1 //===-- llvm/IR/Statepoint.h - gc.statepoint utilities ------ --*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file contains utility functions and a wrapper class analogous to 11 // CallSite for accessing the fields of gc.statepoint, gc.relocate, and 12 // gc.result intrinsics 13 // 14 //===----------------------------------------------------------------------===// 15 16 #ifndef LLVM_IR_STATEPOINT_H 17 #define LLVM_IR_STATEPOINT_H 18 19 #include "llvm/ADT/iterator_range.h" 20 #include "llvm/IR/BasicBlock.h" 21 #include "llvm/IR/CallSite.h" 22 #include "llvm/IR/Constants.h" 23 #include "llvm/IR/Function.h" 24 #include "llvm/IR/Instructions.h" 25 #include "llvm/IR/Intrinsics.h" 26 #include "llvm/Support/Compiler.h" 27 28 namespace llvm { 29 /// The statepoint intrinsic accepts a set of flags as its third argument. 30 /// Valid values come out of this set. 31 enum class StatepointFlags { 32 None = 0, 33 GCTransition = 1, ///< Indicates that this statepoint is a transition from 34 ///< GC-aware code to code that is not GC-aware. 35 36 MaskAll = GCTransition ///< A bitmask that includes all valid flags. 37 }; 38 39 class GCRelocateOperands; 40 class ImmutableStatepoint; 41 42 bool isStatepoint(const ImmutableCallSite &CS); 43 bool isStatepoint(const Value *V); 44 bool isStatepoint(const Value &V); 45 46 bool isGCRelocate(const Value *V); 47 bool isGCRelocate(const ImmutableCallSite &CS); 48 49 bool isGCResult(const Value *V); 50 bool isGCResult(const ImmutableCallSite &CS); 51 52 /// Analogous to CallSiteBase, this provides most of the actual 53 /// functionality for Statepoint and ImmutableStatepoint. It is 54 /// templatized to allow easily specializing of const and non-const 55 /// concrete subtypes. This is structured analogous to CallSite 56 /// rather than the IntrinsicInst.h helpers since we want to support 57 /// invokable statepoints in the near future. 58 template <typename FunTy, typename InstructionTy, typename ValueTy, 59 typename CallSiteTy> 60 class StatepointBase { 61 CallSiteTy StatepointCS; 62 void *operator new(size_t, unsigned) = delete; 63 void *operator new(size_t s) = delete; 64 65 protected: 66 explicit StatepointBase(InstructionTy *I) { 67 if (isStatepoint(I)) { 68 StatepointCS = CallSiteTy(I); 69 assert(StatepointCS && "isStatepoint implies CallSite"); 70 } 71 } 72 explicit StatepointBase(CallSiteTy CS) { 73 if (isStatepoint(CS)) 74 StatepointCS = CS; 75 } 76 77 public: 78 typedef typename CallSiteTy::arg_iterator arg_iterator; 79 80 enum { 81 IDPos = 0, 82 NumPatchBytesPos = 1, 83 CalledFunctionPos = 2, 84 NumCallArgsPos = 3, 85 FlagsPos = 4, 86 CallArgsBeginPos = 5, 87 }; 88 89 explicit operator bool() const { 90 // We do not assign non-statepoint CallSites to StatepointCS. 91 return (bool)StatepointCS; 92 } 93 94 /// Return the underlying CallSite. 95 CallSiteTy getCallSite() const { 96 assert(*this && "check validity first!"); 97 return StatepointCS; 98 } 99 100 uint64_t getFlags() const { 101 return cast<ConstantInt>(getCallSite().getArgument(FlagsPos)) 102 ->getZExtValue(); 103 } 104 105 /// Return the ID associated with this statepoint. 106 uint64_t getID() const { 107 const Value *IDVal = getCallSite().getArgument(IDPos); 108 return cast<ConstantInt>(IDVal)->getZExtValue(); 109 } 110 111 /// Return the number of patchable bytes associated with this statepoint. 112 uint32_t getNumPatchBytes() const { 113 const Value *NumPatchBytesVal = getCallSite().getArgument(NumPatchBytesPos); 114 uint64_t NumPatchBytes = 115 cast<ConstantInt>(NumPatchBytesVal)->getZExtValue(); 116 assert(isInt<32>(NumPatchBytes) && "should fit in 32 bits!"); 117 return NumPatchBytes; 118 } 119 120 /// Return the value actually being called or invoked. 