http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50494
--- Comment #15 from Michael Meissner <meissner at gcc dot gnu.org> 2013-02-13 22:38:12 UTC --- The patch does align the .rodata section to 16 byte alignment, but the code to load up the auto vector from constant memory does not do vectorization. If I use -fno-section-anchors, it aligns .rodata to 4 byte alignment, and does not vectorize the code. If I use -fno-merge-constants, it aligns .rodata to 16 byte alignment, and does vectorize the code. If I use -fno-merge-constants without -flto, it aligns .rodata to 16 byte alignment, but it uses unaligned vector loads/stores. So the patch does help in that the tests now pass that were randomly failing. While it would be nice if we could get the initialization to be vectorized, I'm not how performance critical this is. Eric: if the alignment of the constant data that is used to initialize the auto array is a mismatch, and you use Altivec instructions, when the compiler auto-vectorizes the copy, the wrong data gets used.
