CGStmt.cpp revision 444be7366d0a1e172c0290a1ea54c1cb16b5947c
1//===--- CGStmt.cpp - Emit LLVM Code from Statements ----------------------===// 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 Stmt nodes as LLVM code. 11// 12//===----------------------------------------------------------------------===// 13 14#include "CGDebugInfo.h" 15#include "CodeGenModule.h" 16#include "CodeGenFunction.h" 17#include "clang/AST/StmtVisitor.h" 18#include "clang/Basic/PrettyStackTrace.h" 19#include "clang/Basic/TargetInfo.h" 20#include "llvm/ADT/StringExtras.h" 21#include "llvm/InlineAsm.h" 22#include "llvm/Intrinsics.h" 23#include "llvm/Target/TargetData.h" 24using namespace clang; 25using namespace CodeGen; 26 27//===----------------------------------------------------------------------===// 28// Statement Emission 29//===----------------------------------------------------------------------===// 30 31void CodeGenFunction::EmitStopPoint(const Stmt *S) { 32 if (CGDebugInfo *DI = getDebugInfo()) { 33 DI->setLocation(S->getLocStart()); 34 DI->EmitStopPoint(CurFn, Builder); 35 } 36} 37 38void CodeGenFunction::EmitStmt(const Stmt *S) { 39 assert(S && "Null statement?"); 40 41 // Check if we can handle this without bothering to generate an 42 // insert point or debug info. 43 if (EmitSimpleStmt(S)) 44 return; 45 46 // Check if we are generating unreachable code. 47 if (!HaveInsertPoint()) { 48 // If so, and the statement doesn't contain a label, then we do not need to 49 // generate actual code. This is safe because (1) the current point is 50 // unreachable, so we don't need to execute the code, and (2) we've already 51 // handled the statements which update internal data structures (like the 52 // local variable map) which could be used by subsequent statements. 53 if (!ContainsLabel(S)) { 54 // Verify that any decl statements were handled as simple, they may be in 55 // scope of subsequent reachable statements. 56 assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!"); 57 return; 58 } 59 60 // Otherwise, make a new block to hold the code. 61 EnsureInsertPoint(); 62 } 63 64 // Generate a stoppoint if we are emitting debug info. 65 EmitStopPoint(S); 66 67 switch (S->getStmtClass()) { 68 default: 69 // Must be an expression in a stmt context. Emit the value (to get 70 // side-effects) and ignore the result. 71 if (!isa<Expr>(S)) 72 ErrorUnsupported(S, "statement"); 73 74 EmitAnyExpr(cast<Expr>(S), 0, false, true); 75 76 // Expression emitters don't handle unreachable blocks yet, so look for one 77 // explicitly here. This handles the common case of a call to a noreturn 78 // function. 79 if (llvm::BasicBlock *CurBB = Builder.GetInsertBlock()) { 80 if (CurBB->empty() && CurBB->use_empty()) { 81 CurBB->eraseFromParent(); 82 Builder.ClearInsertionPoint(); 83 } 84 } 85 break; 86 case Stmt::IndirectGotoStmtClass: 87 EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break; 88 89 case Stmt::IfStmtClass: EmitIfStmt(cast<IfStmt>(*S)); break; 90 case Stmt::WhileStmtClass: EmitWhileStmt(cast<WhileStmt>(*S)); break; 91 case Stmt::DoStmtClass: EmitDoStmt(cast<DoStmt>(*S)); break; 92 case Stmt::ForStmtClass: EmitForStmt(cast<ForStmt>(*S)); break; 93 94 case Stmt::ReturnStmtClass: EmitReturnStmt(cast<ReturnStmt>(*S)); break; 95 96 case Stmt::SwitchStmtClass: EmitSwitchStmt(cast<SwitchStmt>(*S)); break; 97 case Stmt::AsmStmtClass: EmitAsmStmt(cast<AsmStmt>(*S)); break; 98 99 case Stmt::ObjCAtTryStmtClass: 100 EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S)); 101 break; 102 case Stmt::ObjCAtCatchStmtClass: 103 assert(0 && "@catch statements should be handled by EmitObjCAtTryStmt"); 104 break; 105 case Stmt::ObjCAtFinallyStmtClass: 106 assert(0 && "@finally statements should be handled by EmitObjCAtTryStmt"); 107 break; 108 case Stmt::ObjCAtThrowStmtClass: 109 EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S)); 110 break; 111 case Stmt::ObjCAtSynchronizedStmtClass: 112 EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S)); 113 break; 114 case Stmt::ObjCForCollectionStmtClass: 115 EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S)); 116 break; 117 118 case Stmt::CXXTryStmtClass: 119 EmitCXXTryStmt(cast<CXXTryStmt>(*S)); 120 break; 121 } 122} 123 124bool CodeGenFunction::EmitSimpleStmt(const Stmt *S) { 125 switch (S->getStmtClass()) { 126 default: return false; 127 case Stmt::NullStmtClass: break; 128 case Stmt::CompoundStmtClass: EmitCompoundStmt(cast<CompoundStmt>(*S)); break; 129 case Stmt::DeclStmtClass: EmitDeclStmt(cast<DeclStmt>(*S)); break; 130 case Stmt::LabelStmtClass: EmitLabelStmt(cast<LabelStmt>(*S)); break; 131 case Stmt::GotoStmtClass: EmitGotoStmt(cast<GotoStmt>(*S)); break; 132 case Stmt::BreakStmtClass: EmitBreakStmt(cast<BreakStmt>(*S)); break; 133 case Stmt::ContinueStmtClass: EmitContinueStmt(cast<ContinueStmt>(*S)); break; 134 case Stmt::DefaultStmtClass: EmitDefaultStmt(cast<DefaultStmt>(*S)); break; 135 case Stmt::CaseStmtClass: EmitCaseStmt(cast<CaseStmt>(*S)); break; 136 } 137 138 return true; 139} 140 141/// EmitCompoundStmt - Emit a compound statement {..