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-rw-r--r--lib/Transforms/Scalar/LoopUnswitch.cpp50
1 files changed, 26 insertions, 24 deletions
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 717917e..009ee7b 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -77,7 +77,6 @@ namespace {
bool redoLoop;
Loop *currentLoop;
- DominanceFrontier *DF;
DominatorTree *DT;
BasicBlock *loopHeader;
BasicBlock *loopPreheader;
@@ -93,14 +92,16 @@ namespace {
static char ID; // Pass ID, replacement for typeid
explicit LoopUnswitch(bool Os = false) :
LoopPass(ID), OptimizeForSize(Os), redoLoop(false),
- currentLoop(NULL), DF(NULL), DT(NULL), loopHeader(NULL),
- loopPreheader(NULL) {}
+ currentLoop(NULL), DT(NULL), loopHeader(NULL),
+ loopPreheader(NULL) {
+ initializeLoopUnswitchPass(*PassRegistry::getPassRegistry());
+ }
bool runOnLoop(Loop *L, LPPassManager &LPM);
bool processCurrentLoop();
/// This transformation requires natural loop information & requires that
- /// loop preheaders be inserted into the CFG...
+ /// loop preheaders be inserted into the CFG.
///
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(LoopSimplifyID);
@@ -110,7 +111,6 @@ namespace {
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
AU.addPreserved<DominatorTree>();
- AU.addPreserved<DominanceFrontier>();
}
private:
@@ -160,7 +160,13 @@ namespace {
};
}
char LoopUnswitch::ID = 0;
-INITIALIZE_PASS(LoopUnswitch, "loop-unswitch", "Unswitch loops", false, false);
+INITIALIZE_PASS_BEGIN(LoopUnswitch, "loop-unswitch", "Unswitch loops",
+ false, false)
+INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
+INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_DEPENDENCY(LCSSA)
+INITIALIZE_PASS_END(LoopUnswitch, "loop-unswitch", "Unswitch loops",
+ false, false)
Pass *llvm::createLoopUnswitchPass(bool Os) {
return new LoopUnswitch(Os);
@@ -201,7 +207,6 @@ static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) {
bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
LI = &getAnalysis<LoopInfo>();
LPM = &LPM_Ref;
- DF = getAnalysisIfAvailable<DominanceFrontier>();
DT = getAnalysisIfAvailable<DominatorTree>();
currentLoop = L;
Function *F = currentLoop->getHeader()->getParent();
@@ -216,8 +221,6 @@ bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
// FIXME: Reconstruct dom info, because it is not preserved properly.
if (DT)
DT->runOnFunction(*F);
- if (DF)
- DF->runOnFunction(*F);
}
return Changed;
}
@@ -282,19 +285,18 @@ bool LoopUnswitch::processCurrentLoop() {
return Changed;
}
-/// isTrivialLoopExitBlock - Check to see if all paths from BB either:
-/// 1. Exit the loop with no side effects.
-/// 2. Branch to the latch block with no side-effects.
+/// isTrivialLoopExitBlock - Check to see if all paths from BB exit the
+/// loop with no side effects (including infinite loops).
///
-/// If these conditions are true, we return true and set ExitBB to the block we
+/// If true, we return true and set ExitBB to the block we
/// exit through.
///
static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB,
BasicBlock *&ExitBB,
std::set<BasicBlock*> &Visited) {
if (!Visited.insert(BB).second) {
- // Already visited and Ok, end of recursion.
- return true;
+ // Already visited. Without more analysis, this could indicate an infinte loop.
+ return false;
} else if (!L->contains(BB)) {
// Otherwise, this is a loop exit, this is fine so long as this is the
// first exit.
@@ -324,7 +326,7 @@ static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB,
/// process. If so, return the block that is exited to, otherwise return null.
static BasicBlock *isTrivialLoopExitBlock(Loop *L, BasicBlock *BB) {
std::set<BasicBlock*> Visited;
- Visited.insert(L->getHeader()); // Branches to header are ok.
+ Visited.insert(L->getHeader()); // Branches to header make infinite loops.
BasicBlock *ExitBB = 0;
if (isTrivialLoopExitBlockHelper(L, BB, ExitBB, Visited))
return ExitBB;
@@ -356,8 +358,8 @@ bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val,
if (!BI->isConditional() || BI->getCondition() != Cond)
return false;
- // Check to see if a successor of the branch is guaranteed to go to the
- // latch block or exit through a one exit block without having any
+ // Check to see if a successor of the branch is guaranteed to
+ // exit through a unique exit block without having any
// side-effects. If so, determine the value of Cond that causes it to do
// this.
if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop,
@@ -460,10 +462,10 @@ bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val) {
// current values into those specified by VMap.
//
static inline void RemapInstruction(Instruction *I,
- ValueMap<const Value *, Value*> &VMap) {
+ ValueToValueMapTy &VMap) {
for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) {
Value *Op = I->getOperand(op);
- ValueMap<const Value *, Value*>::iterator It = VMap.find(Op);
+ ValueToValueMapTy::iterator It = VMap.find(Op);
if (It != VMap.end()) Op = It->second;
I->setOperand(op, Op);
}
@@ -471,7 +473,7 @@ static inline void RemapInstruction(Instruction *I,
/// CloneLoop - Recursively clone the specified loop and all of its children,
/// mapping the blocks with the specified map.
-static Loop *CloneLoop(Loop *L, Loop *PL, ValueMap<const Value*, Value*> &VM,
+static Loop *CloneLoop(Loop *L, Loop *PL, ValueToValueMapTy &VM,
LoopInfo *LI, LPPassManager *LPM) {
Loop *New = new Loop();
LPM->insertLoop(New, PL);
@@ -615,7 +617,7 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
// the loop preheader and exit blocks), keeping track of the mapping between
// the instructions and blocks.
NewBlocks.reserve(LoopBlocks.size());
- ValueMap<const Value*, Value*> VMap;
+ ValueToValueMapTy VMap;
for (unsigned i = 0, e = LoopBlocks.size(); i != e; ++i) {
BasicBlock *NewBB = CloneBasicBlock(LoopBlocks[i], VMap, ".us", F);
NewBlocks.push_back(NewBB);
@@ -653,7 +655,7 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
for (BasicBlock::iterator I = ExitSucc->begin(); isa<PHINode>(I); ++I) {
PN = cast<PHINode>(I);
Value *V = PN->getIncomingValueForBlock(ExitBlocks[i]);
- ValueMap<const Value *, Value*>::iterator It = VMap.find(V);
+ ValueToValueMapTy::iterator It = VMap.find(V);
if (It != VMap.end()) V = It->second;
PN->addIncoming(V, NewExit);
}
@@ -992,7 +994,7 @@ void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) {
// See if instruction simplification can hack this up. This is common for
// things like "select false, X, Y" after unswitching made the condition be
// 'false'.
- if (Value *V = SimplifyInstruction(I)) {
+ if (Value *V = SimplifyInstruction(I, 0, DT)) {
ReplaceUsesOfWith(I, V, Worklist, L, LPM);
continue;
}
generated by cgit v1.1 at 2025-08-25 08:16:53 +0000