1694342 - SIMD optimization: Optimize splats of simple constants

Status: RESOLVED DUPLICATE of bug 1644424

(Core :: JavaScript: WebAssembly, enhancement, P3)

Description

[Lars T Hansen [:lth]]

There is some evidence (https://crbug.com/v8/11093) that compilers emit splats of simple constants such as zero. In the cases where we can generate in-line code for the constant that is faster than a constant load, we should emit that code. In cases where the constant load will beat the splat because the splat requires elaborate code, we should emit the constant load.

Caveat: It is possible compilers emit such splats due to the current emscripten weirdness with v128.const (it won't generate it unless you ask nicely), and that the problem will go away, but it's worth revisiting when we have a corpus of benchmark programs to test against.

Comment 1

[Lars T Hansen [:lth]]

Already implemented.