CGExprConstant.cpp revision f6c43965c41e042f0541bdd47b1511d585b2dcfd
1//===--- CGExprConstant.cpp - Emit LLVM Code from Constant Expressions ----===// 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 contains code to emit Constant Expr nodes as LLVM code. 11// 12//===----------------------------------------------------------------------===// 13 14#include "CodeGenFunction.h" 15#include "CodeGenModule.h" 16#include "CGObjCRuntime.h" 17#include "clang/AST/APValue.h" 18#include "clang/AST/ASTContext.h" 19#include "clang/AST/RecordLayout.h" 20#include "clang/AST/StmtVisitor.h" 21#include "clang/Basic/Builtins.h" 22#include "llvm/Constants.h" 23#include "llvm/Function.h" 24#include "llvm/GlobalVariable.h" 25#include "llvm/Support/Compiler.h" 26#include "llvm/Target/TargetData.h" 27using namespace clang; 28using namespace CodeGen; 29 30namespace { 31 32class VISIBILITY_HIDDEN ConstStructBuilder { 33 CodeGenModule &CGM; 34 CodeGenFunction *CGF; 35 36 bool Packed; 37 38 unsigned NextFieldOffsetInBytes; 39 40 std::vector<llvm::Constant *> Elements; 41 42 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF) 43 : CGM(CGM), CGF(CGF), Packed(false), NextFieldOffsetInBytes(0) { } 44 45 bool AppendField(const FieldDecl *Field, uint64_t FieldOffset, 46 const Expr *InitExpr) { 47 uint64_t FieldOffsetInBytes = FieldOffset / 8; 48 49 assert(NextFieldOffsetInBytes <= FieldOffsetInBytes 50 && "Field offset mismatch!"); 51 52 // Emit the field. 53 llvm::Constant *C = CGM.EmitConstantExpr(InitExpr, Field->getType(), CGF); 54 if (!C) 55 return false; 56 57 unsigned FieldAlignment = getAlignment(C); 58 59 // Round up the field offset to the alignment of the field type. 60 uint64_t AlignedNextFieldOffsetInBytes = 61 llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment); 62 63 if (AlignedNextFieldOffsetInBytes > FieldOffsetInBytes) { 64 std::vector<llvm::Constant *> PackedElements; 65 66 assert(!Packed && "Alignment is wrong even with a packed struct!"); 67 68 // Convert the struct to a packed struct. 69 uint64_t ElementOffsetInBytes = 0; 70 71 for (unsigned i = 0, e = Elements.size(); i != e; ++i) { 72 llvm::Constant *C = Elements[i]; 73 74 unsigned ElementAlign = 75 CGM.getTargetData().getABITypeAlignment(C->getType()); 76 uint64_t AlignedElementOffsetInBytes = 77 llvm::RoundUpToAlignment(ElementOffsetInBytes, ElementAlign); 78 79 if (AlignedElementOffsetInBytes > ElementOffsetInBytes) { 80 // We need some padding. 81 uint64_t NumBytes = 82 AlignedElementOffsetInBytes - ElementOffsetInBytes; 83 84 const llvm::Type *Ty = llvm::Type::Int8Ty; 85 if (NumBytes > 1) 86 Ty = llvm::ArrayType::get(Ty, NumBytes); 87 88 llvm::Constant *Padding = llvm::Constant::getNullValue(Ty); 89 PackedElements.push_back(Padding); 90 ElementOffsetInBytes += getSizeInBytes(Padding); 91 } 92 93 PackedElements.push_back(C); 94 ElementOffsetInBytes += getSizeInBytes(C); 95 } 96 97 assert(ElementOffsetInBytes == NextFieldOffsetInBytes && 98 "Packing the struct changed its size!"); 99 100 Elements = PackedElements; 101 Packed = true; 102 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 103 } 104 105 if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) { 106 // We need to append padding. 107 AppendPadding(FieldOffsetInBytes - NextFieldOffsetInBytes); 108 109 assert(NextFieldOffsetInBytes == FieldOffsetInBytes && 110 "Did not add enough padding!"); 111 112 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 113 } 114 115 // Add the field. 116 Elements.push_back(C); 117 NextFieldOffsetInBytes = AlignedNextFieldOffsetInBytes + getSizeInBytes(C); 118 119 return true; 120 } 121 122 bool AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, 123 const Expr *InitExpr) { 124 llvm::ConstantInt *CI = 125 cast_or_null<llvm::ConstantInt>(CGM.EmitConstantExpr(InitExpr, 126 Field->getType(), 127 CGF)); 128 // FIXME: Can this ever happen? 