diff options
Diffstat (limited to 'lib/Transforms/Scalar/LoopDeletion.cpp')
-rw-r--r-- | lib/Transforms/Scalar/LoopDeletion.cpp | 54 |
1 files changed, 28 insertions, 26 deletions
diff --git a/lib/Transforms/Scalar/LoopDeletion.cpp b/lib/Transforms/Scalar/LoopDeletion.cpp index 9c67e327e2..0b62050b17 100644 --- a/lib/Transforms/Scalar/LoopDeletion.cpp +++ b/lib/Transforms/Scalar/LoopDeletion.cpp @@ -34,13 +34,9 @@ namespace { } // Possibly eliminate loop L if it is dead. - bool runOnLoop(Loop* L, LPPassManager& LPM); + bool runOnLoop(Loop *L, LPPassManager &LPM); - bool IsLoopDead(Loop* L, SmallVector<BasicBlock*, 4>& exitingBlocks, - SmallVector<BasicBlock*, 4>& exitBlocks, - bool &Changed, BasicBlock *Preheader); - - virtual void getAnalysisUsage(AnalysisUsage& AU) const { + virtual void getAnalysisUsage(AnalysisUsage &AU) const { AU.addRequired<DominatorTree>(); AU.addRequired<LoopInfo>(); AU.addRequired<ScalarEvolution>(); @@ -53,6 +49,12 @@ namespace { AU.addPreservedID(LoopSimplifyID); AU.addPreservedID(LCSSAID); } + + private: + bool isLoopDead(Loop *L, SmallVector<BasicBlock*, 4> &exitingBlocks, + SmallVector<BasicBlock*, 4> &exitBlocks, + bool &Changed, BasicBlock *Preheader); + }; } @@ -67,18 +69,18 @@ INITIALIZE_PASS_DEPENDENCY(LCSSA) INITIALIZE_PASS_END(LoopDeletion, "loop-deletion", "Delete dead loops", false, false) -Pass* llvm::createLoopDeletionPass() { +Pass *llvm::createLoopDeletionPass() { return new LoopDeletion(); } -/// IsLoopDead - Determined if a loop is dead. This assumes that we've already +/// isLoopDead - Determined if a loop is dead. This assumes that we've already /// checked for unique exit and exiting blocks, and that the code is in LCSSA /// form. -bool LoopDeletion::IsLoopDead(Loop* L, - SmallVector<BasicBlock*, 4>& exitingBlocks, - SmallVector<BasicBlock*, 4>& exitBlocks, +bool LoopDeletion::isLoopDead(Loop *L, + SmallVector<BasicBlock*, 4> &exitingBlocks, + SmallVector<BasicBlock*, 4> &exitBlocks, bool &Changed, BasicBlock *Preheader) { - BasicBlock* exitBlock = exitBlocks[0]; + BasicBlock *exitBlock = exitBlocks[0]; // Make sure that all PHI entries coming from the loop are loop invariant. // Because the code is in LCSSA form, any values used outside of the loop @@ -86,19 +88,19 @@ bool LoopDeletion::IsLoopDead(Loop* L, // sufficient to guarantee that no loop-variant values are used outside // of the loop. BasicBlock::iterator BI = exitBlock->begin(); - while (PHINode* P = dyn_cast<PHINode>(BI)) { - Value* incoming = P->getIncomingValueForBlock(exitingBlocks[0]); + while (PHINode *P = dyn_cast<PHINode>(BI)) { + Value *incoming = P->getIncomingValueForBlock(exitingBlocks[0]); // Make sure all exiting blocks produce the same incoming value for the exit // block. If there are different incoming values for different exiting // blocks, then it is impossible to statically determine which value should // be used. - for (unsigned i = 1; i < exitingBlocks.size(); ++i) { + for (unsigned i = 1, e = exitingBlocks.size(); i < e; ++i) { if (incoming != P->getIncomingValueForBlock(exitingBlocks[i])) return false; } - if (Instruction* I = dyn_cast<Instruction>(incoming)) + if (Instruction *I = dyn_cast<Instruction>(incoming)) if (!L->makeLoopInvariant(I, Changed, Preheader->getTerminator())) return false; @@ -127,10 +129,10 @@ bool LoopDeletion::IsLoopDead(Loop* L, /// so could change the halting/non-halting nature of a program. /// NOTE: This entire process relies pretty heavily on LoopSimplify and LCSSA /// in order to make various safety checks work. -bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) { +bool LoopDeletion::runOnLoop(Loop *L, LPPassManager &LPM) { // We can only remove the loop if there is a preheader that we can // branch from after removing it. - BasicBlock* preheader = L->getLoopPreheader(); + BasicBlock *preheader = L->getLoopPreheader(); if (!preheader) return false; @@ -158,19 +160,19 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) { // Finally, we have to check that the loop really is dead. bool Changed = false; - if (!IsLoopDead(L, exitingBlocks, exitBlocks, Changed, preheader)) + if (!isLoopDead(L, exitingBlocks, exitBlocks, Changed, preheader)) return Changed; // Don't remove loops for which we can't solve the trip count. // They could be infinite, in which case we'd be changing program behavior. - ScalarEvolution& SE = getAnalysis<ScalarEvolution>(); + ScalarEvolution &SE = getAnalysis<ScalarEvolution>(); const SCEV *S = SE.getMaxBackedgeTakenCount(L); if (isa<SCEVCouldNotCompute>(S)) return Changed; // Now that we know the removal is safe, remove the loop by changing the // branch from the preheader to go to the single exit block. - BasicBlock* exitBlock = exitBlocks[0]; + BasicBlock *exitBlock = exitBlocks[0]; // Because we're deleting a large chunk of code at once, the sequence in which // we remove things is very important to avoid invalidation issues. Don't @@ -182,14 +184,14 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) { SE.forgetLoop(L); // Connect the preheader directly to the exit block. - TerminatorInst* TI = preheader->getTerminator(); + TerminatorInst *TI = preheader->getTerminator(); TI->replaceUsesOfWith(L->getHeader(), exitBlock); // Rewrite phis in the exit block to get their inputs from // the preheader instead of the exiting block. - BasicBlock* exitingBlock = exitingBlocks[0]; + BasicBlock *exitingBlock = exitingBlocks[0]; BasicBlock::iterator BI = exitBlock->begin(); - while (PHINode* P = dyn_cast<PHINode>(BI)) { + while (PHINode *P = dyn_cast<PHINode>(BI)) { int j = P->getBasicBlockIndex(exitingBlock); assert(j >= 0 && "Can't find exiting block in exit block's phi node!"); P->setIncomingBlock(j, preheader); @@ -200,7 +202,7 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) { // Update the dominator tree and remove the instructions and blocks that will // be deleted from the reference counting scheme. - DominatorTree& DT = getAnalysis<DominatorTree>(); + DominatorTree &DT = getAnalysis<DominatorTree>(); SmallVector<DomTreeNode*, 8> ChildNodes; for (Loop::block_iterator LI = L->block_begin(), LE = L->block_end(); LI != LE; ++LI) { @@ -230,7 +232,7 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) { // Finally, the blocks from loopinfo. This has to happen late because // otherwise our loop iterators won't work. - LoopInfo& loopInfo = getAnalysis<LoopInfo>(); + LoopInfo &loopInfo = getAnalysis<LoopInfo>(); SmallPtrSet<BasicBlock*, 8> blocks; blocks.insert(L->block_begin(), L->block_end()); for (SmallPtrSet<BasicBlock*,8>::iterator I = blocks.begin(), |