An update on GNU performance

Re:An update on GNU performance by Someone on Sunday October 21, 2018 @05:25PM (#18270359)

Performance. Historically, ARM didn’t have a “load byte and sign extend” instruction (http://www.drdobbs.com/architecture-and-design/portability-t...), making loading a signed char and promoting it to an int slower than loading an unsigned char and promoting it to an int.

In C, a function argument or return value of type char gets promoted to int. So, code that uses char a lot does a lot of such promotions.

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Re:An update on GNU performance by loeg on Sunday October 21, 2018 @06:37PM (#18270757)

> In C, a function argument or return value of type char gets promoted to int. So, code that uses char a lot does a lot of such promotions.

I think you're confusing standard C and machine/implementation-specific behavior. (If not for yourself, for people who read your comment.)

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Re:An update on GNU performance by caf on Sunday October 21, 2018 @08:21PM (#18271205)

It's worse than that, arithmetic is never done in types narrower than int so even using + with a char type will do a such a promotion.

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