Re: Why did Intel change his static branch prediction mechanism over these years?

[Florian Weimer <fweimer at redhat dot com>]

On 08/15/2018 01:16 PM, 2016 quekong wrote:
> Hi, Florian.
>
> > > > There is a movement to replace table-driven stack unwinding with a conditional branch after most function calls...

> I am sorry I don't understand its meaning, forgive my poor knowledge
> of dynamic prediction, I am reading relative materials these days,
> could you explain a little more for this sentence, or give me some
> keywords for google ?

See Herb Sutter, “Zero-overhead deterministic exceptions: Throwing 
values”.  (The “Zero-overhead” is misleading.)

> > > > programmers tend to misuse __builtin_expect ..

> I believe you must have strong factual basis saying such words,  I can
> quite accept  the CPU manufacturer's ignoring branch prediction hints
> for some reasons, but not this,

We just removed a __builtin_except from the dynamic linker that 
indicated the wrong way for more than a decade, maybe even two decades. 
We have anymore that strongly suggest that you run in the C locale or in 
a single-byte locale, neither of which are generally true these days.

Thanks,
Florian