129 if (!CI) 130 return false; 131 132 if (FieldOffset > NextFieldOffsetInBytes * 8) { 133 // We need to add padding. 134 uint64_t NumBytes = 135 llvm::RoundUpToAlignment(FieldOffset - 136 NextFieldOffsetInBytes * 8, 8) / 8; 137 138 AppendPadding(NumBytes); 139 } 140 141 uint64_t FieldSize = 142 Field->getBitWidth()->EvaluateAsInt(CGM.getContext()).getZExtValue(); 143 144 llvm::APInt FieldValue = CI->getValue(); 145 146 // Promote the size of FieldValue if necessary 147 // FIXME: This should never occur, but currently it can because initializer 148 // constants are cast to bool, and because clang is not enforcing bitfield 149 // width limits. 150 if (FieldSize > FieldValue.getBitWidth()) 151 FieldValue.zext(FieldSize); 152 153 // Truncate the size of FieldValue to the bit field size. 154 if (FieldSize < FieldValue.getBitWidth()) 155 FieldValue.trunc(FieldSize); 156 157 if (FieldOffset < NextFieldOffsetInBytes * 8) { 158 // Either part of the field or the entire field can go into the previous 159 // byte. 160 assert(!Elements.empty() && "Elements can't be empty!"); 161 162 unsigned BitsInPreviousByte = 163 NextFieldOffsetInBytes * 8 - FieldOffset; 164 165 bool FitsCompletelyInPreviousByte = 166 BitsInPreviousByte >= FieldValue.getBitWidth(); 167 168 llvm::APInt Tmp = FieldValue; 169 170 if (!FitsCompletelyInPreviousByte) { 171 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte; 172 173 if (CGM.getTargetData().isBigEndian()) { 174 Tmp = Tmp.lshr(NewFieldWidth); 175 Tmp.trunc(BitsInPreviousByte); 176 177 // We want the remaining high bits. 178 FieldValue.trunc(NewFieldWidth); 179 } else { 180 Tmp.trunc(BitsInPreviousByte); 181 182 // We want the remaining low bits. 183 FieldValue = FieldValue.lshr(BitsInPreviousByte); 184 FieldValue.trunc(NewFieldWidth); 185 } 186 } 187 188 Tmp.zext(8); 189 if (CGM.getTargetData().isBigEndian()) { 190 if (FitsCompletelyInPreviousByte) 191 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth()); 192 } else { 193 Tmp = Tmp.shl(8 - BitsInPreviousByte); 194 } 195 196 // Or in the bits that go into the previous byte. 197 Tmp |= cast<llvm::ConstantInt>(Elements.back())->getValue(); 198 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp); 199 200 if (FitsCompletelyInPreviousByte) 201 return true; 202 } 203 204 while (FieldValue.getBitWidth() > 8) { 205 llvm::APInt Tmp; 206 207 if (CGM.getTargetData().isBigEndian()) { 208 // We want the high bits. 209 Tmp = FieldValue; 210 Tmp = Tmp.lshr(Tmp.getBitWidth() - 8); 211 Tmp.trunc(8); 212 } else { 213 // We want the low bits. 214 Tmp = FieldValue; 215 Tmp.trunc(8); 216 217 FieldValue = FieldValue.lshr(8); 218 } 219 220 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp)); 221 NextFieldOffsetInBytes++; 222 223 FieldValue.trunc(FieldValue.getBitWidth() - 8); 224 } 225 226 assert(FieldValue.getBitWidth() > 0 && 227 "Should have at least one bit left!"); 228 assert(FieldValue.getBitWidth() <= 8 && 229 "Should not have more than a byte left!"); 230 231 if (FieldValue.getBitWidth() < 8) { 232 if (CGM.getTargetData().isBigEndian()) { 233 unsigned BitWidth = FieldValue.getBitWidth(); 234 235 FieldValue.zext(8); 236 FieldValue = FieldValue << (8 - BitWidth); 237 } else 238 FieldValue.zext(8); 239 } 240 241 // Append the last element. 