} node. If GetLast is true, 142/// this captures the expression result of the last sub-statement and returns it 143/// (for use by the statement expression extension). 144RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast, 145 llvm::Value *AggLoc, bool isAggVol) { 146 PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(), 147 "LLVM IR generation of compound statement ('{}')"); 148 149 CGDebugInfo *DI = getDebugInfo(); 150 if (DI) { 151 DI->setLocation(S.getLBracLoc()); 152 DI->EmitRegionStart(CurFn, Builder); 153 } 154 155 // Keep track of the current cleanup stack depth. 156 size_t CleanupStackDepth = CleanupEntries.size(); 157 bool OldDidCallStackSave = DidCallStackSave; 158 DidCallStackSave = false; 159 160 for (CompoundStmt::const_body_iterator I = S.body_begin(), 161 E = S.body_end()-GetLast; I != E; ++I) 162 EmitStmt(*I); 163 164 if (DI) { 165 DI->setLocation(S.getLBracLoc()); 166 DI->EmitRegionEnd(CurFn, Builder); 167 } 168 169 RValue RV; 170 if (!GetLast) 171 RV = RValue::get(0); 172 else { 173 // We have to special case labels here. They are statements, but when put 174 // at the end of a statement expression, they yield the value of their 175 // subexpression. Handle this by walking through all labels we encounter, 176 // emitting them before we evaluate the subexpr. 177 const Stmt *LastStmt = S.body_back(); 178 while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) { 179 EmitLabel(*LS); 180 LastStmt = LS->getSubStmt(); 181 } 182 183 EnsureInsertPoint(); 184 185 RV = EmitAnyExpr(cast<Expr>(LastStmt), AggLoc); 186 } 187 188 DidCallStackSave = OldDidCallStackSave; 189 190 EmitCleanupBlocks(CleanupStackDepth); 191 192 return RV; 193} 194 195void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) { 196 llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator()); 197 198 // If there is a cleanup stack, then we it isn't worth trying to 199 // simplify this block (we would need to remove it from the scope map 200 // and cleanup entry). 201 if (!CleanupEntries.empty()) 202 return; 203 204 // Can only simplify direct branches. 205 if (!BI || !BI->isUnconditional()) 206 return; 207 208 BB->replaceAllUsesWith(BI->getSuccessor(0)); 209 BI->eraseFromParent(); 210 BB->eraseFromParent(); 211} 212 213void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) { 214 // Fall out of the current block (if necessary). 215 EmitBranch(BB); 216 217 if (IsFinished && BB->use_empty()) { 218 delete BB; 219 return; 220 } 221 222 // If necessary, associate the block with the cleanup stack size. 223 if (!CleanupEntries.empty()) { 224 // Check if the basic block has already been inserted. 225 BlockScopeMap::iterator I = BlockScopes.find(BB); 226 if (I != BlockScopes.end()) { 227 assert(I->second == CleanupEntries.size() - 1); 228 } else { 229 BlockScopes[BB] = CleanupEntries.size() - 1; 230 CleanupEntries.back().Blocks.push_back(BB); 231 } 232 } 233 234 CurFn->getBasicBlockList().push_back(BB); 235 Builder.SetInsertPoint(BB); 236} 237 238void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) { 239 // Emit a branch from the current block to the target one if this 240 // was a real block. If this was just a fall-through block after a 241 // terminator, don't emit it. 242 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 243 244 if (!CurBB || CurBB->getTerminator()) { 245 // If there is no insert point or the previous block is already 246 // terminated, don't touch it. 247 } else { 248 // Otherwise, create a fall-through branch. 249 Builder.CreateBr(Target); 250 } 251 252 Builder.ClearInsertionPoint(); 253} 254 255void CodeGenFunction::EmitLabel(const LabelStmt &S) { 256 EmitBlock(getBasicBlockForLabel(&S)); 257} 258 259 260void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) { 261 EmitLabel(S); 262 EmitStmt(S.getSubStmt()); 263} 264 265void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) { 266 // If this code is reachable then emit a stop point (if generating 267 // debug info). We have to do this ourselves because we are on the 268 // "simple" statement path. 269 if (HaveInsertPoint()) 270 EmitStopPoint(&S); 271 272 EmitBranchThroughCleanup(getBasicBlockForLabel(S.getLabel())); 273} 274 275 276void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) { 277 // Ensure that we have an i8* for our PHI node. 278 llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()), 279 llvm::Type::getInt8PtrTy(VMContext), 280 "addr"); 281 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 282 283 284 // Get the basic block for the indirect goto. 285 llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock(); 286 287 // The first instruction in the block has to be the PHI for the switch dest, 288 // add an entry for this branch. 