Re: [PATCH] Optimize logarithm addition and subtraction

[Marc Glisse <marc dot glisse at inria dot fr>]

On Sun, 5 Aug 2018, Bernd Edlinger wrote:

> > merging log a + log b => log a*b and
>
> Maybe a*b could overflow, while adding the logarithms would not?

Well, that's a discussion that happens every time a new transformation is 
added to -funsafe-math-optimizations (I assume this one is under that 
umbrella?). We already may get extra overflow with -fassociative-math for 
instance. Sure, the overflow (or underflow!) is more likely for log than 
for addition, but this still seems like the kind of transformation that 
-ffast-math should enable, in my opinion. Now we can see if I am in the 
minority...

--
Marc Glisse