BasicBlockUtils.cpp revision afc36a9520971832dfbebc0333593bf5d3098296
14d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner//===-- BasicBlockUtils.cpp - BasicBlock Utilities -------------------------==// 2fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 54ee451de366474b9c228b4e5fa573795a715216dChris Lattner// This file is distributed under the University of Illinois Open Source 64ee451de366474b9c228b4e5fa573795a715216dChris Lattner// License. See LICENSE.TXT for details. 7fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 94d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner// 104d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner// This family of functions perform manipulations on basic blocks, and 114d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner// instructions contained within basic blocks. 124d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner// 134d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner//===----------------------------------------------------------------------===// 144d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 154d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner#include "llvm/Transforms/Utils/BasicBlockUtils.h" 164d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner#include "llvm/Function.h" 1747b14a4a6a455c7be169cfd312fcbe796f0ad426Misha Brukman#include "llvm/Instructions.h" 18bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen#include "llvm/IntrinsicInst.h" 19b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner#include "llvm/Constant.h" 20b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner#include "llvm/Type.h" 2154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner#include "llvm/Analysis/AliasAnalysis.h" 228019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel#include "llvm/Analysis/LoopInfo.h" 238019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel#include "llvm/Analysis/Dominators.h" 24ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner#include "llvm/Target/TargetData.h" 25afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman#include "llvm/Transforms/Utils/Local.h" 26afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman#include "llvm/Support/ValueHandle.h" 274d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner#include <algorithm> 28f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerusing namespace llvm; 29d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 3071af9b07a58a264064813545889cf6473ce23de6Chris Lattner/// DeleteDeadBlock - Delete the specified block, which must have no 3171af9b07a58a264064813545889cf6473ce23de6Chris Lattner/// predecessors. 3271af9b07a58a264064813545889cf6473ce23de6Chris Lattnervoid llvm::DeleteDeadBlock(BasicBlock *BB) { 332973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner assert((pred_begin(BB) == pred_end(BB) || 342973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner // Can delete self loop. 352973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner BB->getSinglePredecessor() == BB) && "Block is not dead!"); 362b1ba24fb75e633560846e551acadade92783bb3Chris Lattner TerminatorInst *BBTerm = BB->getTerminator(); 375622f07a21b799964dc172925b9ebc38191859f6Devang Patel 382b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Loop through all of our successors and make sure they know that one 392b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // of their predecessors is going away. 402b1ba24fb75e633560846e551acadade92783bb3Chris Lattner for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i) 412b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BBTerm->getSuccessor(i)->removePredecessor(BB); 422b1ba24fb75e633560846e551acadade92783bb3Chris Lattner 432b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Zap all the instructions in the block. 442b1ba24fb75e633560846e551acadade92783bb3Chris Lattner while (!BB->empty()) { 452b1ba24fb75e633560846e551acadade92783bb3Chris Lattner Instruction &I = BB->back(); 462b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // If this instruction is used, replace uses with an arbitrary value. 472b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Because control flow can't get here, we don't care what we replace the 482b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // value with. Note that since this block is unreachable, and all values 492b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // contained within it must dominate their uses, that all uses will 502b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // eventually be removed (they are themselves dead). 512b1ba24fb75e633560846e551acadade92783bb3Chris Lattner if (!I.use_empty()) 522b1ba24fb75e633560846e551acadade92783bb3Chris Lattner I.replaceAllUsesWith(UndefValue::get(I.getType())); 532b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BB->getInstList().pop_back(); 542b1ba24fb75e633560846e551acadade92783bb3Chris Lattner } 555622f07a21b799964dc172925b9ebc38191859f6Devang Patel 562b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Zap the block! 572b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BB->eraseFromParent(); 582b1ba24fb75e633560846e551acadade92783bb3Chris Lattner} 592b1ba24fb75e633560846e551acadade92783bb3Chris Lattner 6029874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// FoldSingleEntryPHINodes - We know that BB has one predecessor. If there are 6129874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// any single-entry PHI nodes in it, fold them away. This handles the case 6229874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// when all entries to the PHI nodes in a block are guaranteed equal, such as 6329874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// when the block has exactly one predecessor. 6429874e0dc6c4e55bc384611273343bb358982cc3Chris Lattnervoid llvm::FoldSingleEntryPHINodes(BasicBlock *BB) { 6529874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner if (!isa<PHINode>(BB->begin())) 6629874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner return; 6729874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 6829874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { 6929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner if (PN->getIncomingValue(0) != PN) 7029874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->replaceAllUsesWith(PN->getIncomingValue(0)); 7129874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner else 7229874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->replaceAllUsesWith(UndefValue::get(PN->getType())); 7329874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->eraseFromParent(); 7429874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner } 7529874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner} 7629874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 7729874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 78afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it 79afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// is dead. Also recursively delete any operands that become dead as 80afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// a result. This includes tracing the def-use list from the PHI to see if 81afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// it is ultimately unused or if it reaches an unused cycle. If a 82afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// ValueDeletionListener is specified, it is notified of the deletions. 