//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
+#include "llvm/DerivedTypes.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
#include <algorithm>
#include <functional>
#include <set>
#include <map>
using namespace llvm;
+STATISTIC(NumSpeculations, "Number of speculative executed instructions");
+
/// SafeToMergeTerminators - Return true if it is safe to merge these two
/// terminator instructions together.
///
// conflicting incoming values from the two switch blocks.
BasicBlock *SI1BB = SI1->getParent();
BasicBlock *SI2BB = SI2->getParent();
- std::set<BasicBlock*> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB));
+ SmallPtrSet<BasicBlock*, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB));
for (succ_iterator I = succ_begin(SI2BB), E = succ_end(SI2BB); I != E; ++I)
if (SI1Succs.count(*I))
static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!");
- // Check to see if one of the predecessors of BB is already a predecessor of
- // Succ. If so, we cannot do the transformation if there are any PHI nodes
- // with incompatible values coming in from the two edges!
- //
- if (isa<PHINode>(Succ->front())) {
- std::set<BasicBlock*> BBPreds(pred_begin(BB), pred_end(BB));
- for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);
- PI != PE; ++PI)
- if (std::find(BBPreds.begin(), BBPreds.end(), *PI) != BBPreds.end()) {
- // Loop over all of the PHI nodes checking to see if there are
- // incompatible values coming in.
- for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
- PHINode *PN = cast<PHINode>(I);
- // Loop up the entries in the PHI node for BB and for *PI if the
- // values coming in are non-equal, we cannot merge these two blocks
- // (instead we should insert a conditional move or something, then
- // merge the blocks).
- if (PN->getIncomingValueForBlock(BB) !=
- PN->getIncomingValueForBlock(*PI))
- return false; // Values are not equal...
+ DOUT << "Looking to fold " << BB->getNameStart() << " into "
+ << Succ->getNameStart() << "\n";
+ // Shortcut, if there is only a single predecessor is 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));
+
+ // Use that list to make another list of common predecessors of BB and Succ
+ BlockSet CommonPreds;
+ for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);
+ PI != PE; ++PI)
+ if (BBPreds.count(*PI))
+ CommonPreds.insert(*PI);
+
+ // Shortcut, if there are no common predecessors, merging is always safe
+ if (CommonPreds.begin() == CommonPreds.end())
+ return true;
+
+ // Look at all the phi nodes in Succ, to see if they present a conflict when
+ // merging these blocks
+ for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+
+ // If the incoming value from BB is again a PHINode in
+ // BB which has the same incoming value for *PI as PN does, we can
+ // merge the phi nodes and then the blocks can still be merged
+ PHINode *BBPN = dyn_cast<PHINode>(PN->getIncomingValueForBlock(BB));
+ if (BBPN && BBPN->getParent() == BB) {
+ for (BlockSet::iterator PI = CommonPreds.begin(), PE = CommonPreds.end();
+ 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";
+ 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();
+ PI != PE; PI++) {
+ // See if the incoming value for the common predecessor is equal to the
+ // 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";
+ return false;
}
}
- }
-
- // Finally, if BB has PHI nodes that are used by things other than the PHIs in
- // Succ and Succ has predecessors that are not Succ and not Pred, we cannot
- // fold these blocks, as we don't know whether BB dominates Succ or not to
- // update the PHI nodes correctly.
- if (!isa<PHINode>(BB->begin()) || Succ->getSinglePredecessor()) return true;
-
- // If the predecessors of Succ are only BB and Succ itself, we can handle this.
- bool IsSafe = true;
- for (pred_iterator PI = pred_begin(Succ), E = pred_end(Succ); PI != E; ++PI)
- if (*PI != Succ && *PI != BB) {
- IsSafe = false;
- break;
}
- if (IsSafe) return true;
-
- // If the PHI nodes in BB are only used by instructions in Succ, we are ok if
- // BB and Succ have no common predecessors.
- for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I) {
- PHINode *PN = cast<PHINode>(I);
- for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); UI != E;
- ++UI)
- if (cast<Instruction>(*UI)->getParent() != Succ)
+ }
+
+ // 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;
+ }
}
-
- // Scan the predecessor sets of BB and Succ, making sure there are no common
- // predecessors. Common predecessors would cause us to build a phi node with
- // differing incoming values, which is not legal.
- std::set<BasicBlock*> BBPreds(pred_begin(BB), pred_end(BB));
- for (pred_iterator PI = pred_begin(Succ), E = pred_end(Succ); PI != E; ++PI)
- if (BBPreds.count(*PI))
- return false;
-
+
return true;
}
/// branch. If possible, eliminate BB.
static bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
BasicBlock *Succ) {
- // If our successor has PHI nodes, then we need to update them to include
- // entries for BB's predecessors, not for BB itself. Be careful though,
- // if this transformation fails (returns true) then we cannot do this
- // transformation!
