BasicBlockUtils.cpp revision c23197a26f34f559ea9797de51e187087c039c42
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" 277d696d80409aad20bb5da0fc4eccab941dd371d4Torok Edwin#include "llvm/Support/ErrorHandling.h" 28afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman#include "llvm/Support/ValueHandle.h" 294d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner#include <algorithm> 30f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerusing namespace llvm; 31d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 3271af9b07a58a264064813545889cf6473ce23de6Chris Lattner/// DeleteDeadBlock - Delete the specified block, which must have no 3371af9b07a58a264064813545889cf6473ce23de6Chris Lattner/// predecessors. 3471af9b07a58a264064813545889cf6473ce23de6Chris Lattnervoid llvm::DeleteDeadBlock(BasicBlock *BB) { 352973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner assert((pred_begin(BB) == pred_end(BB) || 362973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner // Can delete self loop. 372973a25dbc0ee1081e34421e53b8f4308b624854Chris Lattner BB->getSinglePredecessor() == BB) && "Block is not dead!"); 382b1ba24fb75e633560846e551acadade92783bb3Chris Lattner TerminatorInst *BBTerm = BB->getTerminator(); 395622f07a21b799964dc172925b9ebc38191859f6Devang Patel 402b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Loop through all of our successors and make sure they know that one 412b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // of their predecessors is going away. 422b1ba24fb75e633560846e551acadade92783bb3Chris Lattner for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i) 432b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BBTerm->getSuccessor(i)->removePredecessor(BB); 442b1ba24fb75e633560846e551acadade92783bb3Chris Lattner 452b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Zap all the instructions in the block. 462b1ba24fb75e633560846e551acadade92783bb3Chris Lattner while (!BB->empty()) { 472b1ba24fb75e633560846e551acadade92783bb3Chris Lattner Instruction &I = BB->back(); 482b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // If this instruction is used, replace uses with an arbitrary value. 492b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Because control flow can't get here, we don't care what we replace the 502b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // value with. Note that since this block is unreachable, and all values 512b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // contained within it must dominate their uses, that all uses will 522b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // eventually be removed (they are themselves dead). 532b1ba24fb75e633560846e551acadade92783bb3Chris Lattner if (!I.use_empty()) 540a205a459884ec745df1c529396dd921f029dafdOwen Anderson I.replaceAllUsesWith(BB->getContext()->getUndef(I.getType())); 552b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BB->getInstList().pop_back(); 562b1ba24fb75e633560846e551acadade92783bb3Chris Lattner } 575622f07a21b799964dc172925b9ebc38191859f6Devang Patel 582b1ba24fb75e633560846e551acadade92783bb3Chris Lattner // Zap the block! 592b1ba24fb75e633560846e551acadade92783bb3Chris Lattner BB->eraseFromParent(); 602b1ba24fb75e633560846e551acadade92783bb3Chris Lattner} 612b1ba24fb75e633560846e551acadade92783bb3Chris Lattner 6229874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// FoldSingleEntryPHINodes - We know that BB has one predecessor. If there are 6329874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// any single-entry PHI nodes in it, fold them away. This handles the case 6429874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// when all entries to the PHI nodes in a block are guaranteed equal, such as 6529874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner/// when the block has exactly one predecessor. 6629874e0dc6c4e55bc384611273343bb358982cc3Chris Lattnervoid llvm::FoldSingleEntryPHINodes(BasicBlock *BB) { 6729874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner if (!isa<PHINode>(BB->begin())) 6829874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner return; 6929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 7029874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { 7129874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner if (PN->getIncomingValue(0) != PN) 7229874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->replaceAllUsesWith(PN->getIncomingValue(0)); 7329874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner else 740a205a459884ec745df1c529396dd921f029dafdOwen Anderson PN->replaceAllUsesWith(BB->getContext()->getUndef(PN->getType())); 7529874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->eraseFromParent(); 7629874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner } 7729874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner} 7829874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 7929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 80afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it 81afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// is dead. Also recursively delete any operands that become dead as 82afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// a result. This includes tracing the def-use list from the PHI to see if 8335738ac150afafe2359268d4b2169498c6c98c5fDan Gohman/// it is ultimately unused or if it reaches an unused cycle. 8435738ac150afafe2359268d4b2169498c6c98c5fDan Gohmanvoid llvm::DeleteDeadPHIs(BasicBlock *BB) { 85afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman // Recursively deleting a PHI may cause multiple PHIs to be deleted 86afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman // or RAUW'd undef, so use an array of WeakVH for the PHIs to delete. 87afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman SmallVector<WeakVH, 8> PHIs; 88afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman for (BasicBlock::iterator I = BB->begin(); 89afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman PHINode *PN = dyn_cast<PHINode>(I); ++I) 90afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman PHIs.push_back(PN); 91afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman 92afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman for (unsigned i = 0, e = PHIs.size(); i != e; ++i) 93afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*())) 9435738ac150afafe2359268d4b2169498c6c98c5fDan Gohman RecursivelyDeleteDeadPHINode(PN); 95afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman} 96afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman 97b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, 98b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson/// if possible. The return value indicates success or failure. 