1 //===- MemoryLocation.cpp - Memory location descriptions -------------------==// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "llvm/Analysis/MemoryLocation.h" 10 #include "llvm/Analysis/TargetLibraryInfo.h" 11 #include "llvm/IR/BasicBlock.h" 12 #include "llvm/IR/DataLayout.h" 13 #include "llvm/IR/Instructions.h" 14 #include "llvm/IR/IntrinsicInst.h" 15 #include "llvm/IR/IntrinsicsARM.h" 16 #include "llvm/IR/LLVMContext.h" 17 #include "llvm/IR/Module.h" 18 #include "llvm/IR/Type.h" 19 using namespace llvm; 20 21 void LocationSize::print(raw_ostream &OS) const { 22 OS << "LocationSize::"; 23 if (*this == beforeOrAfterPointer()) 24 OS << "beforeOrAfterPointer"; 25 else if (*this == afterPointer()) 26 OS << "afterPointer"; 27 else if (*this == mapEmpty()) 28 OS << "mapEmpty"; 29 else if (*this == mapTombstone()) 30 OS << "mapTombstone"; 31 else if (isPrecise()) 32 OS << "precise(" << getValue() << ')'; 33 else 34 OS << "upperBound(" << getValue() << ')'; 35 } 36 37 MemoryLocation MemoryLocation::get(const LoadInst *LI) { 38 const auto &DL = LI->getModule()->getDataLayout(); 39 40 return MemoryLocation( 41 LI->getPointerOperand(), 42 LocationSize::precise(DL.getTypeStoreSize(LI->getType())), 43 LI->getAAMetadata()); 44 } 45 46 MemoryLocation MemoryLocation::get(const StoreInst *SI) { 47 const auto &DL = SI->getModule()->getDataLayout(); 48 49 return MemoryLocation(SI->getPointerOperand(), 50 LocationSize::precise(DL.getTypeStoreSize( 51 SI->getValueOperand()->getType())), 52 SI->getAAMetadata()); 53 } 54 55 MemoryLocation MemoryLocation::get(const VAArgInst *VI) { 56 return MemoryLocation(VI->getPointerOperand(), 57 LocationSize::afterPointer(), VI->getAAMetadata()); 58 } 59 60 MemoryLocation MemoryLocation::get(const AtomicCmpXchgInst *CXI) { 61 const auto &DL = CXI->getModule()->getDataLayout(); 62 63 return MemoryLocation(CXI->getPointerOperand(), 64 LocationSize::precise(DL.getTypeStoreSize( 65 CXI->getCompareOperand()->getType())), 66 CXI->getAAMetadata()); 67 } 68 69 MemoryLocation MemoryLocation::get(const AtomicRMWInst *RMWI) { 70 const auto &DL = RMWI->getModule()->getDataLayout(); 71 72 return MemoryLocation(RMWI->getPointerOperand(), 73 LocationSize::precise(DL.getTypeStoreSize( 74 RMWI->getValOperand()->getType())), 75 RMWI->getAAMetadata()); 76 } 77 78 Optional<MemoryLocation> MemoryLocation::getOrNone(const Instruction *Inst) { 79 switch (Inst->getOpcode()) { 80 case Instruction::Load: 81 return get(cast<LoadInst>(Inst)); 82 case Instruction::Store: 83 return get(cast<StoreInst>(Inst)); 84 case Instruction::VAArg: 85 return get(cast<VAArgInst>(Inst)); 86 case Instruction::AtomicCmpXchg: 87 return get(cast<AtomicCmpXchgInst>(Inst)); 88 case Instruction::AtomicRMW: 89 return get(cast<AtomicRMWInst>(Inst)); 90 default: 91 return None; 92 } 93 } 94 95 MemoryLocation MemoryLocation::getForSource(const MemTransferInst *MTI) { 96 return getForSource(cast<AnyMemTransferInst>(MTI)); 97 } 98 99 MemoryLocation MemoryLocation::getForSource(const AtomicMemTransferInst *MTI) { 100 return getForSource(cast<AnyMemTransferInst>(MTI)); 101 } 102 103 MemoryLocation MemoryLocation::getForSource(const AnyMemTransferInst *MTI) { 104 auto Size = LocationSize::afterPointer(); 105 if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength())) 106 Size = LocationSize::precise(C->getValue().getZExtValue()); 107 108 // memcpy/memmove can have AA tags. For memcpy, they apply 109 // to both the source and the destination. 