[RFC] Marking C++ new operator as malloc?

[Martin Jambor <jamborm at matfyz dot cz>]

Hi,

when trying  to analyse dynamically  allocated objects in C++,  I came
across the need to identify results  of the new operator (at least the
non-overridden  standard  one)   as  malloc-allocated.   The  cleanest
approach would probably be to  mark the new operator function with the
malloc attribute.   So I did  that (see the extra-short  patch below),
bootstrapped c  and c++ on  i686-linux (with "all,fold"  checking) and
ran the test suite. To my surprise, there were no new regressions.

I  am  now  wondering  why  the  function  is  not  marked  as  malloc
already. In fact, its implementation  always returns what it gets from
the built-in malloc. Are there  any known issues or concerns with this
that the test suite cannot reveal? Can anyone comment on this?

Moreover, just before sending this  email, I have found out that there
is  already PR23383  (builtin array  operator new  is not  marked with
malloc attribute) about  the array variant of the  new operator. Given
its implementation, it is probably the same thing...

Thank you very much in advance,

Martin



Index: libstdc++-v3/libsupc++/new
===================================================================
--- libstdc++-v3/libsupc++/new	(revision 128207)
+++ libstdc++-v3/libsupc++/new	(working copy)
@@ -92,7 +92,8 @@
  *  Placement new and delete signatures (take a memory address argument,
  *  does nothing) may not be replaced by a user's program.
 */
-void* operator new(std::size_t) throw (std::bad_alloc);
+void* operator new(std::size_t) throw (std::bad_alloc) 
+    __attribute__ ((malloc));
 void* operator new[](std::size_t) throw (std::bad_alloc);
 void operator delete(void*) throw();
 void operator delete[](void*) throw();