99b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Andersonbool llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) { 10011f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson pred_iterator PI(pred_begin(BB)), PE(pred_end(BB)); 101b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Can't merge the entry block. 102b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (pred_begin(BB) == pred_end(BB)) return false; 103b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 10411f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson BasicBlock *PredBB = *PI++; 10511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson for (; PI != PE; ++PI) // Search all predecessors, see if they are all same 10611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (*PI != PredBB) { 10711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson PredBB = 0; // There are multiple different predecessors... 10811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson break; 10911f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson } 110b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 11111f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Can't merge if there are multiple predecessors. 11211f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!PredBB) return false; 1133ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson // Don't break self-loops. 1143ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson if (PredBB == BB) return false; 1153ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson // Don't break invokes. 1163ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson if (isa<InvokeInst>(PredBB->getTerminator())) return false; 11711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 11811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB)); 11911f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson BasicBlock* OnlySucc = BB; 12011f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson for (; SI != SE; ++SI) 12111f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (*SI != OnlySucc) { 12211f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson OnlySucc = 0; // There are multiple distinct successors! 12311f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson break; 12411f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson } 12511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 12611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Can't merge if there are multiple successors. 12711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!OnlySucc) return false; 128e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel 129e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel // Can't merge if there is PHI loop. 130e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; ++BI) { 131e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel if (PHINode *PN = dyn_cast<PHINode>(BI)) { 132e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 133e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel if (PN->getIncomingValue(i) == PN) 134e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel return false; 135e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel } else 136e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel break; 137e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel } 138e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel 139b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Begin by getting rid of unneeded PHIs. 140b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) { 141b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PN->replaceAllUsesWith(PN->getIncomingValue(0)); 142b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->getInstList().pop_front(); // Delete the phi node... 143b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 144b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 145b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Delete the unconditional branch from the predecessor... 146b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PredBB->getInstList().pop_back(); 147b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 148b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Move all definitions in the successor to the predecessor... 149b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PredBB->getInstList().splice(PredBB->end(), BB->getInstList()); 150b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 151b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Make all PHI nodes that referred to BB now refer to Pred as their 152b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // source... 153b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->replaceAllUsesWith(PredBB); 154b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 15511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson // Inherit predecessors name if it exists. 15611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!PredBB->hasName()) 15711f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson PredBB->takeName(BB); 15811f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 159b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Finally, erase the old block and update dominator info. 160b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (P) { 1611465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominatorTree* DT = P->getAnalysisIfAvailable<DominatorTree>()) { 162b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DomTreeNode* DTN = DT->getNode(BB); 163b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DomTreeNode* PredDTN = DT->getNode(PredBB); 164b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 165b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (DTN) { 166b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson SmallPtrSet<DomTreeNode*, 8> Children(DTN->begin(), DTN->end()); 167b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson for (SmallPtrSet<DomTreeNode*, 8>::iterator DI = Children.begin(), 168b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DE = Children.end(); DI != DE; ++DI) 169b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DT->changeImmediateDominator(*DI, PredDTN); 170b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 171b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DT->eraseNode(BB); 172b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 173b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 174b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 175b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 176b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->eraseFromParent(); 177b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 178b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 179b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson return true; 180b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson} 181b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 1820f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI) 1830f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// with a value, then remove and delete the original instruction. 