83afc36a9520971832dfbebc0333593bf5d3098296Dan Gohmanvoid llvm::DeleteDeadPHIs(BasicBlock *BB, ValueDeletionListener *VDL) { 84afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman // Recursively deleting a PHI may cause multiple PHIs to be deleted 85afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman // or RAUW'd undef, so use an array of WeakVH for the PHIs to delete. 86afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman SmallVector<WeakVH, 8> PHIs; 87afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman for (BasicBlock::iterator I = BB->begin(); 88afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman PHINode *PN = dyn_cast<PHINode>(I); ++I) 89afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman PHIs.push_back(PN); 90afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman 91afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman for (unsigned i = 0, e = PHIs.size(); i != e; ++i) 92afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*())) 93afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman RecursivelyDeleteDeadPHINode(PN, VDL); 94afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman} 95afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman 96b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, 97b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson/// if possible. The return value indicates success or failure. 98b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Andersonbool llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) { 9911f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson pred_iterator PI(pred_begin(BB)), PE(pred_end(BB)); 100b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Can't merge the entry block. 101b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (pred_begin(BB) == pred_end(BB)) return false; 102b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 10311f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson BasicBlock *PredBB = *PI++; 10411f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson for (; PI != PE; ++PI) // Search all predecessors, see if they are all same 10511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (*PI != PredBB) { 10611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson PredBB = 0; // There are multiple different predecessors... 10711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson break; 10811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson } 109b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 11011f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Can't merge if there are multiple predecessors. 11111f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!PredBB) return false; 1123ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson // Don't break self-loops. 1133ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson if (PredBB == BB) return false; 1143ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson // Don't break invokes. 1153ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson if (isa<InvokeInst>(PredBB->getTerminator())) return false; 11611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 11711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB)); 11811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson BasicBlock* OnlySucc = BB; 11911f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson for (; SI != SE; ++SI) 12011f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (*SI != OnlySucc) { 12111f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson OnlySucc = 0; // There are multiple distinct successors! 12211f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson break; 12311f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson } 12411f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 12511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Can't merge if there are multiple successors. 12611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!OnlySucc) return false; 127e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel 128e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel // Can't merge if there is PHI loop. 129e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; ++BI) { 130e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel if (PHINode *PN = dyn_cast<PHINode>(BI)) { 131e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 132e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel if (PN->getIncomingValue(i) == PN) 133e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel return false; 134e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel } else 135e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel break; 136e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel } 137e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel 138b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Begin by getting rid of unneeded PHIs. 139b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) { 140b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PN->replaceAllUsesWith(PN->getIncomingValue(0)); 141b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->getInstList().pop_front(); // Delete the phi node... 142b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 143b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 144b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Delete the unconditional branch from the predecessor... 145b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PredBB->getInstList().pop_back(); 146b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 147b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Move all definitions in the successor to the predecessor... 148b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PredBB->getInstList().splice(PredBB->end(), BB->getInstList()); 149b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 150b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Make all PHI nodes that referred to BB now refer to Pred as their 151b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // source... 152b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->replaceAllUsesWith(PredBB); 153b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 15411f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Inherit predecessors name if it exists. 