;
+
+ if (PBI->getSuccessor(0) == TrueDest)
+ Opc = Instruction::Or;
+ else if (PBI->getSuccessor(1) == FalseDest)
+ Opc = Instruction::And;
+ else if (PBI->getSuccessor(0) == FalseDest)
+ Opc = Instruction::And, InvertPredCond = true;
+ else if (PBI->getSuccessor(1) == TrueDest)
+ Opc = Instruction::Or, InvertPredCond = true;
+ else
+ continue;
+
// Ensure that any values used in the bonus instruction are also used
// by the terminator of the predecessor. This means that those values
// must already have been resolved, so we won't be inhibiting the
if (!UsedValues.empty()) return false;
}
-
- Instruction::BinaryOps Opc;
- bool InvertPredCond = false;
-
- if (PBI->getSuccessor(0) == TrueDest)
- Opc = Instruction::Or;
- else if (PBI->getSuccessor(1) == FalseDest)
- Opc = Instruction::And;
- else if (PBI->getSuccessor(0) == FalseDest)
- Opc = Instruction::And, InvertPredCond = true;
- else if (PBI->getSuccessor(1) == TrueDest)
- Opc = Instruction::Or, InvertPredCond = true;
- else
- continue;
DEBUG(dbgs() << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB);
New->takeName(Cond);
Cond->setName(New->getName()+".old");
- Value *NewCond = BinaryOperator::Create(Opc, PBI->getCondition(),
- New, "or.cond", PBI);
+ Instruction *NewCond = BinaryOperator::Create(Opc, PBI->getCondition(),
+ New, "or.cond", PBI);
+ NewCond->setDebugLoc(PBI->getDebugLoc());
PBI->setCondition(NewCond);
if (PBI->getSuccessor(0) == BB) {
AddPredecessorToBlock(TrueDest, PredBlock, BB);
PBI->setSuccessor(1, FalseDest);
}
- // Move dbg value intrinsics in PredBlock.
- for (SmallVector<DbgInfoIntrinsic *, 8>::iterator DBI = DbgValues.begin(),
- DBE = DbgValues.end(); DBI != DBE; ++DBI) {
- DbgInfoIntrinsic *DB = *DBI;
- DB->removeFromParent();
- DB->insertBefore(PBI);
- }
+ // Copy any debug value intrinsics into the end of PredBlock.
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+ if (isa<DbgInfoIntrinsic>(*I))
+ I->clone()->insertBefore(PBI);
+
return true;
}
return false;
Succ->removePredecessor(OldTerm->getParent());
}
+ IRBuilder<> Builder(OldTerm);
+ Builder.SetCurrentDebugLocation(OldTerm->getDebugLoc());
+
// Insert an appropriate new terminator.
if ((KeepEdge1 == 0) && (KeepEdge2 == 0)) {
if (TrueBB == FalseBB)
// We were only looking for one successor, and it was present.
// Create an unconditional branch to it.
- BranchInst::Create(TrueBB, OldTerm);
+ Builder.CreateBr(TrueBB);
else
// We found both of the successors we were looking for.
// Create a conditional branch sharing the condition of the select.
- BranchInst::Create(TrueBB, FalseBB, Cond, OldTerm);
+ Builder.CreateCondBr(Cond, TrueBB, FalseBB);
} else if (KeepEdge1 && (KeepEdge2 || TrueBB == FalseBB)) {
// Neither of the selected blocks were successors, so this
// terminator must be unreachable.
// the edge to the one that wasn't must be unreachable.
if (KeepEdge1 == 0)
// Only TrueBB was found.
- BranchInst::Create(TrueBB, OldTerm);
+ Builder.CreateBr(TrueBB);
else
// Only FalseBB was found.
- BranchInst::Create(FalseBB, OldTerm);
+ Builder.CreateBr(FalseBB);
}
EraseTerminatorInstAndDCECond(OldTerm);
/// We prefer to split the edge to 'end' so that there is a true/false entry to
/// the PHI, merging the third icmp into the switch.
static bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI,
- const TargetData *TD) {
+ const TargetData *TD,
+ IRBuilder<> &Builder) {
BasicBlock *BB = ICI->getParent();
+
// If the block has any PHIs in it or the icmp has multiple uses, it is too
// complex.
if (isa<PHINode>(BB->begin()) || !ICI->hasOneUse()) return false;
SI->addCase(Cst, NewBB);
// NewBB branches to the phi block, add the uncond branch and the phi entry.
