r277787 - [Sema] Add sizeof diagnostics for bzero

David Majnemer via cfe-commits cfe-commits at lists.llvm.org
Fri Aug 5 10:09:41 PDT 2016


On Thu, Aug 4, 2016 at 4:55 PM, Bruno Cardoso Lopes via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> Author: bruno
> Date: Thu Aug  4 18:55:22 2016
> New Revision: 277787
>
> URL: http://llvm.org/viewvc/llvm-project?rev=277787&view=rev
> Log:
> [Sema] Add sizeof diagnostics for bzero
>
> For memset (and others) we can get diagnostics like:
>
>   struct stat { int x; };
>   void foo(struct stat *stamps) {
>     bzero(stamps, sizeof(stamps));
>     memset(stamps, 0, sizeof(stamps));
>   }
>
>   t.c:7:28: warning: 'memset' call operates on objects of type 'struct
> stat' while the size is based on a different type 'struct stat *'
> [-Wsizeof-pointer-memaccess]
>     memset(stamps, 0, sizeof(stamps));
>            ~~~~~~            ^~~~~~
>   t.c:7:28: note: did you mean to dereference the argument to 'sizeof'
> (and multiply it by the number of elements)?
>     memset(stamps, 0, sizeof(stamps));
>                              ^~~~~~
>
> This patch implements the same class of warnings for bzero.
>
> Differential Revision: https://reviews.llvm.org/D22525
>
> rdar://problem/18963514
>
> Modified:
>     cfe/trunk/lib/AST/Decl.cpp
>     cfe/trunk/lib/Sema/SemaChecking.cpp
>     cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp
>
> Modified: cfe/trunk/lib/AST/Decl.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/
> Decl.cpp?rev=277787&r1=277786&r2=277787&view=diff
> ============================================================
> ==================
> --- cfe/trunk/lib/AST/Decl.cpp (original)
> +++ cfe/trunk/lib/AST/Decl.cpp Thu Aug  4 18:55:22 2016
> @@ -3408,6 +3408,10 @@ unsigned FunctionDecl::getMemoryFunction
>    case Builtin::BIstrlen:
>      return Builtin::BIstrlen;
>
> +  case Builtin::BI__builtin_bzero:
> +  case Builtin::BIbzero:
> +    return Builtin::BIbzero;
> +
>    default:
>      if (isExternC()) {
>        if (FnInfo->isStr("memset"))
> @@ -3430,6 +3434,8 @@ unsigned FunctionDecl::getMemoryFunction
>          return Builtin::BIstrndup;
>        else if (FnInfo->isStr("strlen"))
>          return Builtin::BIstrlen;
> +      else if (FnInfo->isStr("bzero"))
> +        return Builtin::BIbzero;
>      }
>      break;
>    }
>
> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/
> SemaChecking.cpp?rev=277787&r1=277786&r2=277787&view=diff
> ============================================================
> ==================
> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Thu Aug  4 18:55:22 2016
> @@ -6179,13 +6179,15 @@ void Sema::CheckMemaccessArguments(const
>
>    // It is possible to have a non-standard definition of memset.  Validate
>    // we have enough arguments, and if not, abort further checking.
> -  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
> +  unsigned ExpectedNumArgs =
> +      (BId == Builtin::BIstrndup || Builtin::BIbzero ? 2 : 3);
>

This looks suspicious.  Should it be (BId == Builtin::BIstrndup || Bld ==
Builtin::BIbzero ? 2 : 3);


