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- Subject: Re: Performance problem with table.move
- From: Andrew Gierth <andrew@...>
- Date: Mon, 07 Dec 2020 04:15:13 +0000
>>>>> "Ranier" == Ranier Vilela <firstname.lastname@example.org> writes:
Ranier> For loops, the quickest option, are variables with the natural
Ranier> size of the machine.
Ranier> No what?
I mean: No, that is a false statement.
For a concrete example: on 64-bit intel, there is an explicit
optimization guideline (from Intel's own optimization reference manual):
Assembly/Compiler Coding Rule 63. (H impact, M generality) Use the
32-bit versions of instructions in 64-bit mode to reduce code size
unless the 64-bit version is necessary to access 64-bit data or
("H impact" = high impact, "M generality" = medium generality)
Other 64-bit architectures typically have equal performance for 32-bit
and 64-bit operations.
If you want to prove me wrong, show an example of _actual code_ where
either 64-bit values or unsigned 32-bit are an improvement over signed