242 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), 243 FieldValue)); 244 NextFieldOffsetInBytes++; 245 return true; 246 } 247 248 void AppendPadding(uint64_t NumBytes) { 249 if (!NumBytes) 250 return; 251 252 const llvm::Type *Ty = llvm::Type::Int8Ty; 253 if (NumBytes > 1) 254 Ty = llvm::ArrayType::get(Ty, NumBytes); 255 256 llvm::Constant *C = llvm::Constant::getNullValue(Ty); 257 Elements.push_back(C); 258 assert(getAlignment(C) == 1 && "Padding must have 1 byte alignment!"); 259 260 NextFieldOffsetInBytes += getSizeInBytes(C); 261 } 262 263 void AppendTailPadding(uint64_t RecordSize) { 264 assert(RecordSize % 8 == 0 && "Invalid record size!"); 265 266 uint64_t RecordSizeInBytes = RecordSize / 8; 267 assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!"); 268 269 unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes; 270 AppendPadding(NumPadBytes); 271 } 272 273 bool Build(const InitListExpr *ILE) { 274 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 275 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 276 277 unsigned FieldNo = 0; 278 unsigned ElementNo = 0; 279 for (RecordDecl::field_iterator Field = RD->field_begin(), 280 FieldEnd = RD->field_end(); 281 ElementNo < ILE->getNumInits() && Field != FieldEnd; 282 ++Field, ++FieldNo) { 283 if (Field->isBitField()) { 284 if (!Field->getIdentifier()) 285 continue; 286 287 if (!AppendBitField(*Field, Layout.getFieldOffset(FieldNo), 288 ILE->getInit(ElementNo))) 289 return false; 290 } else { 291 if (!AppendField(*Field, Layout.getFieldOffset(FieldNo), 292 ILE->getInit(ElementNo))) 293 return false; 294 } 295 296 ElementNo++; 297 } 298 299 uint64_t LayoutSizeInBytes = Layout.getSize() / 8; 300 301 if (NextFieldOffsetInBytes > LayoutSizeInBytes) { 302 // If the struct is bigger than the size of the record type, 303 // we must have a flexible array member at the end. 304 assert(RD->hasFlexibleArrayMember() && 305 "Must have flexible array member if struct is bigger than type!"); 306 307 // No tail padding is necessary. 308 return true; 309 } 310 311 // Append tail padding if necessary. 312 AppendTailPadding(Layout.getSize()); 313 314 assert(Layout.getSize() / 8 == NextFieldOffsetInBytes && 315 "Tail padding mismatch!"); 316 317 return true; 318 } 319 320 unsigned getAlignment(const llvm::Constant *C) const { 321 if (Packed) 322 return 1; 323 324 return CGM.getTargetData().getABITypeAlignment(C->getType()); 325 } 326 327 uint64_t getSizeInBytes(const llvm::Constant *C) const { 328 return CGM.getTargetData().getTypeAllocSize(C->getType()); 329 } 330 331public: 332 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, 333 const InitListExpr *ILE) { 334 ConstStructBuilder Builder(CGM, CGF); 335 336 if (!Builder.Build(ILE)) 337 return 0; 338 339 llvm::Constant *Result = 340 llvm::ConstantStruct::get(Builder.Elements, Builder.Packed); 341 342 assert(llvm::RoundUpToAlignment(Builder.NextFieldOffsetInBytes, 343 Builder.getAlignment(Result)) == 344 Builder.getSizeInBytes(Result) && "Size mismatch!"); 345 346 return Result; 347 } 348}; 349 350class VISIBILITY_HIDDEN ConstExprEmitter : 351 public StmtVisitor<ConstExprEmitter, llvm::Constant*> { 352 CodeGenModule &CGM; 353 CodeGenFunction *CGF; 354 llvm::LLVMContext &VMContext; 355public: 356 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) 357 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) { 358 } 359 360 //===--------------------------------------------------------------------===// 361 // Visitor Methods 362 //===--------------------------------------------------------------------===// 363 364 llvm::Constant *VisitStmt(Stmt *S) { 365 return 0; 366 } 367 368 llvm::Constant *VisitParenExpr(ParenExpr *PE) { 369 return Visit(PE->getSubExpr()); 370 } 371 372 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 373 return Visit(E->getInitializer()); 374 } 375 376 llvm::Constant *VisitCastExpr(CastExpr* E) { 377 // GCC cast to union extension 378 if (E->getType()->isUnionType()) { 379 const llvm::Type *Ty = ConvertType(E->getType()); 380 Expr *SubExpr = E->getSubExpr(); 381 return EmitUnion(CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF), 382 Ty); 383 } 384 // Explicit and