[PATCH] Optimise the fpclassify builtin to perform integer operations when possible

[Jakub Jelinek]

On Mon, Sep 12, 2016 at 04:19:32PM +0000, Tamar Christina wrote:
> This patch adds an optimized route to the fpclassify builtin
> for floating point numbers which are similar to IEEE-754 in format.
> 
> The goal is to make it faster by:
> 1. Trying to determine the most common case first
>    (e.g. the float is a Normal number) and then the
>    rest. The amount of code generated at -O2 are
>    about the same +/- 1 instruction, but the code
>    is much better.
> 2. Using integer operation in the optimized path.

Is it generally preferable to use integer operations for this instead
of floating point operations?  I mean various targets have quite high costs
of moving data in between the general purpose and floating point register
file, often it has to go through memory etc.

	Jakub