121 ValueTy *getCalledValue() const { 122 return getCallSite().getArgument(CalledFunctionPos); 123 } 124 125 InstructionTy *getInstruction() const { 126 return getCallSite().getInstruction(); 127 } 128 129 /// Return the function being called if this is a direct call, otherwise 130 /// return null (if it's an indirect call). 131 FunTy *getCalledFunction() const { 132 return dyn_cast<Function>(getCalledValue()); 133 } 134 135 /// Return the caller function for this statepoint. 136 FunTy *getCaller() const { return getCallSite().getCaller(); } 137 138 /// Determine if the statepoint cannot unwind. 139 bool doesNotThrow() const { 140 Function *F = getCalledFunction(); 141 return getCallSite().doesNotThrow() || (F ? F->doesNotThrow() : false); 142 } 143 144 /// Return the type of the value returned by the call underlying the 145 /// statepoint. 146 Type *getActualReturnType() const { 147 auto *FTy = cast<FunctionType>( 148 cast<PointerType>(getCalledValue()->getType())->getElementType()); 149 return FTy->getReturnType(); 150 } 151 152 /// Number of arguments to be passed to the actual callee. 153 int getNumCallArgs() const { 154 const Value *NumCallArgsVal = getCallSite().getArgument(NumCallArgsPos); 155 return cast<ConstantInt>(NumCallArgsVal)->getZExtValue(); 156 } 157 158 size_t arg_size() const { return getNumCallArgs(); } 159 typename CallSiteTy::arg_iterator arg_begin() const { 160 assert(CallArgsBeginPos <= (int)getCallSite().arg_size()); 161 return getCallSite().arg_begin() + CallArgsBeginPos; 162 } 163 typename CallSiteTy::arg_iterator arg_end() const { 164 auto I = arg_begin() + arg_size(); 165 assert((getCallSite().arg_end() - I) >= 0); 166 return I; 167 } 168 169 ValueTy *getArgument(unsigned Index) { 170 assert(Index < arg_size() && "out of bounds!"); 171 return *(arg_begin() + Index); 172 } 173 174 /// range adapter for call arguments 175 iterator_range<arg_iterator> call_args() const { 176 return make_range(arg_begin(), arg_end()); 177 } 178 179 /// \brief Return true if the call or the callee has the given attribute. 180 bool paramHasAttr(unsigned i, Attribute::AttrKind A) const { 181 Function *F = getCalledFunction(); 182 return getCallSite().paramHasAttr(i + CallArgsBeginPos, A) || 183 (F ? F->getAttributes().hasAttribute(i, A) : false); 184 } 185 186 /// Number of GC transition args. 187 int getNumTotalGCTransitionArgs() const { 188 const Value *NumGCTransitionArgs = *arg_end(); 189 return cast<ConstantInt>(NumGCTransitionArgs)->getZExtValue(); 190 } 191 typename CallSiteTy::arg_iterator gc_transition_args_begin() const { 192 auto I = arg_end() + 1; 193 assert((getCallSite().arg_end() - I) >= 0); 194 return I; 195 } 196 typename CallSiteTy::arg_iterator gc_transition_args_end() const { 197 auto I = gc_transition_args_begin() + getNumTotalGCTransitionArgs(); 198 assert((getCallSite().arg_end() - I) >= 0); 199 return I; 200 } 201 202 /// range adapter for GC transition arguments 203 iterator_range<arg_iterator> gc_transition_args() const { 204 return make_range(gc_transition_args_begin(), gc_transition_args_end()); 205 } 206 207 /// Number of additional arguments excluding those intended 208 /// for garbage collection. 