[nextaccountic]

> The reason Stitch is slightly faster than Wasm3 on Mac, but slightly slower on Linux, is likely because Stitch has more variants per instruction compared to Wasm3, which puts pressure on the instruction cache. I suspect this gives Stitch the edge on the Apple M2 Pro, with its large instruction cache, but Wasm3 the edge on the Intel Xeon E312xx, with its smaller instruciton cache.

What means "more variants per instruction" here?

[ejpbruel]

Stitch lazily compiles each wasm function to a form of threaded code in which each instruction has multiple variants, depending on where it loads its operands from.

Each operand is either stored on the stack (s), a virtual register (r), or as an immediate value (i). The add instruction, for instance, has an add_ss variant, an add_rs, and an add_ri variant, among others.

Most instructions store their result in a register, so that subsequent instructions operating on the result can avoid a stack load.

i32/i64/f32/f64.const instructions are completely elided: instead of storing constant values on the stack, they are stored as an immediate operand for the next instruction (this is one area where stitch differs from wasm3, which preloads all constants for a function on the stack every time the function is called)

I hope that clarifies things :-)