1//===----- CGCall.h - Encapsulate calling convention details ----*- 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//
9// These classes wrap the information about a call or function
10// definition used to handle ABI compliancy.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LIB_CODEGEN_CGCALL_H
15#define LLVM_CLANG_LIB_CODEGEN_CGCALL_H
16
17#include "CGValue.h"
18#include "EHScopeStack.h"
19#include "clang/AST/ASTFwd.h"
20#include "clang/AST/CanonicalType.h"
21#include "clang/AST/GlobalDecl.h"
22#include "clang/AST/Type.h"
23#include "llvm/IR/Value.h"
24
25// FIXME: Restructure so we don't have to expose so much stuff.
26#include "ABIInfo.h"
27
28namespace llvm {
29class AttributeList;
30class Function;
31class Type;
32class Value;
33} // namespace llvm
34
35namespace clang {
36class ASTContext;
37class Decl;
38class FunctionDecl;
39class ObjCMethodDecl;
40class VarDecl;
41
42namespace CodeGen {
43
44/// Abstract information about a function or function prototype.
45class CGCalleeInfo {
46  /// The function prototype of the callee.
47  const FunctionProtoType *CalleeProtoTy;
48  /// The function declaration of the callee.
49  GlobalDecl CalleeDecl;
50
51public:
52  explicit CGCalleeInfo() : CalleeProtoTy(nullptr), CalleeDecl() {}
53  CGCalleeInfo(const FunctionProtoType *calleeProtoTy, GlobalDecl calleeDecl)
54      : CalleeProtoTy(calleeProtoTy), CalleeDecl(calleeDecl) {}
55  CGCalleeInfo(const FunctionProtoType *calleeProtoTy)
56      : CalleeProtoTy(calleeProtoTy), CalleeDecl() {}
57  CGCalleeInfo(GlobalDecl calleeDecl)
58      : CalleeProtoTy(nullptr), CalleeDecl(calleeDecl) {}
59
60  const FunctionProtoType *getCalleeFunctionProtoType() const {
61    return CalleeProtoTy;
62  }
63  const GlobalDecl getCalleeDecl() const { return CalleeDecl; }
64};
65
66/// All available information about a concrete callee.
67class CGCallee {
68  enum class SpecialKind : uintptr_t {
69    Invalid,
70    Builtin,
71    PseudoDestructor,
72    Virtual,
73
74    Last = Virtual
75  };
76
77  struct BuiltinInfoStorage {
78    const FunctionDecl *Decl;
79    unsigned ID;
80  };
81  struct PseudoDestructorInfoStorage {
82    const CXXPseudoDestructorExpr *Expr;
83  };
84  struct VirtualInfoStorage {
85    const CallExpr *CE;
86    GlobalDecl MD;
87    Address Addr;
88    llvm::FunctionType *FTy;
89  };
90
91  SpecialKind KindOrFunctionPointer;
92  union {
93    CGCalleeInfo AbstractInfo;
94    BuiltinInfoStorage BuiltinInfo;
95    PseudoDestructorInfoStorage PseudoDestructorInfo;
96    VirtualInfoStorage VirtualInfo;
97  };
98
99  explicit CGCallee(SpecialKind kind) : KindOrFunctionPointer(kind) {}
100
101  CGCallee(const FunctionDecl *builtinDecl, unsigned builtinID)
102      : KindOrFunctionPointer(SpecialKind::Builtin) {
103    BuiltinInfo.Decl = builtinDecl;
104    BuiltinInfo.ID = builtinID;
105  }
106
107public:
108  CGCallee() : KindOrFunctionPointer(SpecialKind::Invalid) {}
109
110  /// Construct a callee.  Call this constructor directly when this
111  /// isn't a direct call.