- //
+ // 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;
// If there is more than one pred of succ, and there are PHI nodes in
// the successor, then we need to add incoming edges for the PHI nodes
//
- const std::vector<BasicBlock*> BBPreds(pred_begin(BB), pred_end(BB));
+ const SmallVector<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
// Loop over all of the PHI nodes in the successor of BB.
for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
if (isa<PHINode>(OldVal) && cast<PHINode>(OldVal)->getParent() == BB) {
PHINode *OldValPN = cast<PHINode>(OldVal);
for (unsigned i = 0, e = OldValPN->getNumIncomingValues(); i != e; ++i)
+ // Note that, since we are merging phi nodes and BB and Succ might
+ // have common predecessors, we could end up with a phi node with
+ // identical incoming branches. This will be cleaned up later (and
+ // will trigger asserts if we try to clean it up now, without also
+ // simplifying the corresponding conditional branch).
PN->addIncoming(OldValPN->getIncomingValue(i),
OldValPN->getIncomingBlock(i));
} else {
- for (std::vector<BasicBlock*>::const_iterator PredI = BBPreds.begin(),
- End = BBPreds.end(); PredI != End; ++PredI) {
- // Add an incoming value for each of the new incoming values...
- PN->addIncoming(OldVal, *PredI);
- }
+ // Add an incoming value for each of the new incoming values.
+ for (unsigned i = 0, e = BBPreds.size(); i != e; ++i)
+ PN->addIncoming(OldVal, BBPreds[i]);
}
}
}
if (isa<PHINode>(&BB->front())) {
- std::vector<BasicBlock*>
+ SmallVector<BasicBlock*, 16>
OldSuccPreds(pred_begin(Succ), pred_end(Succ));
// Move all PHI nodes in BB to Succ if they are alive, otherwise
// users of the PHI nodes.
PN->eraseFromParent();
} else {
- // The instruction is alive, so this means that Succ must have
- // *ONLY* had BB as a predecessor, and the PHI node is still valid
- // now. Simply move it into Succ, because we know that BB
- // strictly dominated Succ.
+ // 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,
- // this means that we should any newly added incoming edges should
- // use the PHI node as the value for these edges, because they are
- // loop back edges.
+ // 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]);
}
// Everything that jumped to BB now goes to Succ.
- std::string OldName = BB->getName();
BB->replaceAllUsesWith(Succ);
+ if (!Succ->hasName()) Succ->takeName(BB);
BB->eraseFromParent(); // Delete the old basic block.
-
- if (!OldName.empty() && !Succ->hasName()) // Transfer name if we can
- Succ->setName(OldName);
return true;
}
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
- case Instruction::SetEQ:
- case Instruction::SetNE:
- case Instruction::SetLT:
- case Instruction::SetGT:
- case Instruction::SetLE:
- case Instruction::SetGE:
+ 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.
}
// Okay, we can only really hoist these out if their operands are not
// defined in the conditional region.
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (!DominatesMergePoint(I->getOperand(i), BB, 0))
+ for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
+ if (!DominatesMergePoint(*i, BB, 0))
return false;
// Okay, it's safe to do this! Remember this instruction.
AggressiveInsts->insert(I);
return true;
}
-// GatherConstantSetEQs - Given a potentially 'or'd together collection of seteq
-// 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::SetEQ) {
+ if (Instruction *Inst = dyn_cast<Instruction>(V)) {
+ if (Inst->getOpcode() == Instruction::ICmp &&
+ cast<ICmpInst>(Inst)->getPredicate() == ICmpInst::ICMP_EQ) {
if (ConstantInt *C = dyn_cast<ConstantInt>(Inst->getOperand(1))) {
Values.push_back(C);
return Inst->getOperand(0);
if (LHS == RHS)
return LHS;
}
+ }
return 0;
}
// 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::SetNE) {
+ if (Instruction *Inst = dyn_cast<Instruction>(V)) {
+ if (Inst->getOpcode() == Instruction::ICmp &&
+ cast<ICmpInst>(Inst)->getPredicate() == ICmpInst::ICMP_NE) {
if (ConstantInt *C = dyn_cast<ConstantInt>(Inst->getOperand(1))) {
Values.push_back(C);
return Inst->getOperand(0);
Values.push_back(C);
return Inst->getOperand(1);
}
- } else if (Inst->getOpcode() == Instruction::Cast) {
- // Cast of X to bool is really a comparison against zero.
- assert(Inst->getType() == Type::BoolTy && "Can only handle bool values!");
- Values.push_back(ConstantInt::get(Inst->getOperand(0)->getType(), 0));
- return Inst->getOperand(0);
} else if (Inst->getOpcode() == Instruction::And) {
if (Value *LHS = GatherConstantSetNEs(Inst->getOperand(0), Values))
if (Value *RHS = GatherConstantSetNEs(Inst->getOperand(1), Values))
if (LHS == RHS)
return LHS;
}
+ }
return 0;
}
static void ErasePossiblyDeadInstructionTree(Instruction *I) {
if (!isInstructionTriviallyDead(I)) return;
- std::vector<Instruction*> InstrsToInspect;
+ SmallVector<Instruction*, 16> InstrsToInspect;
InstrsToInspect.push_back(I);
while (!InstrsToInspect.empty()) {
}
// Add operands of dead instruction to worklist.
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
+ for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
+ if (Instruction *OpI = dyn_cast<Instruction>(*i))
InstrsToInspect.push_back(OpI);
// Remove dead instruction.