1840f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 185f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithValue(BasicBlock::InstListType &BIL, 186f7703df4968084c18c248c1feea9961c19a32e6aChris Lattner BasicBlock::iterator &BI, Value *V) { 18718961504fc2b299578dba817900a0696cf3ccc4dChris Lattner Instruction &I = *BI; 1884d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Replaces all of the uses of the instruction with uses of the value 18918961504fc2b299578dba817900a0696cf3ccc4dChris Lattner I.replaceAllUsesWith(V); 1904d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 19186cc42355593dd1689f7d58d56695c451215b02bChris Lattner // Make sure to propagate a name if there is one already. 19286cc42355593dd1689f7d58d56695c451215b02bChris Lattner if (I.hasName() && !V->hasName()) 19386cc42355593dd1689f7d58d56695c451215b02bChris Lattner V->takeName(&I); 194fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 1955560c9d49ccae132cabf1155f18aa0480dce3edaMisha Brukman // Delete the unnecessary instruction now... 19618961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BI = BIL.erase(BI); 1974d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 1984d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 1994d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2000f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithInst - Replace the instruction specified by BI with the 2010f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// instruction specified by I. The original instruction is deleted and BI is 2020f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// updated to point to the new instruction. 2030f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 204f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithInst(BasicBlock::InstListType &BIL, 205f7703df4968084c18c248c1feea9961c19a32e6aChris Lattner BasicBlock::iterator &BI, Instruction *I) { 2064d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner assert(I->getParent() == 0 && 2074d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner "ReplaceInstWithInst: Instruction already inserted into basic block!"); 2084d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2094d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Insert the new instruction into the basic block... 21018961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BasicBlock::iterator New = BIL.insert(BI, I); 2114d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2124d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Replace all uses of the old instruction, and delete it. 2134d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner ReplaceInstWithValue(BIL, BI, I); 2144d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2154d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Move BI back to point to the newly inserted instruction 21618961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BI = New; 2174d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 2184d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2190f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithInst - Replace the instruction specified by From with the 2200f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// instruction specified by To. 2210f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 222f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithInst(Instruction *From, Instruction *To) { 22318961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BasicBlock::iterator BI(From); 22418961504fc2b299578dba817900a0696cf3ccc4dChris Lattner ReplaceInstWithInst(From->getParent()->getInstList(), BI, To); 2254d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 226b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 2270f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// RemoveSuccessor - Change the specified terminator instruction such that its 228bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// successor SuccNum no longer exists. Because this reduces the outgoing 2290f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// degree of the current basic block, the actual terminator instruction itself 230bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// may have to be changed. In the case where the last successor of the block 231bc2eba1ca2d99836af6b5e12128c08e022930918Reid Spencer/// is deleted, a return instruction is inserted in its place which can cause a 2320f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// surprising change in program behavior if it is not expected. 2330f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 234f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum) { 235b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner assert(SuccNum < TI->getNumSuccessors() && 236b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner "Trying to remove a nonexistant successor!"); 237b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 238b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // If our old successor block contains any PHI nodes, remove the entry in the 239b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // PHI nodes that comes from this branch... 240b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // 241b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner BasicBlock *BB = TI->getParent(); 242b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner TI->getSuccessor(SuccNum)->removePredecessor(BB); 243b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 244b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner TerminatorInst *NewTI = 0; 245b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner switch (TI->getOpcode()) { 246b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner case Instruction::Br: 247b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // If this is a conditional branch... convert to unconditional branch. 248b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner if (TI->getNumSuccessors() == 2) { 249b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner cast<BranchInst>(TI)->setUnconditionalDest(TI->getSuccessor(1-SuccNum)); 250b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner } else { // Otherwise convert to a return instruction... 251b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner Value *RetVal = 0; 252fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 253b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // Create a value to return... if the function doesn't return null... 254b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner if (BB->getParent()->getReturnType() != Type::VoidTy) 2550a205a459884ec745df1c529396dd921f029dafdOwen Anderson RetVal = TI->getParent()->getContext()->getNullValue( 2560a205a459884ec745df1c529396dd921f029dafdOwen Anderson BB->getParent()->getReturnType()); 257b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 258b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner // Create the return... 