clang/lib/CodeGen/CGCall.h

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