Linked by ebasconp on Fri 10th Jun 2011 22:22 UTC
Benchmarks "Google has released a research paper that suggests C++ is the best-performing programming language in the market. The internet giant implemented a compact algorithm in four languages - C++, Java, Scala and its own programming language Go - and then benchmarked results to find 'factors of difference'."
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RE[6]: GCC isn't all that great
by Alfman on Mon 13th Jun 2011 01:35 UTC in reply to "RE[5]: GCC isn't all that great"
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"You are forgetting something in your examples."

Fair enough, but what?

"It used to be so that most humans could beat compiler generated code. In this day and age it is only true for small code snippets or simple processors."

I was asked for an example, which I provided. Then I provided another example with division. In these examples, I'm not aware of any processor for which GCC generated optimal code, which is what I set out to demonstrate; Nothing more, nothing less.

"Most up to date processors use out-of-order execution with superscalar processing units, and translate CISC instructions into microcode RISC like code. And this varies from processor model to processor model within the same family even!"

I have some observations:

1. In practice x86 binary code is precompiled and shared among many models. If you have an Intel Core2 Q6600, you cannot simply purchase/download software specifically for that model.

2. I don't believe GCC even allows model-specific compilation (I doubt ICC does either, but I could be wrong). You can specify a processor family, but that's it.

"It is very hard for most humans to still be able to keep all processor features on their head while coding assembly and still be able to beat the code generated from high performance compilers. Not GCC, but the ones you pay several thousand euros/dollars for, with years of research put into them."

Well there you go, in conclusion it seems that you do agree with my argument that we can beat GCC? I'm not moving goalposts here, this is what I said from the beginning - it's even in the title of the thread.

Edited 2011-06-13 01:48 UTC

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