PruneEH.cpp revision 94c22716d60ff5edf6a98a3c67e0faa001be1142
13e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner//===- PruneEH.cpp - Pass which deletes unused exception handlers ---------===// 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//===----------------------------------------------------------------------===// 93e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner// 103e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner// This file implements a simple interprocedural pass which walks the 1194c22716d60ff5edf6a98a3c67e0faa001be1142Sylvestre Ledru// call-graph, turning invoke instructions into calls, iff the callee cannot 12cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands// throw an exception, and marking functions 'nounwind' if they cannot throw. 13cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands// It implements this as a bottom-up traversal of the call-graph. 143e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner// 153e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner//===----------------------------------------------------------------------===// 163e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner 1786453c52ba02e743d29c08456e51006500041456Chris Lattner#define DEBUG_TYPE "prune-eh" 181e2385b941242f2f96398dc62767420622856149Chris Lattner#include "llvm/Transforms/IPO.h" 193e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner#include "llvm/CallGraphSCCPass.h" 20d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner#include "llvm/Constants.h" 213e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner#include "llvm/Function.h" 2214ce9ef2e9013ba56e1daafebd91fe3ee1e8647eOwen Anderson#include "llvm/LLVMContext.h" 2347b14a4a6a455c7be169cfd312fcbe796f0ad426Misha Brukman#include "llvm/Instructions.h" 241f67ce4aa3f65619f54c8a3072539da5b0022841Dale Johannesen#include "llvm/IntrinsicInst.h" 253e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner#include "llvm/Analysis/CallGraph.h" 266cccf03d02936e16319e7cebf7a158643a8b1040Duncan Sands#include "llvm/ADT/SmallPtrSet.h" 2793e985f1b17aef62d58e3198a4604f9f6cfe8d19Chris Lattner#include "llvm/ADT/SmallVector.h" 28551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/ADT/Statistic.h" 29d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner#include "llvm/Support/CFG.h" 30f26801b0e6ab958001f796fd42367e93e9feb96eChris Lattner#include <algorithm> 311e2385b941242f2f96398dc62767420622856149Chris Lattnerusing namespace llvm; 32d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 3386453c52ba02e743d29c08456e51006500041456Chris LattnerSTATISTIC(NumRemoved, "Number of invokes removed"); 3486453c52ba02e743d29c08456e51006500041456Chris LattnerSTATISTIC(NumUnreach, "Number of noreturn calls optimized"); 353e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner 3686453c52ba02e743d29c08456e51006500041456Chris Lattnernamespace { 376726b6d75a8b679068a58cb954ba97cf9d1690baNick Lewycky struct PruneEH : public CallGraphSCCPass { 38ecd94c804a563f2a86572dcf1d2e81f397e19daaNick Lewycky static char ID; // Pass identification, replacement for typeid 39081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson PruneEH() : CallGraphSCCPass(ID) { 40081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson initializePruneEHPass(*PassRegistry::getPassRegistry()); 41081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson } 42794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel 433e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner // runOnSCC - Analyze the SCC, performing the transformation if possible. 442decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner bool runOnSCC(CallGraphSCC &SCC); 45d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 46d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner bool SimplifyFunction(Function *F); 47d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner void DeleteBasicBlock(BasicBlock *BB); 483e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner }; 493e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner} 503e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner 51844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanchar PruneEH::ID = 0; 52ae0a7bc68303ce0c8721f0e981ae602601390e68Owen AndersonINITIALIZE_PASS_BEGIN(PruneEH, "prune-eh", 53ae0a7bc68303ce0c8721f0e981ae602601390e68Owen Anderson "Remove unused exception handling info", false, false) 54ae0a7bc68303ce0c8721f0e981ae602601390e68Owen AndersonINITIALIZE_AG_DEPENDENCY(CallGraph) 55ae0a7bc68303ce0c8721f0e981ae602601390e68Owen AndersonINITIALIZE_PASS_END(PruneEH, "prune-eh", 56ce665bd2e2b581ab0858d1afe359192bac96b868Owen Anderson "Remove unused exception handling info", false, false) 57844731a7f1909f55935e3514c9e713a62d67662eDan Gohman 58c71ca3cdd2d7a08b043ebb717cad0beadaf47450Devang PatelPass *llvm::createPruneEHPass() { return new PruneEH(); } 59f6fb96f5591de185f45ba8cd6ba3a3d98e04a86dChris Lattner 603e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner 612decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattnerbool PruneEH::runOnSCC(CallGraphSCC &SCC) { 626cccf03d02936e16319e7cebf7a158643a8b1040Duncan Sands SmallPtrSet<CallGraphNode *, 8> SCCNodes; 633e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner CallGraph &CG = getAnalysis<CallGraph>(); 64d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner bool MadeChange = false; 65d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 666cccf03d02936e16319e7cebf7a158643a8b1040Duncan Sands // Fill SCCNodes with the elements of the SCC. Used for quickly 676cccf03d02936e16319e7cebf7a158643a8b1040Duncan