289 cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB); 290 291 EmitBranch(IndGotoBB); 292} 293 294void CodeGenFunction::EmitIfStmt(const IfStmt &S) { 295 // C99 6.8.4.1: The first substatement is executed if the expression compares 296 // unequal to 0. The condition must be a scalar type. 297 298 // If the condition constant folds and can be elided, try to avoid emitting 299 // the condition and the dead arm of the if/else. 300 if (int Cond = ConstantFoldsToSimpleInteger(S.getCond())) { 301 // Figure out which block (then or else) is executed. 302 const Stmt *Executed = S.getThen(), *Skipped = S.getElse(); 303 if (Cond == -1) // Condition false? 304 std::swap(Executed, Skipped); 305 306 // If the skipped block has no labels in it, just emit the executed block. 307 // This avoids emitting dead code and simplifies the CFG substantially. 308 if (!ContainsLabel(Skipped)) { 309 if (Executed) 310 EmitStmt(Executed); 311 return; 312 } 313 } 314 315 // Otherwise, the condition did not fold, or we couldn't elide it. Just emit 316 // the conditional branch. 317 llvm::BasicBlock *ThenBlock = createBasicBlock("if.then"); 318 llvm::BasicBlock *ContBlock = createBasicBlock("if.end"); 319 llvm::BasicBlock *ElseBlock = ContBlock; 320 if (S.getElse()) 321 ElseBlock = createBasicBlock("if.else"); 322 EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock); 323 324 // Emit the 'then' code. 325 EmitBlock(ThenBlock); 326 EmitStmt(S.getThen()); 327 EmitBranch(ContBlock); 328 329 // Emit the 'else' code if present. 330 if (const Stmt *Else = S.getElse()) { 331 EmitBlock(ElseBlock); 332 EmitStmt(Else); 333 EmitBranch(ContBlock); 334 } 335 336 // Emit the continuation block for code after the if. 337 EmitBlock(ContBlock, true); 338} 339 340void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) { 341 // Emit the header for the loop, insert it, which will create an uncond br to 342 // it. 343 llvm::BasicBlock *LoopHeader = createBasicBlock("while.cond"); 344 EmitBlock(LoopHeader); 345 346 // Create an exit block for when the condition fails, create a block for the 347 // body of the loop. 348 llvm::BasicBlock *ExitBlock = createBasicBlock("while.end"); 349 llvm::BasicBlock *LoopBody = createBasicBlock("while.body"); 350 351 // Store the blocks to use for break and continue. 352 BreakContinueStack.push_back(BreakContinue(ExitBlock, LoopHeader)); 353 354 // Evaluate the conditional in the while header. C99 6.8.5.1: The 355 // evaluation of the controlling expression takes place before each 356 // execution of the loop body. 357 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 358 359 // while(1) is common, avoid extra exit blocks. Be sure 360 // to correctly handle break/continue though. 361 bool EmitBoolCondBranch = true; 362 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 363 if (C->isOne()) 364 EmitBoolCondBranch = false; 365 366 // As long as the condition is true, go to the loop body. 367 if (EmitBoolCondBranch) 368 Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock); 369 370 // Emit the loop body. 371 EmitBlock(LoopBody); 372 EmitStmt(S.getBody()); 373 374 BreakContinueStack.pop_back(); 375 376 // Cycle to the condition. 377 EmitBranch(LoopHeader); 378 379 // Emit the exit block. 380 EmitBlock(ExitBlock, true); 381 382 // The LoopHeader typically is just a branch if we skipped emitting 383 // a branch, try to erase it. 384 if (!EmitBoolCondBranch) 385 SimplifyForwardingBlocks(LoopHeader); 386} 387 388void CodeGenFunction::EmitDoStmt(const DoStmt &S) { 389 // Emit the body for the loop, insert it, which will create an uncond br to 390 // it. 391 llvm::BasicBlock *LoopBody = createBasicBlock("do.body"); 392 llvm::BasicBlock *AfterDo = createBasicBlock("do.end"); 393 EmitBlock(LoopBody); 394 395 llvm::BasicBlock *DoCond = createBasicBlock("do.cond"); 396 397 // Store the blocks to use for break and continue. 398 BreakContinueStack.push_back(BreakContinue(AfterDo, DoCond)); 399 400 // Emit the body of the loop into the block. 401 EmitStmt(S.getBody()); 402 403 BreakContinueStack.pop_back(); 404 405 EmitBlock(DoCond); 406 407 // C99 6.8.5.2: "The evaluation of the controlling expression takes place 408 // after each execution of the loop body." 409 410 // Evaluate the conditional in the while header. 