// This function splits a single succeesor block following an guard and is used to // do the following transform // block - cold1 block - cold1 // \ / => | | // nextBlock nextBlock nextBlock' (called tailSplitBlock below) // | \ / // ... ... void TR_VirtualGuardHeadMerger::tailSplitBlock(TR::Block * block, TR::Block * cold1) { TR::CFG *cfg = comp()->getFlowGraph(); cfg->setStructure(NULL); TR_BlockCloner cloner(cfg); TR::Block *tailSplitBlock = cloner.cloneBlocks(block->getNextBlock(), block->getNextBlock()); tailSplitBlock->setFrequency(cold1->getFrequency()); if (cold1->isCold()) tailSplitBlock->setIsCold(); // physically put the block after cold1 since we want cold1 to fall through tailSplitBlock->getExit()->join(cold1->getExit()->getNextTreeTop()); cold1->getExit()->join(tailSplitBlock->getEntry()); // remove cold1's goto TR::TransformUtil::removeTree(comp(), cold1->getExit()->getPrevRealTreeTop()); // copy the exception edges for (auto e = block->getNextBlock()->getExceptionSuccessors().begin(); e != block->getNextBlock()->getExceptionSuccessors().end(); ++e) cfg->addExceptionEdge(tailSplitBlock, (*e)->getTo()); cfg->addEdge(cold1, tailSplitBlock); // lastly fix up the exit of tailSplitBlock TR::Node *tailSplitEnd = tailSplitBlock->getExit()->getPrevRealTreeTop()->getNode(); if (tailSplitEnd->getOpCode().isGoto()) { tailSplitEnd->setBranchDestination(block->getNextBlock()->getLastRealTreeTop()->getNode()->getBranchDestination()); cfg->addEdge(tailSplitBlock, block->getNextBlock()->getSuccessors().front()->getTo()); } else if (tailSplitEnd->getOpCode().isBranch()) { TR::Block *gotoBlock = TR::Block::createEmptyBlock(tailSplitEnd, comp(), cold1->getFrequency()); if (cold1->isCold()) gotoBlock->setIsCold(true); gotoBlock->getExit()->join(tailSplitBlock->getExit()->getNextTreeTop()); tailSplitBlock->getExit()->join(gotoBlock->getEntry()); cfg->addNode(gotoBlock); gotoBlock->append(TR::TreeTop::create(comp(), TR::Node::create(tailSplitEnd, TR::Goto, 0, block->getNextBlock()->getExit()->getNextTreeTop()))); cfg->addEdge(tailSplitBlock, gotoBlock); cfg->addEdge(tailSplitBlock, tailSplitBlock->getLastRealTreeTop()->getNode()->getBranchDestination()->getEnclosingBlock()); cfg->addEdge(gotoBlock, block->getNextBlock()->getNextBlock()); } else if ( !tailSplitEnd->getOpCode().isReturn() && !tailSplitEnd->getOpCode().isJumpWithMultipleTargets() && tailSplitEnd->getOpCodeValue() != TR::athrow && !(tailSplitEnd->getNumChildren() >= 1 && tailSplitEnd->getFirstChild()->getOpCodeValue() == TR::athrow) ) { tailSplitBlock->append(TR::TreeTop::create(comp(), TR::Node::create(tailSplitEnd, TR::Goto, 0, block->getNextBlock()->getExit()->getNextTreeTop()))); cfg->addEdge(tailSplitBlock, block->getNextBlock()->getNextBlock()); } else { for (auto e = block->getNextBlock()->getSuccessors().begin(); e != block->getNextBlock()->getSuccessors().end(); ++e) cfg->addEdge(tailSplitBlock, (*e)->getTo()); } cfg->removeEdge(cold1, block->getNextBlock()); optimizer()->setUseDefInfo(NULL); optimizer()->setValueNumberInfo(NULL); }