Sands // looking up whether a given CallGraphNode is in this SCC. 682decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) 692decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner SCCNodes.insert(*I); 706cccf03d02936e16319e7cebf7a158643a8b1040Duncan Sands 71d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner // First pass, scan all of the functions in the SCC, simplifying them 72d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner // according to what we know. 732decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) 742decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner if (Function *F = (*I)->getFunction()) 75d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner MadeChange |= SimplifyFunction(F); 763e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner 77d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner // Next, check to see if any callees might throw or if there are any external 783e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner // functions in this SCC: if so, we cannot prune any functions in this SCC. 796796629611a07bdc9d6bb79ca1cf6cae78325411Dale Johannesen // Definitions that are weak and not declared non-throwing might be 806796629611a07bdc9d6bb79ca1cf6cae78325411Dale Johannesen // overridden at linktime with something that throws, so assume that. 81ee5457cbe88b7f691f774de8515d9a94226d1b00Chris Lattner // If this SCC includes the unwind instruction, we KNOW it throws, so 823e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner // obviously the SCC might throw. 833e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner // 84d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner bool SCCMightUnwind = false, SCCMightReturn = false; 852decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); 862decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner (!SCCMightUnwind || !SCCMightReturn) && I != E; ++I) { 872decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner Function *F = (*I)->getFunction(); 881f7580c5ebfb3ab79c4be77cc5b85408bf3a8cf4Dale Johannesen if (F == 0) { 89bc9fa589efdfba8c86a8dee4f8e92b79025a7419Chris Lattner SCCMightUnwind = true; 90d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner SCCMightReturn = true; 915df3186f598163258fabf3448d9372843804d1abDuncan Sands } else if (F->isDeclaration() || F->mayBeOverridden()) { 922b0e8990ab33ec2dad21286d3ce01dbb4bbe63c1Duncan Sands SCCMightUnwind |= !F->doesNotThrow(); 932b0e8990ab33ec2dad21286d3ce01dbb4bbe63c1Duncan Sands SCCMightReturn |= !F->doesNotReturn(); 94d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner } else { 952b0e8990ab33ec2dad21286d3ce01dbb4bbe63c1Duncan Sands bool CheckUnwind = !SCCMightUnwind && !F->doesNotThrow(); 962b0e8990ab33ec2dad21286d3ce01dbb4bbe63c1Duncan Sands bool CheckReturn = !SCCMightReturn && !F->doesNotReturn(); 97cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 98cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands if (!CheckUnwind && !CheckReturn) 99cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands continue; 100d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 101d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner // Check to see if this function performs an unwind or calls an 102d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner // unwinding function. 103d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { 104aa5abe88d6aa445afa593476a665e3ab14b3524cBill Wendling if (CheckUnwind && isa<ResumeInst>(BB->getTerminator())) { 105bc4fcbbc7b61e21f154ec3a4687178ec20a5f09bBill Wendling // Uses unwind / resume! 106bc9fa589efdfba8c86a8dee4f8e92b79025a7419Chris Lattner SCCMightUnwind = true; 107cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands } else if (CheckReturn && isa<ReturnInst>(BB->getTerminator())) { 108d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner SCCMightReturn = true; 109d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner } 110e0def04e430d741daa48f69b05cfe132adb6db11Chris Lattner 111d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner // Invoke instructions don't allow unwinding to continue, so we are 112d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner // only interested in call instructions. 113cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands if (CheckUnwind && !SCCMightUnwind) 114d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 115d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner if (CallInst *CI = dyn_cast<CallInst>(I)) { 1162b0e8990ab33ec2dad21286d3ce01dbb4bbe63c1Duncan Sands if (CI->doesNotThrow()) { 117cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // This call cannot throw. 118cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands } else if (Function *Callee = CI->getCalledFunction()) { 119d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner CallGraphNode *CalleeNode = CG[Callee]; 120cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // If the callee is outside our current SCC then we may 121cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // throw because it might. 1226cccf03d02936e16319e7cebf7a158643a8b1040Duncan Sands if (!SCCNodes.count(CalleeNode)) { 123d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner SCCMightUnwind = true; 124d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner break; 125d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner } 126d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner } else { 127d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner // Indirect call, it might throw. 