implicit no-op casts 385 QualType Ty = E->getType(), SubTy = E->getSubExpr()->getType(); 386 if (CGM.getContext().hasSameUnqualifiedType(Ty, SubTy)) { 387 return Visit(E->getSubExpr()); 388 } 389 return 0; 390 } 391 392 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 393 return Visit(DAE->getExpr()); 394 } 395 396 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { 397 std::vector<llvm::Constant*> Elts; 398 const llvm::ArrayType *AType = 399 cast<llvm::ArrayType>(ConvertType(ILE->getType())); 400 unsigned NumInitElements = ILE->getNumInits(); 401 // FIXME: Check for wide strings 402 // FIXME: Check for NumInitElements exactly equal to 1?? 403 if (NumInitElements > 0 && 404 (isa<StringLiteral>(ILE->getInit(0)) || 405 isa<ObjCEncodeExpr>(ILE->getInit(0))) && 406 ILE->getType()->getArrayElementTypeNoTypeQual()->isCharType()) 407 return Visit(ILE->getInit(0)); 408 const llvm::Type *ElemTy = AType->getElementType(); 409 unsigned NumElements = AType->getNumElements(); 410 411 // Initialising an array requires us to automatically 412 // initialise any elements that have not been initialised explicitly 413 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 414 415 // Copy initializer elements. 416 unsigned i = 0; 417 bool RewriteType = false; 418 for (; i < NumInitableElts; ++i) { 419 Expr *Init = ILE->getInit(i); 420 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 421 if (!C) 422 return 0; 423 RewriteType |= (C->getType() != ElemTy); 424 Elts.push_back(C); 425 } 426 427 // Initialize remaining array elements. 428 // FIXME: This doesn't handle member pointers correctly! 429 for (; i < NumElements; ++i) 430 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 431 432 if (RewriteType) { 433 // FIXME: Try to avoid packing the array 434 std::vector<const llvm::Type*> Types; 435 for (unsigned i = 0; i < Elts.size(); ++i) 436 Types.push_back(Elts[i]->getType()); 437 const llvm::StructType *SType = llvm::StructType::get(Types, true); 438 return llvm::ConstantStruct::get(SType, Elts); 439 } 440 441 return llvm::ConstantArray::get(AType, Elts); 442 } 443 444 void InsertBitfieldIntoStruct(std::vector<llvm::Constant*>& Elts, 445 FieldDecl* Field, Expr* E) { 446 // Calculate the value to insert 447 llvm::Constant *C = CGM.EmitConstantExpr(E, Field->getType(), CGF); 448 if (!C) 449 return; 450 451 llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(C); 452 if (!CI) { 453 CGM.ErrorUnsupported(E, "bitfield initialization"); 454 return; 455 } 456 llvm::APInt V = CI->getValue(); 457 458 // Calculate information about the relevant field 459 const llvm::Type* Ty = CI->getType(); 460 const llvm::TargetData &TD = CGM.getTypes().getTargetData(); 461 unsigned size = TD.getTypeAllocSizeInBits(Ty); 462 CodeGenTypes::BitFieldInfo Info = CGM.getTypes().getBitFieldInfo(Field); 463 unsigned FieldOffset = Info.FieldNo * size; 464 465 FieldOffset += Info.Start; 466 467 // Find where to start the insertion 468 // FIXME: This is O(n^2) in the number of bit-fields! 469 // FIXME: This won't work if the struct isn't completely packed! 470 unsigned offset = 0, i = 0; 471 while (offset < (FieldOffset & -8)) 472 offset += TD.getTypeAllocSizeInBits(Elts[i++]->getType()); 473 474 // Advance over 0 sized elements (must terminate in bounds since 475 // the bitfield must have a size). 476 while (TD.getTypeAllocSizeInBits(Elts[i]->getType()) == 0) 477 ++i; 478 479 // Promote the size of V if necessary 480 // FIXME: This should never occur, but currently it can because initializer 481 // constants are cast to bool, and because clang is not enforcing bitfield 482 // width limits. 483 if (Info.Size > V.getBitWidth()) 484 V.zext(Info.Size); 485 486 // Insert the bits into the struct 487 // FIXME: This algorthm is only correct on X86! 