Coverage Report

Created: 2022-07-16 07:03

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/CodeGen/CGCoroutine.cpp
Line
Count
Source (jump to first uncovered line)
1
//===----- CGCoroutine.cpp - Emit LLVM Code for C++ coroutines ------------===//
2
//
3
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4
// See https://llvm.org/LICENSE.txt for license information.
5
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6
//
7
//===----------------------------------------------------------------------===//
8
//
9
// This contains code dealing with C++ code generation of coroutines.
10
//
11
//===----------------------------------------------------------------------===//
12
13
#include "CGCleanup.h"
14
#include "CodeGenFunction.h"
15
#include "llvm/ADT/ScopeExit.h"
16
#include "clang/AST/StmtCXX.h"
17
#include "clang/AST/StmtVisitor.h"
18
19
using namespace clang;
20
using namespace CodeGen;
21
22
using llvm::Value;
23
using llvm::BasicBlock;
24
25
namespace {
26
enum class AwaitKind { Init, Normal, Yield, Final };
27
static constexpr llvm::StringLiteral AwaitKindStr[] = {"init", "await", "yield",
28
                                                       "final"};
29
}
30
31
struct clang::CodeGen::CGCoroData {
32
  // What is the current await expression kind and how many
33
  // await/yield expressions were encountered so far.
34
  // These are used to generate pretty labels for await expressions in LLVM IR.
35
  AwaitKind CurrentAwaitKind = AwaitKind::Init;
36
  unsigned AwaitNum = 0;
37
  unsigned YieldNum = 0;
38
39
  // How many co_return statements are in the coroutine. Used to decide whether
40
  // we need to add co_return; equivalent at the end of the user authored body.
41
  unsigned CoreturnCount = 0;
42
43
  // A branch to this block is emitted when coroutine needs to suspend.
44
  llvm::BasicBlock *SuspendBB = nullptr;
45
46
  // The promise type's 'unhandled_exception' handler, if it defines one.
47
  Stmt *ExceptionHandler = nullptr;
48
49
  // A temporary i1 alloca that stores whether 'await_resume' threw an
50
  // exception. If it did, 'true' is stored in this variable, and the coroutine
51
  // body must be skipped. If the promise type does not define an exception
52
  // handler, this is null.
53
  llvm::Value *ResumeEHVar = nullptr;
54
55
  // Stores the jump destination just before the coroutine memory is freed.
56
  // This is the destination that every suspend point jumps to for the cleanup
57
  // branch.
58
  CodeGenFunction::JumpDest CleanupJD;
59
60
  // Stores the jump destination just before the final suspend. The co_return
61
  // statements jumps to this point after calling return_xxx promise member.
62
  CodeGenFunction::JumpDest FinalJD;
63
64
  // Stores the llvm.coro.id emitted in the function so that we can supply it
65
  // as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
66
  // Note: llvm.coro.id returns a token that cannot be directly expressed in a
67
  // builtin.
68
  llvm::CallInst *CoroId = nullptr;
69
70
  // Stores the llvm.coro.begin emitted in the function so that we can replace
71
  // all coro.frame intrinsics with direct SSA value of coro.begin that returns
72
  // the address of the coroutine frame of the current coroutine.
73
  llvm::CallInst *CoroBegin = nullptr;
74
75
  // Stores the last emitted coro.free for the deallocate expressions, we use it
76
  // to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
77
  llvm::CallInst *LastCoroFree = nullptr;
78
79
  // If coro.id came from the builtin, remember the expression to give better
80
  // diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
81
  // EmitCoroutineBody.
82
  CallExpr const *CoroIdExpr = nullptr;
83
};
84
85
// Defining these here allows to keep CGCoroData private to this file.
86
315k
clang::CodeGen::CodeGenFunction::CGCoroInfo::CGCoroInfo() {}
87
315k
CodeGenFunction::CGCoroInfo::~CGCoroInfo() {}
88
89
static void createCoroData(CodeGenFunction &CGF,
90
                           CodeGenFunction::CGCoroInfo &CurCoro,
91
                           llvm::CallInst *CoroId,
92
121
                           CallExpr const *CoroIdExpr = nullptr) {
93
121
  if (CurCoro.Data) {
94
1
    if (CurCoro.Data->CoroIdExpr)
95
1
      CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
96
1
                    "only one __builtin_coro_id can be used in a function");
97
0
    else if (CoroIdExpr)
98
0
      CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
99
0
                    "__builtin_coro_id shall not be used in a C++ coroutine");
100
0
    else
101
0
      llvm_unreachable("EmitCoroutineBodyStatement called twice?");
102
103
1
    return;
104
1
  }
105
106
120
  CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
107
120
  CurCoro.Data->CoroId = CoroId;
108
120
  CurCoro.Data->CoroIdExpr = CoroIdExpr;
109
120
}
110
111
// Synthesize a pretty name for a suspend point.