}
if (BranchInst *BI = dyn_cast<BranchInst>(TI))
if (BI->isConditional() && BI->getCondition()->hasOneUse())
- if (SetCondInst *SCI = dyn_cast<SetCondInst>(BI->getCondition()))
- if ((SCI->getOpcode() == Instruction::SetEQ ||
- SCI->getOpcode() == Instruction::SetNE) &&
- isa<ConstantInt>(SCI->getOperand(1)))
- return SCI->getOperand(0);
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition()))
+ if ((ICI->getPredicate() == ICmpInst::ICMP_EQ ||
+ ICI->getPredicate() == ICmpInst::ICMP_NE) &&
+ isa<ConstantInt>(ICI->getOperand(1)))
+ return ICI->getOperand(0);
return 0;
}
}
BranchInst *BI = cast<BranchInst>(TI);
- SetCondInst *SCI = cast<SetCondInst>(BI->getCondition());
- Cases.push_back(std::make_pair(cast<ConstantInt>(SCI->getOperand(1)),
- BI->getSuccessor(SCI->getOpcode() ==
- Instruction::SetNE)));
- return BI->getSuccessor(SCI->getOpcode() == Instruction::SetEQ);
+ ICmpInst *ICI = cast<ICmpInst>(BI->getCondition());
+ Cases.push_back(std::make_pair(cast<ConstantInt>(ICI->getOperand(1)),
+ BI->getSuccessor(ICI->getPredicate() ==
+ ICmpInst::ICMP_NE)));
+ return BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_EQ);
}
-// EliminateBlockCases - Given an vector of bb/value pairs, remove any entries
+// 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) {
assert(ThisCases.size() == 1 && "Branch can only have one case!");
Value *Cond = BTI->getCondition();
// Insert the new branch.
- Instruction *NI = new BranchInst(ThisDef, TI);
+ Instruction *NI = BranchInst::Create(ThisDef, TI);
// Remove PHI node entries for the dead edge.
ThisCases[0].second->removePredecessor(TI->getParent());
} else {
SwitchInst *SI = cast<SwitchInst>(TI);
// Okay, TI has cases that are statically dead, prune them away.
- std::set<Constant*> DeadCases;
+ SmallPtrSet<Constant*, 16> DeadCases;
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
DeadCases.insert(PredCases[i].first);
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].second == TIBB) {
if (TIV == 0)
TIV = PredCases[i].first;
else
return false; // Cannot handle multiple values coming to this block.
+ }
assert(TIV && "No edge from pred to succ?");
// Okay, we found the one constant that our value can be if we get into TI's
CheckEdge = 0;
// Insert the new branch.
- Instruction *NI = new BranchInst(TheRealDest, TI);
+ Instruction *NI = BranchInst::Create(TheRealDest, TI);
DOUT << "Threading pred instr: " << *Pred->getTerminator()
<< "Through successor TI: " << *TI << "Leaving: " << *NI << "\n";
assert(CV && "Not a comparison?");
bool Changed = false;
- std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
+ SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB));
while (!Preds.empty()) {
BasicBlock *Pred = Preds.back();
Preds.pop_back();
// Based on whether the default edge from PTI goes to BB or not, fill in
// PredCases and PredDefault with the new switch cases we would like to
// build.
- std::vector<BasicBlock*> NewSuccessors;
+ SmallVector<BasicBlock*, 8> NewSuccessors;
if (PredDefault == BB) {
// If this is the default destination from PTI, only the edges in TI
AddPredecessorToBlock(NewSuccessors[i], Pred, BB);
// Now that the successors are updated, create the new Switch instruction.
- SwitchInst *NewSI = new SwitchInst(CV, PredDefault, PredCases.size(),PTI);
+ SwitchInst *NewSI = SwitchInst::Create(CV, PredDefault,
+ PredCases.size(), PTI);
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
NewSI->addCase(PredCases[i].first, PredCases[i].second);
if (InfLoopBlock == 0) {
// Insert it at the end of the loop, because it's either code,
// or it won't matter if it's hot. :)
- InfLoopBlock = new BasicBlock("infloop", BB->getParent());
- new BranchInst(InfLoopBlock, InfLoopBlock);
+ InfLoopBlock = BasicBlock::Create("infloop", BB->getParent());
+ BranchInst::Create(InfLoopBlock, InfLoopBlock);
}
NewSI->setSuccessor(i, InfLoopBlock);
}
BasicBlock *BB2 = BI->getSuccessor(1); // The false destination
Instruction *I1 = BB1->begin(), *I2 = BB2->begin();
- if (I1->getOpcode() != I2->getOpcode() || !I1->isIdenticalTo(I2) ||
- isa<PHINode>(I1) || isa<InvokeInst>(I1))
+ if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) ||
+ isa<InvokeInst>(I1) || !I1->isIdenticalTo(I2))
return false;
// If we get here, we can hoist at least one instruction.
if (NT->getType() != Type::VoidTy) {
I1->replaceAllUsesWith(NT);
I2->replaceAllUsesWith(NT);
- NT->setName(I1->getName());
+ NT->takeName(I1);
}
// Hoisting one of the terminators from our successor is a great thing.
// that determines the right value.
SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)];
if (SI == 0)
- SI = new SelectInst(BI->getCondition(), BB1V, BB2V,
- BB1V->getName()+"."+BB2V->getName(), NT);
+ SI = SelectInst::Create(BI->getCondition(), BB1V, BB2V,
+ BB1V->getName()+"."+BB2V->getName(), NT);
// 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)
return true;
}
+/// SpeculativelyExecuteBB - Given a conditional branch that goes to BB1
+/// and an BB2 and the only successor of BB1 is BB2, hoist simple code
+/// (for now, restricted to a single instruction that's side effect free) from
+/// the BB1 into the branch block to speculatively execute it.
+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.
+
+ // Be conservative for now. FP select instruction can often be expensive.
+ Value *BrCond = BI->getCondition();
+ if (isa<Instruction>(BrCond) &&
+ cast<Instruction>(BrCond)->getOpcode() == Instruction::FCmp)
+ return false;
+
+ // If BB1 is actually on the false edge of the conditional branch, remember
+ // to swap the select operands later.
+ bool Invert = false;
+ if (BB1 != BI->getSuccessor(0)) {
+ assert(BB1 == BI->getSuccessor(1) && "No edge from 'if' block?");
+ Invert = true;
+ }
+
+ // Turn
+ // BB:
+ // %t1 = icmp
+ // br i1 %t1, label %BB1, label %BB2
+ // BB1:
+ // %t3 = add %t2, c
+ // br label BB2
+ // BB2:
+ // =>
+ // BB:
+ // %t1 = icmp
+ // %t4 = add %t2, c
+ // %t3 = select i1 %t1, %t2, %t3
+ Instruction *I = BB1->begin();
+ switch (I->getOpcode()) {
+ default: return false; // Not safe / profitable to hoist.
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ if (!I->getOperand(0)->getType()->isInteger())
+ // FP arithmetic might trap. Not worth doing for vector ops.
+ return false;
+ break; // These are all cheap and non-trapping instructions.
+ }
+
+ // Can we speculatively execute the instruction? And what is the value
+ // if the condition is false? Consider the phi uses, if the incoming value
+ // from the "if" block are all the same V, then V is the value of the
+ // select if the condition is false.
+ BasicBlock *BIParent = BI->getParent();
+ SmallVector<PHINode*, 4> PHIUses;
+ Value *FalseV = NULL;
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
+ UI != E; ++UI) {
+ PHINode *PN = dyn_cast<PHINode>(UI);
+ if (!PN)
+ continue;
+ PHIUses.push_back(PN);
+ Value *PHIV = PN->getIncomingValueForBlock(BIParent);
+ if (!FalseV)
+ FalseV = PHIV;
+ else if (FalseV != PHIV)
+ return false; // Don't know the value when condition is false.
+ }
+ if (!FalseV) // Can this happen?
+ return false;
+
+ // 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) {
+ Instruction *OpI = dyn_cast<Instruction>(*i);
+ if (OpI && OpI->getParent() == BIParent &&
+ !OpI->isUsedInBasicBlock(BIParent))
+ return false;
+ }
+
+ // If we get here, we can hoist the instruction. Try to place it before the
+ // icmp instruction preceeding the conditional branch.
+ BasicBlock::iterator InsertPos = BI;
+ if (InsertPos != BIParent->begin())
+ --InsertPos;
+ if (InsertPos == BrCond && !isa<PHINode>(BrCond))
+ BIParent->getInstList().splice(InsertPos, BB1->getInstList(), I);
+ else
+ BIParent->getInstList().splice(BI, BB1->getInstList(), I);
+
+ // 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);
+ else
+ SI = SelectInst::Create(BrCond, I, FalseV,
+ I->getName() + "." + FalseV->getName(), BI);
+
+ // Make the PHI node use the select for all incoming values for "then" and
+ // "if" blocks.
+ for (unsigned i = 0, e = PHIUses.size(); i != e; ++i) {
+ PHINode *PN = PHIUses[i];
+ for (unsigned j = 0, ee = PN->getNumIncomingValues(); j != ee; ++j)
+ if (PN->getIncomingBlock(j) == BB1 ||
+ PN->getIncomingBlock(j) == BIParent)
+ PN->setIncomingValue(j, SI);
+ }
+
+ ++NumSpeculations;
+ return true;
+}
+
/// BlockIsSimpleEnoughToThreadThrough - Return true if we can thread a branch
/// across this block.
static bool BlockIsSimpleEnoughToThreadThrough(BasicBlock *BB) {
// Okay, this is a simple enough basic block. See if any phi values are
// constants.
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- if (ConstantBool *CB = dyn_cast<ConstantBool>(PN->getIncomingValue(i))) {
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ ConstantInt *CB;
+ if ((CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i))) &&
+ CB->getType() == Type::Int1Ty) {
// Okay, we now know that all edges from PredBB should be revectored to
// branch to RealDest.
BasicBlock *PredBB = PN->getIncomingBlock(i);
- BasicBlock *RealDest = BI->getSuccessor(!CB->getValue());
+ BasicBlock *RealDest = BI->getSuccessor(!CB->getZExtValue());
if (RealDest == BB) continue; // Skip self loops.
// 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 = new BasicBlock(RealDest->getName()+".critedge",
- RealDest->getParent(), RealDest);
- new BranchInst(RealDest, EdgeBB);
+ BasicBlock *EdgeBB = BasicBlock::Create(RealDest->getName()+".critedge",
+ RealDest->getParent(), RealDest);
+ BranchInst::Create(RealDest, EdgeBB);
PHINode *PN;
for (BasicBlock::iterator BBI = RealDest->begin();
(PN = dyn_cast<PHINode>(BBI)); ++BBI) {
if (BBI->hasName()) N->setName(BBI->getName()+".c");
// Update operands due to translation.
