1 //===- CoroInternal.h - Internal Coroutine interfaces ---------*- C++ -*---===//
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 // Common definitions/declarations used internally by coroutine lowering passes.
9 //===----------------------------------------------------------------------===//
10 
11 #ifndef LLVM_LIB_TRANSFORMS_COROUTINES_COROINTERNAL_H
12 #define LLVM_LIB_TRANSFORMS_COROUTINES_COROINTERNAL_H
13 
14 #include "CoroInstr.h"
15 #include "llvm/IR/IRBuilder.h"
16 
17 namespace llvm {
18 
19 class CallGraph;
20 
21 namespace coro {
22 
23 bool declaresAnyIntrinsic(const Module &M);
24 bool declaresIntrinsics(const Module &M,
25                         const std::initializer_list<StringRef>);
26 void replaceCoroFree(CoroIdInst *CoroId, bool Elide);
27 
28 /// Recover a dbg.declare prepared by the frontend and emit an alloca
29 /// holding a pointer to the coroutine frame.
30 void salvageDebugInfo(
31     SmallDenseMap<llvm::Value *, llvm::AllocaInst *, 4> &DbgPtrAllocaCache,
32     DbgVariableIntrinsic *DVI, bool OptimizeFrame);
33 
34 // Keeps data and helper functions for lowering coroutine intrinsics.
35 struct LowererBase {
36   Module &TheModule;
37   LLVMContext &Context;
38   PointerType *const Int8Ptr;
39   FunctionType *const ResumeFnType;
40   ConstantPointerNull *const NullPtr;
41 
42   LowererBase(Module &M);
43   Value *makeSubFnCall(Value *Arg, int Index, Instruction *InsertPt);
44 };
45 
46 enum class ABI {
47   /// The "resume-switch" lowering, where there are separate resume and
48   /// destroy functions that are shared between all suspend points.  The
49   /// coroutine frame implicitly stores the resume and destroy functions,
50   /// the current index, and any promise value.
51   Switch,
52 
53   /// The "returned-continuation" lowering, where each suspend point creates a
54   /// single continuation function that is used for both resuming and
55   /// destroying.  Does not support promises.
56   Retcon,
57 
58   /// The "unique returned-continuation" lowering, where each suspend point
59   /// creates a single continuation function that is used for both resuming
60   /// and destroying.  Does not support promises.  The function is known to
61   /// suspend at most once during its execution, and the return value of
62   /// the continuation is void.
63   RetconOnce,
64 
65   /// The "async continuation" lowering, where each suspend point creates a
66   /// single continuation function. The continuation function is available as an
67   /// intrinsic.
68   Async,
69 };
70 
71 // Holds structural Coroutine Intrinsics for a particular function and other
72 // values used during CoroSplit pass.
73 struct LLVM_LIBRARY_VISIBILITY Shape {
74   CoroBeginInst *CoroBegin;
75   SmallVector<AnyCoroEndInst *, 4> CoroEnds;
76   SmallVector<CoroSizeInst *, 2> CoroSizes;
77   SmallVector<CoroAlignInst *, 2> CoroAligns;
78   SmallVector<AnyCoroSuspendInst *, 4> CoroSuspends;
79   SmallVector<CallInst*, 2> SwiftErrorOps;
80 
81   // Field indexes for special fields in the switch lowering.
82   struct SwitchFieldIndex {
83     enum {
84       Resume,
85       Destroy
86 
87       // The promise field is always at a fixed offset from the start of
88       // frame given its type, but the index isn't a constant for all
89       // possible frames.
90 
91       // The switch-index field isn't at a fixed offset or index, either;
92       // we just work it in where it fits best.
93     };
94   };
95 
96   coro::ABI ABI;
97 
98   StructType *FrameTy;
99   Align FrameAlign;
100   uint64_t FrameSize;
101   Value *FramePtr;
102   BasicBlock *AllocaSpillBlock;
103 
104   /// This would only be true if optimization are enabled.
105   bool OptimizeFrame;
106 
107   struct SwitchLoweringStorage {
108     SwitchInst *ResumeSwitch;
109     AllocaInst *PromiseAlloca;
110     BasicBlock *ResumeEntryBlock;
111     unsigned IndexField;
112     unsigned IndexAlign;
113     unsigned IndexOffset;
114     bool HasFinalSuspend;
115   };
116 
117   struct RetconLoweringStorage {
118     Function *ResumePrototype;
119     Function *Alloc;
120     Function *Dealloc;
121     BasicBlock *ReturnBlock;
122     bool IsFrameInlineInStorage;
123   };
124 
125   struct AsyncLoweringStorage {
126     FunctionType *AsyncFuncTy;
127     Value *Context;
128     CallingConv::ID AsyncCC;
129     unsigned ContextArgNo;
130     uint64_t ContextHeaderSize;
131     uint64_t ContextAlignment;
132     uint64_t FrameOffset; // Start of the frame.
133     uint64_t ContextSize; // Includes frame size.
