[llvm-commits] Natural Stack Alignment - Prevent overly aggressive alignment promotion.

[Bob Wilson]

On Oct 9, 2011, at 1:17 PM, Anton Korobeynikov wrote:
> iirc, i64 should be 64 bit aligned on some ARM ABIs, so, it will
> always require stack realignment

AFAIK, the ARM ABIs that require 64-bit alignment for i64 types also require 64-bit alignment for the stack.  The problem here is that even when the ABI requirement is only 32-bit alignment, we still want the preferred alignment to be 64 bits because some things (e.g., global variables) can be forced to that alignment and can help performance.  We need to a way to distinguish the "preferred alignment" for global variables from the "natural stack alignment", which is the point of Lang's proposal.