15511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!PredBB->hasName()) 15611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson PredBB->takeName(BB); 15711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 158b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Finally, erase the old block and update dominator info. 159b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (P) { 1601465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominatorTree* DT = P->getAnalysisIfAvailable<DominatorTree>()) { 161b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DomTreeNode* DTN = DT->getNode(BB); 162b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DomTreeNode* PredDTN = DT->getNode(PredBB); 163b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 164b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (DTN) { 165b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson SmallPtrSet<DomTreeNode*, 8> Children(DTN->begin(), DTN->end()); 166b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson for (SmallPtrSet<DomTreeNode*, 8>::iterator DI = Children.begin(), 167b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DE = Children.end(); DI != DE; ++DI) 168b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DT->changeImmediateDominator(*DI, PredDTN); 169b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 170b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DT->eraseNode(BB); 171b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 172b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 173b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 174b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 175b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->eraseFromParent(); 176b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 177b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 178b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson return true; 179b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson} 180b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 1810f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI) 1820f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// with a value, then remove and delete the original instruction. 1830f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 184f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithValue(BasicBlock::InstListType &BIL, 185f7703df4968084c18c248c1feea9961c19a32e6aChris Lattner BasicBlock::iterator &BI, Value *V) { 18618961504fc2b299578dba817900a0696cf3ccc4dChris Lattner Instruction &I = *BI; 1874d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Replaces all of the uses of the instruction with uses of the value 18818961504fc2b299578dba817900a0696cf3ccc4dChris Lattner I.replaceAllUsesWith(V); 1894d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 19086cc42355593dd1689f7d58d56695c451215b02bChris Lattner // Make sure to propagate a name if there is one already. 19186cc42355593dd1689f7d58d56695c451215b02bChris Lattner if (I.hasName() && !V->hasName()) 19286cc42355593dd1689f7d58d56695c451215b02bChris Lattner V->takeName(&I); 193fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 1945560c9d49ccae132cabf1155f18aa0480dce3edaMisha Brukman // Delete the unnecessary instruction now... 19518961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BI = BIL.erase(BI); 1964d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 1974d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 1984d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 1990f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithInst - Replace the instruction specified by BI with the 2000f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// instruction specified by I. The original instruction is deleted and BI is 2010f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// updated to point to the new instruction. 2020f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 203f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithInst(BasicBlock::InstListType &BIL, 204f7703df4968084c18c248c1feea9961c19a32e6aChris Lattner BasicBlock::iterator &BI, Instruction *I) { 2054d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner assert(I->getParent() == 0 && 2064d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner "ReplaceInstWithInst: Instruction already inserted into basic block!"); 2074d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2084d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Insert the new instruction into the basic block... 20918961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BasicBlock::iterator New = BIL.insert(BI, I); 2104d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2114d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Replace all uses of the old instruction, and delete it. 2124d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner ReplaceInstWithValue(BIL, BI, I); 2134d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2144d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Move BI back to point to the newly inserted instruction 21518961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BI = New; 2164d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 2174d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2180f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithInst - Replace the instruction specified by From with the 2190f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// instruction specified by To. 2200f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 221f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithInst(Instruction *From, Instruction *To) { 22218961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BasicBlock::iterator BI(From); 22318961504fc2b299578dba817900a0696cf3ccc4dChris Lattner ReplaceInstWithInst(From->getParent()->getInstList(), BI, To); 2244d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 225b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 2260f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// RemoveSuccessor - Change the specified terminator instruction such that its 227bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// successor SuccNum no longer exists. Because this reduces the outgoing 2280f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// degree of the current basic block, the actual terminator instruction itself 229bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// may have to be changed. In the case where the last successor of the block 230bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// is deleted, a return instruction is inserted in its place which can cause a 2310f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// surprising change in program behavior if it is not expected. 2320f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 233f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum) { 234b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner assert(SuccNum < TI->getNumSuccessors() && 235b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner "Trying to remove a nonexistant successor!"); 236b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 237b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // If our old successor block contains any PHI nodes, remove the entry in the 238b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // PHI nodes that comes from this branch... 239b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // 240b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner BasicBlock *BB = TI->getParent(); 241b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner TI->getSuccessor(SuccNum)->removePredecessor(BB); 242b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 243b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner TerminatorInst *NewTI = 0; 244b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner switch (TI->getOpcode()) { 245b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Br: 246b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // If this is a conditional branch... convert to unconditional branch. 247b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner if (TI->getNumSuccessors() == 2) { 248b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner cast<BranchInst>(TI)->setUnconditionalDest(TI->getSuccessor(1-SuccNum)); 249b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner } else { // Otherwise convert to a return instruction... 