BasicBlockUtils.cpp revision 8e0d1c03ca7fd86e6879b4e37d0d7f0e982feef6
14d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner//===-- BasicBlockUtils.cpp - BasicBlock Utilities -------------------------==// 2fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 54ee451de366474b9c228b4e5fa573795a715216dChris Lattner// This file is distributed under the University of Illinois Open Source 64ee451de366474b9c228b4e5fa573795a715216dChris Lattner// License. See LICENSE.TXT for details. 7fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 94d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner// 104d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner// This family of functions perform manipulations on basic blocks, and 114d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner// instructions contained within basic blocks. 124d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner// 134d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner//===----------------------------------------------------------------------===// 144d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 154d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner#include "llvm/Transforms/Utils/BasicBlockUtils.h" 164d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner#include "llvm/Function.h" 1747b14a4a6a455c7be169cfd312fcbe796f0ad426Misha Brukman#include "llvm/Instructions.h" 18bd8e650876cc93952dde3120938271dbda6cbbb7Dale Johannesen#include "llvm/IntrinsicInst.h" 19b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner#include "llvm/Constant.h" 20b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner#include "llvm/Type.h" 2154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner#include "llvm/Analysis/AliasAnalysis.h" 22301278719b67dcdd1159d9f91b4db5ef57f025c6Cameron Zwarich#include "llvm/Analysis/Dominators.h" 23b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner#include "llvm/Analysis/LoopInfo.h" 24b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner#include "llvm/Analysis/MemoryDependenceAnalysis.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. 67b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattnervoid llvm::FoldSingleEntryPHINodes(BasicBlock *BB, Pass *P) { 68b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner if (!isa<PHINode>(BB->begin())) return; 69b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner 70b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner AliasAnalysis *AA = 0; 71b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner MemoryDependenceAnalysis *MemDep = 0; 72b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner if (P) { 73b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner AA = P->getAnalysisIfAvailable<AliasAnalysis>(); 74b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner MemDep = P->getAnalysisIfAvailable<MemoryDependenceAnalysis>(); 75b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner } 76b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner 7729874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { 7829874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner if (PN->getIncomingValue(0) != PN) 7929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->replaceAllUsesWith(PN->getIncomingValue(0)); 8029874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner else 819e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson PN->replaceAllUsesWith(UndefValue::get(PN->getType())); 82b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner 83b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner if (MemDep) 84b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner MemDep->removeInstruction(PN); // Memdep updates AA itself. 85b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner else if (AA && isa<PointerType>(PN->getType())) 86b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner AA->deleteValue(PN); 87b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner 8829874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner PN->eraseFromParent(); 8929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner } 9029874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner} 9129874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 9229874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner 93afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it 94afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// is dead. Also recursively delete any operands that become dead as 95afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman/// a result. This includes tracing the def-use list from the PHI to see if 9635738ac150afafe2359268d4b2169498c6c98c5fDan Gohman/// it is ultimately unused or if it reaches an unused cycle. 978e0d1c03ca7fd86e6879b4e37d0d7f0e982feef6Benjamin Kramerbool llvm::DeleteDeadPHIs(BasicBlock *BB, const TargetLibraryInfo *TLI) { 98afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman // Recursively deleting a PHI may cause multiple PHIs to be deleted 99afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman // or RAUW'd undef, so use an array of WeakVH for the PHIs to delete. 100afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman SmallVector<WeakVH, 8> PHIs; 101afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman for (BasicBlock::iterator I = BB->begin(); 102afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman PHINode *PN = dyn_cast<PHINode>(I); ++I) 103afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman PHIs.push_back(PN); 104afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman 10590fe0bd68cdbeb980c08628c4992dffad0dc728fDan Gohman bool Changed = false; 106afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman for (unsigned i = 0, e = PHIs.size(); i != e; ++i) 107afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*())) 1088e0d1c03ca7fd86e6879b4e37d0d7f0e982feef6Benjamin Kramer Changed |= RecursivelyDeleteDeadPHINode(PN, TLI); 10990fe0bd68cdbeb980c08628c4992dffad0dc728fDan Gohman 11090fe0bd68cdbeb980c08628c4992dffad0dc728fDan Gohman return Changed; 111afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman} 112afc36a9520971832dfbebc0333593bf5d3098296Dan Gohman 113438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, 114438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman/// if possible. The return value indicates success or failure. 115882029269e0cf4b497993b8e9a754429ef035facChris Lattnerbool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P) { 1161c034dcbbc86674cc146340a877495f71d9a2569Dan Gohman // Don't merge away blocks who have their address taken. 1171c034dcbbc86674cc146340a877495f71d9a2569Dan Gohman if (BB->hasAddressTaken()) return false; 118438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman 1191c034dcbbc86674cc146340a877495f71d9a2569Dan Gohman // Can't merge if there are multiple predecessors, or no predecessors. 1201c034dcbbc86674cc146340a877495f71d9a2569Dan Gohman BasicBlock *PredBB = BB->getUniquePredecessor(); 121438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman if (!PredBB) return false; 1221c034dcbbc86674cc146340a877495f71d9a2569Dan Gohman 1233ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson // Don't break self-loops. 124438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman if (PredBB == BB) return false; 1253ecaf1b33940470d5bf554135778ba5a8bce9a79Owen Anderson // Don't break invokes. 