112
290
static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
113
290
  unsigned No = 0;
114
290
  switch (Kind) {
115
118
  case AwaitKind::Init:
116
231
  case AwaitKind::Final:
117
231
    break;
118
51
  case AwaitKind::Normal:
119
51
    No = ++Coro.AwaitNum;
120
51
    break;
121
8
  case AwaitKind::Yield:
122
8
    No = ++Coro.YieldNum;
123
8
    break;
124
290
  }
125
290
  SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
126
290
  if (No > 1) {
127
18
    Twine(No).toVector(Prefix);
128
18
  }
129
290
  return Prefix;
130
290
}
131
132
22
static bool memberCallExpressionCanThrow(const Expr *E) {
133
22
  if (const auto *CE = dyn_cast<CXXMemberCallExpr>(E))
134
22
    if (const auto *Proto =
135
22
            CE->getMethodDecl()->getType()->getAs<FunctionProtoType>())
136
22
      if (isNoexceptExceptionSpec(Proto->getExceptionSpecType()) &&
137
22
          
Proto->canThrow() == CT_Cannot19
)
138
19
        return false;
139
3
  return true;
140
22
}
141
142
// Emit suspend expression which roughly looks like:
143
//
144
//   auto && x = CommonExpr();
145
//   if (!x.await_ready()) {
146
//      llvm_coro_save();
147
//      x.await_suspend(...);     (*)
148
//      llvm_coro_suspend(); (**)
149
//   }
150
//   x.await_resume();
151
//
152
// where the result of the entire expression is the result of x.await_resume()
153
//
154
//   (*) If x.await_suspend return type is bool, it allows to veto a suspend:
155
//      if (x.await_suspend(...))
156
//        llvm_coro_suspend();
157
//
158
//  (**) llvm_coro_suspend() encodes three possible continuations as
159
//       a switch instruction:
160
//
161
//  %where-to = call i8 @llvm.coro.suspend(...)
162
//  switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
163
//    i8 0, label %yield.ready   ; go here when resumed
164
//    i8 1, label %yield.cleanup ; go here when destroyed
165
//  ]
166
//
167
//  See llvm's docs/Coroutines.rst for more details.
168
//
169
namespace {
170
  struct LValueOrRValue {
171
    LValue LV;
172
    RValue RV;
173
  };
174
}
175
static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
176
                                    CoroutineSuspendExpr const &S,
177
                                    AwaitKind Kind, AggValueSlot aggSlot,
178
290
                                    bool ignoreResult, bool forLValue) {
179
290
  auto *E = S.getCommonExpr();
180
181
290
  auto Binder =
182
290
      CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
183
290
  auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
184
185
290
  auto Prefix = buildSuspendPrefixStr(Coro, Kind);
186
290
  BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
187
290
  BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
188
290
  BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
189
190
  // If expression is ready, no need to suspend.
191
290
  CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
192
193
  // Otherwise, emit suspend logic.
194
290
  CGF.EmitBlock(SuspendBlock);
195
196
290
  auto &Builder = CGF.Builder;
197
290
  llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
198
290
  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
199
290
  auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
200
201
290
  auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
202
290
  if (SuspendRet != nullptr && 
SuspendRet->getType()->isIntegerTy(1)20
) {
203
    // Veto suspension if requested by bool returning await_suspend.
204
3
    BasicBlock *RealSuspendBlock =
205
3
        CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
206
3
    CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
207
3
    CGF.EmitBlock(RealSuspendBlock);
208
3
  }
209
210
  // Emit the suspend point.
211
290
  const bool IsFinalSuspend = (Kind == AwaitKind::Final);
212
290
  llvm::Function *CoroSuspend =
213
290
      CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
214
290
  auto *SuspendResult = Builder.CreateCall(
215
290
      CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
216
217
  // Create a switch capturing three possible continuations.
