Unverified Commit a699b25b authored by Timm Baeder's avatar Timm Baeder Committed by GitHub
Browse files

[clang][bytecode] Check reference initializers for one-past-the-end pointers (#195501)

parent 25073147

clang/lib/AST/ByteCode/Compiler.cpp

+17 −4
Original line number Diff line number Diff line
@@ -5238,8 +5238,9 @@ template <class Emitter> 
VarCreationState Compiler<Emitter>::visitVarDecl(const VarDecl *VD,

                                                 const Expr *Init,

                                                 bool Toplevel) {

  QualType VarTy = VD->getType();

  // We don't know what to do with these, so just return false.

  if (VD->getType().isNull())

  if (VarTy.isNull())

    return false;



  // This case is EvalEmitter-only. If we won't create any instructions for the
@@ -5299,8 +5300,8 @@ VarCreationState Compiler<Emitter>::visitVarDecl(const VarDecl *VD, 


  if (VarT) {

    unsigned Offset = this->allocateLocalPrimitive(

        VD, *VarT, VD->getType().isConstQualified(),

        VD->getType().isVolatileQualified(), ScopeKind::Block);

        VD, *VarT, VarTy.isConstQualified(), VarTy.isVolatileQualified(),

        ScopeKind::Block);



    if (!Init || Init->getType()->isVoidType())

      return true;
@@ -5315,11 +5316,23 @@ VarCreationState Compiler<Emitter>::visitVarDecl(const VarDecl *VD, 
    }

    if (!this->visit(Init))

      return false;



    if (VarTy->isReferenceType()) {

      // [C++26][decl.ref]

      // The object designated by such a glvalue can be outside its lifetime

      // Because a null pointer value or a pointer past the end of an object

      // does not point to an object, a reference in a well-defined program

      // cannot refer to such things;

      assert(classifyPrim(VarTy) == PT_Ptr);

      if (!this->emitCheckRefInit(Init))

        return false;

    }



    return this->emitSetLocal(*VarT, Offset, VD);

  }

  // Local composite variables.

  if (UnsignedOrNone Offset =

          this->allocateLocal(VD, VD->getType(), ScopeKind::Block)) {

          this->allocateLocal(VD, VarTy, ScopeKind::Block)) {

    if (!Init)

      return true;

clang/lib/AST/ByteCode/Interp.h

+5 −0
Original line number Diff line number Diff line
@@ -1977,6 +1977,11 @@ inline bool GetRefLocal(InterpState &S, CodePtr OpPC, uint32_t I) { 
  return handleReference(S, OpPC, LocalBlock);

}



inline bool CheckRefInit(InterpState &S, CodePtr OpPC) {

  const Pointer &Ptr = S.Stk.peek<Pointer>();

  return CheckRange(S, OpPC, Ptr, AK_Read);

}



inline bool GetPtrParam(InterpState &S, CodePtr OpPC, uint32_t Index) {

  if (S.Current->isBottomFrame())

    return false;

clang/lib/AST/ByteCode/Opcodes.td

+3 −0
Original line number Diff line number Diff line
@@ -325,6 +325,9 @@ def GetPtrLocal : OffsetOpcode { 
def GetRefLocal : OffsetOpcode {

  bit HasCustomEval = 1;

}



def CheckRefInit : Opcode {}



// [] -> [Pointer]

def GetPtrParam : OffsetOpcode;

// [] -> [Pointer]

clang/test/AST/ByteCode/cxx14.cpp

+7 −0
Original line number Diff line number Diff line
@@ -28,3 +28,10 @@ constexpr int foo() { 
  return s.b[0];

}

static_assert(foo() == 12, "");



int arr[3]; // both-note {{declared here}}

constexpr bool f() { // both-error {{constexpr function never produces a constant expression}}

  int &r  = arr[3]; // both-note {{read of dereferenced one-past-the-end pointer}} \

                    // both-warning {{array index 3 is past the end of the array}}

  return true;

}