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}