218
290
  auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
219
290
  Switch->addCase(Builder.getInt8(0), ReadyBlock);
220
290
  Switch->addCase(Builder.getInt8(1), CleanupBlock);
221
222
  // Emit cleanup for this suspend point.
223
290
  CGF.EmitBlock(CleanupBlock);
224
290
  CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
225
226
  // Emit await_resume expression.
227
290
  CGF.EmitBlock(ReadyBlock);
228
229
  // Exception handling requires additional IR. If the 'await_resume' function
230
  // is marked as 'noexcept', we avoid generating this additional IR.
231
290
  CXXTryStmt *TryStmt = nullptr;
232
290
  if (Coro.ExceptionHandler && 
Kind == AwaitKind::Init46
&&
233
290
      
memberCallExpressionCanThrow(S.getResumeExpr())22
) {
234
3
    Coro.ResumeEHVar =
235
3
        CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
236
3
    Builder.CreateFlagStore(true, Coro.ResumeEHVar);
237
238
3
    auto Loc = S.getResumeExpr()->getExprLoc();
239
3
    auto *Catch = new (CGF.getContext())
240
3
        CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
241
3
    auto *TryBody = CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(),
242
3
                                         FPOptionsOverride(), Loc, Loc);
243
3
    TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
244
3
    CGF.EnterCXXTryStmt(*TryStmt);
245
3
  }
246
247
290
  LValueOrRValue Res;
248
290
  if (forLValue)
249
6
    Res.LV = CGF.EmitLValue(S.getResumeExpr());
250
284
  else
251
284
    Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
252
253
290
  if (TryStmt) {
254
3
    Builder.CreateFlagStore(false, Coro.ResumeEHVar);
255
3
    CGF.ExitCXXTryStmt(*TryStmt);
256
3
  }
257
258
290
  return Res;
259
290
}
260
261
RValue CodeGenFunction::EmitCoawaitExpr(const CoawaitExpr &E,
262
                                        AggValueSlot aggSlot,
263
278
                                        bool ignoreResult) {
264
278
  return emitSuspendExpression(*this, *CurCoro.Data, E,
265
278
                               CurCoro.Data->CurrentAwaitKind, aggSlot,
266
278
                               ignoreResult, /*forLValue*/false).RV;
267
278
}
268
RValue CodeGenFunction::EmitCoyieldExpr(const CoyieldExpr &E,
269
                                        AggValueSlot aggSlot,
270
6
                                        bool ignoreResult) {
271
6
  return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
272
6
                               aggSlot, ignoreResult, /*forLValue*/false).RV;
273
6
}
274
275
114
void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
276
114
  ++CurCoro.Data->CoreturnCount;
277
114
  const Expr *RV = S.getOperand();
278
114
  if (RV && 
RV->getType()->isVoidType()13
&&
!isa<InitListExpr>(RV)4
) {
279
    // Make sure to evaluate the non initlist expression of a co_return
280
    // with a void expression for side effects.
281
2
    RunCleanupsScope cleanupScope(*this);
282
2
    EmitIgnoredExpr(RV);
283
2
  }
284
114
  EmitStmt(S.getPromiseCall());
285
114
  EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
286
114
}
287
288
289
#ifndef NDEBUG
290
static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx,
291
6
  const CoroutineSuspendExpr *E) {
292
6
  const auto *RE = E->getResumeExpr();
293
  // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
294
  // a MemberCallExpr?
295
6
  assert(isa<CallExpr>(RE) && "unexpected suspend expression type");
296
0
  return cast<CallExpr>(RE)->getCallReturnType(Ctx);
297
6
}
298
#endif
299
300
LValue
301
4
CodeGenFunction::EmitCoawaitLValue(const CoawaitExpr *E) {
302
4
  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
303
4
         "Can't have a scalar return unless the return type is a "
304
4
         "reference type!");
305
0
  return emitSuspendExpression(*this, *CurCoro.Data, *E,
306
4
                               CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
307
4
                               /*ignoreResult*/false, /*forLValue*/true).LV;
308
4
}
309
310
LValue
311
2
CodeGenFunction::EmitCoyieldLValue(const CoyieldExpr *E) {
312
2
  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
313
2
         "Can't have a scalar return unless the return type is a "
314
2
         "reference type!");
315
0
  return emitSuspendExpression(*this, *CurCoro.Data, *E,
316
2
                               AwaitKind::Yield, AggValueSlot::ignored(),
317
2
                               /*ignoreResult*/false, /*forLValue*/true).LV;
318
2
}
319
320
// Hunts for the parameter reference in the parameter copy/move declaration.
