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(
114 SpecialKind(reinterpret_cast<uintptr_t>(functionPtr))) {
115 AbstractInfo = abstractInfo;
116 assert(functionPtr && "configuring callee without function pointer");
117 assert(functionPtr->getType()->isPointerTy());
118 assert(functionPtr->getType()->getPointerElementType()->isFunctionTy());
119 }
120
121 static CGCallee forBuiltin(unsigned builtinID,
122 const FunctionDecl *builtinDecl) {
123 CGCallee result(SpecialKind::Builtin);
124 result.BuiltinInfo.Decl = builtinDecl;
125 result.BuiltinInfo.ID = builtinID;
126 return result;
127 }
128
129 static CGCallee forPseudoDestructor(const CXXPseudoDestructorExpr *E) {
130 CGCallee result(SpecialKind::PseudoDestructor);
131 result.PseudoDestructorInfo.Expr = E;
132 return result;
133 }
134
135 static CGCallee forDirect(llvm::Constant *functionPtr,
136 const CGCalleeInfo &abstractInfo = CGCalleeInfo()) {
137 return CGCallee(abstractInfo, functionPtr);
138 }
139
140 static CGCallee forDirect(llvm::FunctionCallee functionPtr,
141 const CGCalleeInfo &abstractInfo = CGCalleeInfo()) {
142 return CGCallee(abstractInfo, functionPtr.getCallee());
143 }
144
145 static CGCallee forVirtual(const CallExpr *CE, GlobalDecl MD, Address Addr,
146 llvm::FunctionType *FTy) {
147 CGCallee result(SpecialKind::Virtual);
148 result.VirtualInfo.CE = CE;
149 result.VirtualInfo.MD = MD;
150 result.VirtualInfo.Addr = Addr;
151 result.VirtualInfo.FTy = FTy;
152 return result;
153 }
154
155 bool isBuiltin() const {
156 return KindOrFunctionPointer == SpecialKind::Builtin;
157 }
158 const FunctionDecl *getBuiltinDecl() const {
159 assert(isBuiltin());
160 return BuiltinInfo.Decl;
161 }
162 unsigned getBuiltinID() const {
163 assert(isBuiltin());
164 return BuiltinInfo.ID;
165 }
166
167 bool isPseudoDestructor() const {
168 return KindOrFunctionPointer == SpecialKind::PseudoDestructor;
169 }
170 const CXXPseudoDestructorExpr *getPseudoDestructorExpr() const {
171 assert(isPseudoDestructor());
172 return PseudoDestructorInfo.Expr;
173 }
174
175 bool isOrdinary() const {
176 return uintptr_t(KindOrFunctionPointer) > uintptr_t(SpecialKind::Last);
177 }
178 CGCalleeInfo getAbstractInfo() const {
179 if (isVirtual())
180 return VirtualInfo.MD;
181 assert(isOrdinary());
182 return AbstractInfo;
183 }
184 llvm::Value *getFunctionPointer() const {
185 assert(isOrdinary());
186 return reinterpret_cast<llvm::Value *>(uintptr_t(KindOrFunctionPointer));
187 }
188 void setFunctionPointer(llvm::Value *functionPtr) {
189 assert(isOrdinary());
190 KindOrFunctionPointer =
191 SpecialKind(reinterpret_cast<uintptr_t>(functionPtr));
192 }
193
194 bool isVirtual() const {
195 return KindOrFunctionPointer == SpecialKind::Virtual;
196 }
197 const CallExpr *getVirtualCallExpr() const {
198 assert(isVirtual());
199 return VirtualInfo.CE;
200 }
201 GlobalDecl getVirtualMethodDecl() const {
202 assert(isVirtual());
203 return VirtualInfo.MD;
204 }
205 Address getThisAddress() const {
206 assert(isVirtual());
207 return VirtualInfo.Addr;
208 }
209 llvm::FunctionType *getVirtualFunctionType() const {
210 assert(isVirtual());
211 return VirtualInfo.FTy;
212 }
213
214 /// If this is a delayed callee computation of some sort, prepare
215 /// a concrete callee.
216 CGCallee prepareConcreteCallee(CodeGenFunction &CGF) const;
217};
218
219struct CallArg {
220private:
221 union {
222 RValue RV;
223 LValue LV; /// The argument is semantically a load from this l-value.
224 };
225 bool HasLV;
226
227 /// A data-flow flag to make sure getRValue and/or copyInto are not
228 /// called twice for duplicated IR emission.
229 mutable bool IsUsed;
230
231public:
232 QualType Ty;
233 CallArg(RValue rv, QualType ty)
234 : RV(rv), HasLV(false), IsUsed(false), Ty(ty) {}
235 CallArg(LValue lv, QualType ty)
236 : LV(lv), HasLV(true), IsUsed(false), Ty(ty) {}
237 bool hasLValue() const { return HasLV; }
238 QualType getType() const { return Ty; }
239
240 /// \returns an independent RValue. If the CallArg contains an LValue,
241 /// a temporary copy is returned.
