clang/lib/Sema/ScopeInfo.cpp

   1 //===--- ScopeInfo.cpp - Information about a semantic context -------------===//
   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 // This file implements FunctionScopeInfo and its subclasses, which contain
  10 // information about a single function, block, lambda, or method body.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "clang/Sema/ScopeInfo.h"
  15 #include "clang/AST/Decl.h"
  16 #include "clang/AST/DeclCXX.h"
  17 #include "clang/AST/DeclObjC.h"
  18 #include "clang/AST/Expr.h"
  19 #include "clang/AST/ExprCXX.h"
  20 #include "clang/AST/ExprObjC.h"
  21
  22 using namespace clang;
  23 using namespace sema;
  24
  25 void FunctionScopeInfo::Clear() {
  26   HasBranchProtectedScope = false;
  27   HasBranchIntoScope = false;
  28   HasIndirectGoto = false;
  29   HasDroppedStmt = false;
  30   HasOMPDeclareReductionCombiner = false;
  31   HasFallthroughStmt = false;
  32   UsesFPIntrin = false;
  33   HasPotentialAvailabilityViolations = false;
  34   ObjCShouldCallSuper = false;
  35   ObjCIsDesignatedInit = false;
  36   ObjCWarnForNoDesignatedInitChain = false;
  37   ObjCIsSecondaryInit = false;
  38   ObjCWarnForNoInitDelegation = false;
  39   FirstReturnLoc = SourceLocation();
  40   FirstCXXOrObjCTryLoc = SourceLocation();
  41   FirstSEHTryLoc = SourceLocation();
  42   FoundImmediateEscalatingExpression = false;
  43
  44   // Coroutine state
  45   FirstCoroutineStmtLoc = SourceLocation();
  46   CoroutinePromise = nullptr;
  47   CoroutineParameterMoves.clear();
  48   NeedsCoroutineSuspends = true;
  49   CoroutineSuspends.first = nullptr;
  50   CoroutineSuspends.second = nullptr;
  51
  52   SwitchStack.clear();
  53   Returns.clear();
  54   ErrorTrap.reset();
  55   PossiblyUnreachableDiags.clear();
  56   WeakObjectUses.clear();
  57   ModifiedNonNullParams.clear();
  58   Blocks.clear();
  59   ByrefBlockVars.clear();
  60   AddrLabels.clear();
  61 }
  62
  63 static const NamedDecl *getBestPropertyDecl(const ObjCPropertyRefExpr *PropE) {
  64   if (PropE->isExplicitProperty())
  65     return PropE->getExplicitProperty();
  66
  67   return PropE->getImplicitPropertyGetter();
  68 }
  69
  70 FunctionScopeInfo::WeakObjectProfileTy::BaseInfoTy
  71 FunctionScopeInfo::WeakObjectProfileTy::getBaseInfo(const Expr *E) {
  72   E = E->IgnoreParenCasts();
  73
  74   const NamedDecl *D = nullptr;
  75   bool IsExact = false;
  76
  77   switch (E->getStmtClass()) {
  78   case Stmt::DeclRefExprClass:
  79     D = cast<DeclRefExpr>(E)->getDecl();
  80     IsExact = isa<VarDecl>(D);
  81     break;
  82   case Stmt::MemberExprClass: {
  83     const MemberExpr *ME = cast<MemberExpr>(E);
  84     D = ME->getMemberDecl();
  85     IsExact = isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts());
  86     break;
  87   }
  88   case Stmt::ObjCIvarRefExprClass: {
  89     const ObjCIvarRefExpr *IE = cast<ObjCIvarRefExpr>(E);
  90     D = IE->getDecl();
  91     IsExact = IE->getBase()->isObjCSelfExpr();
  92     break;
  93   }
  94   case Stmt::PseudoObjectExprClass: {
  95     const PseudoObjectExpr *POE = cast<PseudoObjectExpr>(E);
  96     const ObjCPropertyRefExpr *BaseProp =
  97       dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
  98     if (BaseProp) {
  99       D = getBestPropertyDecl(BaseProp);
 100
 101       if (BaseProp->isObjectReceiver()) {
 102         const Expr *DoubleBase = BaseProp->getBase();
 103         if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(DoubleBase))
 104           DoubleBase = OVE->getSourceExpr();
 105
 106         IsExact = DoubleBase->isObjCSelfExpr();
 107       }
 108     }
 109     break;
 110   }
 111   default:
 112     break;
 113   }
 114
 115   return BaseInfoTy(D, IsExact);
 116 }
 117
 118 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
 119                                           const ObjCPropertyRefExpr *PropE)
 120     : Base(nullptr, true), Property(getBestPropertyDecl(PropE)) {
 121
 122   if (PropE->isObjectReceiver()) {
 123     const OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(PropE->getBase());
 124     const Expr *E = OVE->getSourceExpr();
 125     Base = getBaseInfo(E);
 126   } else if (PropE->isClassReceiver()) {
 127     Base.setPointer(PropE->getClassReceiver());
 128   } else {
 129     assert(PropE->isSuperReceiver());
 130   }
 131 }
 132
 133 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(const Expr *BaseE,
 134                                                 const ObjCPropertyDecl *Prop)
 135     : Base(nullptr, true), Property(Prop) {
 136   if (BaseE)
 137     Base = getBaseInfo(BaseE);
 138   // else, this is a message accessing a property on super.
