BasicBlockUtils.cpp revision 5c89b5240c90eb8171f999e5f06f815502d0321c
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" 190a205a459884ec745df1c529396dd921f029dafdOwen Anderson#include "llvm/LLVMContext.h" 20b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner#include "llvm/Constant.h" 21b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner#include "llvm/Type.h" 2254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner#include "llvm/Analysis/AliasAnalysis.h" 238019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel#include "llvm/Analysis/LoopInfo.h" 248019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel#include "llvm/Analysis/Dominators.h" 25ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner#include "llvm/Target/TargetData.h" 26afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman#include "llvm/Transforms/Utils/Local.h" 275c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman#include "llvm/Transforms/Scalar.h" 287d696d80409aad20bb5da0fc4eccab941dd371d4Torok Edwin#include "llvm/Support/ErrorHandling.h" 29afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman#include "llvm/Support/ValueHandle.h" 304d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner#include <algorithm> 31f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerusing namespace llvm; 32d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 3371af9b07a58a264064813545889cf6473ce23de6Chris Lattner/// DeleteDeadBlock - Delete the specified block, which must have no 3471af9b07a58a264064813545889cf6473ce23de6Chris Lattner/// predecessors. 3571af9b07a58a264064813545889cf6473ce23de6Chris Lattnervoid llvm::DeleteDeadBlock(BasicBlock *BB) { 362973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner assert((pred_begin(BB) == pred_end(BB) || 372973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner // Can delete self loop. 382973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner BB->getSinglePredecessor() == BB) && "Block is not dead!"); 392b1ba24fb75e633560846e551acadade92783bb3Chris Lattner TerminatorInst *BBTerm = BB->getTerminator(); 405622f07a21b799964dc172925b9ebc38191859f6Devang Patel 412b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Loop through all of our successors and make sure they know that one 422b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // of their predecessors is going away. 432b1ba24fb75e633560846e551acadade92783bb3Chris Lattner for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i) 442b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BBTerm->getSuccessor(i)->removePredecessor(BB); 452b1ba24fb75e633560846e551acadade92783bb3Chris Lattner 462b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Zap all the instructions in the block. 472b1ba24fb75e633560846e551acadade92783bb3Chris Lattner while (!BB->empty()) { 482b1ba24fb75e633560846e551acadade92783bb3Chris Lattner Instruction &I = BB->back(); 492b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // If this instruction is used, replace uses with an arbitrary value. 502b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Because control flow can't get here, we don't care what we replace the 512b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // value with. Note that since this block is unreachable, and all values 522b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // contained within it must dominate their uses, that all uses will 532b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // eventually be removed (they are themselves dead). 542b1ba24fb75e633560846e551acadade92783bb3Chris Lattner if (!I.use_empty()) 559e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson I.replaceAllUsesWith(UndefValue::get(I.getType())); 562b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BB->getInstList().pop_back(); 572b1ba24fb75e633560846e551acadade92783bb3Chris Lattner } 585622f07a21b799964dc172925b9ebc38191859f6Devang Patel 592b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Zap the block! 602b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BB->eraseFromParent(); 612b1ba24fb75e633560846e551acadade92783bb3Chris Lattner} 622b1ba24fb75e633560846e551acadade92783bb3Chris Lattner 6329874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// FoldSingleEntryPHINodes - We know that BB has one predecessor. If there are 6429874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// any single-entry PHI nodes in it, fold them away. This handles the case 6529874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// when all entries to the PHI nodes in a block are guaranteed equal, such as 6629874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// when the block has exactly one predecessor. 6729874e0dc6c4e55bc384611273343bb358982cc3Chris Lattnervoid llvm::FoldSingleEntryPHINodes(BasicBlock *BB) { 6829874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner if (!isa<PHINode>(BB->begin())) 6929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner return; 7029874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 7129874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { 7229874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner if (PN->getIncomingValue(0) != PN) 7329874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->replaceAllUsesWith(PN->getIncomingValue(0)); 7429874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner else 759e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson PN->replaceAllUsesWith(UndefValue::get(PN->getType())); 7629874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->eraseFromParent(); 7729874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner } 7829874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner} 7929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 8029874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 81afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it 82afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// is dead. Also recursively delete any operands that become dead as 83afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// a result. This includes tracing the def-use list from the PHI to see if 8435738ac150afafe2359268d4b2169498c6c98c5fDan Gohman/// it is ultimately unused or if it reaches an unused cycle. 8535738ac150afafe2359268d4b2169498c6c98c5fDan Gohmanvoid llvm::DeleteDeadPHIs(BasicBlock *BB) { 86afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman // Recursively deleting a PHI may cause multiple PHIs to be deleted 87afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman // or RAUW'd undef, so use an array of WeakVH for the PHIs to delete. 88afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman SmallVector<WeakVH, 8> PHIs; 89afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman for (BasicBlock::iterator I = BB->begin(); 90afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman PHINode *PN = dyn_cast<PHINode>(I); ++I) 91afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman PHIs.push_back(PN); 92afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman 93afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman for (unsigned i = 0, e = PHIs.size(); i != e; ++i) 94afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*())) 9535738ac150afafe2359268d4b2169498c6c98c5fDan Gohman RecursivelyDeleteDeadPHINode(PN); 96afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman} 97afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman 98b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, 99b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson/// if possible. The return value indicates success or failure. 