[PATCH] Use broadcasts to optimize overall size when loading constant splat vectors (x86-64 with AVX or AVX2)

[Rafael Espíndola]

> Note: Is there any optimization pass in LLVM that merges constant pool data from different functions? This could also be done at link time? If that exists, it might change the criteria for generating a broadcast because we might not want to generate extra instructions if the same constant data was loaded multiple times.

Depends on the type. For ELF, if the data is being put in a section like

.section        .foo,"aM", at progbits,8

Then yes, the linker will merge them. For ELF the entsize can be any
value, no sure if linkers actually merge all possible sizes. We could
do a better job at merging these in the IR, but we don't at the
moment.

Cheers,
Rafael