112  CGCallee(const CGCalleeInfo &abstractInfo, llvm::Value *functionPtr)
113      : KindOrFunctionPointer(SpecialKind(uintptr_t(functionPtr))) {
114    AbstractInfo = abstractInfo;
115    assert(functionPtr && "configuring callee without function pointer");
116    assert(functionPtr->getType()->isPointerTy());
117    assert(functionPtr->getType()->getPointerElementType()->isFunctionTy());
118  }
119
120  static CGCallee forBuiltin(unsigned builtinID,
121                             const FunctionDecl *builtinDecl) {
122    CGCallee result(SpecialKind::Builtin);
123    result.BuiltinInfo.Decl = builtinDecl;
124    result.BuiltinInfo.ID = builtinID;
125    return result;
126  }
127
128  static CGCallee forPseudoDestructor(const CXXPseudoDestructorExpr *E) {
129    CGCallee result(SpecialKind::PseudoDestructor);
130    result.PseudoDestructorInfo.Expr = E;
131    return result;
132  }
133
134  static CGCallee forDirect(llvm::Constant *functionPtr,
135                            const CGCalleeInfo &abstractInfo = CGCalleeInfo()) {
136    return CGCallee(abstractInfo, functionPtr);
137  }
138
139  static CGCallee forDirect(llvm::FunctionCallee functionPtr,
140                            const CGCalleeInfo &abstractInfo = CGCalleeInfo()) {
141    return CGCallee(abstractInfo, functionPtr.getCallee());
142  }
143
144  static CGCallee forVirtual(const CallExpr *CE, GlobalDecl MD, Address Addr,
145                             llvm::FunctionType *FTy) {
146    CGCallee result(SpecialKind::Virtual);
147    result.VirtualInfo.CE = CE;
148    result.VirtualInfo.MD = MD;
149    result.VirtualInfo.Addr = Addr;
150    result.VirtualInfo.FTy = FTy;
151    return result;
152  }
153
154  bool isBuiltin() const {
155    return KindOrFunctionPointer == SpecialKind::Builtin;
156  }
157  const FunctionDecl *getBuiltinDecl() const {
158    assert(isBuiltin());
159    return BuiltinInfo.Decl;
160  }
161  unsigned getBuiltinID() const {
162    assert(isBuiltin());
163    return BuiltinInfo.ID;
164  }
165
166  bool isPseudoDestructor() const {
167    return KindOrFunctionPointer == SpecialKind::PseudoDestructor;
168  }
169  const CXXPseudoDestructorExpr *getPseudoDestructorExpr() const {
170    assert(isPseudoDestructor());
171    return PseudoDestructorInfo.Expr;
172  }
173
174  bool isOrdinary() const {
175    return uintptr_t(KindOrFunctionPointer) > uintptr_t(SpecialKind::Last);
176  }
177  CGCalleeInfo getAbstractInfo() const {
178    if (isVirtual())
179      return VirtualInfo.MD;
180    assert(isOrdinary());
181    return AbstractInfo;
182  }
183  llvm::Value *getFunctionPointer() const {
184    assert(isOrdinary());
185    return reinterpret_cast<llvm::Value *>(uintptr_t(KindOrFunctionPointer));
186  }
187  void setFunctionPointer(llvm::Value *functionPtr) {
188    assert(isOrdinary());
189    KindOrFunctionPointer = SpecialKind(uintptr_t(functionPtr));
190  }
191
192  bool isVirtual() const {
193    return KindOrFunctionPointer == SpecialKind::Virtual;
194  }
195  const CallExpr *getVirtualCallExpr() const {
196    assert(isVirtual());
197    return VirtualInfo.CE;
198  }
199  GlobalDecl getVirtualMethodDecl() const {
200    assert(isVirtual());
201    return VirtualInfo.MD;
202  }
203  Address getThisAddress() const {
204    assert(isVirtual());
205    return VirtualInfo.Addr;
206  }
207  llvm::FunctionType *getVirtualFunctionType() const {
208    assert(isVirtual());
209    return VirtualInfo.FTy;
210  }
211
212  /// If this is a delayed callee computation of some sort, prepare
213  /// a concrete callee.
214  CGCallee prepareConcreteCallee(CodeGenFunction &CGF) const;
215};
216
217struct CallArg {
218private:
219  union {
220    RValue RV;
221    LValue LV; /// The argument is semantically a load from this l-value.
222  };
223  bool HasLV;
224
225  /// A data-flow flag to make sure getRValue and/or copyInto are not
226  /// called twice for duplicated IR emission.
227  mutable bool IsUsed;
228
229public:
230  QualType Ty;
231  CallArg(RValue rv, QualType ty)
232      : RV(rv), HasLV(false), IsUsed(false), Ty(ty) {}
233  CallArg(LValue lv, QualType ty)
234      : LV(lv), HasLV(true), IsUsed(false), Ty(ty) {}
235  bool hasLValue() const { return HasLV; }
236  QualType getType() const { return Ty; }
237
238  /// \returns an independent RValue. If the CallArg contains an LValue,
239  /// a temporary copy is returned.
240  RValue getRValue(CodeGenFunction &CGF) const;
241
242  LValue getKnownLValue() const {
243    assert(HasLV && !IsUsed);
244    return LV;
245  }
246  RValue getKnownRValue() const {
247    assert(!HasLV && !IsUsed);
248    return RV;
249  }
250  void setRValue(RValue _RV) {
251    assert(!HasLV);
252    RV = _RV;
253  }
254
255  bool isAggregate() const { return HasLV || RV.isAggregate(); }
256
257  void copyInto(CodeGenFunction &CGF, Address A) const;
258};
259
260/// CallArgList - Type for representing both the value and type of
261/// arguments in a call.
262class CallArgList : public SmallVector<CallArg, 8> {
263public:
264  CallArgList() : StackBase(nullptr) {}
265
266  struct Writeback {
267    /// The original argument.  Note that the argument l-value
268    /// is potentially null.
