search for: memeq

Hi all, We'd like to suggest *adding a -memeq-lib-function* flag to allow the user to specify a `*memeq()*` function to improve string equality check performance. Right now, when llvm encounters a *string equality check*, e.g. `if (memcmp(a, b, s) == 0)`, it tries to expand to an equality comparison if `s` is a small compile-time constant, a...

Thanks for the suggestions Hal, So if I understand correctly, you're recommending we add a module flag <https://llvm.org/docs/LangRef.html#module-flags-metadata> to LLVM, something like: !llvm.module.flags = !{..., !123} !123 = !{i32 1, !"memeq_lib_function", !"user_memeq"} I've given it a try in the following patch: https://reviews.llvm.org/D56311 If this sounds reasonable I can start working on adding a CodeGenOptions to clang to see what this entails. I don't think the function attribute works here because we w...

...or why it was actually a > quite valuable function and should be reinstated into the standard as well. > > On Thu, Jan 3, 2019 at 4:30 AM Clement Courbet via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > >> Hi all, >> >> We'd like to suggest *adding a -memeq-lib-function* flag to allow the >> user to specify a `*memeq()*` function to improve string equality check >> performance. >> >> Right now, when llvm encounters a *string equality check*, e.g. `if >> (memcmp(a, b, s) == 0)`, it tries to expand to an equality compariso...

On Mon, Jan 7, 2019 at 5:50 AM Clement Courbet <courbet at google.com> wrote: > On Fri, Jan 4, 2019 at 12:34 PM James Y Knight via llvm-dev < >> llvm-dev at lists.llvm.org> wrote: >> >>> This seems a somewhat odd and overcomplicated way to go about this. >>> >>> Given that bcmp was required in POSIX until relatively recently, I will

On Tue, Jan 8, 2019 at 9:24 AM Clement Courbet <courbet at google.com> wrote: > > > On Mon, Jan 7, 2019 at 10:26 PM James Y Knight <jyknight at google.com> > wrote: > I'm afraid about the "almost" and "generally": what about users who don't ? > Even so, it should be fine to enable it for those platforms which do include it. I do note,

On Thu, Jan 10, 2019 at 4:47 PM Clement Courbet <courbet at google.com> wrote: > > > On Wed, Jan 9, 2019 at 6:16 PM James Y Knight <jyknight at google.com> wrote: > >> >> >> On Tue, Jan 8, 2019 at 9:24 AM Clement Courbet <courbet at google.com> >> wrote: >> >>> >>> >>> On Mon, Jan 7, 2019 at 10:26 PM James Y