Stream: git-wasmtime

Topic: wasmtime / issue #11033 Cranelift:

Wasmtime GitHub notifications bot (Jun 13 2025 at 14:51):

akldc opened issue #11033:

.clif Test Case

Please see the attachment for the complete case.

test1.zip

Environment

qemu-riscv64 to emulate execution on an x86 machine.

Description

When set opt_level = none, it executes correctly.

%main() -> [-1377347706, 7919883821509745605, -0x1.891b7ep-1]

When set opt_level = speed, it crashes with a Illegal instruction (exit code -4).

Here is an IR snippet from the main function.

block1:
    v48 = stack_addr.i64 ss0
    atomic_store.i32 little v6, v48
    return v6, v41, v19

block5:
    jump block4(v13, v20)

block6:
    jump block4(v13, v3)

block7:
    jump block4(v13, v10)

block3:
    v40 = bitcast.i32x4 little v33
    jump block4(v40, v20)

block4(v78: i32x4, v79: f64):

    v42 = swizzle v11, v11
    v43 = fcmp.f64 ugt v10, v20
    v44 = avg_round v78, v78
    jump block1

block8:
    v21 = stack_addr.i64 ss1
    v22 = load.i16x8 little v21+1
    v23 = stack_addr.i64 ss0
    v24 = load.f32x4 little v23+9
    v25 = stack_load.f64x2 ss1
    v26 = bitrev.i16 v5
    v27 = fsub.f32 v9, v9
    br_table v6, block9, [block11, block12, block14]

block11:
    jump block10(v24, v12)  ; v12 = const0

block12:
    jump block10(v24, v22)

block14:
    jump block15

With opt_level=speed, I tried removing some dead code, such as v48 and the atomic_store in block1, which makes the program execute correctly.
I also tried replacing all jumps to block14 with jumps to block15, which still results in correct execution of the test case.
I can't figure out the reason behind this illegal instruction.

Wasmtime GitHub notifications bot (Jun 13 2025 at 14:51):

akldc added the bug label to Issue #11033.

Wasmtime GitHub notifications bot (Jun 13 2025 at 14:51):

akldc added the cranelift label to Issue #11033.

Last updated: Dec 06 2025 at 06:05 UTC