>    if (Call->getNumArgs() < ExpectedNumArgs)
>      return;
>
> -  unsigned LastArg = (BId == Builtin::BImemset ||
> +  unsigned LastArg = (BId == Builtin::BImemset || BId == Builtin::BIbzero
> ||
>                        BId == Builtin::BIstrndup ? 1 : 2);
> -  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
> +  unsigned LenArg =
> +      (BId == Builtin::BIbzero || BId == Builtin::BIstrndup ? 1 : 2);
>    const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
>
>    if (CheckMemorySizeofForComparison(*this, LenExpr, FnName,
>
> Modified: cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/
> SemaCXX/warn-memset-bad-sizeof.cpp?rev=277787&r1=
> 277786&r2=277787&view=diff
> ============================================================
> ==================
> --- cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp (original)
> +++ cfe/trunk/test/SemaCXX/warn-memset-bad-sizeof.cpp Thu Aug  4 18:55:22
> 2016
> @@ -1,5 +1,6 @@
>  // RUN: %clang_cc1 -fsyntax-only -verify -Wno-sizeof-array-argument %s
>  //
> +extern "C" void *bzero(void *, unsigned);
>  extern "C" void *memset(void *, int, unsigned);
>  extern "C" void *memmove(void *s1, const void *s2, unsigned n);
>  extern "C" void *memcpy(void *s1, const void *s2, unsigned n);
> @@ -47,6 +48,19 @@ void f(Mat m, const Foo& const_foo, char
>    memset(heap_buffer, 0, sizeof(heap_buffer));  // \
>        // expected-warning {{'memset' call operates on objects of type
> 'char' while the size is based on a different type 'char *'}}
> expected-note{{did you mean to provide an explicit length?}}
>
> +  bzero(&s, sizeof(&s));  // \
> +      // expected-warning {{'bzero' call operates on objects of type 'S'
> while the size is based on a different type 'S *'}} expected-note{{did you
> mean to remove the addressof in the argument to 'sizeof' (and multiply it
> by the number of elements)?}}
> +  bzero(ps, sizeof(ps));  // \
> +      // expected-warning {{'bzero' call operates on objects of type 'S'
> while the size is based on a different type 'S *'}} expected-note{{did you
> mean to dereference the argument to 'sizeof' (and multiply it by the number
> of elements)?}}
> +  bzero(ps2, sizeof(ps2));  // \
> +      // expected-warning {{'bzero' call operates on objects of type 'S'
> while the size is based on a different type 'PS' (aka 'S *')}}
> expected-note{{did you mean to dereference the argument to 'sizeof' (and
> multiply it by the number of elements)?}}
> +  bzero(ps2, sizeof(typeof(ps2)));  // \
> +      // expected-warning {{argument to 'sizeof' in 'bzero' call is the
> same pointer type}}
> +  bzero(ps2, sizeof(PS));  // \
> +      // expected-warning {{argument to 'sizeof' in 'bzero' call is the
> same pointer type}}
> +  bzero(heap_buffer, sizeof(heap_buffer));  // \
> +      // expected-warning {{'bzero' call operates on objects of type
> 'char' while the size is based on a different type 'char *'}}
> expected-note{{did you mean to provide an explicit length?}}
> +
>    memcpy(&s, 0, sizeof(&s));  // \
>        // expected-warning {{'memcpy' call operates on objects of type 'S'
> while the size is based on a different type 'S *'}} expected-note{{did you
> mean to remove the addressof in the argument to 'sizeof' (and multiply it
> by the number of elements)?}}
>    memcpy(0, &s, sizeof(&s));  // \
> @@ -73,6 +87,21 @@ void f(Mat m, const Foo& const_foo, char
>    memset(arr, 0, sizeof(arr));
>    memset(parr, 0, sizeof(parr));
>
> +  bzero((void*)&s, sizeof(&s));
> +  bzero(&s, sizeof(s));
> +  bzero(&s, sizeof(S));
> +  bzero(&s, sizeof(const S));
> +  bzero(&s, sizeof(volatile S));
> +  bzero(&s, sizeof(volatile const S));
> +  bzero(&foo, sizeof(CFoo));
> +  bzero(&foo, sizeof(VFoo));
> +  bzero(&foo, sizeof(CVFoo));
> +  bzero(ps, sizeof(*ps));
> +  bzero(ps2, sizeof(*ps2));
> +  bzero(ps2, sizeof(typeof(*ps2)));
> +  bzero(arr, sizeof(arr));
> +  bzero(parr, sizeof(parr));
> +
>    memcpy(&foo, &const_foo, sizeof(Foo));
>    memcpy((void*)&s, 0, sizeof(&s));
>    memcpy(0, (void*)&s, sizeof(&s));
> @@ -96,12 +125,17 @@ void f(Mat m, const Foo& const_foo, char
>    int iarr[14];
>    memset(&iarr[0], 0, sizeof iarr);
>    memset(iarr, 0, sizeof iarr);
> +  bzero(&iarr[0], sizeof iarr);
> +  bzero(iarr, sizeof iarr);
>
>    int* iparr[14];
>    memset(&iparr[0], 0, sizeof iparr);
>    memset(iparr, 0, sizeof iparr);
> +  bzero(&iparr[0], sizeof iparr);
> +  bzero(iparr, sizeof iparr);
>
>    memset(m, 0, sizeof(Mat));
> +  bzero(m, sizeof(Mat));
>
>    // Copy to raw buffer shouldn't warn either
>    memcpy(&foo, &arr, sizeof(Foo));
> @@ -114,12 +148,21 @@ void f(Mat m, const Foo& const_foo, char
>      for (;;) {}
>      &s;
>    }), 0, sizeof(s));
> +
> +  bzero(({
> +    if (0) {}
> +    while (0) {}
> +    for (;;) {}
> +    &s;
> +  }), sizeof(s));
>  }
>
>  namespace ns {
>  void memset(void* s, char c, int n);
> +void bzero(void* s, int n);
>  void f(int* i) {
>    memset(i, 0, sizeof(i));
> +  bzero(i, sizeof(i));
>  }
>  }
>
>
>
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> cfe-commits at lists.llvm.org
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