- BranchInst::Create(SuccBlock, NewBB);
+ Builder.SetInsertPoint(NewBB);
+ Builder.SetCurrentDebugLocation(SI->getDebugLoc());
+ Builder.CreateBr(SuccBlock);
PHIUse->addIncoming(NewCst, NewBB);
return true;
}
/// SimplifyBranchOnICmpChain - The specified branch is a conditional branch.
/// Check to see if it is branching on an or/and chain of icmp instructions, and
/// fold it into a switch instruction if so.
-static bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD) {
+static bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD,
+ IRBuilder<> &Builder) {
Instruction *Cond = dyn_cast<Instruction>(BI->getCondition());
if (Cond == 0) return false;
BasicBlock *NewBB = BB->splitBasicBlock(BI, "switch.early.test");
// Remove the uncond branch added to the old block.
TerminatorInst *OldTI = BB->getTerminator();
-
+ Builder.SetInsertPoint(OldTI);
+
if (TrueWhenEqual)
- BranchInst::Create(EdgeBB, NewBB, ExtraCase, OldTI);
+ Builder.CreateCondBr(ExtraCase, EdgeBB, NewBB);
else
- BranchInst::Create(NewBB, EdgeBB, ExtraCase, OldTI);
+ Builder.CreateCondBr(ExtraCase, NewBB, EdgeBB);
OldTI->eraseFromParent();
<< "\nEXTRABB = " << *BB);
BB = NewBB;
}
-
+
+ Builder.SetInsertPoint(BI);
// Convert pointer to int before we switch.
if (CompVal->getType()->isPointerTy()) {
assert(TD && "Cannot switch on pointer without TargetData");
- CompVal = new PtrToIntInst(CompVal,
- TD->getIntPtrType(CompVal->getContext()),
- "magicptr", BI);
+ CompVal = Builder.CreatePtrToInt(CompVal,
+ TD->getIntPtrType(CompVal->getContext()),
+ "magicptr");
}
// Create the new switch instruction now.
- SwitchInst *New = SwitchInst::Create(CompVal, DefaultBB, Values.size(), BI);
-
+ SwitchInst *New = Builder.CreateSwitch(CompVal, DefaultBB, Values.size());
+
// Add all of the 'cases' to the switch instruction.
for (unsigned i = 0, e = Values.size(); i != e; ++i)
New->addCase(Values[i], EdgeBB);
return true;
}
-bool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI) {
+bool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) {
BasicBlock *BB = RI->getParent();
if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false;
// Check to see if the non-BB successor is also a return block.
if (isa<ReturnInst>(BI->getSuccessor(0)->getTerminator()) &&
isa<ReturnInst>(BI->getSuccessor(1)->getTerminator()) &&
- SimplifyCondBranchToTwoReturns(BI))
+ SimplifyCondBranchToTwoReturns(BI, Builder))
return true;
}
return false;
}
-bool SimplifyCFGOpt::SimplifyUnwind(UnwindInst *UI) {
+bool SimplifyCFGOpt::SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder) {
// 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.
if (II && II->getUnwindDest() == BB) {
// Insert a new branch instruction before the invoke, because this
// is now a fall through.
- BranchInst *BI = BranchInst::Create(II->getNormalDest(), II);
+ Builder.SetInsertPoint(II);
+ BranchInst *BI = Builder.CreateBr(II->getNormalDest());
Pred->getInstList().remove(II); // Take out of symbol table
// Insert the call now.
SmallVector<Value*,8> Args(II->op_begin(), II->op_end()-3);
- CallInst *CI = CallInst::Create(II->getCalledValue(),
- Args.begin(), Args.end(),
- II->getName(), BI);
+ Builder.SetInsertPoint(BI);
+ CallInst *CI = Builder.CreateCall(II->getCalledValue(),
+ Args.begin(), Args.end(),
+ II->getName());
CI->setCallingConv(II->getCallingConv());
CI->setAttributes(II->getAttributes());
// If the invoke produced a value, the Call now does instead.
SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB));
for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
TerminatorInst *TI = Preds[i]->getTerminator();
-
+ IRBuilder<> Builder(TI);
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
if (BI->isUnconditional()) {
if (BI->getSuccessor(0) == BB) {
}
} else {
if (BI->getSuccessor(0) == BB) {
- BranchInst::Create(BI->getSuccessor(1), BI);
+ Builder.CreateBr(BI->getSuccessor(1));
EraseTerminatorInstAndDCECond(BI);
} else if (BI->getSuccessor(1) == BB) {
- BranchInst::Create(BI->getSuccessor(0), BI);
+ Builder.CreateBr(BI->getSuccessor(0));
EraseTerminatorInstAndDCECond(BI);
Changed = true;
}
if (II->getUnwindDest() == BB) {
// Convert the invoke to a call instruction. This would be a good
// place to note that the call does not throw though.
- BranchInst *BI = BranchInst::Create(II->getNormalDest(), II);
+ BranchInst *BI = Builder.CreateBr(II->getNormalDest());
II->removeFromParent(); // Take out of symbol table
// Insert the call now...
SmallVector<Value*, 8> Args(II->op_begin(), II->op_end()-3);
- CallInst *CI = CallInst::Create(II->getCalledValue(),
- Args.begin(), Args.end(),
- II->getName(), BI);
+ Builder.SetInsertPoint(BI);
+ CallInst *CI = Builder.CreateCall(II->getCalledValue(),
+ Args.begin(), Args.end(),
+ II->getName());
CI->setCallingConv(II->getCallingConv());
CI->setAttributes(II->getAttributes());
// If the invoke produced a value, the call does now instead.
/// TurnSwitchRangeIntoICmp - Turns a switch with that contains only a
/// integer range comparison into a sub, an icmp and a branch.
-static bool TurnSwitchRangeIntoICmp(SwitchInst *SI) {
+static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
assert(SI->getNumCases() > 2 && "Degenerate switch?");
// Make sure all cases point to the same destination and gather the values.
Value *Sub = SI->getCondition();
if (!Offset->isNullValue())
- Sub = BinaryOperator::CreateAdd(Sub, Offset, Sub->getName()+".off", SI);
- Value *Cmp = new ICmpInst(SI, ICmpInst::ICMP_ULT, Sub, NumCases, "switch");
- BranchInst::Create(SI->getSuccessor(1), SI->getDefaultDest(), Cmp, SI);
+ Sub = Builder.CreateAdd(Sub, Offset, Sub->getName()+".off");
+ Value *Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch");
+ Builder.CreateCondBr(Cmp, SI->getSuccessor(1), SI->getDefaultDest());
// Prune obsolete incoming values off the successor's PHI nodes.
for (BasicBlock::iterator BBI = SI->getSuccessor(1)->begin();
return true;
}
-bool SimplifyCFGOpt::SimplifySwitch(SwitchInst *SI) {
+/// EliminateDeadSwitchCases - Compute masked bits for the condition of a switch
+/// and use it to remove dead cases.
+static bool EliminateDeadSwitchCases(SwitchInst *SI) {
+ Value *Cond = SI->getCondition();
+ unsigned Bits = cast<IntegerType>(Cond->getType())->getBitWidth();
+ APInt KnownZero(Bits, 0), KnownOne(Bits, 0);
+ ComputeMaskedBits(Cond, APInt::getAllOnesValue(Bits), KnownZero, KnownOne);
+
+ // Gather dead cases.
+ SmallVector<ConstantInt*, 8> DeadCases;
+ for (unsigned I = 1, E = SI->getNumCases(); I != E; ++I) {
+ if ((SI->getCaseValue(I)->getValue() & KnownZero) != 0 ||
+ (SI->getCaseValue(I)->getValue() & KnownOne) != KnownOne) {
+ DeadCases.push_back(SI->getCaseValue(I));
+ DEBUG(dbgs() << "SimplifyCFG: switch case '"
+ << SI->getCaseValue(I)->getValue() << "' is dead.\n");
+ }
+ }
+
+ // Remove dead cases from the switch.
+ for (unsigned I = 0, E = DeadCases.size(); I != E; ++I) {
+ unsigned Case = SI->findCaseValue(DeadCases[I]);
+ // Prune unused values from PHI nodes.
