xref: /llvm-project/clang/lib/CodeGen/CGCall.h (revision 9de972e3e1ecea506a3884bd2fc47570ce83e4df) 
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 "CGPointerAuthInfo.h"
18 #include "CGValue.h"
19 #include "EHScopeStack.h"
20 #include "clang/AST/ASTFwd.h"
21 #include "clang/AST/CanonicalType.h"
22 #include "clang/AST/GlobalDecl.h"
23 #include "clang/AST/Type.h"
24 #include "llvm/ADT/STLForwardCompat.h"
25 #include "llvm/IR/Value.h"
26 
27 namespace llvm {
28 class Type;
29 class Value;
30 } // namespace llvm
31 
32 namespace clang {
33 class Decl;
34 class FunctionDecl;
35 class TargetOptions;
36 class VarDecl;
37 
38 namespace CodeGen {
39 
40 /// Abstract information about a function or function prototype.
41 class CGCalleeInfo {
42   /// The function prototype of the callee.
43   const FunctionProtoType *CalleeProtoTy;
44   /// The function declaration of the callee.
45   GlobalDecl CalleeDecl;
46 
47 public:
48   explicit CGCalleeInfo() : CalleeProtoTy(nullptr) {}
49   CGCalleeInfo(const FunctionProtoType *calleeProtoTy, GlobalDecl calleeDecl)
50       : CalleeProtoTy(calleeProtoTy), CalleeDecl(calleeDecl) {}
51   CGCalleeInfo(const FunctionProtoType *calleeProtoTy)
52       : CalleeProtoTy(calleeProtoTy) {}
53   CGCalleeInfo(GlobalDecl calleeDecl)
54       : CalleeProtoTy(nullptr), CalleeDecl(calleeDecl) {}
55 
56   const FunctionProtoType *getCalleeFunctionProtoType() const {
57     return CalleeProtoTy;
58   }
59   const GlobalDecl getCalleeDecl() const { return CalleeDecl; }
60 };
61 
62 /// All available information about a concrete callee.
63 class CGCallee {
64   enum class SpecialKind : uintptr_t {
65     Invalid,
66     Builtin,
67     PseudoDestructor,
68     Virtual,
69 
70     Last = Virtual
71   };
72 
73   struct OrdinaryInfoStorage {
74     CGCalleeInfo AbstractInfo;
75     CGPointerAuthInfo PointerAuthInfo;
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     OrdinaryInfoStorage OrdinaryInfo;
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 
107 public:
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            /* FIXME: make parameter pointerAuthInfo mandatory */
114            const CGPointerAuthInfo &pointerAuthInfo = CGPointerAuthInfo())
115       : KindOrFunctionPointer(
116             SpecialKind(reinterpret_cast<uintptr_t>(functionPtr))) {
117     OrdinaryInfo.AbstractInfo = abstractInfo;
118     OrdinaryInfo.PointerAuthInfo = pointerAuthInfo;
119     assert(functionPtr && "configuring callee without function pointer");
120     assert(functionPtr->getType()->isPointerTy());
121   }
122 
123   static CGCallee forBuiltin(unsigned builtinID,
124                              const FunctionDecl *builtinDecl) {
125     CGCallee result(SpecialKind::Builtin);
126     result.BuiltinInfo.Decl = builtinDecl;
127     result.BuiltinInfo.ID = builtinID;
128     return result;
129   }
130 
131   static CGCallee forPseudoDestructor(const CXXPseudoDestructorExpr *E) {
132     CGCallee result(SpecialKind::PseudoDestructor);
133     result.PseudoDestructorInfo.Expr = E;
134     return result;
135   }
136 
137   static CGCallee forDirect(llvm::Constant *functionPtr,
138                             const CGCalleeInfo &abstractInfo = CGCalleeInfo()) {
139     return CGCallee(abstractInfo, functionPtr);
140   }
141 
142   static CGCallee forDirect(llvm::FunctionCallee functionPtr,
143                             const CGCalleeInfo &abstractInfo = CGCalleeInfo()) {
144     return CGCallee(abstractInfo, functionPtr.getCallee());
145   }
146 
147   static CGCallee forVirtual(const CallExpr *CE, GlobalDecl MD, Address Addr,
148                              llvm::FunctionType *FTy) {
149     CGCallee result(SpecialKind::Virtual);
150     result.VirtualInfo.CE = CE;
151     result.VirtualInfo.MD = MD;
