diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/ADCE.cpp | 52 |
1 files changed, 33 insertions, 19 deletions
diff --git a/llvm/lib/Transforms/Scalar/ADCE.cpp b/llvm/lib/Transforms/Scalar/ADCE.cpp index 11f84334c25..4c0169171b2 100644 --- a/llvm/lib/Transforms/Scalar/ADCE.cpp +++ b/llvm/lib/Transforms/Scalar/ADCE.cpp @@ -188,34 +188,30 @@ void ADCE::doADCE(DominanceFrontier &CDG) { // std::set<BasicBlock*> VisitedBlocks; BasicBlock *EntryBlock = fixupCFG(Func->front(), VisitedBlocks, AliveBlocks); - if (EntryBlock && EntryBlock != Func->front()) { - // We need to move the new entry block to be the first bb of the function - Function::iterator EBI = find(Func->begin(), Func->end(), EntryBlock); - std::swap(*EBI, *Func->begin()); // Exchange old location with start of fn - - while (PHINode *PN = dyn_cast<PHINode>(EntryBlock->front())) { - assert(PN->getNumIncomingValues() == 1 && - "Can only have a single incoming value at this point..."); - // The incoming value must be outside of the scope of the function, a - // global variable, constant or parameter maybe... - // - PN->replaceAllUsesWith(PN->getIncomingValue(0)); - - // Nuke the phi node... - delete EntryBlock->getInstList().remove(EntryBlock->begin()); - } - } // Now go through and tell dead blocks to drop all of their references so they - // can be safely deleted. + // can be safely deleted. Also, as we are doing so, if the block has + // successors that are still live (and that have PHI nodes in them), remove + // the entry for this block from the phi nodes. // for (Function::iterator BI = Func->begin(), BE = Func->end(); BI != BE; ++BI){ BasicBlock *BB = *BI; if (!AliveBlocks.count(BB)) { + // Remove entries from successors PHI nodes if they are still alive... + for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI) + if (AliveBlocks.count(*SI)) { // Only if the successor is alive... + BasicBlock *Succ = *SI; + for (BasicBlock::iterator I = Succ->begin();// Loop over all PHI nodes + PHINode *PN = dyn_cast<PHINode>(*I); ++I) + PN->removeIncomingValue(BB); // Remove value for this block + } + BB->dropAllReferences(); } } + cerr << "Before Deleting Blocks: " << Func; + // Now loop through all of the blocks and delete them. We can safely do this // now because we know that there are no references to dead blocks (because // they have dropped all of their references... @@ -228,6 +224,24 @@ void ADCE::doADCE(DominanceFrontier &CDG) { } ++BI; // Increment iterator... } + + if (EntryBlock && EntryBlock != Func->front()) { + // We need to move the new entry block to be the first bb of the function + Function::iterator EBI = find(Func->begin(), Func->end(), EntryBlock); + std::swap(*EBI, *Func->begin()); // Exchange old location with start of fn + } + + while (PHINode *PN = dyn_cast<PHINode>(EntryBlock->front())) { + assert(PN->getNumIncomingValues() == 1 && + "Can only have a single incoming value at this point..."); + // The incoming value must be outside of the scope of the function, a + // global variable, constant or parameter maybe... + // + PN->replaceAllUsesWith(PN->getIncomingValue(0)); + + // Nuke the phi node... + delete EntryBlock->getInstList().remove(EntryBlock->begin()); + } } @@ -284,7 +298,7 @@ BasicBlock *ADCE::fixupCFG(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks, for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI) { BasicBlock *RetBB = fixupCFG(*SI, VisitedBlocks, AliveBlocks); if (RetBB) { - assert(ReturnBB == 0 && "One one live child allowed!"); + assert(ReturnBB == 0 && "At most one live child allowed!"); ReturnBB = RetBB; } } |