- for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
+ for (User::op_iterator i = N->op_begin(), e = N->op_end();
+ i != e; ++i) {
std::map<Value*, Value*>::iterator PI =
- TranslateMap.find(N->getOperand(i));
+ TranslateMap.find(*i);
if (PI != TranslateMap.end())
- N->setOperand(i, PI->second);
+ *i = PI->second;
}
// Check for trivial simplification.
// Recurse, simplifying any other constants.
return FoldCondBranchOnPHI(BI) | true;
}
+ }
return false;
}
Value *FalseVal =
PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue);
- std::string Name = PN->getName(); PN->setName("");
- PN->replaceAllUsesWith(new SelectInst(IfCond, TrueVal, FalseVal,
- Name, AfterPHIIt));
+ Value *NV = SelectInst::Create(IfCond, TrueVal, FalseVal, "", AfterPHIIt);
+ PN->replaceAllUsesWith(NV);
+ NV->takeName(PN);
+
BB->getInstList().erase(PN);
}
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) {
+ assert(BI->isConditional() && "Must be a conditional branch");
+ BasicBlock *TrueSucc = BI->getSuccessor(0);
+ BasicBlock *FalseSucc = BI->getSuccessor(1);
+ ReturnInst *TrueRet = cast<ReturnInst>(TrueSucc->getTerminator());
+ ReturnInst *FalseRet = cast<ReturnInst>(FalseSucc->getTerminator());
+
+ // 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.
+
+ // 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(0, BI);
+ BI->eraseFromParent();
+ return true;
+ }
+
+ // Otherwise, build up the result values for the new return.
+ SmallVector<Value*, 4> TrueResult;
+ SmallVector<Value*, 4> FalseResult;
+
+ for (unsigned i = 0, e = TrueRet->getNumOperands(); i != e; ++i) {
+ // Otherwise, figure out what the true and false return values are
+ // so we can insert a new select instruction.
+ Value *TrueValue = TrueRet->getOperand(i);
+ Value *FalseValue = FalseRet->getOperand(i);
+
+ // Unwrap any PHI nodes in the return blocks.
+ if (PHINode *TVPN = dyn_cast<PHINode>(TrueValue))
+ if (TVPN->getParent() == TrueSucc)
+ TrueValue = TVPN->getIncomingValueForBlock(BI->getParent());
+ if (PHINode *FVPN = dyn_cast<PHINode>(FalseValue))
+ if (FVPN->getParent() == FalseSucc)
+ FalseValue = FVPN->getIncomingValueForBlock(BI->getParent());
+
+ // In order for this transformation to be safe, we must be able to
+ // unconditionally execute both operands to the return. This is
+ // normally the case, but we could have a potentially-trapping
+ // constant expression that prevents this transformation from being
+ // safe.
+ if (ConstantExpr *TCV = dyn_cast<ConstantExpr>(TrueValue))
+ if (TCV->canTrap())
+ return false;
+ if (ConstantExpr *FCV = dyn_cast<ConstantExpr>(FalseValue))
+ if (FCV->canTrap())
+ return false;
+
+ TrueResult.push_back(TrueValue);
+ FalseResult.push_back(FalseValue);
+ }
+
+ // Okay, we collected all the mapped values and checked them for sanity, and
+ // defined to really do this transformation. First, update the CFG.
+ TrueSucc->removePredecessor(BI->getParent());
+ FalseSucc->removePredecessor(BI->getParent());
+
+ // Insert select instructions where needed.
+ Value *BrCond = BI->getCondition();
+ for (unsigned i = 0, e = TrueRet->getNumOperands(); i != e; ++i) {
+ // Insert a select if the results differ.
+ if (TrueResult[i] == FalseResult[i] || isa<UndefValue>(FalseResult[i]))
+ continue;
+ if (isa<UndefValue>(TrueResult[i])) {
+ TrueResult[i] = FalseResult[i];
+ continue;
+ }
+
+ TrueResult[i] = SelectInst::Create(BrCond, TrueResult[i],
+ FalseResult[i], "retval", BI);
+ }
+
+ Value *RI = ReturnInst::Create(&TrueResult[0], TrueResult.size(), BI);
+
+ DOUT << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:"
+ << "\n " << *BI << "NewRet = " << *RI
+ << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc;
+
+ BI->eraseFromParent();
+
+ if (Instruction *BrCondI = dyn_cast<Instruction>(BrCond))
+ ErasePossiblyDeadInstructionTree(BrCondI);
+ 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->getZExtValue() < RHS->getZExtValue();
+ return LHS->getValue().ult(RHS->getValue());
}
};
}
assert(BB && BB->getParent() && "Block not embedded in function!");
assert(BB->getTerminator() && "Degenerate basic block encountered!");
- assert(&BB->getParent()->front() != BB && "Can't Simplify entry block!");
+ assert(&BB->getParent()->getEntryBlock() != BB &&
+ "Can't Simplify entry block!");
// Remove basic blocks that have no predecessors... which are unreachable.
