Stream: git-wasmtime

Topic: wasmtime / issue #11722 Missed optimizations

Wasmtime GitHub notifications bot (Sep 19 2025 at 21:27):

khagankhan opened issue #11722:

Hello. I am doing some fun project myself and I would like to know whether you are interested in missed otimizations in cranelift. For example:

Not optimized to a constant matching execution (-1). Dumping CLIF from /tmp/.tmp1PhnFo/wasm[0]--function[0]--main.clif:

=================== CLIF BEGIN ===================
;; Intermediate Representation of function <wasm[0]::function[0]::main>:
function u0:0(i64 vmctx, i64) -> i32 tail {
    gv0 = vmctx
    gv1 = load.i64 notrap aligned readonly gv0+8
    gv2 = load.i64 notrap aligned gv1+16
    stack_limit = gv2

                                block0(v0: i64, v1: i64):
@002e                               jump block1

                                block1:
@0022                               v3 = iconst.i32 -355
@0025                               v4 = iconst.i32 20
@0027                               v5 = rotl v3, v4  ; v3 = -355, v4 = 20
@0028                               v6 = iconst.i32 -9828254
@002d                               v7 = bor v5, v6  ; v6 = -9828254
@002e                               return v7
}

==================== CLIF END ====================
khan22@node0:~/wasmoi/code_generator$ cat p.wat
(module
  (func $main (export "main") (result i32)
    (i32.or
      (i32.rotl (i32.const -355) (i32.const 20))
      (i32.const -9828254))))

Wasmtime GitHub notifications bot (Sep 19 2025 at 21:56):

cfallin commented on issue #11722:

It appears we don't have a mid-end rule for constant-propagating rotates (e.g. rotl) in our constant-propagation rules; PRs welcome if you want to try your hand at these!

Wasmtime GitHub notifications bot (Sep 19 2025 at 21:58):

khagankhan commented on issue #11722:

That would be fun! I am building an automated tool to find missed opts. So I think I can find them and also make a PR each time :)

Last updated: Dec 06 2025 at 06:05 UTC