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    <p>EDIT, okay that was fun...</p> <p>Folks that make the blanket statement that compilers outperform humans, are the ones that have not actually checked. Anything a compiler can create a human can create. But a compiler cannot always create the code a human can create. It is that simple. For projects anywhere from a few lines to a few dozen lines or larger, it becomes easier and easier to hand fix the optimizations made by a compiler. Compiler and target help close that gap but there will always be the educated someone that will be able to meet or exceed the compilers output.</p> <blockquote> <p>The claim I would like to prove or disprove is that compilers generate code that is 2-4X "fatter" (and therefore consume 2-4X times as much power) compared with hand written assembly code.</p> </blockquote> <p>Unless you are defining "fatter" to mean uses that much power. Size of a binary and power consumption are not related. If this whole question/project is related to power consumption, the compiler wont take into account the bios settings you have chosen (assuming you are talking about pcs), the video card, hard disk, monitor, mouse, keyboard, etc, etc. In addition to the processor which is only one (relatively small) part of the equation. And even if it did would someone make a compiler that only makes your code efficient, they cant and wont tune the compiler for every system on the planet. Aint gonna happen. </p> <p>If you are talking a mobile phone which is a very controlled environment the app may get tuned to save power, but the compiler is not the master of that, it is the user, the compiler does part of it the rest is hand tuned by the programmer.</p> <pre><code>I can compile the above snippet with -O3 and read the assembly, but I couldn't write it myself. </code></pre> <p>If you go into this with that kind of attitude then you have automatically failed. Yes you can meet or beat the compiler, period. It is a matter of confidence and will power and time/effort. That statement means you have not really studied the problem, which is why you are asking the question you are asking. Take some time, do some more research, ask detailed questions at stackoverflow (not open ended ones like this one), and with time you will understand what compilers do and dont do and why, in particular why they are not perfect (for any one or many rulers by which that opinion is defined). This question is wholly about opinion and will spark flame wars, and such and will get closed and eventually removed from this site. Instead write and compile and publish code segments and ask questions about "why did the compiler produce this output, why didnt it to [this] instead?" Those kinds of questions have a better chance at real answers and of staying here for others to learn from.</p>
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    1. POHow can I prove or disprove the efficiency of compilation?
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    1. COI agree with most of what you say - until you get to "...and eventually eradicate the human race". I think you are getting carried away a little bit there. Just cut the power to the darn things and show them who is boss. Time for a cabin in Montana.
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    2. COMontana or Texas, either works...
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    3. COI would disagree. While you can certainly find isolated cases where a human can do better, on the whole a good optimizing compiler will *vastly* outperform a human assembly programmer. And be *much* more reliable to boot. I'd say it's quite "definitive". (And I've written tens of thousands of lines of assembly code, and likely a million lines of HLL code.)
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