134     GlobalVariable *AsyncFuncPointer;
135 
136     Align getContextAlignment() const { return Align(ContextAlignment); }
137   };
138 
139   union {
140     SwitchLoweringStorage SwitchLowering;
141     RetconLoweringStorage RetconLowering;
142     AsyncLoweringStorage AsyncLowering;
143   };
144 
145   CoroIdInst *getSwitchCoroId() const {
146     assert(ABI == coro::ABI::Switch);
147     return cast<CoroIdInst>(CoroBegin->getId());
148   }
149 
150   AnyCoroIdRetconInst *getRetconCoroId() const {
151     assert(ABI == coro::ABI::Retcon ||
152            ABI == coro::ABI::RetconOnce);
153     return cast<AnyCoroIdRetconInst>(CoroBegin->getId());
154   }
155 
156   CoroIdAsyncInst *getAsyncCoroId() const {
157     assert(ABI == coro::ABI::Async);
158     return cast<CoroIdAsyncInst>(CoroBegin->getId());
159   }
160 
161   unsigned getSwitchIndexField() const {
162     assert(ABI == coro::ABI::Switch);
163     assert(FrameTy && "frame type not assigned");
164     return SwitchLowering.IndexField;
165   }
166   IntegerType *getIndexType() const {
167     assert(ABI == coro::ABI::Switch);
168     assert(FrameTy && "frame type not assigned");
169     return cast<IntegerType>(FrameTy->getElementType(getSwitchIndexField()));
170   }
171   ConstantInt *getIndex(uint64_t Value) const {
172     return ConstantInt::get(getIndexType(), Value);
173   }
174 
175   PointerType *getSwitchResumePointerType() const {
176     assert(ABI == coro::ABI::Switch);
177   assert(FrameTy && "frame type not assigned");
178   return cast<PointerType>(FrameTy->getElementType(SwitchFieldIndex::Resume));
179   }
180 
181   FunctionType *getResumeFunctionType() const {
182     switch (ABI) {
183     case coro::ABI::Switch:
184       return FunctionType::get(Type::getVoidTy(FrameTy->getContext()),
185                                FrameTy->getPointerTo(), /*IsVarArg*/false);
186     case coro::ABI::Retcon:
187     case coro::ABI::RetconOnce:
188       return RetconLowering.ResumePrototype->getFunctionType();
189     case coro::ABI::Async:
190       // Not used. The function type depends on the active suspend.
191       return nullptr;
192     }
193 
194     llvm_unreachable("Unknown coro::ABI enum");
195   }
196 
197   ArrayRef<Type*> getRetconResultTypes() const {
198     assert(ABI == coro::ABI::Retcon ||
199            ABI == coro::ABI::RetconOnce);
200     auto FTy = CoroBegin->getFunction()->getFunctionType();
201 
202     // The safety of all this is checked by checkWFRetconPrototype.
203     if (auto STy = dyn_cast<StructType>(FTy->getReturnType())) {
204       return STy->elements().slice(1);
205     } else {
206       return ArrayRef<Type*>();
207     }
208   }
209 
210   ArrayRef<Type*> getRetconResumeTypes() const {
211     assert(ABI == coro::ABI::Retcon ||
212            ABI == coro::ABI::RetconOnce);
213 
214     // The safety of all this is checked by checkWFRetconPrototype.
215     auto FTy = RetconLowering.ResumePrototype->getFunctionType();
216     return FTy->params().slice(1);
217   }
218 
219   CallingConv::ID getResumeFunctionCC() const {
220     switch (ABI) {
221     case coro::ABI::Switch:
222       return CallingConv::Fast;
223 
224     case coro::ABI::Retcon:
225     case coro::ABI::RetconOnce:
226       return RetconLowering.ResumePrototype->getCallingConv();
227     case coro::ABI::Async:
228       return AsyncLowering.AsyncCC;
229     }
230     llvm_unreachable("Unknown coro::ABI enum");
231   }
232 
233   AllocaInst *getPromiseAlloca() const {
234     if (ABI == coro::ABI::Switch)
235       return SwitchLowering.PromiseAlloca;
236     return nullptr;
237   }
238 
239   Instruction *getInsertPtAfterFramePtr() const {
240     if (auto *I = dyn_cast<Instruction>(FramePtr))
241       return I->getNextNode();
242     return &cast<Argument>(FramePtr)->getParent()->getEntryBlock().front();
243   }
244 
245   /// Allocate memory according to the rules of the active lowering.
246   ///
247   /// \param CG - if non-null, will be updated for the new call
248   Value *emitAlloc(IRBuilder<> &Builder, Value *Size, CallGraph *CG) const;
249 
250   /// Deallocate memory according to the rules of the active lowering.
251   ///
252   /// \param CG - if non-null, will be updated for the new call
253   void emitDealloc(IRBuilder<> &Builder, Value *Ptr, CallGraph *CG) const;
254 
255   Shape() = default;
256   explicit Shape(Function &F, bool OptimizeFrame = false)
257       : OptimizeFrame(OptimizeFrame) {
258     buildFrom(F);
259   }
260   void buildFrom(Function &F);
261 };
262 
263 void buildCoroutineFrame(Function &F, Shape &Shape);
264 CallInst *createMustTailCall(DebugLoc Loc, Function *MustTailCallFn,
265                              ArrayRef<Value *> Arguments, IRBuilder<> &);
266 } // End namespace coro.
267 } // End namespace llvm
268 
269 #endif
270