488 // FIXME: THis algorthm assumes bit-fields only have byte-size elements! 489 unsigned bitsToInsert = Info.Size; 490 unsigned curBits = std::min(8 - (FieldOffset & 7), bitsToInsert); 491 unsigned byte = V.getLoBits(curBits).getZExtValue() << (FieldOffset & 7); 492 do { 493 llvm::Constant* byteC = 494 llvm::ConstantInt::get(llvm::Type::Int8Ty, byte); 495 Elts[i] = llvm::ConstantExpr::getOr(Elts[i], byteC); 496 ++i; 497 V = V.lshr(curBits); 498 bitsToInsert -= curBits; 499 500 if (!bitsToInsert) 501 break; 502 503 curBits = bitsToInsert > 8 ? 8 : bitsToInsert; 504 byte = V.getLoBits(curBits).getZExtValue(); 505 } while (true); 506 } 507 508 llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { 509 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 510 511 // FIXME: Remove the old struct builder once we're sure that the new one 512 // works well enough! 513 const llvm::StructType *SType = 514 cast<llvm::StructType>(ConvertType(ILE->getType())); 515 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 516 std::vector<llvm::Constant*> Elts; 517 518 // Initialize the whole structure to zero. 519 // FIXME: This doesn't handle member pointers correctly! 520 for (unsigned i = 0; i < SType->getNumElements(); ++i) { 521 const llvm::Type *FieldTy = SType->getElementType(i); 522 Elts.push_back(llvm::Constant::getNullValue(FieldTy)); 523 } 524 525 // Copy initializer elements. Skip padding fields. 526 unsigned EltNo = 0; // Element no in ILE 527 bool RewriteType = false; 528 for (RecordDecl::field_iterator Field = RD->field_begin(), 529 FieldEnd = RD->field_end(); 530 EltNo < ILE->getNumInits() && Field != FieldEnd; ++Field) { 531 if (Field->isBitField()) { 532 if (!Field->getIdentifier()) 533 continue; 534 InsertBitfieldIntoStruct(Elts, *Field, ILE->getInit(EltNo)); 535 } else { 536 unsigned FieldNo = CGM.getTypes().getLLVMFieldNo(*Field); 537 llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(EltNo), 538 Field->getType(), CGF); 539 if (!C) return 0; 540 RewriteType |= (C->getType() != Elts[FieldNo]->getType()); 541 Elts[FieldNo] = C; 542 } 543 EltNo++; 544 } 545 546 if (RewriteType) { 547 // FIXME: Make this work for non-packed structs 548 assert(SType->isPacked() && "Cannot recreate unpacked structs"); 549 std::vector<const llvm::Type*> Types; 550 for (unsigned i = 0; i < Elts.size(); ++i) 551 Types.push_back(Elts[i]->getType()); 552 SType = llvm::StructType::get(Types, true); 553 } 554 555 return llvm::ConstantStruct::get(SType, Elts); 556 } 557 558 llvm::Constant *EmitUnion(llvm::Constant *C, const llvm::Type *Ty) { 559 if (!C) 560 return 0; 561 562 // Build a struct with the union sub-element as the first member, 563 // and padded to the appropriate size 564 std::vector<llvm::Constant*> Elts; 565 std::vector<const llvm::Type*> Types; 566 Elts.push_back(C); 567 Types.push_back(C->getType()); 568 unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType()); 569 unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(Ty); 570 571 assert(CurSize <= TotalSize && "Union size mismatch!"); 572 if (unsigned NumPadBytes = TotalSize - CurSize) { 573 const llvm::Type *Ty = llvm::Type::Int8Ty; 574 if (NumPadBytes > 1) 575 Ty = llvm::ArrayType::get(Ty, NumPadBytes); 576 577 Elts.push_back(llvm::Constant::getNullValue(Ty)); 578 Types.push_back(Ty); 579 } 580 581 llvm::StructType* STy = llvm::StructType::get(Types, false); 582 return llvm::ConstantStruct::get(STy, Elts); 583 } 584 585 llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { 586 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 587 588 const llvm::Type *Ty = ConvertType(ILE->getType()); 589 590 FieldDecl* curField = ILE->getInitializedFieldInUnion(); 591 if (!curField) { 592 // There's no field to initialize, so value-initialize the union. 