On 04/08/2012 01:55 PM, Stefan Plantikow wrote:
Hi,
Am Sonntag, 8. April 2012 um 22:32 schrieb Brian Anderson:
Hashing algorithms (hopscotch, bloom filters) could greatly benefit from having
access to the llvm bit manipulation intrinsics (ctpop, ctlz, cttz, bswap). I
think the general plan was to access these using some form of inline llvm asm.
However in the absence of that I wonder wether we should just have support for
those directly in core or std for all the integer types (quite some languages
do that).
We used to have an 'llvm' ABI for native mods that was intended to give
access to the llvm intrinsics. We could add that back, or just add them
as rust intrinsics ('rust-intrinsic' ABI) as needed.
That would be nice. For hash table algorithms, ctpop/ctlz/cttz will be really
useful (should also speedup the sudoku benchmark :). And swap is quite helpful
for dealing with utf8 byte order swapping. How would one call these via the
rust intrinsics? I am not deep enough into the llvm-rust-bits.
As a rust intrinsic perhaps like
#[abi = "rust-intrinsic"]
native mod intrinsics {
fn bswap_i16(i: i16) -> i16;
}
The rust intrinsics would all just be hardcoded into the compiler to
translate to the appropriate llvm intrinsics.
As an llvm intrinsic:
#[abi = "llvm-intrinsic"]
native mod intrinsics {
#[link_name = "bswap.i16"]
fn bswap_i16(i16: i16) -> i16;
}
In this case rustc probably doesn't need to know anything specific about
the intrinsic - we just generate an intrinsic instruction with the given
name and types.
Feedback/Suggestions?
Is going for hopscotch a good idea? Ah well, will try in any case ;)
I'm not really familiar with the subject. If the intent is to replace
std::map then presumably anything that demonstrates better performance
is a good idea.
PS: Is there yet a plan on how to move towards more use of interfaces in the
libs, and (by extension) rustc?
I don't think there's a plan yet. It's probably worth waiting for classes.
Ok, that makes sense to some extent, though things like comparison etc already
could move towards using interfaces, I guess.
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