126438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman if (isa<InvokeInst>(PredBB->getTerminator())) return false; 127438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman 128438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB)); 129dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner BasicBlock *OnlySucc = BB; 130438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman for (; SI != SE; ++SI) 131438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman if (*SI != OnlySucc) { 132438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman OnlySucc = 0; // There are multiple distinct successors! 133438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman break; 134438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman } 135438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman 136438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman // Can't merge if there are multiple successors. 137438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman if (!OnlySucc) return false; 138e435a5d9374b61049b16ef69e6314542815fadb4Devang Patel 139438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman // Can't merge if there is PHI loop. 140438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; ++BI) { 141438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman if (PHINode *PN = dyn_cast<PHINode>(BI)) { 142438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 143438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman if (PN->getIncomingValue(i) == PN) 144438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman return false; 145438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman } else 146438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman break; 147438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman } 148438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman 149438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman // Begin by getting rid of unneeded PHIs. 150dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner if (isa<PHINode>(BB->front())) 151b5b7997fd0765f73b711ea4c72e4433ce3637794Chris Lattner FoldSingleEntryPHINodes(BB, P); 152438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman 153b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Delete the unconditional branch from the predecessor... 154b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson PredBB->getInstList().pop_back(); 155b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 156b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Make all PHI nodes that referred to BB now refer to Pred as their 157b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // source... 158b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->replaceAllUsesWith(PredBB); 159b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 16095c3e48f9557adb6064d580684bb14cacec2f826Jay Foad // Move all definitions in the successor to the predecessor... 16195c3e48f9557adb6064d580684bb14cacec2f826Jay Foad PredBB->getInstList().splice(PredBB->end(), BB->getInstList()); 16295c3e48f9557adb6064d580684bb14cacec2f826Jay Foad 163438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman // Inherit predecessors name if it exists. 16411f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson if (!PredBB->hasName()) 16511f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson PredBB->takeName(BB); 16611f2ec8eb534502a0d5b7e3c13c1a38e877876b2Owen Anderson 167b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson // Finally, erase the old block and update dominator info. 168b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson if (P) { 169dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) { 170dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner if (DomTreeNode *DTN = DT->getNode(BB)) { 171dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner DomTreeNode *PredDTN = DT->getNode(PredBB); 172fbbd4abfe5a89e432240d2c05201b44a5e2f2f78Jakob Stoklund Olesen SmallVector<DomTreeNode*, 8> Children(DTN->begin(), DTN->end()); 173fbbd4abfe5a89e432240d2c05201b44a5e2f2f78Jakob Stoklund Olesen for (SmallVector<DomTreeNode*, 8>::iterator DI = Children.begin(), 174b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DE = Children.end(); DI != DE; ++DI) 175b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DT->changeImmediateDominator(*DI, PredDTN); 176b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 177b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson DT->eraseNode(BB); 178b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 179dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner 180dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>()) 181dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner LI->removeBlock(BB); 182b6810991a9648a40fe05162d744f42c3c178dba7Chris Lattner 183b6810991a9648a40fe05162d744f42c3c178dba7Chris Lattner if (MemoryDependenceAnalysis *MD = 184b6810991a9648a40fe05162d744f42c3c178dba7Chris Lattner P->getAnalysisIfAvailable<MemoryDependenceAnalysis>()) 185b6810991a9648a40fe05162d744f42c3c178dba7Chris Lattner MD->invalidateCachedPredecessors(); 186b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 187b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson } 188b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 189b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson BB->eraseFromParent(); 190438b583dbd20f63b70d0b5abb7780a50bf03dd83Dan Gohman return true; 191b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson} 192b31b06d04b81c5383e2fba0cd44d4ba3f324a794Owen Anderson 1930f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI) 1940f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// with a value, then remove and delete the original instruction. 1950f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 196f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithValue(BasicBlock::InstListType &BIL, 197f7703df4968084c18c248c1feea9961c19a32e6aChris Lattner BasicBlock::iterator &BI, Value *V) { 19818961504fc2b299578dba817900a0696cf3ccc4dChris Lattner Instruction &I = *BI; 1994d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Replaces all of the uses of the instruction with uses of the value 20018961504fc2b299578dba817900a0696cf3ccc4dChris Lattner I.replaceAllUsesWith(V); 2014d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 20286cc42355593dd1689f7d58d56695c451215b02bChris Lattner // Make sure to propagate a name if there is one already. 20386cc42355593dd1689f7d58d56695c451215b02bChris Lattner if (I.hasName() && !V->hasName()) 20486cc42355593dd1689f7d58d56695c451215b02bChris Lattner V->takeName(&I); 205fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 2065560c9d49ccae132cabf1155f18aa0480dce3edaMisha Brukman // Delete the unnecessary instruction now... 20718961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BI = BIL.erase(BI); 2084d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 2094d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2104d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2110f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithInst - Replace the instruction specified by BI with the 2120f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// instruction specified by I. The original instruction is deleted and BI is 2130f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// updated to point to the new instruction. 