There is no 'printf'

#1

Post by pr0zac » Wed, Oct 20, 2021, 3:01 PM UTC

Re: There is no 'printf'

#2

Post by tptacek » Thu, Oct 21, 2021, 8:16 PM UTC

Huh, this is pretty great; I've always fussily used fputs() when I'm just printing static strings, and apparently I don't need to bother, since the compiler will just do it for me.

Re: There is no 'printf'

#3

Post by eikenberry » Thu, Oct 21, 2021, 8:21 PM UTC

https://web.archive.org/web/20211019052752/https://www.netme...

Re: There is no 'printf'

#4

Post by cyberge99 » Thu, Oct 21, 2021, 8:28 PM UTC

Apparently there is no available capacity for that site either.

Re: There is no 'printf'

#5

Post by RcouF1uZ4gsC » Thu, Oct 21, 2021, 8:35 PM UTC

This is a bit like saying there is no '+';

Because if you put in

    return 1+2+3;

And look at the assembly code, you will see that the compiler generated something like

    return 6;

The compiler is allowed to take advantage of the standard to substitute in more efficient code that does the same thing.

IIRC, for C++, it would actually be ok if std::vector was implemented completely as a compiler intrinsic with no actual header file. (No compiler I am aware of actually does it that way).

Re: There is no 'printf'

#6

Post by guerrilla » Thu, Oct 21, 2021, 8:42 PM UTC

Moar please. I'm loving these counterintuitive C optimization gotchas lately[1]. They are like little brain teasers.

1. https://news.ycombinator.com/item?id=28930271

Re: There is no 'printf'

#7

Post by [deleted] » Thu, Oct 21, 2021, 8:47 PM UTC

[deleted]

Re: There is no 'printf'

#8

Post by malkia » Thu, Oct 21, 2021, 8:47 PM UTC

RcouF1uZ4gsC wrote: post #5

This is a bit like saying there is no '+'; Because if you put in return 1+2+3; And look at the assembly code, you will see that the compiler generated something like return 6; The compiler is allowed to take advantage of the standard to substitute in more efficient code that does the same thing. IIRC, for C++, it would actually be ok if std::vector was implemented completely as a compiler intrinsic with no actual hea…

Is there more info to this, I remember this from Commmon Lisp (but details evade me) that the compiler can take benefit of certain specific functions and rely on them being... "open coded" - e.g. it can produce more efficient code by replacing these with something more suitable... http://www.sbcl.org/manual/#Open-Coding-and-Inline-Expansion

https://www.thecodingforums.com/threads/what-is-the-meaning-...

Re: There is no 'printf'

#9

Post by Bang2Bay » Thu, Oct 21, 2021, 8:49 PM UTC

cyberge99 wrote: post #4

Apparently there is no available capacity for that site either.

https://search.yahoo.com/ for

There is no 'printf'

and look through the cache

Re: There is no 'printf'

#10

Post by talaketu » Thu, Oct 21, 2021, 8:50 PM UTC

RcouF1uZ4gsC wrote: post #5

This is a bit like saying there is no '+'; Because if you put in return 1+2+3; And look at the assembly code, you will see that the compiler generated something like return 6; The compiler is allowed to take advantage of the standard to substitute in more efficient code that does the same thing. IIRC, for C++, it would actually be ok if std::vector was implemented completely as a compiler intrinsic with no actual hea…

> more efficient code that does the same thing

In this case, it produces a different result.