100b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Andersonbool llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) { 10111f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson pred_iterator PI(pred_begin(BB)), PE(pred_end(BB)); 102b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Can't merge the entry block. 103b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (pred_begin(BB) == pred_end(BB)) return false; 104b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 10511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson BasicBlock *PredBB = *PI++; 10611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson for (; PI != PE; ++PI) // Search all predecessors, see if they are all same 10711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (*PI != PredBB) { 10811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson PredBB = 0; // There are multiple different predecessors... 10911f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson break; 11011f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson } 111b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 11211f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Can't merge if there are multiple predecessors. 11311f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!PredBB) return false; 1143ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson // Don't break self-loops. 1153ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson if (PredBB == BB) return false; 1163ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson // Don't break invokes. 1173ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson if (isa<InvokeInst>(PredBB->getTerminator())) return false; 11811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 11911f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB)); 12011f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson BasicBlock* OnlySucc = BB; 12111f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson for (; SI != SE; ++SI) 12211f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (*SI != OnlySucc) { 12311f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson OnlySucc = 0; // There are multiple distinct successors! 12411f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson break; 12511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson } 12611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 12711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Can't merge if there are multiple successors. 12811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!OnlySucc) return false; 129e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel 130e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel // Can't merge if there is PHI loop. 131e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; ++BI) { 132e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel if (PHINode *PN = dyn_cast<PHINode>(BI)) { 133e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 134e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel if (PN->getIncomingValue(i) == PN) 135e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel return false; 136e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel } else 137e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel break; 138e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel } 139e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel 140b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Begin by getting rid of unneeded PHIs. 141b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) { 142b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PN->replaceAllUsesWith(PN->getIncomingValue(0)); 143b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->getInstList().pop_front(); // Delete the phi node... 144b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 145b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 146b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Delete the unconditional branch from the predecessor... 147b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PredBB->getInstList().pop_back(); 148b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 149b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Move all definitions in the successor to the predecessor... 150b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PredBB->getInstList().splice(PredBB->end(), BB->getInstList()); 151b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 152b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Make all PHI nodes that referred to BB now refer to Pred as their 153b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // source... 154b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->replaceAllUsesWith(PredBB); 155b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 15611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Inherit predecessors name if it exists. 15711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!PredBB->hasName()) 15811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson PredBB->takeName(BB); 15911f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 160b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Finally, erase the old block and update dominator info. 161b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (P) { 1621465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominatorTree* DT = P->getAnalysisIfAvailable<DominatorTree>()) { 163b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DomTreeNode* DTN = DT->getNode(BB); 164b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DomTreeNode* PredDTN = DT->getNode(PredBB); 165b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 166b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (DTN) { 167b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson SmallPtrSet<DomTreeNode*, 8> Children(DTN->begin(), DTN->end()); 168b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson for (SmallPtrSet<DomTreeNode*, 8>::iterator DI = Children.begin(), 169b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DE = Children.end(); DI != DE; ++DI) 170b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DT->changeImmediateDominator(*DI, PredDTN); 171b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 172b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DT->eraseNode(BB); 173b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 174b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 175b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 176b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 177b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->eraseFromParent(); 178b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 179b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 180b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson return true; 181b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson} 182b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 1830f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI) 1840f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// with a value, then remove and delete the original instruction. 