2140f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 215f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithInst(BasicBlock::InstListType &BIL, 216f7703df4968084c18c248c1feea9961c19a32e6aChris Lattner BasicBlock::iterator &BI, Instruction *I) { 2174d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner assert(I->getParent() == 0 && 2184d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner "ReplaceInstWithInst: Instruction already inserted into basic block!"); 2194d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2204d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Insert the new instruction into the basic block... 22118961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BasicBlock::iterator New = BIL.insert(BI, I); 2224d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2234d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Replace all uses of the old instruction, and delete it. 2244d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner ReplaceInstWithValue(BIL, BI, I); 2254d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2264d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner // Move BI back to point to the newly inserted instruction 22718961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BI = New; 2284d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 2294d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner 2300f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// ReplaceInstWithInst - Replace the instruction specified by From with the 2310f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// instruction specified by To. 2320f67dd6237eb7227aa58e9b77cd95f354989b891Chris Lattner/// 233f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnervoid llvm::ReplaceInstWithInst(Instruction *From, Instruction *To) { 23418961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BasicBlock::iterator BI(From); 23518961504fc2b299578dba817900a0696cf3ccc4dChris Lattner ReplaceInstWithInst(From->getParent()->getInstList(), BI, To); 2364d1e46e7b06534cde262d32fad038135f406b6b7Chris Lattner} 237b0f0ef8f26eb8911ec1bb31380b5fe2d62e1c0ecChris Lattner 238ae23daf63afccd68be965ff4f7acafa818d76aaaBob Wilson/// GetSuccessorNumber - Search for the specified successor of basic block BB 239ae23daf63afccd68be965ff4f7acafa818d76aaaBob Wilson/// and return its position in the terminator instruction's list of 240ae23daf63afccd68be965ff4f7acafa818d76aaaBob Wilson/// successors. It is an error to call this with a block that is not a 241ae23daf63afccd68be965ff4f7acafa818d76aaaBob Wilson/// successor. 242ae23daf63afccd68be965ff4f7acafa818d76aaaBob Wilsonunsigned llvm::GetSuccessorNumber(BasicBlock *BB, BasicBlock *Succ) { 243adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson TerminatorInst *Term = BB->getTerminator(); 2448a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel#ifndef NDEBUG 245adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson unsigned e = Term->getNumSuccessors(); 2468a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel#endif 2478a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel for (unsigned i = 0; ; ++i) { 2488019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel assert(i != e && "Didn't find edge?"); 249adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson if (Term->getSuccessor(i) == Succ) 250adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson return i; 2518019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } 252adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson} 253adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson 254adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson/// SplitEdge - Split the edge connecting specified block. Pass P must 255adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson/// not be NULL. 256adb6f226714dcfae363f51b453c4590b0f42da5eBob WilsonBasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, Pass *P) { 257ae23daf63afccd68be965ff4f7acafa818d76aaaBob Wilson unsigned SuccNum = GetSuccessorNumber(BB, Succ); 2588019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2598019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If this is a critical edge, let SplitCriticalEdge do it. 260adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson TerminatorInst *LatchTerm = BB->getTerminator(); 261adb6f226714dcfae363f51b453c4590b0f42da5eBob Wilson if (SplitCriticalEdge(LatchTerm, SuccNum, P)) 2628019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return LatchTerm->getSuccessor(SuccNum); 2638019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2648019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If the edge isn't critical, then BB has a single successor or Succ has a 2658019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // single pred. Split the block. 2668019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock::iterator SplitPoint; 2678019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel if (BasicBlock *SP = Succ->getSinglePredecessor()) { 2688019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // If the successor only has a single pred, split the top of the successor 2698019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel // block. 2708019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel assert(SP == BB && "CFG broken"); 2718a88a14462db7e8ad96536c89b3ab948b89d0c2bDevang Patel SP = NULL; 2728019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return SplitBlock(Succ, Succ->begin(), P); 2738019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel } 274b0433d4b2fb66922fa3625871840ccb72c8a9decChris Lattner 275b0433d4b2fb66922fa3625871840ccb72c8a9decChris Lattner // Otherwise, if BB has a single successor, split it at the bottom of the 276b0433d4b2fb66922fa3625871840ccb72c8a9decChris Lattner // block. 277b0433d4b2fb66922fa3625871840ccb72c8a9decChris Lattner assert(BB->getTerminator()->getNumSuccessors() == 1 && 278b0433d4b2fb66922fa3625871840ccb72c8a9decChris Lattner "Should have a single succ!"); 279b0433d4b2fb66922fa3625871840ccb72c8a9decChris Lattner return SplitBlock(BB, BB->getTerminator(), P); 2808019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel} 2818019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2828019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// SplitBlock - Split the specified block at the specified instruction - every 2838019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// thing before SplitPt stays in Old and everything starting with SplitPt moves 2848019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// to a new block. The two blocks are joined by an unconditional branch and 2858019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// the loop info is updated. 2868019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel/// 2878019893c3f55a4bfe770888fe285d6dae57cf216Devang PatelBasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P) { 2888019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock::iterator SplitIt = SplitPt; 289ab82fd9ff6874118594bc64bdafcadaa5b7fcb60Bill Wendling while (isa<PHINode>(SplitIt) || isa<LandingPadInst>(SplitIt)) 2908019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel ++SplitIt; 2918019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel BasicBlock *New = Old->splitBasicBlock(SplitIt, Old->getName()+".split"); 2928019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2935c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // The new block lives in whichever loop the old one did. This preserves 2945c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman // LCSSA as well, because we force the split point to be after any PHI nodes. 295dc85f8ab808aec2f673262f5145eda58538cfb26Chris Lattner if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>()) 296a90793b431458c1bac4c7267946738968c4cdf58Owen Anderson if (Loop *L = LI->getLoopFor(Old)) 297a90793b431458c1bac4c7267946738968c4cdf58Owen Anderson L->addBasicBlockToLoop(New, LI->getBase()); 2988019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 2990f1666b480f7ac55af09fdd5ff09c3df7c20e2e4Evan Cheng if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) { 300e2d50046fd29cb3eb2483e080cb7c39b460fbb19Gabor Greif // Old dominates New. New node dominates all other nodes dominated by Old. 301605e2b518445d86491e1a0c812f7c85193d3517aRafael Espindola if (DomTreeNode *OldNode = DT->getNode(Old)) { 302605e2b518445d86491e1a0c812f7c85193d3517aRafael Espindola std::vector<DomTreeNode *> Children; 303605e2b518445d86491e1a0c812f7c85193d3517aRafael Espindola for (DomTreeNode::iterator I = OldNode->begin(), E = OldNode->end(); 304605e2b518445d86491e1a0c812f7c85193d3517aRafael Espindola I != E; ++I) 305605e2b518445d86491e1a0c812f7c85193d3517aRafael Espindola Children.push_back(*I); 3060f1666b480f7ac55af09fdd5ff09c3df7c20e2e4Evan Cheng 3070f1666b480f7ac55af09fdd5ff09c3df7c20e2e4Evan Cheng DomTreeNode *NewNode = DT->addNewBlock(New,Old); 308a8a8a366299863fe3711880add4c041c437b63cfDevang Patel for (std::vector<DomTreeNode *>::iterator I = Children.begin(), 309a8a8a366299863fe3711880add4c041c437b63cfDevang Patel E = Children.end(); I != E; ++I) 310a8a8a366299863fe3711880add4c041c437b63cfDevang Patel DT->changeImmediateDominator(*I, NewNode); 311605e2b518445d86491e1a0c812f7c85193d3517aRafael Espindola } 3120f1666b480f7ac55af09fdd5ff09c3df7c20e2e4Evan Cheng } 3138019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel 3148019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel return New; 3158019893c3f55a4bfe770888fe285d6dae57cf216Devang Patel} 31654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 317a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling/// UpdateAnalysisInformation - Update DominatorTree, LoopInfo, and LCCSA 318a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling/// analysis information. 319d4770144d46992be0321d3cd4dc9315da1aa4d5dBill Wendlingstatic void UpdateAnalysisInformation(BasicBlock *OldBB, BasicBlock *NewBB, 3209210e840ddd2358204281504e9d43a67c5b43219Bill Wendling ArrayRef<BasicBlock *> Preds, 3219210e840ddd2358204281504e9d43a67c5b43219Bill Wendling Pass *P, bool &HasLoopExit) { 322a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (!P) return; 323a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 324a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>(); 325a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling Loop *L = LI ? LI->getLoopFor(OldBB) : 0; 326a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 327a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // If we need to preserve loop analyses, collect some information about how 328a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // this split will affect loops. 329a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling bool IsLoopEntry = !!L; 330a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling bool SplitMakesNewLoopHeader = false; 331a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (LI) { 3327e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling bool PreserveLCSSA = P->mustPreserveAnalysisID(LCSSAID); 3339210e840ddd2358204281504e9d43a67c5b43219Bill Wendling for (ArrayRef<BasicBlock*>::iterator 3349210e840ddd2358204281504e9d43a67c5b43219Bill Wendling i = Preds.begin(), e = Preds.end(); i != e; ++i) { 3359210e840ddd2358204281504e9d43a67c5b43219Bill Wendling BasicBlock *Pred = *i; 3367e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 337a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // If we need to preserve LCSSA, determine if any of the preds is a loop 338a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // exit. 339a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (PreserveLCSSA) 3409210e840ddd2358204281504e9d43a67c5b43219Bill Wendling if (Loop *PL = LI->getLoopFor(Pred)) 341a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (!PL->contains(OldBB)) 342a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling HasLoopExit = true; 343a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 344a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // If we need to preserve LoopInfo, note whether any of the preds crosses 345a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // an interesting loop boundary. 346a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (!L) continue; 3479210e840ddd2358204281504e9d43a67c5b43219Bill Wendling if (L->contains(Pred)) 348a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling IsLoopEntry = false; 349a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling else 350a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling SplitMakesNewLoopHeader = true; 351a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling } 352a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling } 353a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 354a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // Update dominator tree if available. 355a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>(); 356a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (DT) 357a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling DT->splitBlock(NewBB); 358a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 359a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (!L) return; 360a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 361a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (IsLoopEntry) { 362a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // Add the new block to the nearest enclosing loop (and not an adjacent 363a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // loop). To find this, examine each of the predecessors and determine which 364a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // loops enclose them, and select the most-nested loop which contains the 365a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // loop containing the block being split. 366a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling Loop *InnermostPredLoop = 0; 3679210e840ddd2358204281504e9d43a67c5b43219Bill Wendling for (ArrayRef<BasicBlock*>::iterator 3689210e840ddd2358204281504e9d43a67c5b43219Bill Wendling i = Preds.begin(), e = Preds.end(); i != e; ++i) { 3699210e840ddd2358204281504e9d43a67c5b43219Bill Wendling BasicBlock *Pred = *i; 3709210e840ddd2358204281504e9d43a67c5b43219Bill Wendling if (Loop *PredLoop = LI->getLoopFor(Pred)) { 371a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // Seek a loop which actually contains the block being split (to avoid 372a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // adjacent loops). 373a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling while (PredLoop && !PredLoop->contains(OldBB)) 374a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling PredLoop = PredLoop->getParentLoop(); 375a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 376a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // Select the most-nested of these loops which contains the block. 