110 return MemoryLocation(MTI->getRawSource(), Size, MTI->getAAMetadata()); 111 } 112 113 MemoryLocation MemoryLocation::getForDest(const MemIntrinsic *MI) { 114 return getForDest(cast<AnyMemIntrinsic>(MI)); 115 } 116 117 MemoryLocation MemoryLocation::getForDest(const AtomicMemIntrinsic *MI) { 118 return getForDest(cast<AnyMemIntrinsic>(MI)); 119 } 120 121 MemoryLocation MemoryLocation::getForDest(const AnyMemIntrinsic *MI) { 122 auto Size = LocationSize::afterPointer(); 123 if (ConstantInt *C = dyn_cast<ConstantInt>(MI->getLength())) 124 Size = LocationSize::precise(C->getValue().getZExtValue()); 125 126 // memcpy/memmove can have AA tags. For memcpy, they apply 127 // to both the source and the destination. 128 return MemoryLocation(MI->getRawDest(), Size, MI->getAAMetadata()); 129 } 130 131 Optional<MemoryLocation> 132 MemoryLocation::getForDest(const CallBase *CB, const TargetLibraryInfo &TLI) { 133 if (auto *MemInst = dyn_cast<AnyMemIntrinsic>(CB)) 134 return getForDest(MemInst); 135 136 LibFunc LF; 137 if (TLI.getLibFunc(*CB, LF) && TLI.has(LF)) { 138 switch (LF) { 139 case LibFunc_strncpy: 140 case LibFunc_strcpy: 141 case LibFunc_strcat: 142 case LibFunc_strncat: 143 return getForArgument(CB, 0, &TLI); 144 default: 145 break; 146 } 147 } 148 149 return {}; 150 } 151 152 MemoryLocation MemoryLocation::getForArgument(const CallBase *Call, 153 unsigned ArgIdx, 154 const TargetLibraryInfo *TLI) { 155 AAMDNodes AATags = Call->getAAMetadata(); 156 const Value *Arg = Call->getArgOperand(ArgIdx); 157 158 // We may be able to produce an exact size for known intrinsics. 159 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Call)) { 160 const DataLayout &DL = II->getModule()->getDataLayout(); 161 162 switch (II->getIntrinsicID()) { 163 default: 164 break; 165 case Intrinsic::memset: 166 case Intrinsic::memcpy: 167 case Intrinsic::memcpy_inline: 168 case Intrinsic::memmove: 169 assert((ArgIdx == 0 || ArgIdx == 1) && 170 "Invalid argument index for memory intrinsic"); 171 if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getArgOperand(2))) 172 return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()), 173 AATags); 174 return MemoryLocation::getAfter(Arg, AATags); 175 176 case Intrinsic::lifetime_start: 177 case Intrinsic::lifetime_end: 178 case Intrinsic::invariant_start: 179 assert(ArgIdx == 1 && "Invalid argument index"); 180 return MemoryLocation( 181 Arg, 182 LocationSize::precise( 183 cast<ConstantInt>(II->getArgOperand(0))->getZExtValue()), 184 AATags); 185 186 case Intrinsic::masked_load: 187 assert(ArgIdx == 0 && "Invalid argument index"); 188 return MemoryLocation( 189 Arg, 190 LocationSize::upperBound(DL.getTypeStoreSize(II->getType())), 191 AATags); 192 193 case Intrinsic::masked_store: 194 assert(ArgIdx == 1 && "Invalid argument index"); 195 return MemoryLocation( 196 Arg, 197 LocationSize::upperBound( 198 DL.getTypeStoreSize(II->getArgOperand(0)->getType())), 199 AATags); 200 201 case Intrinsic::invariant_end: 202 // The first argument to an invariant.end is a "descriptor" type (e.g. a 203 // pointer to a empty struct) which is never actually dereferenced. 204 if (ArgIdx == 0) 205 return MemoryLocation(Arg, LocationSize::precise(0), AATags); 206 assert(ArgIdx == 2 && "Invalid argument index"); 207 return MemoryLocation( 208 Arg, 209 LocationSize::precise( 210 cast<ConstantInt>(II->getArgOperand(1))->getZExtValue()), 211 AATags); 212 213 case Intrinsic::arm_neon_vld1: 214 assert(ArgIdx == 0 && "Invalid argument index"); 215 // LLVM's vld1 and vst1 intrinsics currently only support a single 216 // vector register. 