GCC Explorer - an interactive take on compilation [LWN.net]

GCC Explorer - an interactive take on compilation

Posted Jun 2, 2012 21:27 UTC (Sat) by vonbrand (subscriber, #4458)
In reply to: GCC Explorer - an interactive take on compilation by alankila
Parent article: GCC Explorer - an interactive take on compilation

Oh, come on. The compiler surely could figure out that this is printf, scan the format string and replace the whole printf("Look at this: %d %x\n", a, b) call by something along the lines of puts("Look at this: "); do_fmt_d(a); do_fmt_x(b); putchar('\n');. Probably pointless (if that is your performance bottleneck, you can do something along those lines yourself).

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GCC Explorer - an interactive take on compilation

Posted Jun 3, 2012 5:37 UTC (Sun) by quotemstr (subscriber, #45331) [Link]

Your transformation isn't valid: consider multithreading. One printf will write to a stream as an atomic operation (enforced by internal stdio locks), but the output from discrete output functions may overlap.

GCC Explorer - an interactive take on compilation

Posted Jun 3, 2012 9:23 UTC (Sun) by dgm (subscriber, #49227) [Link]

That's why a naive coder with a optimizing compiler cannot beat a good coder. The compiler is bound by the precise semantics of the code, even if there are aspects of it that you don't care. The compiler has to care.