242 RValue getRValue(CodeGenFunction &CGF) const;
243
244 LValue getKnownLValue() const {
245 assert(HasLV && !IsUsed);
246 return LV;
247 }
248 RValue getKnownRValue() const {
249 assert(!HasLV && !IsUsed);
250 return RV;
251 }
252 void setRValue(RValue _RV) {
253 assert(!HasLV);
254 RV = _RV;
255 }
256
257 bool isAggregate() const { return HasLV || RV.isAggregate(); }
258
259 void copyInto(CodeGenFunction &CGF, Address A) const;
260};
261
262/// CallArgList - Type for representing both the value and type of
263/// arguments in a call.
264class CallArgList : public SmallVector<CallArg, 8> {
265public:
266 CallArgList() : StackBase(nullptr) {}
267
268 struct Writeback {
269 /// The original argument. Note that the argument l-value
270 /// is potentially null.
271 LValue Source;
272
273 /// The temporary alloca.
274 Address Temporary;
275
276 /// A value to "use" after the writeback, or null.
277 llvm::Value *ToUse;
278 };
279
280 struct CallArgCleanup {
281 EHScopeStack::stable_iterator Cleanup;
282
283 /// The "is active" insertion point. This instruction is temporary and
284 /// will be removed after insertion.
285 llvm::Instruction *IsActiveIP;
286 };
287
288 void add(RValue rvalue, QualType type) { push_back(CallArg(rvalue, type)); }
289
290 void addUncopiedAggregate(LValue LV, QualType type) {
291 push_back(CallArg(LV, type));
292 }
293
294 /// Add all the arguments from another CallArgList to this one. After doing
295 /// this, the old CallArgList retains its list of arguments, but must not
296 /// be used to emit a call.
297 void addFrom(const CallArgList &other) {
298 insert(end(), other.begin(), other.end());
299 Writebacks.insert(Writebacks.end(), other.Writebacks.begin(),
300 other.Writebacks.end());
301 CleanupsToDeactivate.insert(CleanupsToDeactivate.end(),
302 other.CleanupsToDeactivate.begin(),
303 other.CleanupsToDeactivate.end());
304 assert(!(StackBase && other.StackBase) && "can't merge stackbases");
305 if (!StackBase)
306 StackBase = other.StackBase;
307 }
308
309 void addWriteback(LValue srcLV, Address temporary, llvm::Value *toUse) {
310 Writeback writeback = {srcLV, temporary, toUse};
311 Writebacks.push_back(writeback);
312 }
313
314 bool hasWritebacks() const { return !Writebacks.empty(); }
315
316 typedef llvm::iterator_range<SmallVectorImpl<Writeback>::const_iterator>
317 writeback_const_range;
318
319 writeback_const_range writebacks() const {
320 return writeback_const_range(Writebacks.begin(), Writebacks.end());
321 }
322
323 void addArgCleanupDeactivation(EHScopeStack::stable_iterator Cleanup,
324 llvm::Instruction *IsActiveIP) {
325 CallArgCleanup ArgCleanup;
326 ArgCleanup.Cleanup = Cleanup;
327 ArgCleanup.IsActiveIP = IsActiveIP;
328 CleanupsToDeactivate.push_back(ArgCleanup);
329 }
330
331 ArrayRef<CallArgCleanup> getCleanupsToDeactivate() const {
332 return CleanupsToDeactivate;
333 }
334
335 void allocateArgumentMemory(CodeGenFunction &CGF);
336 llvm::Instruction *getStackBase() const { return StackBase; }
337 void freeArgumentMemory(CodeGenFunction &CGF) const;
338
339 /// Returns if we're using an inalloca struct to pass arguments in
340 /// memory.
341 bool isUsingInAlloca() const { return StackBase; }
342
343private:
344 SmallVector<Writeback, 1> Writebacks;
345
346 /// Deactivate these cleanups immediately before making the call. This
347 /// is used to cleanup objects that are owned by the callee once the call
348 /// occurs.
349 SmallVector<CallArgCleanup, 1> CleanupsToDeactivate;
350
351 /// The stacksave call. It dominates all of the argument evaluation.
352 llvm::CallInst *StackBase;
353};
354
355/// FunctionArgList - Type for representing both the decl and type
356/// of parameters to a function. The decl must be either a
357/// ParmVarDecl or ImplicitParamDecl.
358class FunctionArgList : public SmallVector<const VarDecl *, 16> {};
359
360/// ReturnValueSlot - Contains the address where the return value of a
361/// function can be stored, and whether the address is volatile or not.
362class ReturnValueSlot {
363 Address Addr = Address::invalid();
364
365 // Return value slot flags
366 unsigned IsVolatile : 1;
367 unsigned IsUnused : 1;
368 unsigned IsExternallyDestructed : 1;
369
370public:
371 ReturnValueSlot()
372 : IsVolatile(false), IsUnused(false), IsExternallyDestructed(false) {}
373 ReturnValueSlot(Address Addr, bool IsVolatile, bool IsUnused = false,
374 bool IsExternallyDestructed = false)
375 : Addr(Addr), IsVolatile(IsVolatile), IsUnused(IsUnused),
376 IsExternallyDestructed(IsExternallyDestructed) {}
377
378 bool isNull() const { return !Addr.isValid(); }
379 bool isVolatile() const { return IsVolatile; }
380 Address getValue() const { return Addr; }
381 bool isUnused() const { return IsUnused; }
382 bool isExternallyDestructed() const { return IsExternallyDestructed; }
383};
384
385} // end namespace CodeGen
386} // end namespace clang
387
388#endif
389