[Sema] Add sizeof diagnostics for bzero

[bruno]

Summary

For memset (and others) we can get diagnostics like:

struct stat { int x; };
void foo(struct stat *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 adds support for the same class of warnings for bzero.

[bruno]

Thanks! Committed in r277787

lib/AST/Decl.cpp

unsigned FunctionDecl::getMemoryFunctionKind() const {
   case Builtin::BI__builtin_strndup:
   case Builtin::BIstrndup:
     return Builtin::BIstrndup;
 
   case Builtin::BI__builtin_strlen:
   case Builtin::BIstrlen:
     return Builtin::BIstrlen;
 
+  case Builtin::BI__builtin_bzero:
+  case Builtin::BIbzero:
+    return Builtin::BIbzero;
+
   default:
     if (isExternC()) {
       if (FnInfo->isStr("memset"))
         return Builtin::BImemset;
       else if (FnInfo->isStr("memcpy"))
         return Builtin::BImemcpy;
       else if (FnInfo->isStr("memmove"))
         return Builtin::BImemmove;
       else if (FnInfo->isStr("memcmp"))
         return Builtin::BImemcmp;
       else if (FnInfo->isStr("strncpy"))
         return Builtin::BIstrncpy;
       else if (FnInfo->isStr("strncmp"))
         return Builtin::BIstrncmp;
       else if (FnInfo->isStr("strncasecmp"))
         return Builtin::BIstrncasecmp;
       else if (FnInfo->isStr("strncat"))
         return Builtin::BIstrncat;
       else if (FnInfo->isStr("strndup"))
         return Builtin::BIstrndup;
       else if (FnInfo->isStr("strlen"))
         return Builtin::BIstrlen;
+      else if (FnInfo->isStr("bzero"))
+        return Builtin::BIbzero;
     }
     break;
   }
   return 0;
 }
 
 //===----------------------------------------------------------------------===//
 // FieldDecl Implementation

lib/Sema/SemaChecking.cpp

 /// \param Call The call expression to diagnose.
 void Sema::CheckMemaccessArguments(const CallExpr *Call,
                                    unsigned BId,
                                    IdentifierInfo *FnName) {
   assert(BId != 0);
 
   // 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);
   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,
                                      Call->getLocStart(), Call->getRParenLoc()))
     return;
 
   // We have special checking when the length is a sizeof expression.
   QualType SizeOfArgTy = getSizeOfArgType(LenExpr);

test/SemaCXX/warn-memset-bad-sizeof.cpp

 // 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);
 extern "C" void *memcmp(void *s1, const void *s2, unsigned n);
 
 struct S {int a, b, c, d;};
 typedef S* PS;
 
memset(ps2, 0, sizeof(ps2));  // \
       // expected-warning {{'memset' 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)?}}
   memset(ps2, 0, sizeof(typeof(ps2)));  // \
       // expected-warning {{argument to 'sizeof' in 'memset' call is the same pointer type}}
   memset(ps2, 0, sizeof(PS));  // \
       // expected-warning {{argument to 'sizeof' in 'memset' call is the same pointer type}}
   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));  // \
       // 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)?}}
 
   memmove(ps, 0, sizeof(ps));  // \
       // expected-warning {{'memmove' 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)?}}
   memcmp(ps, 0, sizeof(ps));  // \
void f(Mat m, const Foo& const_foo, char *buffer) {
   memset(&foo, 0, sizeof(VFoo));
   memset(&foo, 0, sizeof(CVFoo));
   memset(ps, 0, sizeof(*ps));
   memset(ps2, 0, sizeof(*ps2));
   memset(ps2, 0, sizeof(typeof(*ps2)));
   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));
   char *cptr;
   memcpy(&cptr, buffer, sizeof(cptr));
   memcpy((char*)&cptr, buffer, sizeof(cptr));
 
   CFooRef cfoo = foo;
   memcpy(&foo, &cfoo, sizeof(Foo));
 
   memcpy(0, &arr, sizeof(arr));
   typedef char Buff[8];
   memcpy(0, &arr, sizeof(Buff));
 
   unsigned char* puc;
   bit_cast<char*>(puc);
 
   float* pf;
   bit_cast<int*>(pf);
 
   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));
   memcpy(&arr, &foo, sizeof(Foo));
 
   // Shouldn't warn, and shouldn't crash either.
   memset(({
     if (0) {}
     while (0) {}
     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));
 }
 }
 
 extern "C" int strncmp(const char *s1, const char *s2, unsigned n);
 extern "C" int strncasecmp(const char *s1, const char *s2, unsigned n);
 extern "C" char *strncpy(char *det, const char *src, unsigned n);
 extern "C" char *strncat(char *dst, const char *src, unsigned n);
 extern "C" char *strndup(const  char *src, unsigned n);