1850f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 186f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithValue(BasicBlock::InstListType &BIL, 187f7703df4968084c18c248c1feea9961c19a32e6aChris Lattner BasicBlock::iterator &BI, Value *V) { 18818961504fc2b299578dba817900a0696cf3ccc4dChris Lattner Instruction &I = *BI; 1894d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Replaces all of the uses of the instruction with uses of the value 19018961504fc2b299578dba817900a0696cf3ccc4dChris Lattner I.replaceAllUsesWith(V); 1914d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 19286cc42355593dd1689f7d58d56695c451215b02bChris Lattner // Make sure to propagate a name if there is one already. 19386cc42355593dd1689f7d58d56695c451215b02bChris Lattner if (I.hasName() && !V->hasName()) 19486cc42355593dd1689f7d58d56695c451215b02bChris Lattner V->takeName(&I); 195fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 1965560c9d49ccae132cabf1155f18aa0480dce3edaMisha Brukman // Delete the unnecessary instruction now... 19718961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BI = BIL.erase(BI); 1984d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 1994d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2004d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2010f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithInst - Replace the instruction specified by BI with the 2020f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// instruction specified by I. The original instruction is deleted and BI is 2030f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// updated to point to the new instruction. 2040f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 205f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithInst(BasicBlock::InstListType &BIL, 206f7703df4968084c18c248c1feea9961c19a32e6aChris Lattner BasicBlock::iterator &BI, Instruction *I) { 2074d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner assert(I->getParent() == 0 && 2084d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner "ReplaceInstWithInst: Instruction already inserted into basic block!"); 2094d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2104d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Insert the new instruction into the basic block... 21118961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BasicBlock::iterator New = BIL.insert(BI, I); 2124d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2134d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Replace all uses of the old instruction, and delete it. 2144d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner ReplaceInstWithValue(BIL, BI, I); 2154d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2164d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Move BI back to point to the newly inserted instruction 21718961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BI = New; 2184d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 2194d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2200f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithInst - Replace the instruction specified by From with the 2210f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// instruction specified by To. 2220f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 223f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithInst(Instruction *From, Instruction *To) { 22418961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BasicBlock::iterator BI(From); 22518961504fc2b299578dba817900a0696cf3ccc4dChris Lattner ReplaceInstWithInst(From->getParent()->getInstList(), BI, To); 2264d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 227b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 2280f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// RemoveSuccessor - Change the specified terminator instruction such that its 229bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// successor SuccNum no longer exists. Because this reduces the outgoing 2300f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// degree of the current basic block, the actual terminator instruction itself 231bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// may have to be changed. In the case where the last successor of the block 232bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// is deleted, a return instruction is inserted in its place which can cause a 2330f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// surprising change in program behavior if it is not expected. 2340f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 235f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum) { 236b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner assert(SuccNum < TI->getNumSuccessors() && 237b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner "Trying to remove a nonexistant successor!"); 238b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 239b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // If our old successor block contains any PHI nodes, remove the entry in the 240b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // PHI nodes that comes from this branch... 241b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // 242b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner BasicBlock *BB = TI->getParent(); 243b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner TI->getSuccessor(SuccNum)->removePredecessor(BB); 244b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 245b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner TerminatorInst *NewTI = 0; 246b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner switch (TI->getOpcode()) { 247b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Br: 248b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // If this is a conditional branch... convert to unconditional branch. 249b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner if (TI->getNumSuccessors() == 2) { 250b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner cast<BranchInst>(TI)->setUnconditionalDest(TI->getSuccessor(1-SuccNum)); 251b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner } else { // Otherwise convert to a return instruction... 252b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner Value *RetVal = 0; 253fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 254b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // Create a value to return... if the function doesn't return null... 2551d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson if (BB->getParent()->getReturnType() != Type::getVoidTy(TI->getContext())) 256a7235ea7245028a0723e8ab7fd011386b3900777Owen Anderson RetVal = Constant::getNullValue(BB->getParent()->getReturnType()); 257b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 258b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // Create the return... 2591d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson NewTI = ReturnInst::Create(TI->getContext(), RetVal); 260b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner } 261fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman break; 262b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 263b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Invoke: // Should convert to call 264b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Switch: // Should remove entry 265b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner default: 266b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Ret: // Cannot happen, has no successors! 