411 // C99 6.8.5p2/p4: The first substatement is executed if the expression 412 // compares unequal to 0. The condition must be a scalar type. 413 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 414 415 // "do {} while (0)" is common in macros, avoid extra blocks. Be sure 416 // to correctly handle break/continue though. 417 bool EmitBoolCondBranch = true; 418 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 419 if (C->isZero()) 420 EmitBoolCondBranch = false; 421 422 // As long as the condition is true, iterate the loop. 423 if (EmitBoolCondBranch) 424 Builder.CreateCondBr(BoolCondVal, LoopBody, AfterDo); 425 426 // Emit the exit block. 427 EmitBlock(AfterDo); 428 429 // The DoCond block typically is just a branch if we skipped 430 // emitting a branch, try to erase it. 431 if (!EmitBoolCondBranch) 432 SimplifyForwardingBlocks(DoCond); 433} 434 435void CodeGenFunction::EmitForStmt(const ForStmt &S) { 436 // FIXME: What do we do if the increment (f.e.) contains a stmt expression, 437 // which contains a continue/break? 438 439 // Evaluate the first part before the loop. 440 if (S.getInit()) 441 EmitStmt(S.getInit()); 442 443 // Start the loop with a block that tests the condition. 444 llvm::BasicBlock *CondBlock = createBasicBlock("for.cond"); 445 llvm::BasicBlock *AfterFor = createBasicBlock("for.end"); 446 447 EmitBlock(CondBlock); 448 449 // Evaluate the condition if present. If not, treat it as a 450 // non-zero-constant according to 6.8.5.3p2, aka, true. 451 if (S.getCond()) { 452 // As long as the condition is true, iterate the loop. 453 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 454 455 // C99 6.8.5p2/p4: The first substatement is executed if the expression 456 // compares unequal to 0. The condition must be a scalar type. 457 EmitBranchOnBoolExpr(S.getCond(), ForBody, AfterFor); 458 459 EmitBlock(ForBody); 460 } else { 461 // Treat it as a non-zero constant. Don't even create a new block for the 462 // body, just fall into it. 463 } 464 465 // If the for loop doesn't have an increment we can just use the 466 // condition as the continue block. 467 llvm::BasicBlock *ContinueBlock; 468 if (S.getInc()) 469 ContinueBlock = createBasicBlock("for.inc"); 470 else 471 ContinueBlock = CondBlock; 472 473 // Store the blocks to use for break and continue. 474 BreakContinueStack.push_back(BreakContinue(AfterFor, ContinueBlock)); 475 476 // If the condition is true, execute the body of the for stmt. 477 CGDebugInfo *DI = getDebugInfo(); 478 if (DI) { 479 DI->setLocation(S.getSourceRange().getBegin()); 480 DI->EmitRegionStart(CurFn, Builder); 481 } 482 EmitStmt(S.getBody()); 483 484 BreakContinueStack.pop_back(); 485 486 // If there is an increment, emit it next. 487 if (S.getInc()) { 488 EmitBlock(ContinueBlock); 489 EmitStmt(S.getInc()); 490 } 491 492 // Finally, branch back up to the condition for the next iteration. 493 EmitBranch(CondBlock); 494 if (DI) { 495 DI->setLocation(S.getSourceRange().getEnd()); 496 DI->EmitRegionEnd(CurFn, Builder); 497 } 498 499 // Emit the fall-through block. 500 EmitBlock(AfterFor, true); 501} 502 503void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) { 504 if (RV.isScalar()) { 505 Builder.CreateStore(RV.getScalarVal(), ReturnValue); 506 } else if (RV.isAggregate()) { 507 EmitAggregateCopy(ReturnValue, RV.getAggregateAddr(), Ty); 508 } else { 509 StoreComplexToAddr(RV.getComplexVal(), ReturnValue, false); 510 } 511 EmitBranchThroughCleanup(ReturnBlock); 512} 513 514/// EmitReturnStmt - Note that due to GCC extensions, this can have an operand 515/// if the function returns void, or may be missing one if the function returns 516/// non-void. Fun stuff :). 517void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { 518 // Emit the result value, even if unused, to evalute the side effects. 519 const Expr *RV = S.getRetValue(); 520 521 // FIXME: Clean this up by using an LValue for ReturnTemp, 522 // EmitStoreThroughLValue, and EmitAnyExpr. 523 if (!ReturnValue) { 524 // Make sure not to return anything, but evaluate the expression 525 // for side effects. 526 if (RV) 527 EmitAnyExpr(RV); 528 } else if (RV == 0) { 529 // Do nothing (return value is left uninitialized) 530 } else if (FnRetTy->isReferenceType()) { 531 // If this function returns a reference, take the address of the expression 532 // rather than the value. 