377a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (PredLoop && PredLoop->contains(OldBB) && 378a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling (!InnermostPredLoop || 379a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling InnermostPredLoop->getLoopDepth() < PredLoop->getLoopDepth())) 380a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling InnermostPredLoop = PredLoop; 381a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling } 3829210e840ddd2358204281504e9d43a67c5b43219Bill Wendling } 383a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 384a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (InnermostPredLoop) 385a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling InnermostPredLoop->addBasicBlockToLoop(NewBB, LI->getBase()); 386a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling } else { 387a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling L->addBasicBlockToLoop(NewBB, LI->getBase()); 388a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling if (SplitMakesNewLoopHeader) 389a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling L->moveToHeader(NewBB); 390a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling } 391a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling} 392a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling 3931c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling/// UpdatePHINodes - Update the PHI nodes in OrigBB to include the values coming 3941c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling/// from NewBB. This also updates AliasAnalysis, if available. 3951c44d869cd920f3c2d7fdc9196677db202440089Bill Wendlingstatic void UpdatePHINodes(BasicBlock *OrigBB, BasicBlock *NewBB, 3961c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling ArrayRef<BasicBlock*> Preds, BranchInst *BI, 3971c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling Pass *P, bool HasLoopExit) { 3981c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // Otherwise, create a new PHI node in NewBB for each PHI node in OrigBB. 3991c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling AliasAnalysis *AA = P ? P->getAnalysisIfAvailable<AliasAnalysis>() : 0; 4001c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling for (BasicBlock::iterator I = OrigBB->begin(); isa<PHINode>(I); ) { 4011c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling PHINode *PN = cast<PHINode>(I++); 4021c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling 4031c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // Check to see if all of the values coming in are the same. If so, we 4041c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // don't need to create a new PHI node, unless it's needed for LCSSA. 4051c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling Value *InVal = 0; 4061c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling if (!HasLoopExit) { 4071c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling InVal = PN->getIncomingValueForBlock(Preds[0]); 4081c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling for (unsigned i = 1, e = Preds.size(); i != e; ++i) 4091c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling if (InVal != PN->getIncomingValueForBlock(Preds[i])) { 4101c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling InVal = 0; 4111c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling break; 4121c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling } 4131c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling } 4141c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling 4151c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling if (InVal) { 4161c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // If all incoming values for the new PHI would be the same, just don't 4171c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // make a new PHI. Instead, just remove the incoming values from the old 4181c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // PHI. 4191c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling for (unsigned i = 0, e = Preds.size(); i != e; ++i) 4201c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling PN->removeIncomingValue(Preds[i], false); 4211c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling } else { 4221c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // If the values coming into the block are not the same, we need a PHI. 4231c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // Create the new PHI node, insert it into NewBB at the end of the block 4241c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling PHINode *NewPHI = 4251c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling PHINode::Create(PN->getType(), Preds.size(), PN->getName() + ".ph", BI); 4261c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling if (AA) AA->copyValue(PN, NewPHI); 4271c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling 4281c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // Move all of the PHI values for 'Preds' to the new PHI. 4291c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling for (unsigned i = 0, e = Preds.size(); i != e; ++i) { 4301c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling Value *V = PN->removeIncomingValue(Preds[i], false); 4311c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling NewPHI->addIncoming(V, Preds[i]); 4321c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling } 4331c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling 4341c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling InVal = NewPHI; 4351c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling } 4361c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling 4371c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // Add an incoming value to the PHI node in the loop for the preheader 4381c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // edge. 4391c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling PN->addIncoming(InVal, NewBB); 4401c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling } 4411c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling} 4421c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling 44354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// SplitBlockPredecessors - This method transforms BB by introducing a new 44454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// basic block into the function, and moving some of the predecessors of BB to 44554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// be predecessors of the new block. The new predecessors are indicated by the 44654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// Preds array, which has NumPreds elements in it. The new block is given a 44754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// suffix of 'Suffix'. 44854b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner/// 4495c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree, 450301278719b67dcdd1159d9f91b4db5ef57f025c6Cameron Zwarich/// LoopInfo, and LCCSA but no other analyses. In particular, it does not 451301278719b67dcdd1159d9f91b4db5ef57f025c6Cameron Zwarich/// preserve LoopSimplify (because it's complicated to handle the case where one 452301278719b67dcdd1159d9f91b4db5ef57f025c6Cameron Zwarich/// of the edges being split is an exit of a loop with other exits). 