opened
iximeow
username_0
specifically, pass correct form of "as optimized as possible please" flag to lucet
Fix Sightglass' Lucet flags
issue
created
fst-crenshaw
username_1
Curious: Why not just `speed`?
comment
created
awortman-fastly
username_2
The simple answer: because once upon a time this was ["best"](https://github.com/bytecodealliance/lucet/commit/d45a2aa7eb3eef03af1dac265ce6cef88cefda51#diff-5d226338f361546cf8921b0c019df026) and "speed_and_size" these days maps to "ok cranelift, do the best you can do".

As for why we'd pick `speed_and_size` rather than `speed` when we're measuring... speed: so far as I know, `speed_and_size` won't do anything that would regress speed in favor of size, but does get cranelift to run through instruction squeezing that can do things like reduce offset sizes from four to one (or no!) byte, remove prefixes that aren't necessary, and other optimizations of that nature. This _probably_ doesn't make a measurable impact, but if we're doing the best we can vs the best gcc can, it doesn't hurt to try.
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