[cfe-dev] Does a inline assembly or a memory barrier disable optimizations in a function

[Jeffrey Walton]

GCC disables optimizations in a function if it encounters inline
assembly. That means we can use a memory barrier to ensure dead stores
are not optimized out:

    delete m_ptr;
    m_ptr = NULL:

    __asm__ __volatile__ ("" ::: "memory");

Clang defines __GNUC__, but its not clear to me if the same behavior
is present. Looking at Language Compatibility at
http://clang.llvm.org/compatibility.html, there is no discussion of
the behavior.

Does inline assembly or a memory barrier tame the optimizer in a
function so that dead stores are not removed?

Thanks in advance.