152     result.VirtualInfo.Addr = Addr;
153     result.VirtualInfo.FTy = FTy;
154     return result;
155   }
156 
157   bool isBuiltin() const {
158     return KindOrFunctionPointer == SpecialKind::Builtin;
159   }
160   const FunctionDecl *getBuiltinDecl() const {
161     assert(isBuiltin());
162     return BuiltinInfo.Decl;
163   }
164   unsigned getBuiltinID() const {
165     assert(isBuiltin());
166     return BuiltinInfo.ID;
167   }
168 
169   bool isPseudoDestructor() const {
170     return KindOrFunctionPointer == SpecialKind::PseudoDestructor;
171   }
172   const CXXPseudoDestructorExpr *getPseudoDestructorExpr() const {
173     assert(isPseudoDestructor());
174     return PseudoDestructorInfo.Expr;
175   }
176 
177   bool isOrdinary() const {
178     return uintptr_t(KindOrFunctionPointer) > uintptr_t(SpecialKind::Last);
179   }
180   CGCalleeInfo getAbstractInfo() const {
181     if (isVirtual())
182       return VirtualInfo.MD;
183     assert(isOrdinary());
184     return OrdinaryInfo.AbstractInfo;
185   }
186   const CGPointerAuthInfo &getPointerAuthInfo() const {
187     assert(isOrdinary());
188     return OrdinaryInfo.PointerAuthInfo;
189   }
190   llvm::Value *getFunctionPointer() const {
191     assert(isOrdinary());
192     return reinterpret_cast<llvm::Value *>(uintptr_t(KindOrFunctionPointer));
193   }
194   void setFunctionPointer(llvm::Value *functionPtr) {
195     assert(isOrdinary());
196     KindOrFunctionPointer =
197         SpecialKind(reinterpret_cast<uintptr_t>(functionPtr));
198   }
199   void setPointerAuthInfo(CGPointerAuthInfo PointerAuth) {
200     assert(isOrdinary());
201     OrdinaryInfo.PointerAuthInfo = PointerAuth;
202   }
203 
204   bool isVirtual() const {
205     return KindOrFunctionPointer == SpecialKind::Virtual;
206   }
207   const CallExpr *getVirtualCallExpr() const {
208     assert(isVirtual());
209     return VirtualInfo.CE;
210   }
211   GlobalDecl getVirtualMethodDecl() const {
212     assert(isVirtual());
213     return VirtualInfo.MD;
214   }
215   Address getThisAddress() const {
216     assert(isVirtual());
217     return VirtualInfo.Addr;
218   }
219   llvm::FunctionType *getVirtualFunctionType() const {
220     assert(isVirtual());
221     return VirtualInfo.FTy;
222   }
223 
224   /// If this is a delayed callee computation of some sort, prepare
225   /// a concrete callee.
226   CGCallee prepareConcreteCallee(CodeGenFunction &CGF) const;
227 };
228 
229 struct CallArg {
230 private:
231   union {
232     RValue RV;
233     LValue LV; /// The argument is semantically a load from this l-value.
234   };
235   bool HasLV;
236 
237   /// A data-flow flag to make sure getRValue and/or copyInto are not
238   /// called twice for duplicated IR emission.
239   mutable bool IsUsed;
240 
241 public:
242   QualType Ty;
243   CallArg(RValue rv, QualType ty)
244       : RV(rv), HasLV(false), IsUsed(false), Ty(ty) {}
245   CallArg(LValue lv, QualType ty)
246       : LV(lv), HasLV(true), IsUsed(false), Ty(ty) {}
247   bool hasLValue() const { return HasLV; }
248   QualType getType() const { return Ty; }
249 
250   /// \returns an independent RValue. If the CallArg contains an LValue,
251   /// a temporary copy is returned.
252   RValue getRValue(CodeGenFunction &CGF) const;
253 
254   LValue getKnownLValue() const {
255     assert(HasLV && !IsUsed);
256     return LV;
257   }
258   RValue getKnownRValue() const {
259     assert(!HasLV && !IsUsed);
260     return RV;
261   }
262   void setRValue(RValue _RV) {
263     assert(!HasLV);
264     RV = _RV;
265   }
266 
267   bool isAggregate() const { return HasLV || RV.isAggregate(); }
268 
269   void copyInto(CodeGenFunction &CGF, Address A) const;
270 };
271 
272 /// CallArgList - Type for representing both the value and type of
273 /// arguments in a call.