259051a950000e21935165db56695e35bade668193bGabor Greif NewTI = ReturnInst::Create(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 3238019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // The new block lives in whichever loop the old one did. 3241465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (LoopInfo* LI = P->getAnalysisIfAvailable<LoopInfo>()) 325a90793b431458c1bac4c7267946738968c4cdf58Owen Anderson if (Loop *L = LI->getLoopFor(Old)) 326a90793b431458c1bac4c7267946738968c4cdf58Owen Anderson L->addBasicBlockToLoop(New, LI->getBase()); 3278019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3281465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) 329a8a8a366299863fe3711880add4c041c437b63cfDevang Patel { 330a8a8a366299863fe3711880add4c041c437b63cfDevang Patel // Old dominates New. New node domiantes all other nodes dominated by Old. 331a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DomTreeNode *OldNode = DT->getNode(Old); 332a8a8a366299863fe3711880add4c041c437b63cfDevang Patel std::vector<DomTreeNode *> Children; 333a8a8a366299863fe3711880add4c041c437b63cfDevang Patel for (DomTreeNode::iterator I = OldNode->begin(), E = OldNode->end(); 334a8a8a366299863fe3711880add4c041c437b63cfDevang Patel I != E; ++I) 335a8a8a366299863fe3711880add4c041c437b63cfDevang Patel Children.push_back(*I); 336a8a8a366299863fe3711880add4c041c437b63cfDevang Patel 337a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DomTreeNode *NewNode = DT->addNewBlock(New,Old); 338a8a8a366299863fe3711880add4c041c437b63cfDevang Patel 339a8a8a366299863fe3711880add4c041c437b63cfDevang Patel for (std::vector<DomTreeNode *>::iterator I = Children.begin(), 340a8a8a366299863fe3711880add4c041c437b63cfDevang Patel E = Children.end(); I != E; ++I) 341a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DT->changeImmediateDominator(*I, NewNode); 342a8a8a366299863fe3711880add4c041c437b63cfDevang Patel } 3438019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3441465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominanceFrontier *DF = P->getAnalysisIfAvailable<DominanceFrontier>()) 3458019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel DF->splitBlock(Old); 3468019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3478019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return New; 3488019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel} 34954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 35054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 35154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// SplitBlockPredecessors - This method transforms BB by introducing a new 35254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// basic block into the function, and moving some of the predecessors of BB to 35354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// be predecessors of the new block. The new predecessors are indicated by the 35454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// Preds array, which has NumPreds elements in it. The new block is given a 35554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// suffix of 'Suffix'. 35654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// 35754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree and 35854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// DominanceFrontier, but no other analyses. 35954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris LattnerBasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB, 36054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BasicBlock *const *Preds, 36154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner unsigned NumPreds, const char *Suffix, 36254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Pass *P) { 36354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Create new basic block, insert right before the original block. 36454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BasicBlock *NewBB = 36554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BasicBlock::Create(BB->getName()+Suffix, BB->getParent(), BB); 36654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 36754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // The new block unconditionally branches to the old block. 36854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BranchInst *BI = BranchInst::Create(BB, NewBB); 36954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 37054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Move the edges from Preds to point to NewBB instead of BB. 371280a6e607d8eb7401749a92db624a82de47da777Nick Lewycky for (unsigned i = 0; i != NumPreds; ++i) 37254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB); 37354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 37454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Update dominator tree and dominator frontier if available. 3751465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands DominatorTree *DT = P ? P->getAnalysisIfAvailable<DominatorTree>() : 0; 37654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (DT) 37754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner DT->splitBlock(NewBB); 3781465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands if (DominanceFrontier *DF = P ? P->getAnalysisIfAvailable<DominanceFrontier>():0) 37954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner DF->splitBlock(NewBB); 3801465d61bdd36cfd6021036a527895f0dd358e97dDuncan Sands AliasAnalysis *AA = P ? P->getAnalysisIfAvailable<AliasAnalysis>() : 0; 38154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 38254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 38354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI 38454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // node becomes an incoming value for BB's phi node. However, if the Preds 38554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // list is empty, we need to insert dummy entries into the PHI nodes in BB to 38654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // account for the newly created predecessor. 38754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (NumPreds == 0) { 38854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Insert dummy values as the incoming value. 