533 Builder.CreateStore(EmitLValue(RV).getAddress(), ReturnValue); 534 } else if (!hasAggregateLLVMType(RV->getType())) { 535 Builder.CreateStore(EmitScalarExpr(RV), ReturnValue); 536 } else if (RV->getType()->isAnyComplexType()) { 537 EmitComplexExprIntoAddr(RV, ReturnValue, false); 538 } else { 539 EmitAggExpr(RV, ReturnValue, false); 540 } 541 542 EmitBranchThroughCleanup(ReturnBlock); 543} 544 545void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) { 546 // As long as debug info is modeled with instructions, we have to ensure we 547 // have a place to insert here and write the stop point here. 548 if (getDebugInfo()) { 549 EnsureInsertPoint(); 550 EmitStopPoint(&S); 551 } 552 553 for (DeclStmt::const_decl_iterator I = S.decl_begin(), E = S.decl_end(); 554 I != E; ++I) 555 EmitDecl(**I); 556} 557 558void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) { 559 assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!"); 560 561 // If this code is reachable then emit a stop point (if generating 562 // debug info). We have to do this ourselves because we are on the 563 // "simple" statement path. 564 if (HaveInsertPoint()) 565 EmitStopPoint(&S); 566 567 llvm::BasicBlock *Block = BreakContinueStack.back().BreakBlock; 568 EmitBranchThroughCleanup(Block); 569} 570 571void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) { 572 assert(!BreakContinueStack.empty() && "continue stmt not in a loop!"); 573 574 // If this code is reachable then emit a stop point (if generating 575 // debug info). We have to do this ourselves because we are on the 576 // "simple" statement path. 577 if (HaveInsertPoint()) 578 EmitStopPoint(&S); 579 580 llvm::BasicBlock *Block = BreakContinueStack.back().ContinueBlock; 581 EmitBranchThroughCleanup(Block); 582} 583 584/// EmitCaseStmtRange - If case statement range is not too big then 585/// add multiple cases to switch instruction, one for each value within 586/// the range. If range is too big then emit "if" condition check. 587void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { 588 assert(S.getRHS() && "Expected RHS value in CaseStmt"); 589 590 llvm::APSInt LHS = S.getLHS()->EvaluateAsInt(getContext()); 591 llvm::APSInt RHS = S.getRHS()->EvaluateAsInt(getContext()); 592 593 // Emit the code for this case. We do this first to make sure it is 594 // properly chained from our predecessor before generating the 595 // switch machinery to enter this block. 596 EmitBlock(createBasicBlock("sw.bb")); 597 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 598 EmitStmt(S.getSubStmt()); 599 600 // If range is empty, do nothing. 601 if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS)) 602 return; 603 604 llvm::APInt Range = RHS - LHS; 605 // FIXME: parameters such as this should not be hardcoded. 606 if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) { 607 // Range is small enough to add multiple switch instruction cases. 608 for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) { 609 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, LHS), CaseDest); 610 LHS++; 611 } 612 return; 613 } 614 615 // The range is too big. Emit "if" condition into a new block, 616 // making sure to save and restore the current insertion point. 617 llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock(); 618 619 // Push this test onto the chain of range checks (which terminates 620 // in the default basic block). The switch's default will be changed 621 // to the top of this chain after switch emission is complete. 622 llvm::BasicBlock *FalseDest = CaseRangeBlock; 623 CaseRangeBlock = createBasicBlock("sw.caserange"); 624 625 CurFn->getBasicBlockList().push_back(CaseRangeBlock); 626 Builder.SetInsertPoint(CaseRangeBlock); 627 628 // Emit range check. 629 llvm::Value *Diff = 630 Builder.CreateSub(SwitchInsn->getCondition(), 631 llvm::ConstantInt::get(VMContext, LHS), "tmp"); 632 llvm::Value *Cond = 633 Builder.CreateICmpULE(Diff, 634 llvm::ConstantInt::get(VMContext, Range), "tmp"); 635 Builder.CreateCondBr(Cond, CaseDest, FalseDest); 636 637 // Restore the appropriate insertion point. 638 if (RestoreBB) 639 Builder.SetInsertPoint(RestoreBB); 640 else 641 Builder.ClearInsertionPoint(); 642} 643 644void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { 645 if (S.getRHS()) { 646 EmitCaseStmtRange(S); 647 return; 648 } 649 650 EmitBlock(createBasicBlock("sw.bb")); 651 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 652 llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext()); 653 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, CaseVal), CaseDest); 654 655 // Recursively emitting the statement is acceptable, but is not wonderful for 656 // code where we have many case statements nested together, i.e.: 657 // case 1: 658 // case 2: 659 // case 3: etc. 660 // Handling this recursively will create a new block for each case statement 661 // that falls through to the next case which is IR intensive. It also causes 662 // deep recursion which can run into stack depth limitations. Handle 663 // sequential non-range case statements specially. 