321
namespace {
322
struct GetParamRef : public StmtVisitor<GetParamRef> {
323
public:
324
  DeclRefExpr *Expr = nullptr;
325
71
  GetParamRef() {}
326
71
  void VisitDeclRefExpr(DeclRefExpr *E) {
327
71
    assert(Expr == nullptr && "multilple declref in param move");
328
0
    Expr = E;
329
71
  }
330
100
  void VisitStmt(Stmt *S) {
331
100
    for (auto *C : S->children()) {
332
100
      if (C)
333
100
        Visit(C);
334
100
    }
335
100
  }
336
};
337
}
338
339
// This class replaces references to parameters to their copies by changing
340
// the addresses in CGF.LocalDeclMap and restoring back the original values in
341
// its destructor.
342
343
namespace {
344
  struct ParamReferenceReplacerRAII {
345
    CodeGenFunction::DeclMapTy SavedLocals;
346
    CodeGenFunction::DeclMapTy& LocalDeclMap;
347
348
    ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
349
118
        : LocalDeclMap(LocalDeclMap) {}
350
351
71
    void addCopy(DeclStmt const *PM) {
352
      // Figure out what param it refers to.
353
354
71
      assert(PM->isSingleDecl());
355
0
      VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
356
71
      Expr const *InitExpr = VD->getInit();
357
71
      GetParamRef Visitor;
358
71
      Visitor.Visit(const_cast<Expr*>(InitExpr));
359
71
      assert(Visitor.Expr);
360
0
      DeclRefExpr *DREOrig = Visitor.Expr;
361
71
      auto *PD = DREOrig->getDecl();
362
363
71
      auto it = LocalDeclMap.find(PD);
364
71
      assert(it != LocalDeclMap.end() && "parameter is not found");
365
0
      SavedLocals.insert({ PD, it->second });
366
367
71
      auto copyIt = LocalDeclMap.find(VD);
368
71
      assert(copyIt != LocalDeclMap.end() && "parameter copy is not found");
369
0
      it->second = copyIt->getSecond();
370
71
    }
371
372
118
    ~ParamReferenceReplacerRAII() {
373
118
      for (auto&& SavedLocal : SavedLocals) {
374
71
        LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
375
71
      }
376
118
    }
377
  };
378
}
379
380
// For WinEH exception representation backend needs to know what funclet coro.end
381
// belongs to. That information is passed in a funclet bundle.
382
static SmallVector<llvm::OperandBundleDef, 1>
383
23
getBundlesForCoroEnd(CodeGenFunction &CGF) {
384
23
  SmallVector<llvm::OperandBundleDef, 1> BundleList;
385
386
23
  if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
387
6
    BundleList.emplace_back("funclet", EHPad);
388
389
23
  return BundleList;
390
23
}
391
392
namespace {
393
// We will insert coro.end to cut any of the destructors for objects that
394
// do not need to be destroyed once the coroutine is resumed.
395
// See llvm/docs/Coroutines.rst for more details about coro.end.
396
struct CallCoroEnd final : public EHScopeStack::Cleanup {
397
23
  void Emit(CodeGenFunction &CGF, Flags flags) override {
398
23
    auto &CGM = CGF.CGM;
399
23
    auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
400
23
    llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
401
    // See if we have a funclet bundle to associate coro.end with. (WinEH)
402
23
    auto Bundles = getBundlesForCoroEnd(CGF);
403
23
    auto *CoroEnd = CGF.Builder.CreateCall(
404
23
        CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
405
23
    if (Bundles.empty()) {
406
      // Otherwise, (landingpad model), create a conditional branch that leads
407
      // either to a cleanup block or a block with EH resume instruction.
408
17
      auto *ResumeBB = CGF.getEHResumeBlock(/*isCleanup=*/true);
409
17
      auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
410
17
      CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
411
17
      CGF.EmitBlock(CleanupContBB);
412
17
    }
413
23
  }
414
};
415
}
416
417
namespace {
418
// Make sure to call coro.delete on scope exit.