38954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I) 3900a205a459884ec745df1c529396dd921f029dafdOwen Anderson cast<PHINode>(I)->addIncoming(BB->getContext()->getUndef(I->getType()), 3910a205a459884ec745df1c529396dd921f029dafdOwen Anderson NewBB); 39254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner return NewBB; 39354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 39454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 39554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Otherwise, create a new PHI node in NewBB for each PHI node in BB. 39654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ) { 39754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode *PN = cast<PHINode>(I++); 39854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 39954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Check to see if all of the values coming in are the same. If so, we 40054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // don't need to create a new PHI node. 40154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Value *InVal = PN->getIncomingValueForBlock(Preds[0]); 40254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (unsigned i = 1; i != NumPreds; ++i) 40354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (InVal != PN->getIncomingValueForBlock(Preds[i])) { 40454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner InVal = 0; 40554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner break; 40654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 40754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 40854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (InVal) { 40954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // If all incoming values for the new PHI would be the same, just don't 41054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // make a new PHI. Instead, just remove the incoming values from the old 41154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // PHI. 41254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (unsigned i = 0; i != NumPreds; ++i) 41354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->removeIncomingValue(Preds[i], false); 41454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } else { 41554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // If the values coming into the block are not the same, we need a PHI. 41654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Create the new PHI node, insert it into NewBB at the end of the block 41754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode *NewPHI = 41854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PHINode::Create(PN->getType(), PN->getName()+".ph", BI); 41954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (AA) AA->copyValue(PN, NewPHI); 42054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 42154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Move all of the PHI values for 'Preds' to the new PHI. 42254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (unsigned i = 0; i != NumPreds; ++i) { 42354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Value *V = PN->removeIncomingValue(Preds[i], false); 42454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner NewPHI->addIncoming(V, Preds[i]); 42554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 42654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner InVal = NewPHI; 42754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 42854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 42954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Add an incoming value to the PHI node in the loop for the preheader 43054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // edge. 43154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->addIncoming(InVal, NewBB); 43254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 43354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Check to see if we can eliminate this phi node. 43454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (Value *V = PN->hasConstantValue(DT != 0)) { 43554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Instruction *I = dyn_cast<Instruction>(V); 43654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (!I || DT == 0 || DT->dominates(I, PN)) { 43754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->replaceAllUsesWith(V); 43854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner if (AA) AA->deleteValue(PN); 43954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner PN->eraseFromParent(); 44054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 44154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 44254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 44354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 44454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner return NewBB; 44554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner} 44652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 447fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// FindFunctionBackedges - Analyze the specified function to find all of the 448fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// loop backedges in the function and return them. This is a relatively cheap 449fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// (compared to computing dominators and loop info) analysis. 450fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// 451fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// The output is added to Result, as pairs of <from,to> edge info. 452fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stumpvoid llvm::FindFunctionBackedges(const Function &F, 453fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallVectorImpl<std::pair<const BasicBlock*,const BasicBlock*> > &Result) { 454fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump const BasicBlock *BB = &F.getEntryBlock(); 455fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (succ_begin(BB) == succ_end(BB)) 456fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump return; 457fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 458fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallPtrSet<const BasicBlock*, 8> Visited; 459fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallVector<std::pair<const BasicBlock*, succ_const_iterator>, 8> VisitStack; 460fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallPtrSet<const BasicBlock*, 8> InStack; 461fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 462fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump Visited.insert(BB); 463fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump VisitStack.push_back(std::make_pair(BB, succ_begin(BB))); 464fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.insert(BB); 465fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump do { 466fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump std::pair<const BasicBlock*, succ_const_iterator> &Top = VisitStack.back(); 467fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump const BasicBlock *ParentBB = Top.first; 468fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump succ_const_iterator &I = Top.second; 469fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 470fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump bool FoundNew = false; 471fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump while (I != succ_end(ParentBB)) { 472fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump BB = *I++; 473fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (Visited.insert(BB)) { 474fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump FoundNew = true; 475fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump break; 476fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 477fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Successor is in VisitStack, it's a back edge. 478fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (InStack.count(BB)) 479fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump Result.push_back(std::make_pair(ParentBB, BB)); 480fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 481fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 482fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (FoundNew) { 483fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Go down one level if there is a unvisited successor. 484fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.insert(BB); 485fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump VisitStack.push_back(std::make_pair(BB, succ_begin(BB))); 486fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } else { 487fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Go up one level. 488fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.erase(VisitStack.pop_back_val().first); 489fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 490fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } while (!VisitStack.empty()); 491fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 492fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 493fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump} 494fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 495fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 496fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 4974aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// AreEquivalentAddressValues - Test if A and B will obviously have the same 4984aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// value. This includes recognizing that %t0 and %t1 will have the same 4994aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// value in code like this: 5000f8b53f19d29013ab18f3d444cea1e6305405611Dan Gohman/// %t0 = getelementptr \@a, 0, 3 5014aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// store i32 0, i32* %t0 5020f8b53f19d29013ab18f3d444cea1e6305405611Dan Gohman/// %t1 = getelementptr \@a, 0, 3 5034aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// %t2 = load i32* %t1 5044aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner/// 5054aebaee0e40f2457f1a6588679655a3c600a553bChris Lattnerstatic bool AreEquivalentAddressValues(const Value *A, const Value *B) { 5064aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner // Test if the values are trivially equivalent. 5074aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (A == B) return true; 5084aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 5094aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner // Test if the values come form identical arithmetic instructions. 5104aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (isa<BinaryOperator>(A) || isa<CastInst>(A) || 5114aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner isa<PHINode>(A) || isa<GetElementPtrInst>(A)) 5124aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (const Instruction *BI = dyn_cast<Instruction>(B)) 5134aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (cast<Instruction>(A)->isIdenticalTo(BI)) 5144aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner return true; 5154aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 5164aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner // Otherwise they may not be equivalent. 5174aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner return false; 5184aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner} 5194aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner 52052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at the 52152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// instruction before ScanFrom) checking to see if we have the value at the 52252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// memory address *Ptr locally available within a small number of instructions. 52352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// If the value is available, return it. 52452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// 52552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// If not, return the iterator for the last validated instruction that the 52652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// value would be live through. If we scanned the entire block and didn't find 52752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// something that invalidates *Ptr or provides it, ScanFrom would be left at 52852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// begin() and this returns null. ScanFrom could also be left 52952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// 53052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// MaxInstsToScan specifies the maximum instructions to scan in the block. If 53152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// it is set to 0, it will scan the whole block. You can also optionally 53252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner/// specify an alias analysis implementation, which makes this more precise. 53352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris LattnerValue *llvm::FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB, 53452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner BasicBlock::iterator &ScanFrom, 53552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner unsigned MaxInstsToScan, 53652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner AliasAnalysis *AA) { 53752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (MaxInstsToScan == 0) MaxInstsToScan = ~0U; 538ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 539ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If we're using alias analysis to disambiguate get the size of *Ptr. 540ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner unsigned AccessSize = 0; 541ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA) { 542ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner const Type *AccessTy = cast<PointerType>(Ptr->getType())->getElementType(); 543ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner AccessSize = AA->getTargetData().getTypeStoreSizeInBits(AccessTy); 544ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner } 54552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 54652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner while (ScanFrom != ScanBB->begin()) { 547bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // We must ignore debug info directives when counting (otherwise they 548bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // would affect codegen). 549bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen Instruction *Inst = --ScanFrom; 550bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (isa<DbgInfoIntrinsic>(Inst)) 551bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen continue; 552d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // We skip pointer-to-pointer bitcasts, which are NOPs. 553d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // It is necessary for correctness to skip those that feed into a 554d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen // llvm.dbg.declare, as these are not present when debugging is off. 555d9c05d7711b65bca070da76cb0e9a9b9eb7e69d5Dale Johannesen if (isa<BitCastInst>(Inst) && isa<PointerType>(Inst->getType())) 5564ded40a44da9d67355a103cc8da68c2c1ab40bfdDale Johannesen continue; 5574ded40a44da9d67355a103cc8da68c2c1ab40bfdDale Johannesen 558bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen // Restore ScanFrom to expected value in case next test succeeds 559bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen ScanFrom++; 560bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen 56152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Don't scan huge blocks. 56252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (MaxInstsToScan-- == 0) return 0; 56352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 564bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen --ScanFrom; 56552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is a load of Ptr, the loaded value is available. 56652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) 5674aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (AreEquivalentAddressValues(LI->getOperand(0), Ptr)) 56852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return LI; 56952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 57052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { 57152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is a store through Ptr, the value is available! 5724aebaee0e40f2457f1a6588679655a3c600a553bChris Lattner if (AreEquivalentAddressValues(SI->getOperand(1), Ptr)) 57352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return SI->getOperand(0); 57452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 57552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If Ptr is an alloca and this is a store to a different alloca, ignore 57652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // the store. This is a trivial form of alias analysis that is important 57752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // for reg2mem'd code. 57852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if ((isa<AllocaInst>(Ptr) || isa<GlobalVariable>(Ptr)) && 57952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner (isa<AllocaInst>(SI->getOperand(1)) || 58052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner isa<GlobalVariable>(SI->getOperand(1)))) 58152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner continue; 58252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 583ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If we have alias analysis and it says the store won't modify the loaded 584ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // value, ignore the store. 585ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA && 586ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner (AA->getModRefInfo(SI, Ptr, AccessSize) & AliasAnalysis::Mod) == 0) 587ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner continue; 588ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 58952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Otherwise the store that may or may not alias the pointer, bail out. 59052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner ++ScanFrom; 59152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 59252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 59352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 59452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // If this is some other instruction that may clobber Ptr, bail out. 59552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner if (Inst->mayWriteToMemory()) { 596ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // If alias analysis claims that it really won't modify the load, 597ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner // ignore it. 598ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner if (AA && 599ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner (AA->getModRefInfo(Inst, Ptr, AccessSize) & AliasAnalysis::Mod) == 0) 600ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner continue; 601ee6e10bc8e389ed1a09c33c8cec15b3aa13e813bChris Lattner 60252c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // May modify the pointer, bail out. 60352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner ++ScanFrom; 60452c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 60552c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 60652c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner } 60752c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 60852c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // Got to the start of the block, we didn't find it, but are done for this 60952c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner // block. 61052c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner return 0; 61152c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner} 612bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen 613bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// CopyPrecedingStopPoint - If I is immediately preceded by a StopPoint, 614bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// make a copy of the stoppoint before InsertPos (presumably before copying 615bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen/// or moving I). 616bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesenvoid llvm::CopyPrecedingStopPoint(Instruction *I, 617bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen BasicBlock::iterator InsertPos) { 618bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (I != I->getParent()->begin()) { 619bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen BasicBlock::iterator BBI = I; --BBI; 620bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen if (DbgStopPointInst *DSPI = dyn_cast<DbgStopPointInst>(BBI)) { 621333c40096561218bc3597cf153c0a3895274414cOwen Anderson CallInst *newDSPI = DSPI->clone(*I->getParent()->getContext()); 622bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen newDSPI->insertBefore(InsertPos); 623bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen } 624bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen } 625bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen} 626