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On 30 Aug 2007, at 19:16, Patrick Donnelly wrote:

I'm curious what kind of compiler optimizations Lua does when creating
the byte code, if any?


x = 5 *  32 * i


x = 160 * i


Well, the answer is obviously going to vary a bit. But the answer is approximately "almost none".

It does do (some) constant folding. Constants are also pooled. It mostly eliminates redundant branching in conditional forms.

No code-motion (but there's an opcode for for loops); no dead code elimination (the "if false" example you give); no common sub- expression elimination (in the presence of correctly preserving metatable semantics this wouldn't come up very often anyway); no strength reduction; no data-flow analysis.