Cranelift: `cls` not implemented for any type on x86_64

[afonso360]

👋 Hey,

Fuzzgen found this when adding support for this instruction.

.clif Test Case

test interpret
test run
set enable_llvm_abi_extensions=true
target x86_64

function %a(i64) -> i64 {
block0(v0: i64):
    v1 = cls.i64 v0
    return v1
}
; run: %a(1) == 62

Steps to Reproduce

• clif-util test ./the-above.clif

Expected Results

The above tests to pass.

Actual Results

    Finished dev [unoptimized + debuginfo] target(s) in 0.15s
     Running `/home/afonso/git/wasmtime/target/debug/clif-util test ./lmao.clif`
thread 'worker #0' panicked at 'not implemented: Cls not supported', cranelift/codegen/src/isa/x64/lower.rs:494:24
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 ERROR cranelift_filetests::concurrent > FAIL: panicked in worker #0: not implemented: Cls not supported
FAIL ./lmao.clif: panicked in worker #0: not implemented: Cls not supported
1 tests
Error: 1 failure

Versions and Environment

Cranelift version or commit: main
Operating system: Windows
Architecture: x86_64

[epilys]

This could be labelled "good first issue". It can be implemented in terms of clz if x86 lacks an instruction for it. For example with cranelift_jit I have implemented it as:

let val_shifted = self.builder.ins().sshr_imm(value, 1);
let value = self.builder.ins().bxor(value, val_shifted);
let value = self.builder.ins().clz(value);
let value = self.builder.ins().iadd_imm(value, -1);

[shreyasravi320]

Hi, I'm submitting this as my first contribution. Opened a PR #12644 covering all integer types