[PATCH] D40939: [analyzer] Avoid element regions of void type.

[Roman Lebedev via cfe-commits]

On Tue, Dec 19, 2017 at 8:26 PM, Artem Dergachev via Phabricator via
cfe-commits <cfe-commits at lists.llvm.org> wrote:
> NoQ updated this revision to Diff 127548.
> NoQ added a comment.
>
> - Fix comments as suggested by Devin.
> - Point out that arithmetic on void pointers is a GNU extension.
>
>
> https://reviews.llvm.org/D40939
>
> Files:
>   include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
>   lib/StaticAnalyzer/Core/ExprEngine.cpp
>   lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
No tests?

> Index: lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
> ===================================================================
> --- lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
> +++ lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
> @@ -988,6 +988,12 @@
>          elementType = resultTy->getPointeeType();
>      }
>
> +    // Represent arithmetic on void pointers as arithmetic on char pointers.
> +    // It is fine when a TypedValueRegion of char value type represents
> +    // a void pointer. Note that arithmetic on void pointers is a GCC extension.
> +    if (elementType->isVoidType())
> +      elementType = getContext().CharTy;
> +
>      if (Optional<NonLoc> indexV = index.getAs<NonLoc>()) {
>        return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV,
>                                                         superR, getContext()));
> Index: lib/StaticAnalyzer/Core/ExprEngine.cpp
> ===================================================================
> --- lib/StaticAnalyzer/Core/ExprEngine.cpp
> +++ lib/StaticAnalyzer/Core/ExprEngine.cpp
> @@ -2178,9 +2178,17 @@
>      ProgramStateRef state = Node->getState();
>
>      if (IsGLValueLike) {
> -      SVal V = state->getLValue(A->getType(),
> -          state->getSVal(Idx, LCtx),
> -          state->getSVal(Base, LCtx));
> +      QualType T = A->getType();
> +
> +      // One of the forbidden LValue types! We still need to have sensible
> +      // symbolic locations to represent this stuff. Note that arithmetic on
> +      // void pointers is a GCC extension.
> +      if (T->isVoidType())
> +        T = getContext().CharTy;
> +
> +      SVal V = state->getLValue(T,
> +                                state->getSVal(Idx, LCtx),
> +                                state->getSVal(Base, LCtx));
>        Bldr.generateNode(A, Node, state->BindExpr(A, LCtx, V), nullptr,
>            ProgramPoint::PostLValueKind);
>      } else if (IsVectorType) {
> Index: include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
> ===================================================================
> --- include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
> +++ include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
> @@ -961,7 +961,10 @@
>    CXXThisRegion(const PointerType *thisPointerTy,
>                  const StackArgumentsSpaceRegion *sReg)
>        : TypedValueRegion(sReg, CXXThisRegionKind),
> -        ThisPointerTy(thisPointerTy) {}
> +        ThisPointerTy(thisPointerTy) {
> +    assert(ThisPointerTy->getPointeeType()->getAsCXXRecordDecl() &&
> +           "Invalid region type!");
> +  }
>
>    static void ProfileRegion(llvm::FoldingSetNodeID &ID,
>                              const PointerType *PT,
> @@ -1075,6 +1078,8 @@
>      assert((!Idx.getAs<nonloc::ConcreteInt>() ||
>              Idx.castAs<nonloc::ConcreteInt>().getValue().isSigned()) &&
>             "The index must be signed");
> +    assert(!elementType.isNull() && !elementType->isVoidType() &&
> +           "Invalid region type!");
>    }
>
>    static void ProfileRegion(llvm::FoldingSetNodeID& ID, QualType elementType,
>
>
>
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