269    LValue Source;
270
271    /// The temporary alloca.
272    Address Temporary;
273
274    /// A value to "use" after the writeback, or null.
275    llvm::Value *ToUse;
276  };
277
278  struct CallArgCleanup {
279    EHScopeStack::stable_iterator Cleanup;
280
281    /// The "is active" insertion point.  This instruction is temporary and
282    /// will be removed after insertion.
283    llvm::Instruction *IsActiveIP;
284  };
285
286  void add(RValue rvalue, QualType type) { push_back(CallArg(rvalue, type)); }
287
288  void addUncopiedAggregate(LValue LV, QualType type) {
289    push_back(CallArg(LV, type));
290  }
291
292  /// Add all the arguments from another CallArgList to this one. After doing
293  /// this, the old CallArgList retains its list of arguments, but must not
294  /// be used to emit a call.
295  void addFrom(const CallArgList &other) {
296    insert(end(), other.begin(), other.end());
297    Writebacks.insert(Writebacks.end(), other.Writebacks.begin(),
298                      other.Writebacks.end());
299    CleanupsToDeactivate.insert(CleanupsToDeactivate.end(),
300                                other.CleanupsToDeactivate.begin(),
301                                other.CleanupsToDeactivate.end());
302    assert(!(StackBase && other.StackBase) && "can't merge stackbases");
303    if (!StackBase)
304      StackBase = other.StackBase;
305  }
306
307  void addWriteback(LValue srcLV, Address temporary, llvm::Value *toUse) {
308    Writeback writeback = {srcLV, temporary, toUse};
309    Writebacks.push_back(writeback);
310  }
311
312  bool hasWritebacks() const { return !Writebacks.empty(); }
313
314  typedef llvm::iterator_range<SmallVectorImpl<Writeback>::const_iterator>
315      writeback_const_range;
316
317  writeback_const_range writebacks() const {
318    return writeback_const_range(Writebacks.begin(), Writebacks.end());
319  }
320
321  void addArgCleanupDeactivation(EHScopeStack::stable_iterator Cleanup,
322                                 llvm::Instruction *IsActiveIP) {
323    CallArgCleanup ArgCleanup;
324    ArgCleanup.Cleanup = Cleanup;
325    ArgCleanup.IsActiveIP = IsActiveIP;
326    CleanupsToDeactivate.push_back(ArgCleanup);
327  }
328
329  ArrayRef<CallArgCleanup> getCleanupsToDeactivate() const {
330    return CleanupsToDeactivate;
331  }
332
333  void allocateArgumentMemory(CodeGenFunction &CGF);
334  llvm::Instruction *getStackBase() const { return StackBase; }
335  void freeArgumentMemory(CodeGenFunction &CGF) const;
336
337  /// Returns if we're using an inalloca struct to pass arguments in
338  /// memory.
339  bool isUsingInAlloca() const { return StackBase; }
340
341private:
342  SmallVector<Writeback, 1> Writebacks;
343
344  /// Deactivate these cleanups immediately before making the call.  This
345  /// is used to cleanup objects that are owned by the callee once the call
346  /// occurs.
347  SmallVector<CallArgCleanup, 1> CleanupsToDeactivate;
348
349  /// The stacksave call.  It dominates all of the argument evaluation.
350  llvm::CallInst *StackBase;
351};
352
353/// FunctionArgList - Type for representing both the decl and type
354/// of parameters to a function. The decl must be either a
355/// ParmVarDecl or ImplicitParamDecl.
356class FunctionArgList : public SmallVector<const VarDecl *, 16> {};
357
358/// ReturnValueSlot - Contains the address where the return value of a
359/// function can be stored, and whether the address is volatile or not.
360class ReturnValueSlot {
361  Address Addr = Address::invalid();
362
363  // Return value slot flags
364  unsigned IsVolatile : 1;
365  unsigned IsUnused : 1;
366  unsigned IsExternallyDestructed : 1;
367
368public:
369  ReturnValueSlot()
370      : IsVolatile(false), IsUnused(false), IsExternallyDestructed(false) {}
371  ReturnValueSlot(Address Addr, bool IsVolatile, bool IsUnused = false,
372                  bool IsExternallyDestructed = false)
373      : Addr(Addr), IsVolatile(IsVolatile), IsUnused(IsUnused),
374        IsExternallyDestructed(IsExternallyDestructed) {}
375
376  bool isNull() const { return !Addr.isValid(); }
377  bool isVolatile() const { return IsVolatile; }
378  Address getValue() const { return Addr; }
379  bool isUnused() const { return IsUnused; }
380  bool isExternallyDestructed() const { return IsExternallyDestructed; }
381};
382
383} // end namespace CodeGen
384} // end namespace clang
385
386#endif
387