593#ifndef NDEBUG 594 // Make sure that it's really an empty and not a failure of 595 // semantic analysis. 596 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 597 for (RecordDecl::field_iterator Field = RD->field_begin(), 598 FieldEnd = RD->field_end(); 599 Field != FieldEnd; ++Field) 600 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed"); 601#endif 602 return llvm::Constant::getNullValue(Ty); 603 } 604 605 if (curField->isBitField()) { 606 // Create a dummy struct for bit-field insertion 607 unsigned NumElts = CGM.getTargetData().getTypeAllocSize(Ty); 608 llvm::Constant* NV = 609 llvm::Constant::getNullValue(llvm::Type::Int8Ty); 610 std::vector<llvm::Constant*> Elts(NumElts, NV); 611 612 InsertBitfieldIntoStruct(Elts, curField, ILE->getInit(0)); 613 const llvm::ArrayType *RetTy = 614 llvm::ArrayType::get(NV->getType(), NumElts); 615 return llvm::ConstantArray::get(RetTy, Elts); 616 } 617 618 llvm::Constant *InitElem; 619 if (ILE->getNumInits() > 0) { 620 Expr *Init = ILE->getInit(0); 621 InitElem = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 622 } else { 623 InitElem = CGM.EmitNullConstant(curField->getType()); 624 } 625 return EmitUnion(InitElem, Ty); 626 } 627 628 llvm::Constant *EmitVectorInitialization(InitListExpr *ILE) { 629 const llvm::VectorType *VType = 630 cast<llvm::VectorType>(ConvertType(ILE->getType())); 631 const llvm::Type *ElemTy = VType->getElementType(); 632 std::vector<llvm::Constant*> Elts; 633 unsigned NumElements = VType->getNumElements(); 634 unsigned NumInitElements = ILE->getNumInits(); 635 636 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 637 638 // Copy initializer elements. 639 unsigned i = 0; 640 for (; i < NumInitableElts; ++i) { 641 Expr *Init = ILE->getInit(i); 642 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 643 if (!C) 644 return 0; 645 Elts.push_back(C); 646 } 647 648 for (; i < NumElements; ++i) 649 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 650 651 return llvm::ConstantVector::get(VType, Elts); 652 } 653 654 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) { 655 return CGM.EmitNullConstant(E->getType()); 656 } 657 658 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { 659 if (ILE->getType()->isScalarType()) { 660 // We have a scalar in braces. Just use the first element. 661 if (ILE->getNumInits() > 0) { 662 Expr *Init = ILE->getInit(0); 663 return CGM.EmitConstantExpr(Init, Init->getType(), CGF); 664 } 665 return CGM.EmitNullConstant(ILE->getType()); 666 } 667 668 if (ILE->getType()->isArrayType()) 669 return EmitArrayInitialization(ILE); 670 671 if (ILE->getType()->isStructureType()) 672 return EmitStructInitialization(ILE); 673 674 if (ILE->getType()->isUnionType()) 675 return EmitUnionInitialization(ILE); 676 677 if (ILE->getType()->isVectorType()) 678 return EmitVectorInitialization(ILE); 679 680 assert(0 && "Unable to handle InitListExpr"); 681 // Get rid of control reaches end of void function warning. 682 // Not reached. 683 return 0; 684 } 685 686 llvm::Constant *VisitStringLiteral(StringLiteral *E) { 687 assert(!E->getType()->isPointerType() && "Strings are always arrays"); 688 689 // This must be a string initializing an array in a static initializer. 690 // Don't emit it as the address of the string, emit the string data itself 691 // as an inline array. 692 return llvm::ConstantArray::get(CGM.GetStringForStringLiteral(E), false); 693 } 694 695 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) { 696 // This must be an @encode initializing an array in a static initializer. 697 // Don't emit it as the address of the string, emit the string data itself 698 // as an inline array. 