 139 }
 140
 141 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
 142                                                       const DeclRefExpr *DRE)
 143   : Base(nullptr, true), Property(DRE->getDecl()) {
 144   assert(isa<VarDecl>(Property));
 145 }
 146
 147 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
 148                                                   const ObjCIvarRefExpr *IvarE)
 149   : Base(getBaseInfo(IvarE->getBase())), Property(IvarE->getDecl()) {
 150 }
 151
 152 void FunctionScopeInfo::recordUseOfWeak(const ObjCMessageExpr *Msg,
 153                                         const ObjCPropertyDecl *Prop) {
 154   assert(Msg && Prop);
 155   WeakUseVector &Uses =
 156     WeakObjectUses[WeakObjectProfileTy(Msg->getInstanceReceiver(), Prop)];
 157   Uses.push_back(WeakUseTy(Msg, Msg->getNumArgs() == 0));
 158 }
 159
 160 void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
 161   E = E->IgnoreParenCasts();
 162
 163   if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
 164     markSafeWeakUse(POE->getSyntacticForm());
 165     return;
 166   }
 167
 168   if (const ConditionalOperator *Cond = dyn_cast<ConditionalOperator>(E)) {
 169     markSafeWeakUse(Cond->getTrueExpr());
 170     markSafeWeakUse(Cond->getFalseExpr());
 171     return;
 172   }
 173
 174   if (const BinaryConditionalOperator *Cond =
 175         dyn_cast<BinaryConditionalOperator>(E)) {
 176     markSafeWeakUse(Cond->getCommon());
 177     markSafeWeakUse(Cond->getFalseExpr());
 178     return;
 179   }
 180
 181   // Has this weak object been seen before?
 182   FunctionScopeInfo::WeakObjectUseMap::iterator Uses = WeakObjectUses.end();
 183   if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E)) {
 184     if (!RefExpr->isObjectReceiver())
 185       return;
 186     if (isa<OpaqueValueExpr>(RefExpr->getBase()))
 187      Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
 188     else {
 189       markSafeWeakUse(RefExpr->getBase());
 190       return;
 191     }
 192   }
 193   else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
 194     Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
 195   else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
 196     if (isa<VarDecl>(DRE->getDecl()))
 197       Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
 198   } else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
 199     if (const ObjCMethodDecl *MD = MsgE->getMethodDecl()) {
 200       if (const ObjCPropertyDecl *Prop = MD->findPropertyDecl()) {
 201         Uses =
 202           WeakObjectUses.find(WeakObjectProfileTy(MsgE->getInstanceReceiver(),
 203                                                   Prop));
 204       }
 205     }
 206   }
 207   else
 208     return;
 209
 210   if (Uses == WeakObjectUses.end())
 211     return;
 212
 213   // Has there been a read from the object using this Expr?
 214   FunctionScopeInfo::WeakUseVector::reverse_iterator ThisUse =
 215       llvm::find(llvm::reverse(Uses->second), WeakUseTy(E, true));
 216   if (ThisUse == Uses->second.rend())
 217     return;
 218
 219   ThisUse->markSafe();
 220 }
 221
 222 bool Capture::isInitCapture() const {
 223   // Note that a nested capture of an init-capture is not itself an
 224   // init-capture.
 225   return !isNested() && isVariableCapture() && getVariable()->isInitCapture();
 226 }
 227
 228 bool CapturingScopeInfo::isVLATypeCaptured(const VariableArrayType *VAT) const {
 229   for (auto &Cap : Captures)
 230     if (Cap.isVLATypeCapture() && Cap.getCapturedVLAType() == VAT)
 231       return true;
 232   return false;
 233 }
 234
 235 void LambdaScopeInfo::visitPotentialCaptures(
 236     llvm::function_ref<void(ValueDecl *, Expr *)> Callback) const {
 237   for (Expr *E : PotentiallyCapturingExprs) {
 238     if (auto *DRE = dyn_cast<DeclRefExpr>(E)) {
 239       Callback(cast<ValueDecl>(DRE->getFoundDecl()), E);
 240     } else if (auto *ME = dyn_cast<MemberExpr>(E)) {
 241       Callback(cast<ValueDecl>(ME->getMemberDecl()), E);
 242     } else if (auto *FP = dyn_cast<FunctionParmPackExpr>(E)) {
 243       for (ValueDecl *VD : *FP)
 244         Callback(VD, E);
 245     } else {
 246       llvm_unreachable("unexpected expression in potential captures list");
 247     }
 248   }
 249 }
 250
 251 bool LambdaScopeInfo::lambdaCaptureShouldBeConst() const {
 252   if (ExplicitObjectParameter)
 253     return ExplicitObjectParameter->getType()
 254         .getNonReferenceType()
 255         .isConstQualified();
 256   return !Mutable;
 257 }
 258
 259 FunctionScopeInfo::~FunctionScopeInfo() { }
 260 BlockScopeInfo::~BlockScopeInfo() { }
 261 CapturedRegionScopeInfo::~CapturedRegionScopeInfo() { }