217 return MemoryLocation( 218 Arg, LocationSize::precise(DL.getTypeStoreSize(II->getType())), 219 AATags); 220 221 case Intrinsic::arm_neon_vst1: 222 assert(ArgIdx == 0 && "Invalid argument index"); 223 return MemoryLocation(Arg, 224 LocationSize::precise(DL.getTypeStoreSize( 225 II->getArgOperand(1)->getType())), 226 AATags); 227 } 228 } 229 230 // We can bound the aliasing properties of memset_pattern16 just as we can 231 // for memcpy/memset. This is particularly important because the 232 // LoopIdiomRecognizer likes to turn loops into calls to memset_pattern16 233 // whenever possible. 234 LibFunc F; 235 if (TLI && TLI->getLibFunc(*Call, F) && TLI->has(F)) { 236 switch (F) { 237 case LibFunc_strcpy: 238 case LibFunc_strcat: 239 case LibFunc_strncat: 240 assert((ArgIdx == 0 || ArgIdx == 1) && "Invalid argument index for str function"); 241 return MemoryLocation::getAfter(Arg, AATags); 242 243 case LibFunc_memset_chk: { 244 assert(ArgIdx == 0 && "Invalid argument index for memset_chk"); 245 LocationSize Size = LocationSize::afterPointer(); 246 if (const auto *Len = dyn_cast<ConstantInt>(Call->getArgOperand(2))) { 247 // memset_chk writes at most Len bytes. It may write less, if Len 248 // exceeds the specified max size and aborts. 249 Size = LocationSize::upperBound(Len->getZExtValue()); 250 } 251 return MemoryLocation(Arg, Size, AATags); 252 } 253 case LibFunc_strncpy: { 254 assert((ArgIdx == 0 || ArgIdx == 1) && 255 "Invalid argument index for strncpy"); 256 LocationSize Size = LocationSize::afterPointer(); 257 if (const auto *Len = dyn_cast<ConstantInt>(Call->getArgOperand(2))) { 258 // strncpy is guaranteed to write Len bytes, but only reads up to Len 259 // bytes. 260 Size = ArgIdx == 0 ? LocationSize::precise(Len->getZExtValue()) 261 : LocationSize::upperBound(Len->getZExtValue()); 262 } 263 return MemoryLocation(Arg, Size, AATags); 264 } 265 case LibFunc_memset_pattern16: 266 assert((ArgIdx == 0 || ArgIdx == 1) && 267 "Invalid argument index for memset_pattern16"); 268 if (ArgIdx == 1) 269 return MemoryLocation(Arg, LocationSize::precise(16), AATags); 270 if (const ConstantInt *LenCI = 271 dyn_cast<ConstantInt>(Call->getArgOperand(2))) 272 return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()), 273 AATags); 274 return MemoryLocation::getAfter(Arg, AATags); 275 case LibFunc_bcmp: 276 case LibFunc_memcmp: 277 assert((ArgIdx == 0 || ArgIdx == 1) && 278 "Invalid argument index for memcmp/bcmp"); 279 if (const ConstantInt *LenCI = 280 dyn_cast<ConstantInt>(Call->getArgOperand(2))) 281 return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()), 282 AATags); 283 return MemoryLocation::getAfter(Arg, AATags); 284 case LibFunc_memchr: 285 assert((ArgIdx == 0) && "Invalid argument index for memchr"); 286 if (const ConstantInt *LenCI = 287 dyn_cast<ConstantInt>(Call->getArgOperand(2))) 288 return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()), 289 AATags); 290 return MemoryLocation::getAfter(Arg, AATags); 291 case LibFunc_memccpy: 292 assert((ArgIdx == 0 || ArgIdx == 1) && 293 "Invalid argument index for memccpy"); 294 // We only know an upper bound on the number of bytes read/written. 295 if (const ConstantInt *LenCI = 296 dyn_cast<ConstantInt>(Call->getArgOperand(3))) 297 return MemoryLocation( 298 Arg, LocationSize::upperBound(LenCI->getZExtValue()), AATags); 299 return MemoryLocation::getAfter(Arg, AATags); 300 default: 301 break; 302 }; 303 } 304 // FIXME: Handle memset_pattern4 and memset_pattern8 also. 305 306 return MemoryLocation::getBeforeOrAfter(Call->getArgOperand(ArgIdx), AATags); 307 } 308