699 std::string Str; 700 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str); 701 const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType()); 702 703 // Resize the string to the right size, adding zeros at the end, or 704 // truncating as needed. 705 Str.resize(CAT->getSize().getZExtValue(), '\0'); 706 return llvm::ConstantArray::get(Str, false); 707 } 708 709 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { 710 return Visit(E->getSubExpr()); 711 } 712 713 // Utility methods 714 const llvm::Type *ConvertType(QualType T) { 715 return CGM.getTypes().ConvertType(T); 716 } 717 718public: 719 llvm::Constant *EmitLValue(Expr *E) { 720 switch (E->getStmtClass()) { 721 default: break; 722 case Expr::CompoundLiteralExprClass: { 723 // Note that due to the nature of compound literals, this is guaranteed 724 // to be the only use of the variable, so we just generate it here. 725 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 726 llvm::Constant* C = Visit(CLE->getInitializer()); 727 // FIXME: "Leaked" on failure. 728 if (C) 729 C = new llvm::GlobalVariable(CGM.getModule(), C->getType(), 730 E->getType().isConstQualified(), 731 llvm::GlobalValue::InternalLinkage, 732 C, ".compoundliteral"); 733 return C; 734 } 735 case Expr::DeclRefExprClass: 736 case Expr::QualifiedDeclRefExprClass: { 737 NamedDecl *Decl = cast<DeclRefExpr>(E)->getDecl(); 738 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) 739 return CGM.GetAddrOfFunction(GlobalDecl(FD)); 740 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { 741 // We can never refer to a variable with local storage. 742 if (!VD->hasLocalStorage()) { 743 if (VD->isFileVarDecl() || VD->hasExternalStorage()) 744 return CGM.GetAddrOfGlobalVar(VD); 745 else if (VD->isBlockVarDecl()) { 746 assert(CGF && "Can't access static local vars without CGF"); 747 return CGF->GetAddrOfStaticLocalVar(VD); 748 } 749 } 750 } 751 break; 752 } 753 case Expr::StringLiteralClass: 754 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); 755 case Expr::ObjCEncodeExprClass: 756 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E)); 757 case Expr::ObjCStringLiteralClass: { 758 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); 759 llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(SL); 760 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); 761 } 762 case Expr::PredefinedExprClass: { 763 // __func__/__FUNCTION__ -> "". __PRETTY_FUNCTION__ -> "top level". 764 std::string Str; 765 if (cast<PredefinedExpr>(E)->getIdentType() == 766 PredefinedExpr::PrettyFunction) 767 Str = "top level"; 768 769 return CGM.GetAddrOfConstantCString(Str, ".tmp"); 770 } 771 case Expr::AddrLabelExprClass: { 772 assert(CGF && "Invalid address of label expression outside function."); 773 unsigned id = CGF->GetIDForAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); 774 llvm::Constant *C = llvm::ConstantInt::get(llvm::Type::Int32Ty, id); 775 return llvm::ConstantExpr::getIntToPtr(C, ConvertType(E->getType())); 776 } 777 case Expr::CallExprClass: { 778 CallExpr* CE = cast<CallExpr>(E); 779 if (CE->isBuiltinCall(CGM.getContext()) != 780 Builtin::BI__builtin___CFStringMakeConstantString) 781 break; 782 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); 783 const StringLiteral *Literal = cast<StringLiteral>(Arg); 784 // FIXME: need to deal with UCN conversion issues. 785 return CGM.GetAddrOfConstantCFString(Literal); 786 } 787 case Expr::BlockExprClass: { 788 std::string FunctionName; 789 if (CGF) 790 FunctionName = CGF->CurFn->getName(); 791 else 792 FunctionName = "global"; 793 794 return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str()); 795 } 796 } 797 798 return 0; 799 } 800}; 801 802} // end anonymous namespace. 