[LLVMdev] [RFC] [X86] Mov to push transformation in x86-32 call sequences

[David Chisnall]

On 22 Dec 2014, at 08:03, Chris Lattner <clattner at apple.com> wrote:

> The linux kernel folks really care about the size of the bootloader, for example.

Every FreeBSD clang upgrade involves having to remove some code from the bootloader, so we'd also be very interested in -Oz working well to reverse this change.  There's some low-hanging fruit (I did manage to improve on the size by running clang -O0 and then opt with a hand-tweaked set of passes), but it would be great to have some regression tests for this.

We'd be happy to provide the FreeBSD bootloader code as the source for one of these.  It's pretty small and self-contained, but if the size of the output grows over a certain limit then we can no longer boot.

David