419
struct CallCoroDelete final : public EHScopeStack::Cleanup {
420
  Stmt *Deallocate;
421
422
  // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
423
424
  // Note: That deallocation will be emitted twice: once for a normal exit and
425
  // once for exceptional exit. This usage is safe because Deallocate does not
426
  // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
427
  // builds a single call to a deallocation function which is safe to emit
428
  // multiple times.
429
147
  void Emit(CodeGenFunction &CGF, Flags) override {
430
    // Remember the current point, as we are going to emit deallocation code
431
    // first to get to coro.free instruction that is an argument to a delete
432
    // call.
433
147
    BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
434
435
147
    auto *FreeBB = CGF.createBasicBlock("coro.free");
436
147
    CGF.EmitBlock(FreeBB);
437
147
    CGF.EmitStmt(Deallocate);
438
439
147
    auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
440
147
    CGF.EmitBlock(AfterFreeBB);
441
442
    // We should have captured coro.free from the emission of deallocate.
443
147
    auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
444
147
    if (!CoroFree) {
445
0
      CGF.CGM.Error(Deallocate->getBeginLoc(),
446
0
                    "Deallocation expressoin does not refer to coro.free");
447
0
      return;
448
0
    }
449
450
    // Get back to the block we were originally and move coro.free there.
451
147
    auto *InsertPt = SaveInsertBlock->getTerminator();
452
147
    CoroFree->moveBefore(InsertPt);
453
147
    CGF.Builder.SetInsertPoint(InsertPt);
454
455
    // Add if (auto *mem = coro.free) Deallocate;
456
147
    auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
457
147
    auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
458
147
    CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
459
460
    // No longer need old terminator.
461
147
    InsertPt->eraseFromParent();
462
147
    CGF.Builder.SetInsertPoint(AfterFreeBB);
463
147
  }
464
118
  explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
465
};
466
}
467
468
static void emitBodyAndFallthrough(CodeGenFunction &CGF,
469
118
                                   const CoroutineBodyStmt &S, Stmt *Body) {
470
118
  CGF.EmitStmt(Body);
471
118
  const bool CanFallthrough = CGF.Builder.GetInsertBlock();
472
118
  if (CanFallthrough)
473
31
    if (Stmt *OnFallthrough = S.getFallthroughHandler())
474
31
      CGF.EmitStmt(OnFallthrough);
475
118
}
476
477
118
void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
478
118
  auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
479
118
  auto &TI = CGM.getContext().getTargetInfo();
480
118
  unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
481
482
118
  auto *EntryBB = Builder.GetInsertBlock();
483
118
  auto *AllocBB = createBasicBlock("coro.alloc");
484
118
  auto *InitBB = createBasicBlock("coro.init");
485
118
  auto *FinalBB = createBasicBlock("coro.final");
486
118
  auto *RetBB = createBasicBlock("coro.ret");
487
488
118
  auto *CoroId = Builder.CreateCall(
489
118
      CGM.getIntrinsic(llvm::Intrinsic::coro_id),
490
118
      {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
491
118
  createCoroData(*this, CurCoro, CoroId);
492
118
  CurCoro.Data->SuspendBB = RetBB;
493
118
  assert(ShouldEmitLifetimeMarkers &&
494
118
         "Must emit lifetime intrinsics for coroutines");
495
496
  // Backend is allowed to elide memory allocations, to help it, emit
497
  // auto mem = coro.alloc() ? 0 : ... allocation code ...;
498
0
  auto *CoroAlloc = Builder.CreateCall(
499
118
      CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
500
501
118
  Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
502
503
118
  EmitBlock(AllocBB);
504
118
  auto *AllocateCall = EmitScalarExpr(S.getAllocate());
505
118
  auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
506
507
  // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
508
118
  if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
509
4
    auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
510
511
    // See if allocation was successful.
512
4
    auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
513
4
    auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
514
4
    Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
515
516
    // If not, return OnAllocFailure object.
517
4
    EmitBlock(RetOnFailureBB);
518
4
    EmitStmt(RetOnAllocFailure);
519
4
  }
520
114
  else {
521
114
    Builder.CreateBr(InitBB);
522
114
  }
523
524
118
  EmitBlock(InitBB);
525
526
  // Pass the result of the allocation to coro.begin.