250b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner Value *RetVal = 0; 251fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 252b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // Create a value to return... if the function doesn't return null... 253b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner if (BB->getParent()->getReturnType() != Type::VoidTy) 254b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner RetVal = Constant::getNullValue(BB->getParent()->getReturnType()); 255b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 256b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // Create the return... 257051a950000e21935165db56695e35bade668193bGabor Greif NewTI = ReturnInst::Create(RetVal); 258b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner } 259fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman break; 260b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 261b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Invoke: // Should convert to call 262b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Switch: // Should remove entry 263b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner default: 264b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Ret: // Cannot happen, has no successors! 265b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner assert(0 && "Unhandled terminator instruction type in RemoveSuccessor!"); 266b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner abort(); 267b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner } 268b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 269b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner if (NewTI) // If it's a different instruction, replace. 270b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner ReplaceInstWithInst(TI, NewTI); 271b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner} 272d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 2738019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// SplitEdge - Split the edge connecting specified block. Pass P must 2748019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// not be NULL. 2758019893c3f55a4bfe770888fe285d6dae57cf216Devang PatelBasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, Pass *P) { 2768019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel TerminatorInst *LatchTerm = BB->getTerminator(); 2778019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel unsigned SuccNum = 0; 2788a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel#ifndef NDEBUG 2798a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel unsigned e = LatchTerm->getNumSuccessors(); 2808a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel#endif 2818a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel for (unsigned i = 0; ; ++i) { 2828019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel assert(i != e && "Didn't find edge?"); 2838019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel if (LatchTerm->getSuccessor(i) == Succ) { 2848019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel SuccNum = i; 2858019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel break; 2868019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } 2878019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } 2888019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2898019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If this is a critical edge, let SplitCriticalEdge do it. 2908019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel if (SplitCriticalEdge(BB->getTerminator(), SuccNum, P)) 2918019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return LatchTerm->getSuccessor(SuccNum); 2928019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2938019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If the edge isn't critical, then BB has a single successor or Succ has a 2948019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // single pred. Split the block. 2958019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock::iterator SplitPoint; 2968019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel if (BasicBlock *SP = Succ->getSinglePredecessor()) { 2978019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If the successor only has a single pred, split the top of the successor 2988019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // block. 2998019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel assert(SP == BB && "CFG broken"); 3008a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel SP = NULL; 3018019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return SplitBlock(Succ, Succ->begin(), P); 3028019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } else { 3038019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // Otherwise, if BB has a single successor, split it at the bottom of the 3048019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // block. 3058019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel assert(BB->getTerminator()->getNumSuccessors() == 1 && 3068019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel "Should have a single succ!"); 3078019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return SplitBlock(BB, BB->getTerminator(), P); 3088019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } 3098019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel} 3108019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3118019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// SplitBlock - Split the specified block at the specified instruction - every 3128019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// thing before SplitPt stays in Old and everything starting with SplitPt moves 3138019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// to a new block. The two blocks are joined by an unconditional branch and 3148019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// the loop info is updated. 3158019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// 3168019893c3f55a4bfe770888fe285d6dae57cf216Devang PatelBasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P) { 3178019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock::iterator SplitIt = SplitPt; 3188019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel while (isa<PHINode>(SplitIt)) 3198019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel ++SplitIt; 3208019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock *New = Old->splitBasicBlock(SplitIt, Old->getName()+".split"); 3218019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3228019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // The new block lives in whichever loop the old one did. 3231465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (LoopInfo* LI = P->getAnalysisIfAvailable<LoopInfo>()) 324a90793b431458c1bac4c7267946738968c4cdf58Owen Anderson if (Loop *L = LI->getLoopFor(Old)) 325a90793b431458c1bac4c7267946738968c4cdf58Owen Anderson L->addBasicBlockToLoop(New, LI->getBase()); 3268019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3271465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) 328a8a8a366299863fe3711880add4c041c437b63cfDevang Patel { 329a8a8a366299863fe3711880add4c041c437b63cfDevang Patel // Old