deeppatel1987 at gmail.com
Thu Jan 7 12:28:57 PST 2010
On Thu, Jan 7, 2010 at 5:48 PM, Chris Lattner <clattner at apple.com> wrote:
> On Jan 7, 2010, at 7:06 AM, Jon Harrop wrote:
>> What is the state of sqrt in LLVM?
>> It was an intrinsic but there are no OCaml bindings for it and, last
>> I looked,
>> it generated inefficient code on Linux due to this bug:
>> Is the intrinsic deprecated? Am I losing a lot of performance by
>> calling sqrt
>> from libm instead of using the intrinsic?
> There is a fundamental difference between sqrt() and llvm.sqrt: the
> former is defined on negative values and sets errno (on linux). The
> later is undefined. Both work well for their stated purpose,
> llvm.sqrt should not be slower than sqrt even on linux. Both
> llvm.sqrt and sqrt could be much better on linux, but noone seems
> compelled to do the work.
Many platforms could also benefit from recognizing 1.0/sqrt() as rsqrt().
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