664 const CaseStmt *CurCase = &S; 665 const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); 666 667 // Otherwise, iteratively add consequtive cases to this switch stmt. 668 while (NextCase && NextCase->getRHS() == 0) { 669 CurCase = NextCase; 670 CaseVal = CurCase->getLHS()->EvaluateAsInt(getContext()); 671 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, CaseVal), CaseDest); 672 673 NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); 674 } 675 676 // Normal default recursion for non-cases. 677 EmitStmt(CurCase->getSubStmt()); 678} 679 680void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { 681 llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest(); 682 assert(DefaultBlock->empty() && 683 "EmitDefaultStmt: Default block already defined?"); 684 EmitBlock(DefaultBlock); 685 EmitStmt(S.getSubStmt()); 686} 687 688void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { 689 llvm::Value *CondV = EmitScalarExpr(S.getCond()); 690 691 // Handle nested switch statements. 692 llvm::SwitchInst *SavedSwitchInsn = SwitchInsn; 693 llvm::BasicBlock *SavedCRBlock = CaseRangeBlock; 694 695 // Create basic block to hold stuff that comes after switch 696 // statement. We also need to create a default block now so that 697 // explicit case ranges tests can have a place to jump to on 698 // failure. 699 llvm::BasicBlock *NextBlock = createBasicBlock("sw.epilog"); 700 llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default"); 701 SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock); 702 CaseRangeBlock = DefaultBlock; 703 704 // Clear the insertion point to indicate we are in unreachable code. 705 Builder.ClearInsertionPoint(); 706 707 // All break statements jump to NextBlock. If BreakContinueStack is non empty 708 // then reuse last ContinueBlock. 709 llvm::BasicBlock *ContinueBlock = 0; 710 if (!BreakContinueStack.empty()) 711 ContinueBlock = BreakContinueStack.back().ContinueBlock; 712 713 // Ensure any vlas created between there and here, are undone 714 BreakContinueStack.push_back(BreakContinue(NextBlock, ContinueBlock)); 715 716 // Emit switch body. 717 EmitStmt(S.getBody()); 718 719 BreakContinueStack.pop_back(); 720 721 // Update the default block in case explicit case range tests have 722 // been chained on top. 723 SwitchInsn->setSuccessor(0, CaseRangeBlock); 724 725 // If a default was never emitted then reroute any jumps to it and 726 // discard. 727 if (!DefaultBlock->getParent()) { 728 DefaultBlock->replaceAllUsesWith(NextBlock); 729 delete DefaultBlock; 730 } 731 732 // Emit continuation. 733 EmitBlock(NextBlock, true); 734 735 SwitchInsn = SavedSwitchInsn; 736 CaseRangeBlock = SavedCRBlock; 737} 738 739static std::string 740SimplifyConstraint(const char *Constraint, const TargetInfo &Target, 741 llvm::SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) { 742 std::string Result; 743 744 while (*Constraint) { 745 switch (*Constraint) { 746 default: 747 Result += Target.convertConstraint(*Constraint); 748 break; 749 // Ignore these 750 case '*': 751 case '?': 752 case '!': 753 break; 754 case 'g': 755 Result += "imr"; 756 break; 757 case '[': { 758 assert(OutCons && 759 "Must pass output names to constraints with a symbolic name"); 760 unsigned Index; 761 bool result = Target.resolveSymbolicName(Constraint, 762 &(*OutCons)[0], 763 OutCons->size(), Index); 764 assert(result && "Could not resolve symbolic name"); result=result; 765 Result += llvm::utostr(Index); 766 break; 767 } 768 } 769 770 Constraint++; 771 } 772 773 return Result; 774} 775 776llvm::Value* CodeGenFunction::EmitAsmInput(const AsmStmt &S, 777 const TargetInfo::ConstraintInfo &Info, 778 const Expr *InputExpr, 779 std::string &ConstraintStr) { 780 llvm::Value *Arg; 781 if (Info.allowsRegister() || !Info.allowsMemory()) { 782 const llvm::Type *Ty = ConvertType(InputExpr->getType()); 783 784 if (Ty->isSingleValueType()) { 785 Arg = EmitScalarExpr(InputExpr); 786 } else { 787 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 788 LValue Dest = EmitLValue(InputExpr); 789 790 uint64_t Size = CGM.getTargetData().getTypeSizeInBits(Ty); 791 if (Size <= 64 && llvm::isPowerOf2_64(Size)) { 792 Ty = llvm::IntegerType::get(VMContext, Size); 793 Ty = llvm::PointerType::getUnqual(Ty); 794 795 Arg = Builder.CreateLoad(Builder.CreateBitCast(Dest.getAddress(), Ty)); 796 } else { 797 Arg = Dest.getAddress(); 798 ConstraintStr += '*'; 799 } 800 } 801 } else { 802 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 803 LValue Dest = EmitLValue(InputExpr); 804 Arg = Dest.getAddress(); 805 ConstraintStr += '*'; 806 } 807 808 return Arg; 809} 810 811void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { 812 // Analyze the asm string to decompose it into its pieces. We know that Sema 813 // has already done this, so it is guaranteed to be successful. 