Stream: git-wasmtime

Topic: wasmtime / issue #9041 Cranelift: "constant immediate is ...

Wasmtime GitHub notifications bot (Jul 29 2024 at 19:25):

Kmeakin added the bug label to Issue #9041.

Wasmtime GitHub notifications bot (Jul 29 2024 at 19:25):

Kmeakin added the cranelift label to Issue #9041.

Wasmtime GitHub notifications bot (Jul 29 2024 at 19:25):

Kmeakin opened issue #9041:

Adding this optimization to codegen/src/opts/icmp.isle

;; sge(x, c) == sgt(x, c-1), for c != SMIN.
(rule (simplify (sge (fits_in_64 (ty_int bty)) x (iconst cty (u64_from_imm64 c))))
      (if-let $false (u64_eq c (ty_smin cty)))
      (sgt bty x (iconst cty (imm64 (u64_sub c 1)))))

Triggers a verification error when optimizing filetests/filetests/egraph/icmp-parameterized.clif:

FAIL filetests/filetests/egraph/icmp-parameterized.clif: optimize

Caused by:
    function %icmp_sgt_umax(i32) -> i8 fast {
    block0(v0: i32):
        v5 = iconst.i32 -1
    ;   ^~~~~~~~~~~~~~~~~~
    ; error: inst5 (v5 = iconst.i32 -1): constant immediate is out of bounds

        v10 = icmp sgt v0, v5  ; v5 = -1
        return v10
    }

    ; 1 verifier error detected (see above). Compilation aborted.

I suspect somewhere the immediate is being sign extended when it should be zero extended

Wasmtime GitHub notifications bot (Jul 29 2024 at 20:42):

bjorn3 commented on issue #9041:

-1 in clif ir text files is -1i64, which is the same as u64::MAX. Cranelift used to ignore the upper half of the immediate, but was changed to expect the upper half to be zeroed. We didn't yet change imm64 to uimm64 yet though, so immediates are still represented as signed integers, despite unsigned integers effectively being expected by the backend.

Wasmtime GitHub notifications bot (Aug 06 2024 at 15:13):

Kmeakin commented on issue #9041:

Fixed by https://github.com/bytecodealliance/wasmtime/commit/0683b84b40207d8ec0c9044ef418fbd1f23a62f9#diff-5d1ba23293b47ecf64fcf7a888b452d862ebba5baab61fcb4e4a78917b896b2e

Wasmtime GitHub notifications bot (Aug 06 2024 at 15:13):

Kmeakin edited a comment on issue #9041:

Fixed by https://github.com/bytecodealliance/wasmtime/commit/0683b84b40207d8ec0c9044ef418fbd1f23a62f9

Wasmtime GitHub notifications bot (Aug 06 2024 at 16:10):

Kmeakin edited a comment on issue #9041:

~Fixed by https://github.com/bytecodealliance/wasmtime/commit/0683b84b40207d8ec0c9044ef418fbd1f23a62f9~

Last updated: Dec 23 2024 at 12:05 UTC