On Mon, 10 Jun 2024 at 16:35, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>
> ... which can be compacted down to a single instruction:
>
> addq $bimm,%rax
We'll burn that bridge when we get to it. I'm not actually seeing any
obvious for 32-bit immediates, except as part of some actual operation
sequence (ie you might have a similar hash lookup to the d_hash() one,
except using a mask rather than a shift).
When would you ever add a constant, except when that constant is an
address? And those kinds of runtime constant addresses would always
be the full 64-bit - I don't think 32-bit is interesting enough to
spend any effort on.
(Yes, you can get 32-bit rip-address constants if you start doing
things like conditional link addresses, but that's what things like
static_call() is for - not this runtime constant code)
Linus
