[Bug] PTODSL-vmi, vabs interface, Masked vabs with pmode="zero" incorrectly computes inactive lanes

[chenben09]

Component

PTO Dialect / ODS (include/PTO/IR)

Description

pto.vmi.vabs(source, mask, pmode="zero") 在 PTOAS lowering 过程中丢失了输入的 mask。
根据 VMI 语义，pmode="zero" 的预期行为为：
active lane:
result[i] = abs(source[i])

inactive lane:
result[i] = 0
但是当前 lowering 后的 VABS 实际表现为所有 lane 都执行了 abs：
result[i] = abs(source[i])
因此，inactive lane 没有被置零。

Reproduction (minimal)

@jit_kernel(name, params)
def kernel(src_ptr: pto.ptr(dtype, "gm"), out_ptr: pto.ptr(dtype, "gm")):
    src_ub = pto.castptr(pto.i64(0), pto.ptr(dtype, "ub"))
    out_ub = pto.castptr(pto.i64(nbytes), pto.ptr(dtype, "ub"))
    pto.mte_gm_ub(src_ptr, src_ub, 0, nbytes, nburst=(1, 0, 0))
    pto.set_flag("MTE2", "V", event_id=0)
    pto.wait_flag("MTE2", "V", event_id=0)
    source = pto.vmi.vload(src_ub, pto.const(0, dtype=pto.index), size=vl)
    if masked:
        if mask_kind == "group_prefix":
            predicate = pto.vmi.create_mask(active_lanes, size=vl, group=group)
        else:
            predicate = pto.vmi.create_mask(active_lanes, size=vl)
        result = pto.vmi.vabs(source, predicate, pmode=pmode)
    else:
        result = pto.vmi.vabs(source)
    pto.vmi.vstore(result, out_ub, pto.const(0, dtype=pto.index))
    pto.set_flag("V", "MTE3", event_id=0)
    pto.wait_flag("V", "MTE3", event_id=0)
    pto.mte_ub_gm(out_ub, out_ptr, nbytes, nburst=(1, 0, 0))
测试参数如下：
dtype        = f16
VL           = 256
mask         = all-off
active_lanes = 0
pmode        = zero

Expected behavior

all zero.

Actual behavior / error logs

None

Git commit

e32488c

Host platform

A5 Simulator

Target Ascend arch (if relevant)

None

PTOAS build level (if relevant)

None