On May 6, 2016 1:07:13 PM PDT, Sasha Levin <sasha.levin@xxxxxxxxxx> wrote: >On 05/04/2016 08:30 PM, H. Peter Anvin wrote: >> On 05/04/16 15:06, John Denker wrote: >>> On 05/04/2016 02:56 PM, H. Peter Anvin wrote: >>>>> Beware that shifting by an amount >= the number of bits in the >>>>> word remains Undefined Behavior. >>> >>>> This construct has been supported as a rotate since at least gcc2. >>> >>> How then should we understand the story told in commit d7e35dfa? >>> Is the story wrong? >>> >>> At the very least, something inconsistent is going on. There >>> are 8 functions. Why did d7e35dfa change one of them but >>> not the other 7? >> >> Yes. d7e35dfa is baloney IMNSHO. All it does is produce worse code, >and the description even says so. > >No, the description says that it produces worse code for *really >really* ancient >GCC versions. > >> As I said, gcc has treated the former code as idiomatic since gcc 2, >so that support is beyond ancient. > >Because something works in a specific way on one compiler isn't a >reason to >ignore this noncompliance with the standard. > > >Thanks, >Sasha When the compiler in question is our flagship target and our reference compiler, then yes, it matters. -- Sent from my Android device with K-9 Mail. Please excuse brevity and formatting. -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