128bc9fa589efdfba8c86a8dee4f8e92b79025a7419Chris Lattner SCCMightUnwind = true; 129e0def04e430d741daa48f69b05cfe132adb6db11Chris Lattner break; 130e0def04e430d741daa48f69b05cfe132adb6db11Chris Lattner } 131e0def04e430d741daa48f69b05cfe132adb6db11Chris Lattner } 132d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner if (SCCMightUnwind && SCCMightReturn) break; 133ad9b5f31eaa739940c9ec540cc231afb99343304Chris Lattner } 134d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner } 135d08ddd3300d5244012c1765d34b21cc9e11a80adChris Lattner } 1363e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner 137d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner // If the SCC doesn't unwind or doesn't throw, note this fact. 138cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands if (!SCCMightUnwind || !SCCMightReturn) 1392decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { 1400598866c052147c31b808391f58434ce3dbfb838Devang Patel Attributes NewAttributes = Attribute::None; 141cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 142cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands if (!SCCMightUnwind) 1430598866c052147c31b808391f58434ce3dbfb838Devang Patel NewAttributes |= Attribute::NoUnwind; 144cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands if (!SCCMightReturn) 1450598866c052147c31b808391f58434ce3dbfb838Devang Patel NewAttributes |= Attribute::NoReturn; 146cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 1472decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner Function *F = (*I)->getFunction(); 1482decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner const AttrListPtr &PAL = F->getAttributes(); 14919c874638d9478a5d5028854817a5ee72293bb2bDevang Patel const AttrListPtr &NPAL = PAL.addAttr(~0, NewAttributes); 150cae62e34984e413414304eab959797ec5c2cbf32Duncan Sands if (PAL != NPAL) { 151cae62e34984e413414304eab959797ec5c2cbf32Duncan Sands MadeChange = true; 1522decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner F->setAttributes(NPAL); 153cae62e34984e413414304eab959797ec5c2cbf32Duncan Sands } 154cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands } 1553e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner 1562decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { 1573e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner // Convert any invoke instructions to non-throwing functions in this node 1583e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner // into call instructions with a branch. This makes the exception blocks 1593e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner // dead. 1602decb22222cac46bb1d9163e7b89d7e5be8ef65fChris Lattner if (Function *F = (*I)->getFunction()) 161d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner MadeChange |= SimplifyFunction(F); 1623e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner } 1633e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner 164fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman return MadeChange; 1653e64b2e1a44b0bef896d645e9b293ab84dc16ab8Chris Lattner} 166d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 167d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 168d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner// SimplifyFunction - Given information about callees, simplify the specified 169d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner// function if we have invokes to non-unwinding functions or code after calls to 170d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner// no-return functions. 171d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattnerbool PruneEH::SimplifyFunction(Function *F) { 172d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner bool MadeChange = false; 173d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { 174d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) 1752b0e8990ab33ec2dad21286d3ce01dbb4bbe63c1Duncan Sands if (II->doesNotThrow()) { 176c9f7500d1752feac7cece26d20007a99d21f677cGabor Greif SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3); 177cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // Insert a call instruction before the invoke. 178a3efbb15ddd5aa9006564cd79086723640084878Jay Foad CallInst *Call = CallInst::Create(II->getCalledValue(), Args, "", II); 179cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands Call->takeName(II); 180cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands Call->setCallingConv(II->getCallingConv()); 1810598866c052147c31b808391f58434ce3dbfb838Devang Patel Call->setAttributes(II->getAttributes()); 18265a2f77b0e155f7f1b0a31b0bc9f683b441bc8e2Devang Patel Call->setDebugLoc(II->getDebugLoc()); 183cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 184cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // Anything that used the value produced by the invoke instruction 185a541b0fde2ab6b8b037edf113d42da41a2c5aae9Chris Lattner // now uses the value produced by the call instruction. Note that we 186a541b0fde2ab6b8b037edf113d42da41a2c5aae9Chris Lattner // do this even for void functions and calls with no uses so that the 187a541b0fde2ab6b8b037edf113d42da41a2c5aae9Chris Lattner // callgraph edge is updated. 188cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands II->replaceAllUsesWith(Call); 189cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands BasicBlock *UnwindBlock = II->getUnwindDest(); 190cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands UnwindBlock->removePredecessor(II->getParent()); 191cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 192cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // Insert a branch to the normal destination right before the 193cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // invoke. 194051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(II->getNormalDest(), II); 195cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 196cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // Finally, delete the invoke instruction! 197cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands BB->getInstList().pop_back(); 198cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 199cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // If the unwind block is now dead, nuke it. 200cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands if (pred_begin(UnwindBlock) == pred_end(UnwindBlock)) 201cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands DeleteBasicBlock(UnwindBlock); // Delete the new BB. 202cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 203cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands ++NumRemoved; 204cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands MadeChange = true; 205f336983bbcdc21fba7dcc02f4f6cfc06341b1e6dNick Lewycky } 206d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 207cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) 208280a6e607d8eb7401749a92db624a82de47da777Nick Lewycky if (CallInst *CI = dyn_cast<CallInst>(I++)) 2092b0e8990ab33ec2dad21286d3ce01dbb4bbe63c1Duncan Sands if (CI->doesNotReturn() && !isa<UnreachableInst>(I)) { 210cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // This call calls a function that cannot return. Insert an 211cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // unreachable instruction after it and simplify the code. Do this 212cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // by splitting the BB, adding the unreachable, then deleting the 213cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // new BB. 214cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands BasicBlock *New = BB->splitBasicBlock(I); 215cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands 216cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands // Remove the uncond branch and add an unreachable. 217cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands BB->getInstList().pop_back(); 2181d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson new UnreachableInst(BB->getContext(), BB); 21900b16889ab461b7ecef1c91ade101186b7f1fce2Jeff Cohen 220cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands DeleteBasicBlock(New); // Delete the new BB. 221d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner MadeChange = true; 222cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands ++NumUnreach; 223cbb8badce8838ece47cb806a0399c77d76a7e11bDuncan Sands break; 2243c4a26226f30f2e9a022d155586e660af38aba1fNick Lewycky } 225d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner } 226280a6e607d8eb7401749a92db624a82de47da777Nick Lewycky 227d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner return MadeChange; 228d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner} 229d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 230d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner/// DeleteBasicBlock - remove the specified basic block from the program, 231d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner/// updating the callgraph to reflect any now-obsolete edges due to calls that 232d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner/// exist in the BB. 233d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattnervoid PruneEH::DeleteBasicBlock(BasicBlock *BB) { 234d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner assert(pred_begin(BB) == pred_end(BB) && "BB is not dead!"); 235d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner CallGraph &CG = getAnalysis<CallGraph>(); 236d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 237d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner CallGraphNode *CGN = CG[BB->getParent()]; 238d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; ) { 239d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner --I; 2401f67ce4aa3f65619f54c8a3072539da5b0022841Dale Johannesen if (CallInst *CI = dyn_cast<CallInst>(I)) { 241ca5bec22e0e04d0712f5ac78fc6aeceabcf80955John McCall if (!isa<IntrinsicInst>(I)) 2421f67ce4aa3f65619f54c8a3072539da5b0022841Dale Johannesen CGN->removeCallEdgeFor(CI); 2431f67ce4aa3f65619f54c8a3072539da5b0022841Dale Johannesen } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 244d7b9851c4e634ed3599b1a4c70b1c76c90a11686Duncan Sands CGN->removeCallEdgeFor(II); 245d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner if (!I->use_empty()) 2469e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson I->replaceAllUsesWith(UndefValue::get(I->getType())); 247d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner } 248d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 249d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner // Get the list of successors of this block. 250d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner std::vector<BasicBlock*> Succs(succ_begin(BB), succ_end(BB)); 251d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner 252d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner for (unsigned i = 0, e = Succs.size(); i != e; ++i) 253d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner Succs[i]->removePredecessor(BB); 25400b16889ab461b7ecef1c91ade101186b7f1fce2Jeff Cohen 255d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner BB->eraseFromParent(); 256d651f441ae4c5a9e2c77a9a38604f83d0d4261eaChris Lattner} 257