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nelhage / gojit

JIT code-generation in Go!
MIT License
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Optimization: Prefer ADD and SUB to INC and DEC. #2

Closed alex closed 10 years ago

alex commented 10 years ago

INC and DEC are generally not preferred anymore (at least, not on Intel chips). Though they have shorter encodings, they introduce a false dependency on the carry flag, and thus lead to worse performance.

nelhage commented 10 years ago

Good call. I'm probably going to the trivial peephole optimizer at some point, which will necessitate this optimization anyways. I'll figure out the Addb and Decb encodings, too -- it should be straightforward.

alex commented 10 years ago

Awesome!

On Sun, Apr 27, 2014 at 9:28 AM, Nelson Elhage notifications@github.comwrote:

Good call. I'm probably going to the trivial peephole optimizer at some point, which will necessitate this optimization anyways. I'll figure out the Addb and Decb encodings, too -- it should be straightforward.

— Reply to this email directly or view it on GitHubhttps://github.com/nelhage/gojit/pull/2#issuecomment-41501190 .

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