803 804llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, 805 QualType DestType, 806 CodeGenFunction *CGF) { 807 Expr::EvalResult Result; 808 809 bool Success = false; 810 811 if (DestType->isReferenceType()) 812 Success = E->EvaluateAsLValue(Result, Context); 813 else 814 Success = E->Evaluate(Result, Context); 815 816 if (Success) { 817 assert(!Result.HasSideEffects && 818 "Constant expr should not have any side effects!"); 819 switch (Result.Val.getKind()) { 820 case APValue::Uninitialized: 821 assert(0 && "Constant expressions should be initialized."); 822 return 0; 823 case APValue::LValue: { 824 const llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType); 825 llvm::Constant *Offset = 826 llvm::ConstantInt::get(llvm::Type::Int64Ty, 827 Result.Val.getLValueOffset()); 828 829 llvm::Constant *C; 830 if (const Expr *LVBase = Result.Val.getLValueBase()) { 831 C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase)); 832 833 // Apply offset if necessary. 834 if (!Offset->isNullValue()) { 835 const llvm::Type *Type = 836 llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 837 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type); 838 Casted = llvm::ConstantExpr::getGetElementPtr(Casted, &Offset, 1); 839 C = llvm::ConstantExpr::getBitCast(Casted, C->getType()); 840 } 841 842 // Convert to the appropriate type; this could be an lvalue for 843 // an integer. 844 if (isa<llvm::PointerType>(DestTy)) 845 return llvm::ConstantExpr::getBitCast(C, DestTy); 846 847 return llvm::ConstantExpr::getPtrToInt(C, DestTy); 848 } else { 849 C = Offset; 850 851 // Convert to the appropriate type; this could be an lvalue for 852 // an integer. 853 if (isa<llvm::PointerType>(DestTy)) 854 return llvm::ConstantExpr::getIntToPtr(C, DestTy); 855 856 // If the types don't match this should only be a truncate. 857 if (C->getType() != DestTy) 858 return llvm::ConstantExpr::getTrunc(C, DestTy); 859 860 return C; 861 } 862 } 863 case APValue::Int: { 864 llvm::Constant *C = llvm::ConstantInt::get(VMContext, 865 Result.Val.getInt()); 866 867 if (C->getType() == llvm::Type::Int1Ty) { 868 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 869 C = llvm::ConstantExpr::getZExt(C, BoolTy); 870 } 871 return C; 872 } 873 case APValue::ComplexInt: { 874 llvm::Constant *Complex[2]; 875 876 Complex[0] = llvm::ConstantInt::get(VMContext, 877 Result.Val.getComplexIntReal()); 878 Complex[1] = llvm::ConstantInt::get(VMContext, 879 Result.Val.getComplexIntImag()); 880 881 return llvm::ConstantStruct::get(Complex, 2); 882 } 883 case APValue::Float: 884 return llvm::ConstantFP::get(VMContext, Result.Val.getFloat()); 885 case APValue::ComplexFloat: { 886 llvm::Constant *Complex[2]; 887 888 Complex[0] = llvm::ConstantFP::get(VMContext, 889 Result.Val.getComplexFloatReal()); 890 Complex[1] = llvm::ConstantFP::get(VMContext, 891 Result.Val.getComplexFloatImag()); 892 893 return llvm::ConstantStruct::get(Complex, 2); 894 } 895 case APValue::Vector: { 896 llvm::SmallVector<llvm::Constant *, 4> Inits; 897 unsigned NumElts = Result.Val.getVectorLength(); 898 899 for (unsigned i = 0; i != NumElts; ++i) { 900 APValue &Elt = Result.Val.getVectorElt(i); 901 if (Elt.isInt()) 902 Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt())); 903 else 904 Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat())); 905 } 906 return llvm::ConstantVector::get(&Inits[0], Inits.size()); 907 } 908 } 909 } 910 911 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 912 if (C && C->getType() == llvm::Type::Int1Ty) { 913 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 914 C = llvm::ConstantExpr::getZExt(C, BoolTy); 915 } 916 return C; 917} 918 919llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { 920 // Always return an LLVM null constant for now; this will change when we 921 // get support for IRGen of member pointers. 922 return llvm::Constant::getNullValue(getTypes().ConvertType(T)); 923} 924