GCC 5.2 released • Hacker News Board

Re: GCC 5.2 released

#11

Post by [deleted] » Thu, Jul 16, 2015, 3:30 PM UTC

the8472 wrote: post #7

> Write-only variables are now detected and optimized out. That's probably something one should keep in mind when writing micro-benchmarks.

[deleted]

Re: GCC 5.2 released

#12

Post by revskill » Thu, Jul 16, 2015, 3:31 PM UTC

tosseraccount wrote: post #4

Any benchmarks? How does this compare with previous versions of gcc?

You should investigate by yourself :)

Re: GCC 5.2 released

#13

Post by mrpippy » Thu, Jul 16, 2015, 3:33 PM UTC

[deleted] wrote: post #11

the8472 wrote: post #7

> Write-only variables are now detected and optimized out. That's probably something one should keep in mind when writing micro-benchmarks.

[deleted]

Those pointers always need to be defined as volatile anyway

Re: GCC 5.2 released

#14

Post by agwa » Thu, Jul 16, 2015, 3:37 PM UTC

It's worth noting that, due to GCC's new and esoteric version numbering scheme[1], this is a bugfix-only release on the 5.x branch. The bigger news was when GCC 5.1 (a major stable release) was released in April. That said, GCC 5.2 fixes a pretty serious bug that I was hitting so I'm happy to hear about it!

[1] https://gcc.gnu.org/develop.html#num_scheme

Re: GCC 5.2 released

#15

Post by [deleted] » Thu, Jul 16, 2015, 3:37 PM UTC

mrpippy wrote: post #13

[deleted] wrote: post #11

Earlier quoted context omitted.

[deleted]

Those pointers always need to be defined as volatile anyway

[deleted]

Re: GCC 5.2 released

#16

Post by [deleted] » Thu, Jul 16, 2015, 3:38 PM UTC

[deleted] wrote: post #11

the8472 wrote: post #7

> Write-only variables are now detected and optimized out. That's probably something one should keep in mind when writing micro-benchmarks.

[deleted]

[deleted]

Re: GCC 5.2 released

#17

Post by ademarre » Thu, Jul 16, 2015, 3:47 PM UTC

With this release the golang frontend catches up it'so Go version 1.4.2.

EDIT: I'm wrong. That was GCC 5.1.

Re: GCC 5.2 released

#18

Post by ot » Thu, Jul 16, 2015, 3:55 PM UTC

the8472 wrote: post #7

> Write-only variables are now detected and optimized out. That's probably something one should keep in mind when writing micro-benchmarks.

https://github.com/facebook/folly/blob/master/folly/Benchmar...

Re: GCC 5.2 released

#19

Post by spacehome » Thu, Jul 16, 2015, 3:58 PM UTC

the8472 wrote: post #7

> Write-only variables are now detected and optimized out. That's probably something one should keep in mind when writing micro-benchmarks.

I'm appalled that this wasn't taken care of 20 years ago. It seems like such low-hanging fruit.

Re: GCC 5.2 released

#20

Post by zyngaro » Thu, Jul 16, 2015, 4:00 PM UTC

[deleted] wrote: post #15

mrpippy wrote: post #13

Earlier quoted context omitted.

Those pointers always need to be defined as volatile anyway

[deleted]

The point of using volatile is to make sure not to put the variable in a register or use a cached value; it hits the memory.