4535c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman/// 45454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris LattnerBasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB, 4552fac1d5d61a83c45dcf44119c41dce15ef10e9dcJakub Staszak ArrayRef<BasicBlock*> Preds, 4562fac1d5d61a83c45dcf44119c41dce15ef10e9dcJakub Staszak const char *Suffix, Pass *P) { 45754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Create new basic block, insert right before the original block. 4581d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), BB->getName()+Suffix, 4591d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BB->getParent(), BB); 46054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 46154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // The new block unconditionally branches to the old block. 46254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner BranchInst *BI = BranchInst::Create(BB, NewBB); 46354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner 46454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Move the edges from Preds to point to NewBB instead of BB. 4652fac1d5d61a83c45dcf44119c41dce15ef10e9dcJakub Staszak for (unsigned i = 0, e = Preds.size(); i != e; ++i) { 466b8eb17c80793c33368e3c3af6de4bd8c1b09ba5bDan Gohman // This is slightly more strict than necessary; the minimum requirement 467b8eb17c80793c33368e3c3af6de4bd8c1b09ba5bDan Gohman // is that there be no more than one indirectbr branching to BB. And 468b8eb17c80793c33368e3c3af6de4bd8c1b09ba5bDan Gohman // all BlockAddress uses would need to be updated. 469b8eb17c80793c33368e3c3af6de4bd8c1b09ba5bDan Gohman assert(!isa<IndirectBrInst>(Preds[i]->getTerminator()) && 470b8eb17c80793c33368e3c3af6de4bd8c1b09ba5bDan Gohman "Cannot split an edge from an IndirectBrInst"); 47154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB); 4725c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman } 4735c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 47454b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI 47554b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // node becomes an incoming value for BB's phi node. However, if the Preds 47654b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // list is empty, we need to insert dummy entries into the PHI nodes in BB to 47754b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // account for the newly created predecessor. 4782fac1d5d61a83c45dcf44119c41dce15ef10e9dcJakub Staszak if (Preds.size() == 0) { 47954b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner // Insert dummy values as the incoming value. 48054b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I) 4819e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB); 48254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner return NewBB; 48354b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner } 4845c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 485a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling // Update DominatorTree, LoopInfo, and LCCSA analysis information. 486a644b33e8b9a45044dc531cfc1aac95fe7930605Bill Wendling bool HasLoopExit = false; 4872fac1d5d61a83c45dcf44119c41dce15ef10e9dcJakub Staszak UpdateAnalysisInformation(BB, NewBB, Preds, P, HasLoopExit); 4885c89b5240c90eb8171f999e5f06f815502d0321cDan Gohman 4891c44d869cd920f3c2d7fdc9196677db202440089Bill Wendling // Update the PHI nodes in BB with the values coming from NewBB. 4902fac1d5d61a83c45dcf44119c41dce15ef10e9dcJakub Staszak UpdatePHINodes(BB, NewBB, Preds, BI, P, HasLoopExit); 49154b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner return NewBB; 49254b9c3ba2a5b0aa8fda817bcc72c370040cfb3f8Chris Lattner} 49352c95856b4a40ccae6c4b0e13b2a04101e1f79c9Chris Lattner 4947e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// SplitLandingPadPredecessors - This method transforms the landing pad, 4957e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// OrigBB, by introducing two new basic blocks into the function. One of those 4967e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// new basic blocks gets the predecessors listed in Preds. The other basic 4977e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// block gets the remaining predecessors of OrigBB. The landingpad instruction 4987e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// OrigBB is clone into both of the new basic blocks. The new blocks are given 4997e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// the suffixes 'Suffix1' and 'Suffix2', and are returned in the NewBBs vector. 5007e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// 5017e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree, 5027e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses. In particular, 5037e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// it does not preserve LoopSimplify (because it's complicated to handle the 5047e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// case where one of the edges being split is an exit of a loop with other 5057e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// exits). 5067e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling/// 5077e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendlingvoid llvm::SplitLandingPadPredecessors(BasicBlock *OrigBB, 5087e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling ArrayRef<BasicBlock*> Preds, 5097e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling const char *Suffix1, const char *Suffix2, 5107e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling Pass *P, 5117e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling SmallVectorImpl<BasicBlock*> &NewBBs) { 5127e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling assert(OrigBB->isLandingPad() && "Trying to split a non-landing pad!"); 5137e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 5147e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // Create a new basic block for OrigBB's predecessors listed in Preds. Insert 5157e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // it right before the original block. 5167e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling BasicBlock *NewBB1 = BasicBlock::Create(OrigBB->getContext(), 5177e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling OrigBB->getName() + Suffix1, 5187e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling OrigBB->getParent(), OrigBB); 5197e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling NewBBs.push_back(NewBB1); 5207e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 5217e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // The new block unconditionally branches to the old block. 5227e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling BranchInst *BI1 = BranchInst::Create(OrigBB, NewBB1); 5237e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 5247e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // Move the edges from Preds to point to NewBB1 instead of OrigBB. 5257e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling for (unsigned i = 0, e = Preds.size(); i != e; ++i) { 5267e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // This is slightly more strict than necessary; the minimum requirement 5277e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // is that there be no more than one indirectbr branching to BB. And 5287e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // all BlockAddress uses would need to be updated. 