814 llvm::SmallVector<AsmStmt::AsmStringPiece, 4> Pieces; 815 unsigned DiagOffs; 816 S.AnalyzeAsmString(Pieces, getContext(), DiagOffs); 817 818 // Assemble the pieces into the final asm string. 819 std::string AsmString; 820 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { 821 if (Pieces[i].isString()) 822 AsmString += Pieces[i].getString(); 823 else if (Pieces[i].getModifier() == '\0') 824 AsmString += '$' + llvm::utostr(Pieces[i].getOperandNo()); 825 else 826 AsmString += "${" + llvm::utostr(Pieces[i].getOperandNo()) + ':' + 827 Pieces[i].getModifier() + '}'; 828 } 829 830 // Get all the output and input constraints together. 831 llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; 832 llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; 833 834 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 835 TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), 836 S.getOutputName(i)); 837 bool result = Target.validateOutputConstraint(Info); 838 assert(result && "Failed to parse output constraint"); result=result; 839 OutputConstraintInfos.push_back(Info); 840 } 841 842 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 843 TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), 844 S.getInputName(i)); 845 bool result = Target.validateInputConstraint(OutputConstraintInfos.data(), 846 S.getNumOutputs(), 847 Info); result=result; 848 assert(result && "Failed to parse input constraint"); 849 InputConstraintInfos.push_back(Info); 850 } 851 852 std::string Constraints; 853 854 std::vector<LValue> ResultRegDests; 855 std::vector<QualType> ResultRegQualTys; 856 std::vector<const llvm::Type *> ResultRegTypes; 857 std::vector<const llvm::Type *> ResultTruncRegTypes; 858 std::vector<const llvm::Type*> ArgTypes; 859 std::vector<llvm::Value*> Args; 860 861 // Keep track of inout constraints. 862 std::string InOutConstraints; 863 std::vector<llvm::Value*> InOutArgs; 864 std::vector<const llvm::Type*> InOutArgTypes; 865 866 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 867 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; 868 869 // Simplify the output constraint. 870 std::string OutputConstraint(S.getOutputConstraint(i)); 871 OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1, Target); 872 873 const Expr *OutExpr = S.getOutputExpr(i); 874 OutExpr = OutExpr->IgnoreParenNoopCasts(getContext()); 875 876 LValue Dest = EmitLValue(OutExpr); 877 if (!Constraints.empty()) 878 Constraints += ','; 879 880 // If this is a register output, then make the inline asm return it 881 // by-value. If this is a memory result, return the value by-reference. 882 if (!Info.allowsMemory() && !hasAggregateLLVMType(OutExpr->getType())) { 883 Constraints += "=" + OutputConstraint; 884 ResultRegQualTys.push_back(OutExpr->getType()); 885 ResultRegDests.push_back(Dest); 886 ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType())); 887 ResultTruncRegTypes.push_back(ResultRegTypes.back()); 888 889 // If this output is tied to an input, and if the input is larger, then 890 // we need to set the actual result type of the inline asm node to be the 891 // same as the input type. 892 if (Info.hasMatchingInput()) { 893 unsigned InputNo; 894 for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) { 895 TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo]; 896 if (Input.hasTiedOperand() && 897 Input.getTiedOperand() == i) 898 break; 899 } 900 assert(InputNo != S.getNumInputs() && "Didn't find matching input!"); 901 902 QualType InputTy = S.getInputExpr(InputNo)->getType(); 903 QualType OutputTy = OutExpr->getType(); 904 905 uint64_t InputSize = getContext().getTypeSize(InputTy); 906 if (getContext().getTypeSize(OutputTy) < InputSize) { 907 // Form the asm to return the value as a larger integer type. 908 ResultRegTypes.back() = llvm::IntegerType::get(VMContext, (unsigned)InputSize); 909 } 910 } 911 } else { 912 ArgTypes.push_back(Dest.getAddress()->getType()); 913 Args.push_back(Dest.getAddress()); 914 Constraints += "=*"; 915 Constraints += OutputConstraint; 916 } 917 918 if (Info.isReadWrite()) { 919 InOutConstraints += ','; 920 921 const Expr *InputExpr = S.getOutputExpr(i); 922 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, InOutConstraints); 923 924 if (Info.allowsRegister()) 925 InOutConstraints += llvm::utostr(i); 926 else 927 InOutConstraints += OutputConstraint; 928 929 InOutArgTypes.push_back(Arg->getType()); 930 InOutArgs.push_back(Arg); 931 } 932 } 933 934 unsigned NumConstraints = S.getNumOutputs() + S.getNumInputs(); 935 936 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 937 const Expr *InputExpr = S.getInputExpr(i); 938 939 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 940 941 if (!Constraints.empty()) 942 Constraints += ','; 943 944 // Simplify the input constraint. 