- if (pred_begin(BB) == pred_end(BB) ||
- *pred_begin(BB) == BB && ++pred_begin(BB) == pred_end(BB)) {
+ if ((pred_begin(BB) == pred_end(BB)) ||
+ (*pred_begin(BB) == BB && ++pred_begin(BB) == pred_end(BB))) {
DOUT << "Removing BB: \n" << *BB;
// Loop through all of our successors and make sure they know that one
// away...
Changed |= ConstantFoldTerminator(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);
+
// If this is a returning block with only PHI nodes in it, fold the return
// instruction into any unconditional branch predecessors.
//
BasicBlock::iterator BBI = BB->getTerminator();
if (BBI == BB->begin() || isa<PHINode>(--BBI)) {
// Find predecessors that end with branches.
- std::vector<BasicBlock*> UncondBranchPreds;
- std::vector<BranchInst*> CondBranchPreds;
+ SmallVector<BasicBlock*, 8> UncondBranchPreds;
+ SmallVector<BranchInst*, 8> CondBranchPreds;
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
TerminatorInst *PTI = (*PI)->getTerminator();
- if (BranchInst *BI = dyn_cast<BranchInst>(PTI))
+ if (BranchInst *BI = dyn_cast<BranchInst>(PTI)) {
if (BI->isUnconditional())
UncondBranchPreds.push_back(*PI);
else
CondBranchPreds.push_back(BI);
+ }
}
// If we found some, do the transformation!
// If the return instruction returns a value, and if the value was a
// PHI node in "BB", propagate the right value into the return.
- if (NewRet->getNumOperands() == 1)
- if (PHINode *PN = dyn_cast<PHINode>(NewRet->getOperand(0)))
+ for (User::op_iterator i = NewRet->op_begin(), e = NewRet->op_end();
+ i != e; ++i)
+ if (PHINode *PN = dyn_cast<PHINode>(*i))
if (PN->getParent() == BB)
- NewRet->setOperand(0, PN->getIncomingValueForBlock(Pred));
+ *i = PN->getIncomingValueForBlock(Pred);
+
// Update any PHI nodes in the returning block to realize that we no
// longer branch to them.
BB->removePredecessor(Pred);
while (!CondBranchPreds.empty()) {
BranchInst *BI = CondBranchPreds.back();
CondBranchPreds.pop_back();
- BasicBlock *TrueSucc = BI->getSuccessor(0);
- BasicBlock *FalseSucc = BI->getSuccessor(1);
- BasicBlock *OtherSucc = TrueSucc == BB ? FalseSucc : TrueSucc;
// Check to see if the non-BB successor is also a return block.
- if (isa<ReturnInst>(OtherSucc->getTerminator())) {
- // Check to see if there are only PHI instructions in this block.
- BasicBlock::iterator OSI = OtherSucc->getTerminator();
- if (OSI == OtherSucc->begin() || isa<PHINode>(--OSI)) {
- // 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 (RI->getNumOperands() == 0) {
- TrueSucc->removePredecessor(BI->getParent());
- FalseSucc->removePredecessor(BI->getParent());
- new ReturnInst(0, BI);
- BI->getParent()->getInstList().erase(BI);
- return true;
- }
-
- // Otherwise, figure out what the true and false return values are
- // so we can insert a new select instruction.
- Value *TrueValue = TrueSucc->getTerminator()->getOperand(0);
- Value *FalseValue = FalseSucc->getTerminator()->getOperand(0);
-
- // Unwrap any PHI nodes in the return blocks.
- if (PHINode *TVPN = dyn_cast<PHINode>(TrueValue))
- if (TVPN->getParent() == TrueSucc)
- TrueValue = TVPN->getIncomingValueForBlock(BI->getParent());
- if (PHINode *FVPN = dyn_cast<PHINode>(FalseValue))
- if (FVPN->getParent() == FalseSucc)
- FalseValue = FVPN->getIncomingValueForBlock(BI->getParent());
-
- // In order for this transformation to be safe, we must be able to
- // unconditionally execute both operands to the return. This is
- // normally the case, but we could have a potentially-trapping
- // constant expression that prevents this transformation from being
- // safe.
- if ((!isa<ConstantExpr>(TrueValue) ||
- !cast<ConstantExpr>(TrueValue)->canTrap()) &&
- (!isa<ConstantExpr>(TrueValue) ||
- !cast<ConstantExpr>(TrueValue)->canTrap())) {
- TrueSucc->removePredecessor(BI->getParent());
- FalseSucc->removePredecessor(BI->getParent());
-
- // Insert a new select instruction.
- Value *NewRetVal;
- Value *BrCond = BI->getCondition();
- if (TrueValue != FalseValue)
- NewRetVal = new SelectInst(BrCond, TrueValue,
- FalseValue, "retval", BI);
- else
- NewRetVal = TrueValue;
-
- DOUT << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:"
- << "\n " << *BI << "Select = " << *NewRetVal
- << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc;
-
- new ReturnInst(NewRetVal, BI);
- BI->eraseFromParent();
- if (Instruction *BrCondI = dyn_cast<Instruction>(BrCond))
- if (isInstructionTriviallyDead(BrCondI))
- BrCondI->eraseFromParent();
- return true;
- }
- }
- }
+ if (isa<ReturnInst>(BI->getSuccessor(0)->getTerminator()) &&
+ isa<ReturnInst>(BI->getSuccessor(1)->getTerminator()) &&
+ SimplifyCondBranchToTwoReturns(BI))
+ return true;
}
}
} else if (isa<UnwindInst>(BB->begin())) {
// destination with call instructions, and any unconditional branch
// predecessor with an unwind.