5297e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling assert(!isa<IndirectBrInst>(Preds[i]->getTerminator()) && 5307e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling "Cannot split an edge from an IndirectBrInst"); 5317e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling Preds[i]->getTerminator()->replaceUsesOfWith(OrigBB, NewBB1); 5327e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling } 5337e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 5347e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // Update DominatorTree, LoopInfo, and LCCSA analysis information. 5357e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling bool HasLoopExit = false; 5367e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling UpdateAnalysisInformation(OrigBB, NewBB1, Preds, P, HasLoopExit); 5377e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 5387e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // Update the PHI nodes in OrigBB with the values coming from NewBB1. 5397e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling UpdatePHINodes(OrigBB, NewBB1, Preds, BI1, P, HasLoopExit); 5407e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 5417e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling // Move the remaining edges from OrigBB to point to NewBB2. 5427e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling SmallVector<BasicBlock*, 8> NewBB2Preds; 5437e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling for (pred_iterator i = pred_begin(OrigBB), e = pred_end(OrigBB); 5447e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling i != e; ) { 5457e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling BasicBlock *Pred = *i++; 54694657b964f90107989c61a63a214451c03922649Bill Wendling if (Pred == NewBB1) continue; 5477e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling assert(!isa<IndirectBrInst>(Pred->getTerminator()) && 5487e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling "Cannot split an edge from an IndirectBrInst"); 5497e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling NewBB2Preds.push_back(Pred); 5507e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling e = pred_end(OrigBB); 5517e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling } 5527e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 55394657b964f90107989c61a63a214451c03922649Bill Wendling BasicBlock *NewBB2 = 0; 55494657b964f90107989c61a63a214451c03922649Bill Wendling if (!NewBB2Preds.empty()) { 55594657b964f90107989c61a63a214451c03922649Bill Wendling // Create another basic block for the rest of OrigBB's predecessors. 55694657b964f90107989c61a63a214451c03922649Bill Wendling NewBB2 = BasicBlock::Create(OrigBB->getContext(), 55794657b964f90107989c61a63a214451c03922649Bill Wendling OrigBB->getName() + Suffix2, 55894657b964f90107989c61a63a214451c03922649Bill Wendling OrigBB->getParent(), OrigBB); 55994657b964f90107989c61a63a214451c03922649Bill Wendling NewBBs.push_back(NewBB2); 56094657b964f90107989c61a63a214451c03922649Bill Wendling 56194657b964f90107989c61a63a214451c03922649Bill Wendling // The new block unconditionally branches to the old block. 56294657b964f90107989c61a63a214451c03922649Bill Wendling BranchInst *BI2 = BranchInst::Create(OrigBB, NewBB2); 5637e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 56494657b964f90107989c61a63a214451c03922649Bill Wendling // Move the remaining edges from OrigBB to point to NewBB2. 56594657b964f90107989c61a63a214451c03922649Bill Wendling for (SmallVectorImpl<BasicBlock*>::iterator 56694657b964f90107989c61a63a214451c03922649Bill Wendling i = NewBB2Preds.begin(), e = NewBB2Preds.end(); i != e; ++i) 56794657b964f90107989c61a63a214451c03922649Bill Wendling (*i)->getTerminator()->replaceUsesOfWith(OrigBB, NewBB2); 56894657b964f90107989c61a63a214451c03922649Bill Wendling 56994657b964f90107989c61a63a214451c03922649Bill Wendling // Update DominatorTree, LoopInfo, and LCCSA analysis information. 57094657b964f90107989c61a63a214451c03922649Bill Wendling HasLoopExit = false; 57194657b964f90107989c61a63a214451c03922649Bill Wendling UpdateAnalysisInformation(OrigBB, NewBB2, NewBB2Preds, P, HasLoopExit); 57294657b964f90107989c61a63a214451c03922649Bill Wendling 57394657b964f90107989c61a63a214451c03922649Bill Wendling // Update the PHI nodes in OrigBB with the values coming from NewBB2. 57494657b964f90107989c61a63a214451c03922649Bill Wendling UpdatePHINodes(OrigBB, NewBB2, NewBB2Preds, BI2, P, HasLoopExit); 57594657b964f90107989c61a63a214451c03922649Bill Wendling } 5767e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 5777e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling LandingPadInst *LPad = OrigBB->getLandingPadInst(); 5787e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling Instruction *Clone1 = LPad->clone(); 5797e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling Clone1->setName(Twine("lpad") + Suffix1); 5807e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling NewBB1->getInstList().insert(NewBB1->getFirstInsertionPt(), Clone1); 5817e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 58294657b964f90107989c61a63a214451c03922649Bill Wendling if (NewBB2) { 58394657b964f90107989c61a63a214451c03922649Bill Wendling Instruction *Clone2 = LPad->clone(); 58494657b964f90107989c61a63a214451c03922649Bill Wendling Clone2->setName(Twine("lpad") + Suffix2); 58594657b964f90107989c61a63a214451c03922649Bill Wendling NewBB2->getInstList().insert(NewBB2->getFirstInsertionPt(), Clone2); 58694657b964f90107989c61a63a214451c03922649Bill Wendling 58794657b964f90107989c61a63a214451c03922649Bill Wendling // Create a PHI node for the two cloned landingpad instructions. 58894657b964f90107989c61a63a214451c03922649Bill Wendling PHINode *PN = PHINode::Create(LPad->getType(), 2, "lpad.phi", LPad); 58994657b964f90107989c61a63a214451c03922649Bill Wendling PN->addIncoming(Clone1, NewBB1); 59094657b964f90107989c61a63a214451c03922649Bill Wendling PN->addIncoming(Clone2, NewBB2); 59194657b964f90107989c61a63a214451c03922649Bill Wendling LPad->replaceAllUsesWith(PN); 59294657b964f90107989c61a63a214451c03922649Bill Wendling LPad->eraseFromParent(); 59394657b964f90107989c61a63a214451c03922649Bill Wendling } else { 59494657b964f90107989c61a63a214451c03922649Bill Wendling // There is no second clone. Just replace the landing pad with the first 59594657b964f90107989c61a63a214451c03922649Bill Wendling // clone. 59694657b964f90107989c61a63a214451c03922649Bill Wendling LPad->replaceAllUsesWith(Clone1); 59794657b964f90107989c61a63a214451c03922649Bill Wendling LPad->eraseFromParent(); 59894657b964f90107989c61a63a214451c03922649Bill Wendling } 5997e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling} 6007e8840c4d9ac7cc259fd967d9fe7540740d1ce92Bill Wendling 601fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// FindFunctionBackedges - Analyze the specified function to find all of the 602fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// loop backedges in the function and return them. This is a relatively cheap 603fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// (compared to computing dominators and loop info) analysis. 604fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// 605fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump/// The output is added to Result, as pairs of <from,to> edge info. 606fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stumpvoid llvm::FindFunctionBackedges(const Function &F, 607fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallVectorImpl<std::pair<const BasicBlock*,const BasicBlock*> > &Result) { 608fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump const BasicBlock *BB = &F.getEntryBlock(); 609fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (succ_begin(BB) == succ_end(BB)) 610fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump return; 611fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 612fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallPtrSet<const BasicBlock*, 8> Visited; 613fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallVector<std::pair<const BasicBlock*, succ_const_iterator>, 8> VisitStack; 614fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump SmallPtrSet<const BasicBlock*, 8> InStack; 615fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 616fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump Visited.insert(BB); 617fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump VisitStack.push_back(std::make_pair(BB, succ_begin(BB))); 618fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.insert(BB); 619fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump do { 620fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump std::pair<const BasicBlock*, succ_const_iterator> &Top = VisitStack.back(); 621fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump const BasicBlock *ParentBB = Top.first; 622fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump succ_const_iterator &I = Top.second; 623fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 624fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump bool FoundNew = false; 625fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump while (I != succ_end(ParentBB)) { 626fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump BB = *I++; 627fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (Visited.insert(BB)) { 628fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump FoundNew = true; 629fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump break; 630fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 631fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Successor is in VisitStack, it's a back edge. 632fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (InStack.count(BB)) 633fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump Result.push_back(std::make_pair(ParentBB, BB)); 634fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 635fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump 636fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump if (FoundNew) { 637fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Go down one level if there is a unvisited successor. 638fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.insert(BB); 639fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump VisitStack.push_back(std::make_pair(BB, succ_begin(BB))); 640fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } else { 641fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump // Go up one level. 642fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump InStack.erase(VisitStack.pop_back_val().first); 643fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump } 644c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng } while (!VisitStack.empty()); 645c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng} 646c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng 647c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng/// FoldReturnIntoUncondBranch - This method duplicates the specified return 648c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng/// instruction into a predecessor which ends in an unconditional branch. If 649c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng/// the return instruction returns a value defined by a PHI, propagate the 650c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng/// right value into the return. It returns the new return instruction in the 651c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng/// predecessor. 652c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan ChengReturnInst *llvm::FoldReturnIntoUncondBranch(ReturnInst *RI, BasicBlock *BB, 653c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng BasicBlock *Pred) { 654c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng Instruction *UncondBranch = Pred->getTerminator(); 655c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng // Clone the return and add it to the end of the predecessor. 656c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng Instruction *NewRet = RI->clone(); 657c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng Pred->getInstList().push_back(NewRet); 658c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng 659c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng // If the return instruction returns a value, and if the value was a 660c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng // PHI node in "BB", propagate the right value into the return. 661c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng for (User::op_iterator i = NewRet->op_begin(), e = NewRet->op_end(); 6629c777a484415198b3fb0dbeb57a594573b245152Evan Cheng i != e; ++i) { 6639c777a484415198b3fb0dbeb57a594573b245152Evan Cheng Value *V = *i; 6649c777a484415198b3fb0dbeb57a594573b245152Evan Cheng Instruction *NewBC = 0; 6659c777a484415198b3fb0dbeb57a594573b245152Evan Cheng if (BitCastInst *BCI = dyn_cast<BitCastInst>(V)) { 6669c777a484415198b3fb0dbeb57a594573b245152Evan Cheng // Return value might be bitcasted. Clone and insert it before the 6679c777a484415198b3fb0dbeb57a594573b245152Evan Cheng // return instruction. 6689c777a484415198b3fb0dbeb57a594573b245152Evan Cheng V = BCI->getOperand(0); 6699c777a484415198b3fb0dbeb57a594573b245152Evan Cheng NewBC = BCI->clone(); 6709c777a484415198b3fb0dbeb57a594573b245152Evan Cheng Pred->getInstList().insert(NewRet, NewBC); 6719c777a484415198b3fb0dbeb57a594573b245152Evan Cheng *i = NewBC; 6729c777a484415198b3fb0dbeb57a594573b245152Evan Cheng } 6739c777a484415198b3fb0dbeb57a594573b245152Evan Cheng if (PHINode *PN = dyn_cast<PHINode>(V)) { 6749c777a484415198b3fb0dbeb57a594573b245152Evan Cheng if (PN->getParent() == BB) { 6759c777a484415198b3fb0dbeb57a594573b245152Evan Cheng if (NewBC) 6769c777a484415198b3fb0dbeb57a594573b245152Evan Cheng NewBC->setOperand(0, PN->getIncomingValueForBlock(Pred)); 6779c777a484415198b3fb0dbeb57a594573b245152Evan Cheng else 6789c777a484415198b3fb0dbeb57a594573b245152Evan Cheng *i = PN->getIncomingValueForBlock(Pred); 6799c777a484415198b3fb0dbeb57a594573b245152Evan Cheng } 6809c777a484415198b3fb0dbeb57a594573b245152Evan Cheng } 6819c777a484415198b3fb0dbeb57a594573b245152Evan Cheng } 682c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng 683c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng // Update any PHI nodes in the returning block to realize that we no 684c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng // longer branch to them. 685c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng BB->removePredecessor(Pred); 686c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng UncondBranch->eraseFromParent(); 687c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng return cast<ReturnInst>(NewRet); 688fe095f39e7009c51d1c86769792ccbcad8cdd2ecMike Stump} 68940348e8d1ff564a23101d4fd37fe4dd03d9018abDevang Patel 690