274 class CallArgList : public SmallVector<CallArg, 8> {
275 public:
276   CallArgList() = default;
277 
278   struct Writeback {
279     /// The original argument.  Note that the argument l-value
280     /// is potentially null.
281     LValue Source;
282 
283     /// The temporary alloca.
284     Address Temporary;
285 
286     /// A value to "use" after the writeback, or null.
287     llvm::Value *ToUse;
288 
289     /// An Expression (optional) that performs the writeback with any required
290     /// casting.
291     const Expr *WritebackExpr;
292 
293     // Size for optional lifetime end on the temporary.
294     llvm::Value *LifetimeSz;
295   };
296 
297   struct CallArgCleanup {
298     EHScopeStack::stable_iterator Cleanup;
299 
300     /// The "is active" insertion point.  This instruction is temporary and
301     /// will be removed after insertion.
302     llvm::Instruction *IsActiveIP;
303   };
304 
305   void add(RValue rvalue, QualType type) { push_back(CallArg(rvalue, type)); }
306 
307   void addUncopiedAggregate(LValue LV, QualType type) {
308     push_back(CallArg(LV, type));
309   }
310 
311   /// Add all the arguments from another CallArgList to this one. After doing
312   /// this, the old CallArgList retains its list of arguments, but must not
313   /// be used to emit a call.
314   void addFrom(const CallArgList &other) {
315     insert(end(), other.begin(), other.end());
316     Writebacks.insert(Writebacks.end(), other.Writebacks.begin(),
317                       other.Writebacks.end());
318     CleanupsToDeactivate.insert(CleanupsToDeactivate.end(),
319                                 other.CleanupsToDeactivate.begin(),
320                                 other.CleanupsToDeactivate.end());
321     assert(!(StackBase && other.StackBase) && "can't merge stackbases");
322     if (!StackBase)
323       StackBase = other.StackBase;
324   }
325 
326   void addWriteback(LValue srcLV, Address temporary, llvm::Value *toUse,
327                     const Expr *writebackExpr = nullptr,
328                     llvm::Value *lifetimeSz = nullptr) {
329     Writeback writeback = {srcLV, temporary, toUse, writebackExpr, lifetimeSz};
330     Writebacks.push_back(writeback);
331   }
332 
333   bool hasWritebacks() const { return !Writebacks.empty(); }
334 
335   typedef llvm::iterator_range<SmallVectorImpl<Writeback>::const_iterator>
336       writeback_const_range;
337 
338   writeback_const_range writebacks() const {
339     return writeback_const_range(Writebacks.begin(), Writebacks.end());
340   }
341 
342   void addArgCleanupDeactivation(EHScopeStack::stable_iterator Cleanup,
343                                  llvm::Instruction *IsActiveIP) {
344     CallArgCleanup ArgCleanup;
345     ArgCleanup.Cleanup = Cleanup;
346     ArgCleanup.IsActiveIP = IsActiveIP;
347     CleanupsToDeactivate.push_back(ArgCleanup);
348   }
349 
350   ArrayRef<CallArgCleanup> getCleanupsToDeactivate() const {
351     return CleanupsToDeactivate;
352   }
353 
354   void allocateArgumentMemory(CodeGenFunction &CGF);
355   llvm::Instruction *getStackBase() const { return StackBase; }
356   void freeArgumentMemory(CodeGenFunction &CGF) const;
357 
358   /// Returns if we're using an inalloca struct to pass arguments in
359   /// memory.
360   bool isUsingInAlloca() const { return StackBase; }
361 
362   // Support reversing writebacks for MSVC ABI.
363   void reverseWritebacks() {
364     std::reverse(Writebacks.begin(), Writebacks.end());
365   }
366 
367 private:
368   SmallVector<Writeback, 1> Writebacks;
369 
370   /// Deactivate these cleanups immediately before making the call.  This
371   /// is used to cleanup objects that are owned by the callee once the call
372   /// occurs.