267c23197a26f34f559ea9797de51e187087c039c42Torok Edwin llvm_unreachable("Unhandled terminator instruction type in RemoveSuccessor!"); 268b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner } 269b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 270b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner if (NewTI) // If it's a different instruction, replace. 271b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner ReplaceInstWithInst(TI, NewTI); 272b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner} 273d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 2748019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// SplitEdge - Split the edge connecting specified block. Pass P must 2758019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// not be NULL. 2768019893c3f55a4bfe770888fe285d6dae57cf216Devang PatelBasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, Pass *P) { 2778019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel TerminatorInst *LatchTerm = BB->getTerminator(); 2788019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel unsigned SuccNum = 0; 2798a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel#ifndef NDEBUG 2808a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel unsigned e = LatchTerm->getNumSuccessors(); 2818a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel#endif 2828a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel for (unsigned i = 0; ; ++i) { 2838019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel assert(i != e && "Didn't find edge?"); 2848019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel if (LatchTerm->getSuccessor(i) == Succ) { 2858019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel SuccNum = i; 2868019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel break; 2878019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } 2888019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } 2898019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2908019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If this is a critical edge, let SplitCriticalEdge do it. 2918019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel if (SplitCriticalEdge(BB->getTerminator(), SuccNum, P)) 2928019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return LatchTerm->getSuccessor(SuccNum); 2938019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2948019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If the edge isn't critical, then BB has a single successor or Succ has a 2958019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // single pred. Split the block. 2968019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock::iterator SplitPoint; 2978019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel if (BasicBlock *SP = Succ->getSinglePredecessor()) { 2988019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If the successor only has a single pred, split the top of the successor 2998019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // block. 3008019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel assert(SP == BB && "CFG broken"); 3018a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel SP = NULL; 3028019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return SplitBlock(Succ, Succ->begin(), P); 3038019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } else { 3048019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // Otherwise, if BB has a single successor, split it at the bottom of the 3058019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // block. 3068019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel assert(BB->getTerminator()->getNumSuccessors() == 1 && 3078019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel "Should have a single succ!"); 3088019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return SplitBlock(BB, BB->getTerminator(), P); 3098019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } 3108019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel} 3118019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3128019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// SplitBlock - Split the specified block at the specified instruction - every 3138019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// thing before SplitPt stays in Old and everything starting with SplitPt moves 3148019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// to a new block. The two blocks are joined by an unconditional branch and 3158019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// the loop info is updated. 3168019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// 3178019893c3f55a4bfe770888fe285d6dae57cf216Devang PatelBasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P) { 3188019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock::iterator SplitIt = SplitPt; 3198019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel while (isa<PHINode>(SplitIt)) 3208019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel ++SplitIt; 3218019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock *New = Old->splitBasicBlock(SplitIt, Old->getName()+".split"); 3228019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3235c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // The new block lives in whichever loop the old one did. This preserves 3245c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // LCSSA as well, because we force the split point to be after any PHI nodes. 3251465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (LoopInfo* LI = P->getAnalysisIfAvailable<LoopInfo>()) 326a90793b431458c1bac4c7267946738968c4cdf58Owen Anderson if (Loop *L = LI->getLoopFor(Old)) 327a90793b431458c1bac4c7267946738968c4cdf58Owen Anderson L->addBasicBlockToLoop(New, LI->getBase()); 3288019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3291465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) 330a8a8a366299863fe3711880add4c041c437b63cfDevang Patel { 331a8a8a366299863fe3711880add4c041c437b63cfDevang Patel // Old dominates New. New node domiantes all other nodes dominated by Old. 332a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DomTreeNode *OldNode = DT->getNode(Old); 333a8a8a366299863fe3711880add4c041c437b63cfDevang Patel std::vector<DomTreeNode *> Children; 334a8a8a366299863fe3711880add4c041c437b63cfDevang Patel for (DomTreeNode::iterator I = OldNode->begin(), E = OldNode->end(); 335a8a8a366299863fe3711880add4c041c437b63cfDevang Patel I != E; ++I) 336a8a8a366299863fe3711880add4c041c437b63cfDevang Patel Children.push_back(*I); 337a8a8a366299863fe3711880add4c041c437b63cfDevang Patel 338a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DomTreeNode *NewNode = DT->addNewBlock(New,Old); 339a8a8a366299863fe3711880add4c041c437b63cfDevang Patel 340a8a8a366299863fe3711880add4c041c437b63cfDevang Patel for (std::vector<DomTreeNode *>::iterator I = Children.begin(), 341a8a8a366299863fe3711880add4c041c437b63cfDevang Patel E = Children.end(); I != E; ++I) 342a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DT->changeImmediateDominator(*I, NewNode); 