dominates New. New node domiantes all other nodes dominated by Old. 330a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DomTreeNode *OldNode = DT->getNode(Old); 331a8a8a366299863fe3711880add4c041c437b63cfDevang Patel std::vector<DomTreeNode *> Children; 332a8a8a366299863fe3711880add4c041c437b63cfDevang Patel for (DomTreeNode::iterator I = OldNode->begin(), E = OldNode->end(); 333a8a8a366299863fe3711880add4c041c437b63cfDevang Patel I != E; ++I) 334a8a8a366299863fe3711880add4c041c437b63cfDevang Patel Children.push_back(*I); 335a8a8a366299863fe3711880add4c041c437b63cfDevang Patel 336a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DomTreeNode *NewNode = DT->addNewBlock(New,Old); 337a8a8a366299863fe3711880add4c041c437b63cfDevang Patel 338a8a8a366299863fe3711880add4c041c437b63cfDevang Patel for (std::vector<DomTreeNode *>::iterator I = Children.begin(), 339a8a8a366299863fe3711880add4c041c437b63cfDevang Patel E = Children.end(); I != E; ++I) 340a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DT->changeImmediateDominator(*I, NewNode); 341a8a8a366299863fe3711880add4c041c437b63cfDevang Patel } 3428019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3431465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominanceFrontier *DF = P->getAnalysisIfAvailable<DominanceFrontier>()) 3448019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel DF->splitBlock(Old); 3458019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3468019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return New; 3478019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel} 34854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 34954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 35054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// SplitBlockPredecessors - This method transforms BB by introducing a new 35154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// basic block into the function, and moving some of the predecessors of BB to 35254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// be predecessors of the new block. The new predecessors are indicated by the 35354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// Preds array, which has NumPreds elements in it. The new block is given a 35454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// suffix of 'Suffix'. 35554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// 35654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree and 35754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// DominanceFrontier, but no other analyses. 35854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris LattnerBasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB, 35954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BasicBlock *const *Preds, 36054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner unsigned NumPreds, const char *Suffix, 36154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Pass *P) { 36254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Create new basic block, insert right before the original block. 36354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BasicBlock *NewBB = 36454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BasicBlock::Create(BB->getName()+Suffix, BB->getParent(), BB); 36554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 36654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // The new block unconditionally branches to the old block. 36754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BranchInst *BI = BranchInst::Create(BB, NewBB); 36854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 36954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Move the edges from Preds to point to NewBB instead of BB. 370280a6e607d8eb7401749a92db624a82de47da777Nick Lewycky for (unsigned i = 0; i != NumPreds; ++i) 37154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB); 37254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 37354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Update dominator tree and dominator frontier if available. 3741465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands DominatorTree *DT = P ? P->getAnalysisIfAvailable<DominatorTree>() : 0; 37554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (DT) 37654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner DT->splitBlock(NewBB); 3771465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominanceFrontier *DF = P ? P->getAnalysisIfAvailable<DominanceFrontier>():0) 37854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner DF->splitBlock(NewBB); 3791465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands AliasAnalysis *AA = P ? P->getAnalysisIfAvailable<AliasAnalysis>() : 0; 38054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 38154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 38254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI 38354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // node becomes an incoming value for BB's phi node. However, if the Preds 38454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // list is empty, we need to insert dummy entries into the PHI nodes in BB to 38554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // account for the newly created predecessor. 38654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (NumPreds == 0) { 38754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Insert dummy values as the incoming value. 38854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I) 38954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB); 39054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner return NewBB; 39154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 39254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 39354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Otherwise, create a new PHI node in NewBB for each PHI node in BB. 39454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ) { 39554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode *PN = cast<PHINode>(I++); 39654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 39754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Check to see if all of the values coming in are the same. If so, we 39854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // don't need to create a new PHI node. 39954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Value *InVal = PN->getIncomingValueForBlock(Preds[0]); 40054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (unsigned i = 1; i != NumPreds; ++i) 40154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (InVal != PN->getIncomingValueForBlock(Preds[i])) { 40254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner InVal = 0; 40354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner break; 40454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 40554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 40654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (InVal) { 40754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // If all incoming values for the new PHI would be the same, just don't 40854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // make a new PHI. Instead, just remove the incoming values from the old 40954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // PHI. 41054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (unsigned