527
118
  auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
528
118
  Phi->addIncoming(NullPtr, EntryBB);
529
118
  Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
530
118
  auto *CoroBegin = Builder.CreateCall(
531
118
      CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
532
118
  CurCoro.Data->CoroBegin = CoroBegin;
533
534
118
  CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
535
118
  {
536
118
    CGDebugInfo *DI = getDebugInfo();
537
118
    ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
538
118
    CodeGenFunction::RunCleanupsScope ResumeScope(*this);
539
118
    EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
540
541
    // Create mapping between parameters and copy-params for coroutine function.
542
118
    auto ParamMoves = S.getParamMoves();
543
118
    assert(
544
118
        (ParamMoves.size() == 0 || (ParamMoves.size() == FnArgs.size())) &&
545
118
        "ParamMoves and FnArgs should be the same size for coroutine function");
546
118
    if (ParamMoves.size() == FnArgs.size() && DI)
547
2
      for (const auto Pair : llvm::zip(FnArgs, ParamMoves))
548
6
        DI->getCoroutineParameterMappings().insert(
549
6
            {std::get<0>(Pair), std::get<1>(Pair)});
550
551
    // Create parameter copies. We do it before creating a promise, since an
552
    // evolution of coroutine TS may allow promise constructor to observe
553
    // parameter copies.
554
118
    for (auto *PM : S.getParamMoves()) {
555
71
      EmitStmt(PM);
556
71
      ParamReplacer.addCopy(cast<DeclStmt>(PM));
557
      // TODO: if(CoroParam(...)) need to surround ctor and dtor
558
      // for the copy, so that llvm can elide it if the copy is
559
      // not needed.
560
71
    }
561
562
118
    EmitStmt(S.getPromiseDeclStmt());
563
564
118
    Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
565
118
    auto *PromiseAddrVoidPtr =
566
118
        new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
567
    // Update CoroId to refer to the promise. We could not do it earlier because
568
    // promise local variable was not emitted yet.
569
118
    CoroId->setArgOperand(1, PromiseAddrVoidPtr);
570
571
    // ReturnValue should be valid as long as the coroutine's return type
572
    // is not void. The assertion could help us to reduce the check later.
573
118
    assert(ReturnValue.isValid() == (bool)S.getReturnStmt());
574
    // Now we have the promise, initialize the GRO.
575
    // We need to emit `get_return_object` first. According to:
576
    // [dcl.fct.def.coroutine]p7
577
    // The call to get_return_­object is sequenced before the call to
578
    // initial_suspend and is invoked at most once.
579
    //
580
    // So we couldn't emit return value when we emit return statment,
581
    // otherwise the call to get_return_object wouldn't be in front
582
    // of initial_suspend.
583
118
    if (ReturnValue.isValid()) {
584
60
      EmitAnyExprToMem(S.getReturnValue(), ReturnValue,
585
60
                       S.getReturnValue()->getType().getQualifiers(),
586
60
                       /*IsInit*/ true);
587
60
    }
588
589
118
    EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
590
591
118
    CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
592
118
    CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
593
118
    EmitStmt(S.getInitSuspendStmt());
594
118
    CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
595
596
118
    CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
597
598
118
    if (CurCoro.Data->ExceptionHandler) {
599
      // If we generated IR to record whether an exception was thrown from
600
      // 'await_resume', then use that IR to determine whether the coroutine
601
      // body should be skipped.
602
      // If we didn't generate the IR (perhaps because 'await_resume' was marked
603
      // as 'noexcept'), then we skip this check.
604
22
      BasicBlock *ContBB = nullptr;
605
22
      if (CurCoro.Data->ResumeEHVar) {
606
3
        BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
607
3
        ContBB = createBasicBlock("coro.resumed.cont");
608
3
        Value *SkipBody = Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar,
609
3
                                                 "coro.resumed.eh");
610
3
        Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
611
3
        EmitBlock(BodyBB);
612
3
      }
613
614
22
      auto Loc = S.getBeginLoc();
615
22
      CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
616
22
                         CurCoro.Data->ExceptionHandler);
617
22
      auto *TryStmt =
618
22
          CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
619
620
22
      EnterCXXTryStmt(*TryStmt);
621
22
      emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
622
22
      ExitCXXTryStmt(*TryStmt);
623
624
22
      if (ContBB)
625
3
        EmitBlock(ContBB);
626
22
    }
627
96
    else {
628
96
      emitBodyAndFallthrough(*this, S, S.getBody());
629
96
    }
630
631
    // See if we need to generate final suspend.