209 int getNumTotalVMSArgs() const { 210 const Value *NumVMSArgs = *gc_transition_args_end(); 211 return cast<ConstantInt>(NumVMSArgs)->getZExtValue(); 212 } 213 214 typename CallSiteTy::arg_iterator vm_state_begin() const { 215 auto I = gc_transition_args_end() + 1; 216 assert((getCallSite().arg_end() - I) >= 0); 217 return I; 218 } 219 typename CallSiteTy::arg_iterator vm_state_end() const { 220 auto I = vm_state_begin() + getNumTotalVMSArgs(); 221 assert((getCallSite().arg_end() - I) >= 0); 222 return I; 223 } 224 225 /// range adapter for vm state arguments 226 iterator_range<arg_iterator> vm_state_args() const { 227 return make_range(vm_state_begin(), vm_state_end()); 228 } 229 230 typename CallSiteTy::arg_iterator gc_args_begin() const { 231 return vm_state_end(); 232 } 233 typename CallSiteTy::arg_iterator gc_args_end() const { 234 return getCallSite().arg_end(); 235 } 236 237 unsigned gcArgsStartIdx() const { 238 return gc_args_begin() - getInstruction()->op_begin(); 239 } 240 241 /// range adapter for gc arguments 242 iterator_range<arg_iterator> gc_args() const { 243 return make_range(gc_args_begin(), gc_args_end()); 244 } 245 246 /// Get list of all gc reloactes linked to this statepoint 247 /// May contain several relocations for the same base/derived pair. 248 /// For example this could happen due to relocations on unwinding 249 /// path of invoke. 250 std::vector<GCRelocateOperands> getRelocates() const; 251 252 /// Get the experimental_gc_result call tied to this statepoint. Can be 253 /// nullptr if there isn't a gc_result tied to this statepoint. Guaranteed to 254 /// be a CallInst if non-null. 255 InstructionTy *getGCResult() const { 256 for (auto *U : getInstruction()->users()) 257 if (isGCResult(U)) 258 return cast<CallInst>(U); 259 260 return nullptr; 261 } 262 263 #ifndef NDEBUG 264 /// Asserts if this statepoint is malformed. Common cases for failure 265 /// include incorrect length prefixes for variable length sections or 266 /// illegal values for parameters. 267 void verify() { 268 assert(getNumCallArgs() >= 0 && 269 "number of arguments to actually callee can't be negative"); 270 271 // The internal asserts in the iterator accessors do the rest. 272 (void)arg_begin(); 273 (void)arg_end(); 274 (void)gc_transition_args_begin(); 275 (void)gc_transition_args_end(); 276 (void)vm_state_begin(); 277 (void)vm_state_end(); 278 (void)gc_args_begin(); 279 (void)gc_args_end(); 280 } 281 #endif 282 }; 283 284 /// A specialization of it's base class for read only access 285 /// to a gc.statepoint. 286 class ImmutableStatepoint 287 : public StatepointBase<const Function, const Instruction, const Value, 288 ImmutableCallSite> { 289 typedef StatepointBase<const Function, const Instruction, const Value, 290 ImmutableCallSite> Base; 291 292 public: 293 explicit ImmutableStatepoint(const Instruction *I) : Base(I) {} 294 explicit ImmutableStatepoint(ImmutableCallSite CS) : Base(CS) {} 295 }; 296 297 /// A specialization of it's base class for read-write access 298 /// to a gc.statepoint. 299 class Statepoint 300 : public StatepointBase<Function, Instruction, Value, CallSite> { 301 typedef StatepointBase<Function, Instruction, Value, CallSite> Base; 302 303 public: 304 explicit Statepoint(Instruction *I) : Base(I) {} 305 explicit Statepoint(CallSite CS) : Base(CS) {} 306 }; 307 308 /// Wraps a call to a gc.relocate and provides access to it's operands. 309 /// TODO: This should likely be refactored to resememble the wrappers in 310 /// InstrinsicInst.h. 311 class GCRelocateOperands { 312 ImmutableCallSite RelocateCS; 313 314 public: 315 GCRelocateOperands(const User *U) : RelocateCS(U) { assert(isGCRelocate(U)); } 316 GCRelocateOperands(const Instruction *inst) : RelocateCS(inst) { 317 assert(isGCRelocate(inst)); 318 } 319 GCRelocateOperands(CallSite CS) : RelocateCS(CS) { assert(isGCRelocate(CS)); } 320 321 /// Return true if this relocate is tied to the invoke statepoint. 