<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW --- - Undefined operation in tgsi_ureg.c left shift of 1 by 31 places cannot be represented in type 'int'" href="https://bugs.freedesktop.org/show_bug.cgi?id=80266#c6">Comment # 6</a> on <a class="bz_bug_link bz_status_NEW " title="NEW --- - Undefined operation in tgsi_ureg.c left shift of 1 by 31 places cannot be represented in type 'int'" href="https://bugs.freedesktop.org/show_bug.cgi?id=80266">bug 80266</a> from <a class="email" href="mailto:baggett.patrick@gmail.com" title="Patrick Baggett <baggett.patrick@gmail.com>"> Patrick Baggett</a> <pre>I'm sure that technically shifting any bits into the sign bit of a signed number produces undefined behavior according to C99, so yes, (1<<31) technically is undefined. As a matter of practicality, on basically any CPU, 1<<31 will produce a valid negative number, but the compiler sees it as trying to assign the constant 2147483648 to a 32-bit signed container, which is outside of the 2^31-1 range that it can accept. In the C abstract machine, this would be a serious problem. Obviously you can make such an assignment in hardware, but the result (when interpreted as signed) is not a value of 2147483648, but a value of -2147483648, which is why the compiler gives a warning. It's weird to read that (1<<31) is less than 0. If you don't really mean to assign a value of -2147483648 or 2147483648 and just want a bit pattern, using unsigned is almost always the way to go. I know that Solaris Studio happens to give a warning for the same case, if that means anything.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>