[Bug middle-end/57003] gcc-4.8.0 breaks -O2 optimization with Wine(64) - links/info/bisect of commits included

[kirill.k.smirnov at math dot spbu.ru]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57003

Kirill Smirnov <kirill.k.smirnov at math dot spbu.ru> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kirill.k.smirnov at math
                   |                            |dot spbu.ru

--- Comment #7 from Kirill Smirnov <kirill.k.smirnov at math dot spbu.ru> 2013-04-23 09:44:03 UTC ---
It seems gcc over-optimizes series of memcpy() function calls one after
another. The piece of code does not work:

memcpy( buffer, DIR_Windows, len * sizeof(WCHAR) );
memcpy( buffer + len, default_syswow64W, sizeof(default_syswow64W)

There is a wrapper around memcpy() called memcpy_unaligned() to avoid
builtin/inlining.
And these pieces of code work:

memcpy( buffer, DIR_Windows, len * sizeof(WCHAR) );
memcpy_unaligned( buffer + len, default_syswow64W, sizeof(default_syswow64W) );

and

memcpy_unaligned( buffer, DIR_Windows, len * sizeof(WCHAR) );
memcpy( buffer + len, default_syswow64W, sizeof(default_syswow64W) );

I'm sorry for copy-and-pasting wine code as is, I tried but failed to create a
refined test case.


So this case is opposite as previously suggested: the memcpy_unaligned()
wrapper is OK, but native memcpy() is failing.