322 /// This includes relocates which are on the unwinding path. 323 bool isTiedToInvoke() const { 324 const Value *Token = RelocateCS.getArgument(0); 325 326 return isa<ExtractValueInst>(Token) || isa<InvokeInst>(Token); 327 } 328 329 /// Get enclosed relocate intrinsic 330 ImmutableCallSite getUnderlyingCallSite() { return RelocateCS; } 331 332 /// The statepoint with which this gc.relocate is associated. 333 const Instruction *getStatepoint() { 334 const Value *Token = RelocateCS.getArgument(0); 335 336 // This takes care both of relocates for call statepoints and relocates 337 // on normal path of invoke statepoint. 338 if (!isa<ExtractValueInst>(Token)) { 339 return cast<Instruction>(Token); 340 } 341 342 // This relocate is on exceptional path of an invoke statepoint 343 const BasicBlock *InvokeBB = 344 cast<Instruction>(Token)->getParent()->getUniquePredecessor(); 345 346 assert(InvokeBB && "safepoints should have unique landingpads"); 347 assert(InvokeBB->getTerminator() && 348 "safepoint block should be well formed"); 349 assert(isStatepoint(InvokeBB->getTerminator())); 350 351 return InvokeBB->getTerminator(); 352 } 353 354 /// The index into the associate statepoint's argument list 355 /// which contains the base pointer of the pointer whose 356 /// relocation this gc.relocate describes. 357 unsigned getBasePtrIndex() { 358 return cast<ConstantInt>(RelocateCS.getArgument(1))->getZExtValue(); 359 } 360 361 /// The index into the associate statepoint's argument list which 362 /// contains the pointer whose relocation this gc.relocate describes. 363 unsigned getDerivedPtrIndex() { 364 return cast<ConstantInt>(RelocateCS.getArgument(2))->getZExtValue(); 365 } 366 367 Value *getBasePtr() { 368 ImmutableCallSite CS(getStatepoint()); 369 return *(CS.arg_begin() + getBasePtrIndex()); 370 } 371 372 Value *getDerivedPtr() { 373 ImmutableCallSite CS(getStatepoint()); 374 return *(CS.arg_begin() + getDerivedPtrIndex()); 375 } 376 }; 377 378 template <typename FunTy, typename InstructionTy, typename ValueTy, 379 typename CallSiteTy> 380 std::vector<GCRelocateOperands> 381 StatepointBase<FunTy, InstructionTy, ValueTy, CallSiteTy>::getRelocates() 382 const { 383 384 std::vector<GCRelocateOperands> Result; 385 386 CallSiteTy StatepointCS = getCallSite(); 387 388 // Search for relocated pointers. Note that working backwards from the 389 // gc_relocates ensures that we only get pairs which are actually relocated 390 // and used after the statepoint. 391 for (const User *U : getInstruction()->users()) 392 if (isGCRelocate(U)) 393 Result.push_back(GCRelocateOperands(U)); 394 395 if (!StatepointCS.isInvoke()) 396 return Result; 397 398 // We need to scan thorough exceptional relocations if it is invoke statepoint 399 LandingPadInst *LandingPad = 400 cast<InvokeInst>(getInstruction())->getLandingPadInst(); 401 402 // Search for extract value from landingpad instruction to which 403 // gc relocates will be attached 404 for (const User *LandingPadUser : LandingPad->users()) { 405 if (!isa<ExtractValueInst>(LandingPadUser)) 406 continue; 407 408 // gc relocates should be attached to this extract value 409 for (const User *U : LandingPadUser->users()) 410 if (isGCRelocate(U)) 411 Result.push_back(GCRelocateOperands(U)); 412 } 413 return Result; 414 } 415 } 416 417 #endif 418