Cranelift: Wrong result for fcvt_from_sint.f32 on RISCV

[afonso360]

👋 Hey,

I re-ran the fuzzer today with the issues that were fixed in the past weeks, and it reported some new cases.

.clif Test Case

test interpret
test run
target riscv64gc

function %a(i16 uext) -> f32 {
block0(v0: i16):
    v1 = fcvt_from_sint.f32 v0
    return v1
}

; run: %a(-12800) == -0x1.900000p13

Steps to Reproduce

• clif-util test ./the-above.clif

Expected Results

The test to pass!

Actual Results

 ERROR cranelift_filetests::concurrent > FAIL: run
FAIL ./lmao.clif: run

Caused by:
    Failed test: run: %a(-12800) == -0x1.900000p13, actual: 0x1.9c0000p15
1 tests
Error: 1 failure

Versions and Environment

Cranelift version or commit: main (e2dcb19)

Operating system: Linux

Architecture: RISCV64GC

Extra Info

CC: @yuyang-ok

[yuyang-ok]

@afonso360 Looking at the ISLE lowering rules.I think we should extend from value first.

[yuyang-ok]

@afonso360 Maybe a review. #5964