How the JVM compares strings on x86 using pcmpestri

Re:How the JVM compares strings on x86 using pcmpestri by ghusbands on Sunday January 07, 2018 @06:59AM (#16090511)

tl;dr: The string comparison intrinsic in the JVM uses a vectorised string comparison instruction.

(vpcmpestri (of the pcmpxstrx family) isn't an especially crazy instruction to use for string comparison. That's what it's designed for.)

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Re:How the JVM compares strings on x86 using pcmpestri by amelius on Sunday January 07, 2018 @07:50AM (#16090686)

Thanks for the tl;dr. I think the "crazy" adjective refers to the instruction, and not to the use of it. As the article explains, the instruction is quite complicated and has a large number of parameters.

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Re:How the JVM compares strings on x86 using pcmpestri by B4TMAN on Sunday January 07, 2018 @08:00AM (#16090720)

Is there any place to get a proper manual of all these uses?

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Re:How the JVM compares strings on x86 using pcmpestri by brianon99 on Sunday January 07, 2018 @09:57AM (#16091030)

Agree that using vector instruction is not crazy at all. I am quite interested when I see the article title, and then deeply disappointed after I read it. I was expecting something like the strlen shown in the book The Hackers Delight, which loads 4 bytes into a int, ad then some bit masking and subtraction and a nlz (number of leading zero) to index the first 0 byte. Please read it first and that is what really what meant by crazy.

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