945 std::string InputConstraint(S.getInputConstraint(i)); 946 InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target, 947 &OutputConstraintInfos); 948 949 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints); 950 951 // If this input argument is tied to a larger output result, extend the 952 // input to be the same size as the output. The LLVM backend wants to see 953 // the input and output of a matching constraint be the same size. Note 954 // that GCC does not define what the top bits are here. We use zext because 955 // that is usually cheaper, but LLVM IR should really get an anyext someday. 956 if (Info.hasTiedOperand()) { 957 unsigned Output = Info.getTiedOperand(); 958 QualType OutputTy = S.getOutputExpr(Output)->getType(); 959 QualType InputTy = InputExpr->getType(); 960 961 if (getContext().getTypeSize(OutputTy) > 962 getContext().getTypeSize(InputTy)) { 963 // Use ptrtoint as appropriate so that we can do our extension. 964 if (isa<llvm::PointerType>(Arg->getType())) 965 Arg = Builder.CreatePtrToInt(Arg, 966 llvm::IntegerType::get(VMContext, LLVMPointerWidth)); 967 unsigned OutputSize = (unsigned)getContext().getTypeSize(OutputTy); 968 Arg = Builder.CreateZExt(Arg, llvm::IntegerType::get(VMContext, OutputSize)); 969 } 970 } 971 972 973 ArgTypes.push_back(Arg->getType()); 974 Args.push_back(Arg); 975 Constraints += InputConstraint; 976 } 977 978 // Append the "input" part of inout constraints last. 979 for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) { 980 ArgTypes.push_back(InOutArgTypes[i]); 981 Args.push_back(InOutArgs[i]); 982 } 983 Constraints += InOutConstraints; 984 985 // Clobbers 986 for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) { 987 std::string Clobber(S.getClobber(i)->getStrData(), 988 S.getClobber(i)->getByteLength()); 989 990 Clobber = Target.getNormalizedGCCRegisterName(Clobber.c_str()); 991 992 if (i != 0 || NumConstraints != 0) 993 Constraints += ','; 994 995 Constraints += "~{"; 996 Constraints += Clobber; 997 Constraints += '}'; 998 } 999 1000 // Add machine specific clobbers 1001 std::string MachineClobbers = Target.getClobbers(); 1002 if (!MachineClobbers.empty()) { 1003 if (!Constraints.empty()) 1004 Constraints += ','; 1005 Constraints += MachineClobbers; 1006 } 1007 1008 const llvm::Type *ResultType; 1009 if (ResultRegTypes.empty()) 1010 ResultType = llvm::Type::getVoidTy(VMContext); 1011 else if (ResultRegTypes.size() == 1) 1012 ResultType = ResultRegTypes[0]; 1013 else 1014 ResultType = llvm::StructType::get(VMContext, ResultRegTypes); 1015 1016 const llvm::FunctionType *FTy = 1017 llvm::FunctionType::get(ResultType, ArgTypes, false); 1018 1019 llvm::InlineAsm *IA = 1020 llvm::InlineAsm::get(FTy, AsmString, Constraints, 1021 S.isVolatile() || S.getNumOutputs() == 0); 1022 llvm::CallInst *Result = Builder.CreateCall(IA, Args.begin(), Args.end()); 1023 Result->addAttribute(~0, llvm::Attribute::NoUnwind); 1024 1025 1026 // Extract all of the register value results from the asm. 1027 std::vector<llvm::Value*> RegResults; 1028 if (ResultRegTypes.size() == 1) { 1029 RegResults.push_back(Result); 1030 } else { 1031 for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) { 1032 llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult"); 1033 RegResults.push_back(Tmp); 1034 } 1035 } 1036 1037 for (unsigned i = 0, e = RegResults.size(); i != e; ++i) { 1038 llvm::Value *Tmp = RegResults[i]; 1039 1040 // If the result type of the LLVM IR asm doesn't match the result type of 1041 // the expression, do the conversion. 1042 if (ResultRegTypes[i] != ResultTruncRegTypes[i]) { 1043 const llvm::Type *TruncTy = ResultTruncRegTypes[i]; 1044 // Truncate the integer result to the right size, note that 1045 // ResultTruncRegTypes can be a pointer. 1046 uint64_t ResSize = CGM.getTargetData().getTypeSizeInBits(TruncTy); 1047 Tmp = Builder.CreateTrunc(Tmp, llvm::IntegerType::get(VMContext, (unsigned)ResSize)); 1048 1049 if (Tmp->getType() != TruncTy) { 1050 assert(isa<llvm::PointerType>(TruncTy)); 1051 Tmp = Builder.CreateIntToPtr(Tmp, TruncTy); 1052 } 1053 } 1054 1055 EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i], 1056 ResultRegQualTys[i]); 1057 } 1058} 1059