373   SmallVector<CallArgCleanup, 1> CleanupsToDeactivate;
374 
375   /// The stacksave call.  It dominates all of the argument evaluation.
376   llvm::CallInst *StackBase = nullptr;
377 };
378 
379 /// FunctionArgList - Type for representing both the decl and type
380 /// of parameters to a function. The decl must be either a
381 /// ParmVarDecl or ImplicitParamDecl.
382 class FunctionArgList : public SmallVector<const VarDecl *, 16> {};
383 
384 /// ReturnValueSlot - Contains the address where the return value of a
385 /// function can be stored, and whether the address is volatile or not.
386 class ReturnValueSlot {
387   Address Addr = Address::invalid();
388 
389   // Return value slot flags
390   LLVM_PREFERRED_TYPE(bool)
391   unsigned IsVolatile : 1;
392   LLVM_PREFERRED_TYPE(bool)
393   unsigned IsUnused : 1;
394   LLVM_PREFERRED_TYPE(bool)
395   unsigned IsExternallyDestructed : 1;
396 
397 public:
398   ReturnValueSlot()
399       : IsVolatile(false), IsUnused(false), IsExternallyDestructed(false) {}
400   ReturnValueSlot(Address Addr, bool IsVolatile, bool IsUnused = false,
401                   bool IsExternallyDestructed = false)
402       : Addr(Addr), IsVolatile(IsVolatile), IsUnused(IsUnused),
403         IsExternallyDestructed(IsExternallyDestructed) {}
404 
405   bool isNull() const { return !Addr.isValid(); }
406   bool isVolatile() const { return IsVolatile; }
407   Address getValue() const { return Addr; }
408   bool isUnused() const { return IsUnused; }
409   bool isExternallyDestructed() const { return IsExternallyDestructed; }
410   Address getAddress() const { return Addr; }
411 };
412 
413 /// Adds attributes to \p F according to our \p CodeGenOpts and \p LangOpts, as
414 /// though we had emitted it ourselves. We remove any attributes on F that
415 /// conflict with the attributes we add here.
416 ///
417 /// This is useful for adding attrs to bitcode modules that you want to link
418 /// with but don't control, such as CUDA's libdevice.  When linking with such
419 /// a bitcode library, you might want to set e.g. its functions'
420 /// "unsafe-fp-math" attribute to match the attr of the functions you're
421 /// codegen'ing.  Otherwise, LLVM will interpret the bitcode module's lack of
422 /// unsafe-fp-math attrs as tantamount to unsafe-fp-math=false, and then LLVM
423 /// will propagate unsafe-fp-math=false up to every transitive caller of a
424 /// function in the bitcode library!
425 ///
426 /// With the exception of fast-math attrs, this will only make the attributes
427 /// on the function more conservative.  But it's unsafe to call this on a
428 /// function which relies on particular fast-math attributes for correctness.
429 /// It's up to you to ensure that this is safe.
430 void mergeDefaultFunctionDefinitionAttributes(llvm::Function &F,
431                                               const CodeGenOptions &CodeGenOpts,
432                                               const LangOptions &LangOpts,
433                                               const TargetOptions &TargetOpts,
434                                               bool WillInternalize);
435 
436 enum class FnInfoOpts {
437   None = 0,
438   IsInstanceMethod = 1 << 0,
439   IsChainCall = 1 << 1,
440   IsDelegateCall = 1 << 2,
441 };
442 
443 inline FnInfoOpts operator|(FnInfoOpts A, FnInfoOpts B) {
444   return static_cast<FnInfoOpts>(llvm::to_underlying(A) |
445                                  llvm::to_underlying(B));
446 }
447 
448 inline FnInfoOpts operator&(FnInfoOpts A, FnInfoOpts B) {
449   return static_cast<FnInfoOpts>(llvm::to_underlying(A) &
450                                  llvm::to_underlying(B));
451 }
452 
453 inline FnInfoOpts &operator|=(FnInfoOpts &A, FnInfoOpts B) {
454   A = A | B;
455   return A;
456 }
457 
458 inline FnInfoOpts &operator&=(FnInfoOpts &A, FnInfoOpts B) {
459   A = A & B;
460   return A;
461 }
462 
463 } // end namespace CodeGen
464 } // end namespace clang
465 
466 #endif
467