//
- std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
+ 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 (II->getUnwindDest() == BB) {
// Insert a new branch instruction before the invoke, because this
// is now a fall through...
- BranchInst *BI = new BranchInst(II->getNormalDest(), II);
+ BranchInst *BI = BranchInst::Create(II->getNormalDest(), II);
Pred->getInstList().remove(II); // Take out of symbol table
// Insert the call now...
- std::vector<Value*> Args(II->op_begin()+3, II->op_end());
- CallInst *CI = new CallInst(II->getCalledValue(), Args,
- II->getName(), BI);
+ 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->setParamAttrs(II->getParamAttrs());
// If the invoke produced a value, the Call now does instead
II->replaceAllUsesWith(CI);
delete II;
}
} else if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) {
if (BI->isUnconditional()) {
- BasicBlock::iterator BBI = BB->begin(); // Skip over phi nodes...
- while (isa<PHINode>(*BBI)) ++BBI;
+ BasicBlock::iterator BBI = BB->getFirstNonPHI();
BasicBlock *Succ = BI->getSuccessor(0);
if (BBI->isTerminator() && // Terminator is the only non-phi instruction!
// predecessor and use logical operations to pick the right destination.
BasicBlock *TrueDest = BI->getSuccessor(0);
BasicBlock *FalseDest = BI->getSuccessor(1);
- if (BinaryOperator *Cond = dyn_cast<BinaryOperator>(BI->getCondition()))
- if (Cond->getParent() == BB && &BB->front() == Cond &&
- Cond->getNext() == BI && Cond->hasOneUse() &&
+ if (Instruction *Cond = dyn_cast<Instruction>(BI->getCondition())) {
+ BasicBlock::iterator CondIt = Cond;
+ if ((isa<CmpInst>(Cond) || isa<BinaryOperator>(Cond)) &&
+ Cond->getParent() == BB && &BB->front() == Cond &&
+ &*++CondIt == BI && Cond->hasOneUse() &&
TrueDest != BB && FalseDest != BB)
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI!=E; ++PI)
if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator()))
// Invert the predecessors condition test (xor it with true),
// which allows us to write this code once.
Value *NewCond =
- BinaryOperator::createNot(PBI->getCondition(),
+ BinaryOperator::CreateNot(PBI->getCondition(),
PBI->getCondition()->getName()+".not", PBI);
PBI->setCondition(NewCond);
BasicBlock *OldTrue = PBI->getSuccessor(0);
// Clone Cond into the predecessor basic block, and or/and the
// two conditions together.
Instruction *New = Cond->clone();
- New->setName(Cond->getName());
- Cond->setName(Cond->getName()+".old");
PredBlock->getInstList().insert(PBI, New);
+ New->takeName(Cond);
+ Cond->setName(New->getName()+".old");
Instruction::BinaryOps Opcode =
PBI->getSuccessor(0) == TrueDest ?
Instruction::Or : Instruction::And;
Value *NewCond =
- BinaryOperator::create(Opcode, PBI->getCondition(),
+ BinaryOperator::Create(Opcode, PBI->getCondition(),
New, "bothcond", PBI);
PBI->setCondition(NewCond);
if (PBI->getSuccessor(0) == BB) {
return SimplifyCFG(BB) | 1;
}
}
+ }
- // Scan predessor blocks for conditional branchs.
+ // Scan predessor blocks for conditional branches.
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator()))
if (PBI != BI && PBI->isConditional()) {
// 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.
+ // predecessor that ends on a branch of the same condition, make
+ // this conditional branch redundant.
if (PBI->getCondition() == BI->getCondition() &&
PBI->getSuccessor(0) != PBI->getSuccessor(1)) {
// Okay, the outcome of this conditional branch is statically
if (BB->getSinglePredecessor()) {
// Turn this into a branch on constant.
bool CondIsTrue = PBI->getSuccessor(0) == BB;
- BI->setCondition(ConstantBool::get(CondIsTrue));
+ BI->setCondition(ConstantInt::get(Type::Int1Ty, CondIsTrue));
return SimplifyCFG(BB); // Nuke the branch on constant.
}
- // Otherwise, if there are multiple predecessors, insert a PHI that
- // merges in the constant and simplify the block result.
+ // Otherwise, if there are multiple predecessors, insert a PHI
+ // that merges in the constant and simplify the block result.
if (BlockIsSimpleEnoughToThreadThrough(BB)) {
- PHINode *NewPN = new PHINode(Type::BoolTy,
- BI->getCondition()->getName()+".pr",
- BB->begin());
+ PHINode *NewPN = PHINode::Create(Type::Int1Ty,
+ BI->getCondition()->getName()
+ + ".pr", BB->begin());
for (PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
if ((PBI = dyn_cast<BranchInst>((*PI)->getTerminator())) &&
PBI != BI && PBI->isConditional() &&
PBI->getCondition() == BI->getCondition() &&
PBI->getSuccessor(0) != PBI->getSuccessor(1)) {
bool CondIsTrue = PBI->getSuccessor(0) == BB;
- NewPN->addIncoming(ConstantBool::get(CondIsTrue), *PI);
+ NewPN->addIncoming(ConstantInt::get(Type::Int1Ty,
+ CondIsTrue), *PI);
} else {
NewPN->addIncoming(BI->getCondition(), *PI);
}
// Make sure we get to CommonDest on True&True directions.