343a8a8a366299863fe3711880add4c041c437b63cfDevang Patel } 3448019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3451465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominanceFrontier *DF = P->getAnalysisIfAvailable<DominanceFrontier>()) 3468019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel DF->splitBlock(Old); 3478019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3488019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return New; 3498019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel} 35054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 35154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 35254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// SplitBlockPredecessors - This method transforms BB by introducing a new 35354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// basic block into the function, and moving some of the predecessors of BB to 35454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// be predecessors of the new block. The new predecessors are indicated by the 35554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// Preds array, which has NumPreds elements in it. The new block is given a 35654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// suffix of 'Suffix'. 35754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// 3585c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree, 3595c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses. 3605c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman/// In particular, it does not preserve LoopSimplify (because it's 3615c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman/// complicated to handle the case where one of the edges being split 3625c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman/// is an exit of a loop with other exits). 3635c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman/// 36454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris LattnerBasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB, 36554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BasicBlock *const *Preds, 36654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner unsigned NumPreds, const char *Suffix, 36754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Pass *P) { 36854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Create new basic block, insert right before the original block. 3691d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), BB->getName()+Suffix, 3701d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BB->getParent(), BB); 37154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 37254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // The new block unconditionally branches to the old block. 37354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BranchInst *BI = BranchInst::Create(BB, NewBB); 37454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 3755c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman LoopInfo *LI = P ? P->getAnalysisIfAvailable<LoopInfo>() : 0; 3765c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman Loop *L = LI ? LI->getLoopFor(BB) : 0; 3775c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman bool PreserveLCSSA = P->mustPreserveAnalysisID(LCSSAID); 3785c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 37954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Move the edges from Preds to point to NewBB instead of BB. 3805c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // While here, if we need to preserve loop analyses, collect 3815c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // some information about how this split will affect loops. 3825c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman bool HasLoopExit = false; 3835c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman bool IsLoopEntry = !!L; 3845c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman bool SplitMakesNewLoopHeader = false; 3855c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman for (unsigned i = 0; i != NumPreds; ++i) { 38654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB); 3875c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 3885c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (LI) { 3895c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // If we need to preserve LCSSA, determine if any of 3905c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // the preds is a loop exit. 3915c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (PreserveLCSSA) 3925c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (Loop *PL = LI->getLoopFor(Preds[i])) 3935c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (!PL->contains(BB)) 3945c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman HasLoopExit = true; 3955c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // If we need to preserve LoopInfo, note whether any of the 3965c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // preds crosses an interesting loop boundary. 3975c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (L) { 3985c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (L->contains(Preds[i])) 3995c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman IsLoopEntry = false; 4005c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman else 4015c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman SplitMakesNewLoopHeader = true; 4025c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 4035c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 4045c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 4055c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 40654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Update dominator tree and dominator frontier if available. 4071465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands DominatorTree *DT = P ? P->getAnalysisIfAvailable<DominatorTree>() : 0; 40854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (DT) 40954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner DT->splitBlock(NewBB); 4101465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominanceFrontier *DF = P ? P->getAnalysisIfAvailable<DominanceFrontier>():0) 41154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner DF->splitBlock(NewBB); 4125c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 41354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI 41454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // node becomes an incoming value for BB's phi node. However, if the Preds 41554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // list is empty, we need to insert dummy entries into the PHI nodes in BB to 41654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // account for the newly created predecessor. 41754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (NumPreds == 0) { 41854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Insert dummy values as the incoming value. 