632
118
    const bool CanFallthrough = Builder.GetInsertBlock();
633
118
    const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
634
118
    if (CanFallthrough || 
HasCoreturns99
) {
635
113
      EmitBlock(FinalBB);
636
113
      CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
637
113
      EmitStmt(S.getFinalSuspendStmt());
638
113
    } else {
639
      // We don't need FinalBB. Emit it to make sure the block is deleted.
640
5
      EmitBlock(FinalBB, /*IsFinished=*/true);
641
5
    }
642
118
  }
643
644
0
  EmitBlock(RetBB);
645
  // Emit coro.end before getReturnStmt (and parameter destructors), since
646
  // resume and destroy parts of the coroutine should not include them.
647
118
  llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
648
118
  Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
649
650
118
  if (Stmt *Ret = S.getReturnStmt()) {
651
    // Since we already emitted the return value above, so we shouldn't
652
    // emit it again here.
653
60
    cast<ReturnStmt>(Ret)->setRetValue(nullptr);
654
60
    EmitStmt(Ret);
655
60
  }
656
657
  // LLVM require the frontend to mark the coroutine.
658
118
  CurFn->setPresplitCoroutine();
659
118
}
660
661
// Emit coroutine intrinsic and patch up arguments of the token type.
662
RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
663
646
                                               unsigned int IID) {
664
646
  SmallVector<llvm::Value *, 8> Args;
665
646
  switch (IID) {
666
49
  default:
667
49
    break;
668
  // The coro.frame builtin is replaced with an SSA value of the coro.begin
669
  // intrinsic.
670
443
  case llvm::Intrinsic::coro_frame: {
671
443
    if (CurCoro.Data && CurCoro.Data->CoroBegin) {
672
443
      return RValue::get(CurCoro.Data->CoroBegin);
673
443
    }
674
0
    CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_begin "
675
0
                                "has been used earlier in this function");
676
0
    auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
677
0
    return RValue::get(NullPtr);
678
443
  }
679
  // The following three intrinsics take a token parameter referring to a token
680
  // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
681
  // builtins, we patch it up here.
682
2
  case llvm::Intrinsic::coro_alloc:
683
4
  case llvm::Intrinsic::coro_begin:
684
153
  case llvm::Intrinsic::coro_free: {
685
153
    if (CurCoro.Data && 
CurCoro.Data->CoroId150
) {
686
150
      Args.push_back(CurCoro.Data->CoroId);
687
150
      break;
688
150
    }
689
3
    CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_id has"
690
3
                                " been used earlier in this function");
691
    // Fallthrough to the next case to add TokenNone as the first argument.
692
3
    LLVM_FALLTHROUGH;
693
3
  }
694
  // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
695
  // argument.
696
4
  case llvm::Intrinsic::coro_suspend:
697
4
    Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
698
4
    break;
699
646
  }
700
203
  for (const Expr *Arg : E->arguments())
701
235
    Args.push_back(EmitScalarExpr(Arg));
702
703
203
  llvm::Function *F = CGM.getIntrinsic(IID);
704
203
  llvm::CallInst *Call = Builder.CreateCall(F, Args);
705
706
  // Note: The following code is to enable to emit coro.id and coro.begin by
707
  // hand to experiment with coroutines in C.
708
  // If we see @llvm.coro.id remember it in the CoroData. We will update
709
  // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
710
203
  if (IID == llvm::Intrinsic::coro_id) {
711
3
    createCoroData(*this, CurCoro, Call, E);
712
3
  }
713
200
  else if (IID == llvm::Intrinsic::coro_begin) {
714
2
    if (CurCoro.Data)
715
1
      CurCoro.Data->CoroBegin = Call;
716
2
  }
717
198
  else if (IID == llvm::Intrinsic::coro_free) {
718
    // Remember the last coro_free as we need it to build the conditional
719
    // deletion of the coroutine frame.
720
149
    if (CurCoro.Data)
721
148
      CurCoro.Data->LastCoroFree = Call;
722
149
  }
723
203
  return RValue::get(Call);
724
646
}