In gcc, the value does not change with -mno-sse or -mno-sse2, or based on -m32 or -m64. Same applies in my definition. It is simply a case of "this is the architecture's largest necessary alignment for code correctness" (AVX prefers 32-byte alignment, but only required to be 16-byte aligned - with 32-byte alignment, it apparently works better if it doesn't straddle the cache-lines).
-- Mats On 13 December 2014 at 21:32, Joerg Sonnenberger <[email protected]> wrote: > On Sat, Dec 13, 2014 at 09:15:53PM +0000, mats petersson wrote: > > So, what kind of documentation would you like to see? > > > > The GCC docs here: > > https://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html > > > > say: GCC also provides a target specific macro __BIGGEST_ALIGNMENT__, > which > > is the largest alignment ever used for any data type on the target > machine > > you are compiling for. > > How does that interact with codegen flags like -mno-sse2? What about > support for new target types in later version -- from the writing it is > nowhere clear that this macro is not fixed. > > Joerg > _______________________________________________ > cfe-commits mailing list > [email protected] > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits >
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