+ SI->getSuccessor(Case)->removePredecessor(SI->getParent());
+ SI->removeCase(Case);
+ }
+
+ return !DeadCases.empty();
+}
+
+bool SimplifyCFGOpt::SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) {
// If this switch is too complex to want to look at, ignore it.
if (!isValueEqualityComparison(SI))
return false;
// If we only have one predecessor, and if it is a branch on this value,
// see if that predecessor totally determines the outcome of this switch.
if (BasicBlock *OnlyPred = BB->getSinglePredecessor())
- if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred))
+ if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred, Builder))
return SimplifyCFG(BB) | true;
Value *Cond = SI->getCondition();
while (isa<DbgInfoIntrinsic>(BBI))
++BBI;
if (SI == &*BBI)
- if (FoldValueComparisonIntoPredecessors(SI))
+ if (FoldValueComparisonIntoPredecessors(SI, Builder))
return SimplifyCFG(BB) | true;
// Try to transform the switch into an icmp and a branch.
- if (TurnSwitchRangeIntoICmp(SI))
+ if (TurnSwitchRangeIntoICmp(SI, Builder))
return SimplifyCFG(BB) | true;
-
+
+ // Remove unreachable cases.
+ if (EliminateDeadSwitchCases(SI))
+ return SimplifyCFG(BB) | true;
+
return false;
}
return Changed;
}
-bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI) {
+bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){
BasicBlock *BB = BI->getParent();
// If the Terminator is the only non-phi instruction, simplify the block.
if (ICI->isEquality() && isa<ConstantInt>(ICI->getOperand(1))) {
for (++I; isa<DbgInfoIntrinsic>(I); ++I)
;
- if (I->isTerminator() && TryToSimplifyUncondBranchWithICmpInIt(ICI, TD))
+ if (I->isTerminator()
+ && TryToSimplifyUncondBranchWithICmpInIt(ICI, TD, Builder))
return true;
}
}
-bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI) {
+bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) {
BasicBlock *BB = BI->getParent();
// Conditional branch
// see if that predecessor totally determines the outcome of this
// switch.
if (BasicBlock *OnlyPred = BB->getSinglePredecessor())
- if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred))
+ if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred, Builder))
return SimplifyCFG(BB) | true;
// This block must be empty, except for the setcond inst, if it exists.
while (isa<DbgInfoIntrinsic>(I))
++I;
if (&*I == BI) {
- if (FoldValueComparisonIntoPredecessors(BI))
+ if (FoldValueComparisonIntoPredecessors(BI, Builder))
return SimplifyCFG(BB) | true;
} else if (&*I == cast<Instruction>(BI->getCondition())){
++I;
// Ignore dbg intrinsics.
while (isa<DbgInfoIntrinsic>(I))
++I;
- if (&*I == BI && FoldValueComparisonIntoPredecessors(BI))
+ if (&*I == BI && FoldValueComparisonIntoPredecessors(BI, Builder))
return SimplifyCFG(BB) | true;
}
}
// Try to turn "br (X == 0 | X == 1), T, F" into a switch instruction.
- if (SimplifyBranchOnICmpChain(BI, TD))
+ if (SimplifyBranchOnICmpChain(BI, TD, Builder))
return true;
// We have a conditional branch to two blocks that are only reachable
if (MergeBlockIntoPredecessor(BB))
return true;
+ IRBuilder<> Builder(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()))
if (PN->getNumIncomingValues() == 2)
- Changed |= FoldTwoEntryPHINode(PN, TD);
+ Changed |= FoldTwoEntryPHINode(PN, TD, Builder);
+ Builder.SetInsertPoint(BB->getTerminator());
if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) {
if (BI->isUnconditional()) {
- if (SimplifyUncondBranch(BI)) return true;
+ if (SimplifyUncondBranch(BI, Builder)) return true;
} else {
- if (SimplifyCondBranch(BI)) return true;
+ if (SimplifyCondBranch(BI, Builder)) return true;
}
} else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
- if (SimplifyReturn(RI)) return true;
+ if (SimplifyReturn(RI, Builder)) return true;
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
- if (SimplifySwitch(SI)) return true;
+ if (SimplifySwitch(SI, Builder)) return true;
} else if (UnreachableInst *UI =
dyn_cast<UnreachableInst>(BB->getTerminator())) {
if (SimplifyUnreachable(UI)) return true;
} else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
- if (SimplifyUnwind(UI)) return true;
+ if (SimplifyUnwind(UI, Builder)) return true;
} else if (IndirectBrInst *IBI =
dyn_cast<IndirectBrInst>(BB->getTerminator())) {
if (SimplifyIndirectBr(IBI)) return true;
projects / oota-llvm.git / blobdiff