41954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I) 4209e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB); 42154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner return NewBB; 42254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 4235c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 4245c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman AliasAnalysis *AA = P ? P->getAnalysisIfAvailable<AliasAnalysis>() : 0; 4255c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 4265c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (L) { 4275c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (IsLoopEntry) { 4285c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (Loop *PredLoop = LI->getLoopFor(Preds[0])) { 4295c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // Add the new block to the nearest enclosing loop (and not an 4305c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // adjacent loop). 4315c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman while (PredLoop && !PredLoop->contains(BB)) 4325c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman PredLoop = PredLoop->getParentLoop(); 4335c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (PredLoop) 4345c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman PredLoop->addBasicBlockToLoop(NewBB, LI->getBase()); 4355c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 4365c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } else { 4375c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman L->addBasicBlockToLoop(NewBB, LI->getBase()); 4385c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (SplitMakesNewLoopHeader) 4395c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman L->moveToHeader(NewBB); 4405c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 4415c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 44254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 44354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Otherwise, create a new PHI node in NewBB for each PHI node in BB. 44454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ) { 44554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode *PN = cast<PHINode>(I++); 44654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 44754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Check to see if all of the values coming in are the same. If so, we 4485c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // don't need to create a new PHI node, unless it's needed for LCSSA. 4495c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman Value *InVal = 0; 4505c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (!HasLoopExit) { 4515c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman InVal = PN->getIncomingValueForBlock(Preds[0]); 4525c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman for (unsigned i = 1; i != NumPreds; ++i) 4535c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman if (InVal != PN->getIncomingValueForBlock(Preds[i])) { 4545c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman InVal = 0; 4555c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman break; 4565c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 4575c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 4585c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 45954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (InVal) { 46054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // If all incoming values for the new PHI would be the same, just don't 46154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // make a new PHI. Instead, just remove the incoming values from the old 46254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // PHI. 46354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (unsigned i = 0; i != NumPreds; ++i) 46454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->removeIncomingValue(Preds[i], false); 46554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } else { 46654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // If the values coming into the block are not the same, we need a PHI. 46754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Create the new PHI node, insert it into NewBB at the end of the block 46854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode *NewPHI = 46954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode::Create(PN->getType(), PN->getName()+".ph", BI); 47054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (AA) AA->copyValue(PN, NewPHI); 47154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 47254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Move all of the PHI values for 'Preds' to the new PHI. 47354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (unsigned i = 0; i != NumPreds; ++i) { 47454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Value *V = PN->removeIncomingValue(Preds[i], false); 47554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner NewPHI->addIncoming(V, Preds[i]); 47654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 47754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner InVal = NewPHI; 47854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 47954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 48054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Add an incoming value to the PHI node in the loop for the preheader 48154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // edge. 48254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->addIncoming(InVal, NewBB); 48354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 48454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 48554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner return NewBB; 48654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner} 48752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 488fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// FindFunctionBackedges - Analyze the specified function to find all of the 489fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// loop backedges in the function and return them. This is a relatively cheap 490fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// (compared to computing dominators and loop info) analysis. 491fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// 492fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// The output is added to Result, as pairs of <from,to> edge info. 493fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stumpvoid llvm::FindFunctionBackedges(const Function &F, 494fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallVectorImpl<std::pair<const BasicBlock*,const BasicBlock*> > &Result) { 495fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump const BasicBlock *BB = &F.getEntryBlock(); 496fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (succ_begin(BB) == succ_end(BB)) 497fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump return; 498fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 499fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallPtrSet<const BasicBlock*, 8> Visited; 500fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallVector<std::pair<const BasicBlock*, succ_const_iterator>, 8> VisitStack; 501fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallPtrSet<const BasicBlock*, 8> InStack; 502fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 503fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump Visited.insert(BB); 504fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump VisitStack.push_back(std::make_pair(BB, succ_begin(BB))); 505fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.insert(BB); 506fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump do { 507fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump std::pair<const BasicBlock*, succ_const_iterator> &Top = VisitStack.back(); 508fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump const BasicBlock *ParentBB = Top.first; 509fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump succ_const_iterator &I = Top.second; 510fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 511fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump bool FoundNew = false; 512fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump while (I != succ_end(ParentBB)) { 513fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump BB = *I++; 514fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (Visited.insert(BB)) { 515fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump FoundNew = true; 516fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump break; 517fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 518fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Successor is in VisitStack, it's a back edge. 519fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (InStack.count(BB)) 520fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump Result.push_back(std::make_pair(ParentBB, BB)); 521fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 522fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 523fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (FoundNew) { 524fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Go down one level if there is a unvisited successor. 525fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.insert(BB); 526fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump VisitStack.push_back(std::make_pair(BB, succ_begin(BB))); 527fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } else { 528fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Go up one level. 529fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.erase(VisitStack.pop_back_val().first); 530fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 531fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } while (!VisitStack.empty()); 532fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 533fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 534fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump} 535fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 536fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 537fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 5384aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// AreEquivalentAddressValues - Test if A and B will obviously have the same 5394aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// value. This includes recognizing that %t0 and %t1 will have the same 5404aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// value in code like this: 5410f8b53f19d29013ab18f3d444cea1e6305405611Dan Gohman/// %t0 = getelementptr \@a, 0, 3 5424aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// store i32 0, i32* %t0 5430f8b53f19d29013ab18f3d444cea1e6305405611Dan Gohman/// %t1 = getelementptr \@a, 0, 3 5444aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// %t2 = load i32* %t1 5454aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// 5464aebaee0e40f2457f1a6588679655a3c600a553bChris Lattnerstatic bool AreEquivalentAddressValues(const Value *A, const Value *B) { 5474aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner // Test if the values are trivially equivalent. 5484aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (A == B) return true; 5494aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 55058cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman // Test if the values come from identical arithmetic instructions. 55158cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman // Use isIdenticalToWhenDefined instead of isIdenticalTo because 55258cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman // this function is only used when one address use dominates the 55358cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman // other, which means that they'll always either have the same 55458cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman // value or one of them will have an undefined value. 5554aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (isa<BinaryOperator>(A) || isa<CastInst>(A) || 5564aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner isa<PHINode>(A) || isa<GetElementPtrInst>(A)) 5574aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (const Instruction *BI = dyn_cast<Instruction>(B)) 55858cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI)) 5594aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner return true; 5604aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 5614aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner // Otherwise they may not be equivalent. 5624aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner return false; 5634aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner} 5644aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 56552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at the 56652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// instruction before ScanFrom) checking to see if we have the value at the 56752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// memory address *Ptr locally available within a small number of instructions. 56852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// If the value is available, return it. 56952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// 57052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// If not, return the iterator for the last validated instruction that the 57152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// value would be live through. If we scanned the entire block and didn't find 57252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// something that invalidates *Ptr or provides it, ScanFrom would be left at 57352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// begin() and this returns null. ScanFrom could also be left 57452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// 57552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// MaxInstsToScan specifies the maximum instructions to scan in the block. If 57652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// it is set to 0, it will scan the whole block. You can also optionally 57752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// specify an alias analysis implementation, which makes this more precise. 57852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris LattnerValue *llvm::FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB, 57952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner BasicBlock::iterator &ScanFrom, 58052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner unsigned MaxInstsToScan, 58152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner AliasAnalysis *AA) { 58252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (MaxInstsToScan == 0) MaxInstsToScan = ~0U; 583ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 584ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If we're using alias analysis to disambiguate get the size of *Ptr. 585ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner unsigned AccessSize = 0; 586ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA) { 587ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner const Type *AccessTy = cast<PointerType>(Ptr->getType())->getElementType(); 588fc2a3ed0c9e32cf7edaf5030fa0972b916cc5f0bDan Gohman AccessSize = AA->getTypeStoreSize(AccessTy); 589ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner } 59052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 59152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner while (ScanFrom != ScanBB->begin()) { 592bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // We must ignore debug info directives when counting (otherwise they 593bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // would affect codegen). 594bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen Instruction *Inst = --ScanFrom; 595bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (isa<DbgInfoIntrinsic>(Inst)) 596bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen continue; 597d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // We skip pointer-to-pointer bitcasts, which are NOPs. 598d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // It is necessary for correctness to skip those that feed into a 599d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // llvm.dbg.declare, as these are not present when debugging is off. 600d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen if (isa<BitCastInst>(Inst) && isa<PointerType>(Inst->getType())) 6014ded40a44da9d67355a103cc8da68c2c1ab40bfdDale Johannesen continue; 6024ded40a44da9d67355a103cc8da68c2c1ab40bfdDale Johannesen 603bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // Restore ScanFrom to expected value in case next test succeeds 604bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen ScanFrom++; 605bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen 60652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Don't scan huge blocks. 60752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (MaxInstsToScan-- == 0) return 0; 60852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 609bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen --ScanFrom; 61052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is a load of Ptr, the loaded value is available. 61152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) 6124aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (AreEquivalentAddressValues(LI->getOperand(0), Ptr)) 61352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return LI; 61452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 61552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { 61652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is a store through Ptr, the value is available! 6174aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (AreEquivalentAddressValues(SI->getOperand(1), Ptr)) 61852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return SI->getOperand(0); 61952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 62052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If Ptr is an alloca and this is a store to a different alloca, ignore 62152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // the store. This is a trivial form of alias analysis that is important 62252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // for reg2mem'd code. 62352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if ((isa<AllocaInst>(Ptr) || isa<GlobalVariable>(Ptr)) && 62452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner (isa<AllocaInst>(SI->getOperand(1)) || 62552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner isa<GlobalVariable>(SI->getOperand(1)))) 62652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner continue; 62752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 628ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If we have alias analysis and it says the store won't modify the loaded 629ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // value, ignore the store. 630ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA && 631ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner (AA->getModRefInfo(SI, Ptr, AccessSize) & AliasAnalysis::Mod) == 0) 632ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner continue; 633ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 63452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Otherwise the store that may or may not alias the pointer, bail out. 63552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner ++ScanFrom; 63652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 63752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 63852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 63952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is some other instruction that may clobber Ptr, bail out. 64052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (Inst->mayWriteToMemory()) { 641ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If alias analysis claims that it really won't modify the load, 642ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // ignore it. 643ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA && 644ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner (AA->getModRefInfo(Inst, Ptr, AccessSize) & AliasAnalysis::Mod) == 0) 645ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner continue; 646ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 64752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // May modify the pointer, bail out. 64852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner ++ScanFrom; 64952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 65052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 65152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 65252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 65352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Got to the start of the block, we didn't find it, but are done for this 65452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // block. 65552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 65652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner} 657bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen 658bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// CopyPrecedingStopPoint - If I is immediately preceded by a StopPoint, 659bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// make a copy of the stoppoint before InsertPos (presumably before copying 660bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// or moving I). 661bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesenvoid llvm::CopyPrecedingStopPoint(Instruction *I, 662bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen BasicBlock::iterator InsertPos) { 663bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (I != I->getParent()->begin()) { 664bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen BasicBlock::iterator BBI = I; --BBI; 665bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (DbgStopPointInst *DSPI = dyn_cast<DbgStopPointInst>(BBI)) { 666e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson CallInst *newDSPI = DSPI->clone(I->getContext()); 667bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen newDSPI->insertBefore(InsertPos); 668bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen } 669bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen } 670bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen} 671