Value *PBICond = PBI->getCondition();
if (PBIOp)
- PBICond = BinaryOperator::createNot(PBICond,
+ PBICond = BinaryOperator::CreateNot(PBICond,
PBICond->getName()+".not",
PBI);
Value *BICond = BI->getCondition();
if (BIOp)
- BICond = BinaryOperator::createNot(BICond,
+ BICond = BinaryOperator::CreateNot(BICond,
BICond->getName()+".not",
PBI);
// Merge the conditions.
Value *Cond =
- BinaryOperator::createOr(PBICond, BICond, "brmerge", PBI);
+ BinaryOperator::CreateOr(PBICond, BICond, "brmerge", PBI);
// Modify PBI to branch on the new condition to the new dests.
PBI->setCondition(Cond);
Value *PBIV = PN->getIncomingValue(PBBIdx);
if (BIV != PBIV) {
// Insert a select in PBI to pick the right value.
- Value *NV = new SelectInst(PBICond, PBIV, BIV,
- PBIV->getName()+".mux", PBI);
+ Value *NV = SelectInst::Create(PBICond, PBIV, BIV,
+ PBIV->getName()+".mux", PBI);
PN->setIncomingValue(PBBIdx, NV);
}
}
// If the unreachable instruction is the first in the block, take a gander
// at all of the predecessors of this instruction, and simplify them.
if (&BB->front() == Unreachable) {
- std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
+ 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();
}
} else {
if (BI->getSuccessor(0) == BB) {
- new BranchInst(BI->getSuccessor(1), BI);
+ BranchInst::Create(BI->getSuccessor(1), BI);
BI->eraseFromParent();
} else if (BI->getSuccessor(1) == BB) {
- new BranchInst(BI->getSuccessor(0), BI);
+ BranchInst::Create(BI->getSuccessor(0), BI);
BI->eraseFromParent();
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 = new BranchInst(II->getNormalDest(), II);
+ BranchInst *BI = BranchInst::Create(II->getNormalDest(), II);
II->removeFromParent(); // Take out of symbol table
// Insert the call now...
- std::vector<Value*> Args(II->op_begin()+3, II->op_end());
- CallInst *CI = new CallInst(II->getCalledValue(), Args,
- II->getName(), BI);
+ 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->setParamAttrs(II->getParamAttrs());
// If the invoke produced a value, the Call does now instead.
II->replaceAllUsesWith(CI);
delete II;
//
while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
PN->replaceAllUsesWith(PN->getIncomingValue(0));
- BB->getInstList().pop_front(); // Delete the phi node...
+ BB->getInstList().pop_front(); // Delete the phi node.
}
- // Delete the unconditional branch from the predecessor...
+ // Delete the unconditional branch from the predecessor.
OnlyPred->getInstList().pop_back();
- // Move all definitions in the successor to the predecessor...
+ // Move all definitions in the successor to the predecessor.
OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
// Make all PHI nodes that referred to BB now refer to Pred as their
- // source...
+ // source.
BB->replaceAllUsesWith(OnlyPred);
- std::string OldName = BB->getName();
-
- // Erase basic block from the function...
+ // Inherit predecessors name if it exists.
+ if (!OnlyPred->hasName())
+ OnlyPred->takeName(BB);
+
+ // Erase basic block from the function.
M->getBasicBlockList().erase(BB);
- // Inherit predecessors name if it exists...
- if (!OldName.empty() && !OnlyPred->hasName())
- OnlyPred->setName(OldName);
-
return true;
}
// so see if there is any identical code in the "then" and "else"
// blocks. If so, we can hoist it up to the branching block.
Changed |= HoistThenElseCodeToIf(BI);
+ } else {
+ OnlySucc = NULL;
+ for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
+ SI != SE; ++SI) {
+ if (!OnlySucc)
+ OnlySucc = *SI;
+ else if (*SI != OnlySucc) {
+ OnlySucc = 0; // There are multiple distinct successors!
+ break;
+ }
+ }
+
+ if (OnlySucc == OtherBB) {
+ // If BB's only successor is the other successor of the predecessor,
+ // i.e. a triangle, see if we can hoist any code from this block up
+ // to the "if" block.
+ Changed |= SpeculativelyExecuteBB(BI, BB);
+ }
}
}
if (!TrueWhenEqual) std::swap(DefaultBB, EdgeBB);
// Create the new switch instruction now.
- SwitchInst *New = new SwitchInst(CompVal, DefaultBB,Values.size(),BI);
+ SwitchInst *New = SwitchInst::Create(CompVal, DefaultBB,
+ Values.size(), BI);
// Add all of the 'cases' to the switch instruction.
for (unsigned i = 0, e = Values.size(); i != e; ++i)
}
}
- // 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);
-
return Changed;
}
projects / oota-llvm.git / blobdiff