i = 0; i != NumPreds; ++i) 41154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->removeIncomingValue(Preds[i], false); 41254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } else { 41354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // If the values coming into the block are not the same, we need a PHI. 41454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Create the new PHI node, insert it into NewBB at the end of the block 41554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode *NewPHI = 41654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode::Create(PN->getType(), PN->getName()+".ph", BI); 41754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (AA) AA->copyValue(PN, NewPHI); 41854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 41954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Move all of the PHI values for 'Preds' to the new PHI. 42054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (unsigned i = 0; i != NumPreds; ++i) { 42154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Value *V = PN->removeIncomingValue(Preds[i], false); 42254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner NewPHI->addIncoming(V, Preds[i]); 42354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 42454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner InVal = NewPHI; 42554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 42654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 42754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Add an incoming value to the PHI node in the loop for the preheader 42854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // edge. 42954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->addIncoming(InVal, NewBB); 43054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 43154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Check to see if we can eliminate this phi node. 43254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (Value *V = PN->hasConstantValue(DT != 0)) { 43354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Instruction *I = dyn_cast<Instruction>(V); 43454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (!I || DT == 0 || DT->dominates(I, PN)) { 43554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->replaceAllUsesWith(V); 43654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (AA) AA->deleteValue(PN); 43754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->eraseFromParent(); 43854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 43954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 44054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 44154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 44254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner return NewBB; 44354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner} 44452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 4454aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// AreEquivalentAddressValues - Test if A and B will obviously have the same 4464aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// value. This includes recognizing that %t0 and %t1 will have the same 4474aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// value in code like this: 4480f8b53f19d29013ab18f3d444cea1e6305405611Dan Gohman/// %t0 = getelementptr \@a, 0, 3 4494aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// store i32 0, i32* %t0 4500f8b53f19d29013ab18f3d444cea1e6305405611Dan Gohman/// %t1 = getelementptr \@a, 0, 3 4514aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// %t2 = load i32* %t1 4524aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// 4534aebaee0e40f2457f1a6588679655a3c600a553bChris Lattnerstatic bool AreEquivalentAddressValues(const Value *A, const Value *B) { 4544aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner // Test if the values are trivially equivalent. 4554aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (A == B) return true; 4564aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 4574aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner // Test if the values come form identical arithmetic instructions. 4584aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (isa<BinaryOperator>(A) || isa<CastInst>(A) || 4594aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner isa<PHINode>(A) || isa<GetElementPtrInst>(A)) 4604aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (const Instruction *BI = dyn_cast<Instruction>(B)) 4614aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (cast<Instruction>(A)->isIdenticalTo(BI)) 4624aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner return true; 4634aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 4644aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner // Otherwise they may not be equivalent. 4654aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner return false; 4664aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner} 4674aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 46852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at the 46952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// instruction before ScanFrom) checking to see if we have the value at the 47052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// memory address *Ptr locally available within a small number of instructions. 47152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// If the value is available, return it. 47252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// 47352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// If not, return the iterator for the last validated instruction that the 47452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// value would be live through. If we scanned the entire block and didn't find 47552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// something that invalidates *Ptr or provides it, ScanFrom would be left at 47652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// begin() and this returns null. ScanFrom could also be left 47752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// 47852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// MaxInstsToScan specifies the maximum instructions to scan in the block. If 47952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// it is set to 0, it will scan the whole block. You can also optionally 48052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// specify an alias analysis implementation, which makes this more precise. 48152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris LattnerValue *llvm::FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB, 48252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner BasicBlock::iterator &ScanFrom, 48352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner unsigned MaxInstsToScan, 48452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner AliasAnalysis *AA) { 48552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (MaxInstsToScan == 0) MaxInstsToScan = ~0U; 486ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 487ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If we're using alias analysis to disambiguate get the size of *Ptr. 488ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner unsigned AccessSize = 0; 489ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA) { 490ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner const Type *AccessTy = cast<PointerType>(Ptr->getType())->getElementType(); 491ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner AccessSize = AA->getTargetData().getTypeStoreSizeInBits(AccessTy); 492ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner } 49352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 49452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner while (ScanFrom != ScanBB->begin()) { 495bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // We must ignore debug info directives when counting (otherwise they 496bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // would affect codegen). 497bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen Instruction *Inst = --ScanFrom; 498bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (isa<DbgInfoIntrinsic>(Inst)) 499bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen continue; 500d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // We skip pointer-to-pointer bitcasts, which are NOPs. 501d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // It is necessary for correctness to skip those that feed into a 502d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // llvm.dbg.declare, as these are not present when debugging is off. 503d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen if (isa<BitCastInst>(Inst) && isa<PointerType>(Inst->getType())) 5044ded40a44da9d67355a103cc8da68c2c1ab40bfdDale Johannesen continue; 5054ded40a44da9d67355a103cc8da68c2c1ab40bfdDale Johannesen 506bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // Restore ScanFrom to expected value in case next test succeeds 507bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen ScanFrom++; 508bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen 50952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Don't scan huge blocks. 51052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (MaxInstsToScan-- == 0) return 0; 51152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 512bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen --ScanFrom; 51352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is a load of Ptr, the loaded value is available. 51452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) 5154aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (AreEquivalentAddressValues(LI->getOperand(0), Ptr)) 51652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return LI; 51752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 51852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { 51952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is a store through Ptr, the value is available! 5204aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (AreEquivalentAddressValues(SI->getOperand(1), Ptr)) 52152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return SI->getOperand(0); 52252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 52352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If Ptr is an alloca and this is a store to a different alloca, ignore 52452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // the store. This is a trivial form of alias analysis that is important 52552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // for reg2mem'd code. 52652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if ((isa<AllocaInst>(Ptr) || isa<GlobalVariable>(Ptr)) && 52752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner (isa<AllocaInst>(SI->getOperand(1)) || 52852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner isa<GlobalVariable>(SI->getOperand(1)))) 52952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner continue; 53052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 531ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If we have alias analysis and it says the store won't modify the loaded 532ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // value, ignore the store. 533ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA && 534ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner (AA->getModRefInfo(SI, Ptr, AccessSize) & AliasAnalysis::Mod) == 0) 535ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner continue; 536ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 53752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Otherwise the store that may or may not alias the pointer, bail out. 53852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner ++ScanFrom; 53952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 54052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 54152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 54252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is some other instruction that may clobber Ptr, bail out. 54352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (Inst->mayWriteToMemory()) { 544ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If alias analysis claims that it really won't modify the load, 545ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // ignore it. 546ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA && 547ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner (AA->getModRefInfo(Inst, Ptr, AccessSize) & AliasAnalysis::Mod) == 0) 548ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner continue; 549ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 55052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // May modify the pointer, bail out. 55152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner ++ScanFrom; 55252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 55352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 55452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 55552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 55652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Got to the start of the block, we didn't find it, but are done for this 55752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // block. 55852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 55952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner} 560bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen 561bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// CopyPrecedingStopPoint - If I is immediately preceded by a StopPoint, 562bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// make a copy of the stoppoint before InsertPos (presumably before copying 563bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// or moving I). 564bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesenvoid llvm::CopyPrecedingStopPoint(Instruction *I, 565bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen BasicBlock::iterator InsertPos) { 566bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (I != I->getParent()->begin()) { 567bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen BasicBlock::iterator BBI = I; --BBI; 568bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (DbgStopPointInst *DSPI = dyn_cast<DbgStopPointInst>(BBI)) { 5694945c657848523410a449280c6b88ee1f507511fDale Johannesen CallInst *newDSPI = DSPI->clone(); 570bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen newDSPI->insertBefore(InsertPos); 571bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen } 572bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen } 573bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen} 574