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      1 //===- DynamicExtent.cpp - Dynamic extent related APIs ----------*- 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 //  This file defines APIs that track and query dynamic extent information.
     10 //
     11 //===----------------------------------------------------------------------===//
     12 
     13 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicExtent.h"
     14 #include "clang/AST/Expr.h"
     15 #include "clang/Basic/LLVM.h"
     16 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
     17 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
     18 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
     19 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
     20 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
     21 
     22 REGISTER_MAP_WITH_PROGRAMSTATE(DynamicExtentMap, const clang::ento::MemRegion *,
     23                                clang::ento::DefinedOrUnknownSVal)
     24 
     25 namespace clang {
     26 namespace ento {
     27 
     28 DefinedOrUnknownSVal getDynamicExtent(ProgramStateRef State,
     29                                       const MemRegion *MR, SValBuilder &SVB) {
     30   MR = MR->StripCasts();
     31 
     32   if (const DefinedOrUnknownSVal *Size = State->get<DynamicExtentMap>(MR))
     33     return *Size;
     34 
     35   return MR->getMemRegionManager().getStaticSize(MR, SVB);
     36 }
     37 
     38 DefinedOrUnknownSVal getElementExtent(QualType Ty, SValBuilder &SVB) {
     39   return SVB.makeIntVal(SVB.getContext().getTypeSizeInChars(Ty).getQuantity(),
     40                         SVB.getArrayIndexType());
     41 }
     42 
     43 DefinedOrUnknownSVal getDynamicElementCount(ProgramStateRef State,
     44                                             const MemRegion *MR,
     45                                             SValBuilder &SVB,
     46                                             QualType ElementTy) {
     47   MR = MR->StripCasts();
     48 
     49   DefinedOrUnknownSVal Size = getDynamicExtent(State, MR, SVB);
     50   SVal ElementSize = getElementExtent(ElementTy, SVB);
     51 
     52   SVal ElementCount =
     53       SVB.evalBinOp(State, BO_Div, Size, ElementSize, SVB.getArrayIndexType());
     54 
     55   return ElementCount.castAs<DefinedOrUnknownSVal>();
     56 }
     57 
     58 SVal getDynamicExtentWithOffset(ProgramStateRef State, SVal BufV) {
     59   SValBuilder &SvalBuilder = State->getStateManager().getSValBuilder();
     60   const MemRegion *MRegion = BufV.getAsRegion();
     61   if (!MRegion)
     62     return UnknownVal();
     63   RegionOffset Offset = MRegion->getAsOffset();
     64   if (Offset.hasSymbolicOffset())
     65     return UnknownVal();
     66   const MemRegion *BaseRegion = MRegion->getBaseRegion();
     67   if (!BaseRegion)
     68     return UnknownVal();
     69 
     70   NonLoc OffsetInBytes = SvalBuilder.makeArrayIndex(
     71       Offset.getOffset() /
     72       MRegion->getMemRegionManager().getContext().getCharWidth());
     73   DefinedOrUnknownSVal ExtentInBytes =
     74       getDynamicExtent(State, BaseRegion, SvalBuilder);
     75 
     76   return SvalBuilder.evalBinOp(State, BinaryOperator::Opcode::BO_Sub,
     77                                ExtentInBytes, OffsetInBytes,
     78                                SvalBuilder.getArrayIndexType());
     79 }
     80 
     81 ProgramStateRef setDynamicExtent(ProgramStateRef State, const MemRegion *MR,
     82                                  DefinedOrUnknownSVal Size, SValBuilder &SVB) {
     83   MR = MR->StripCasts();
     84 
     85   if (Size.isUnknown())
     86     return State;
     87 
     88   return State->set<DynamicExtentMap>(MR->StripCasts(), Size);
     89 }
     90 
     91 } // namespace ento
     92 } // namespace clang
     93