Re: mspgcc "undefines" too-many-bits shifts in weird way
Paul Sokolovsky <[email protected]>
| Newsgroups | gmane.comp.hardware.texas-instruments.msp430.gcc.user |
|---|---|
| Message-ID | <20130422021009.3e7f19f5@x34f> |
Hello, On Sun, 21 Apr 2013 17:06:51 -0500 Peter Bigot <[email protected]> wrote: > This decision was intentional, as documented in > https://sourceforge.net/p/mspgcc/bugs/118/. My recollection is that > the choice of how to make things consistent was informed by similar > behavior in the contemporaneous gcc for x86 or at least one other > target architecture. Thanks for the reference. So, I tested it with x86 gcc 4.4, 4.5, 4.6, 4.7 (packages as shipped by Ubuntu), all of them produce mathematically expected result. msp430-gcc 4.5.3, 4.7.0 both produce unexpected result. > As you say, the behavior is undefined. Anybody who expects any > particular behavior for this situation is confused about how C works > and should take the issue up with JTC1/SC22/WG14. That's why I wrote so many words in the original mail. Yes, in small world of JTC1/SC22/WG14 C standard the behavior is undefined. But in much bigger world of: mathematics, well-known gcc targets, user expectations, principle of least surprise, etc. - it's all pretty well defined. So, when something is undefined in small area, it's still a good idea to have affinity towards how it's done/expected in wider areas. So, the request is just that - please kindly consider changing that behavior ;-). > > Peter > -- Best regards, Paul mailto:[email protected] ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter