BSTART.MGATHER.CAS

assembly

[
  "BSTART.MGATHER.CAS DataType"
]

block

[
  "BSTART.MGATHER.CAS DataType",
  "B.DATR PadValue, Layout (optional)",
  "B.DIM LB0=ValidCol",
  "B.DIM LB1=ValidRow (optional)",
  "B.DIM LB2=Col (optional)",
  "B.IOT IndexTile, ExpectedTile, mask=PE_MASK",
  "B.IOT ReplacementTile, mask=PE_MASK, <last>, ->DstTile<TSize>",
  "B.IOR BaseGPR, zero, zero, ->zero",
  "BSTOP"
]

catalog_indices

[
  23
]

catalog_records

[
  {
    "asm": "BSTART.MGATHER.CAS DataType",
    "constraints": [
      {
        "field": "DataType",
        "operator": "one-of",
        "values": [
          0,
          1,
          2,
          3,
          4,
          5,
          6,
          7,
          8,
          9,
          10,
          11,
          12,
          13,
          14,
          16,
          17,
          18,
          19,
          20,
          24,
          25,
          26,
          27,
          28
        ]
      }
    ],
    "encoding": [
      {
        "index": 0,
        "mask": "0x07ffffff",
        "match": "0x00811181",
        "width_bits": 32
      }
    ],
    "encoding_kind": "L32",
    "fields": [
      {
        "name": "DataType",
        "pieces": [
          {
            "instruction_lsb": 27,
            "value_lsb": 0,
            "width": 5
          }
        ],
        "signedness": "encoding-defined",
        "width": 5
      }
    ],
    "form_id": "bstart_mgather_cas_32_fd8c8a3b720a",
    "length_bits": 32,
    "mnemonic": "BSTART.MGATHER.CAS",
    "semantic_family": "CMD",
    "semantic_group": "Bundle Split",
    "semantic_handler": "ExecuteBundleStart",
    "semantic_summary": "Begins a TLSU byte-displacement atomic compare-and-swap gather block.",
    "status": "accepted"
  }
]

classification

[
  "execution"
]

contract

{
  "block_composition": [
    "BSTART.MGATHER.CAS DataType",
    "B.DATR PadValue, Layout (optional)",
    "B.DIM LB0=ValidCol",
    "B.DIM LB1=ValidRow (optional)",
    "B.DIM LB2=Col (optional)",
    "B.IOT IndexTile, ExpectedTile, mask=PE_MASK",
    "B.IOT ReplacementTile, mask=PE_MASK, <last>, ->DstTile<TSize>",
    "B.IOR BaseGPR, zero, zero, ->zero",
    "BSTOP"
  ],
  "canonical_assembly": [
    "BSTART.MGATHER.CAS DataType"
  ],
  "defaults": [
    "DataType is always encoded and selects the transfer, comparison, replacement, and destination element type.",
    "The completed schema requires explicit B.IOR and LB0. Omitted LB1 defaults to one, omitted LB2 defaults to LB0, and omitted B.DATR selects Null padding with NORM layout."
  ],
  "encoding_class": "standalone-encoded",
  "examples": [
    "BSTART.MGATHER.CAS DataType; B.DATR PadValue, Layout (optional); B.DIM LB0=ValidCol; B.DIM LB1=ValidRow (optional); B.DIM LB2=Col (optional); B.IOT IndexTile, ExpectedTile, mask=PE_MASK; B.IOT ReplacementTile, mask=PE_MASK, <last>, ->DstTile<TSize>; B.IOR BaseGPR, zero, zero, ->zero; BSTOP"
  ],
  "exceptions": [
    "Reserved DataType encodings raise Fault_IllegalInstruction before architectural effects.",
    "At bundle completion, malformed two-command B.IOT composition, missing B.IOR or LB0, packed transfer types, non-integer indices, mismatched source type or shape, invalid dimensions, or any read/write access fault is rejected before destination allocation, atomic events, or memory writes."
  ],
  "field_contracts": {
    "DataType": {
      "ref": "PTO-FIELD-BLOCK-DATATYPE"
    }
  },
  "field_zero_meanings": {
    "DataType": "Encoded zero selects FP64."
  },
  "legality": [
    "bstart_mgather_cas_32_fd8c8a3b720a.DataType accepts only 0..14, 16..20, and 24..28 at decode; all other encodings are reserved.",
    "Indexed TLSU transfer additionally rejects E2M1X2, E1M2X2, HiF4X2, S4X2, and U4X2 because MGATHER.CAS carries no nibble selector.",
    "The body must complete the exact two-B.IOT Local schema documented by PTO-TILE-MGATHER-CAS. B.IOS and extra bindings are not accepted.",
    "PE_MASK=0000 is a strict no-op before all schema, GPR, source, dimension, allocation, address, and fault checks."
  ],
  "memory_effects": [
    "The start itself performs no memory access. BSTOP or the next BSTART performs the fully preflighted per-lane atomic compare-and-swap sequence.",
    "Duplicate-address lanes are legal and serialize in an implementation-defined order; each lane still supplies one atomic event."
  ],
  "operands": [
    {
      "field": "DataType",
      "role": "transfer, comparison, replacement, and destination element type"
    }
  ],
  "ordering": [
    "Each valid lane is one atomic read-modify-write under the block aq/rl attributes. No fixed order is defined between duplicate-address lanes or between PEs."
  ],
  "standalone_opcode": true,
  "state_effects": [
    "Closes any preceding block, initializes a TileMemory descriptor, and selects TLSU function 8 with the encoded transfer DataType.",
    "No destination is allocated until the completed block passes schema, source, dimension, and complete access preflight."
  ]
}

depends_on

[
  "PTO-BLOCK-MODEL-SCHEMA-PROFILE-ENCODING"
]

id

PTO-BLOCK-BSTART-MGATHER-CAS

mnemonic

BSTART.MGATHER.CAS

summary

Begins a TLSU byte-displacement atomic compare-and-swap gather block.

surface

block

{
  "classification": [
    "execution"
  ],
  "documentation": "docs/block/execution/BSTART.MGATHER.CAS.md",
  "id": "PTO-BLOCK-BSTART-MGATHER-CAS",
  "instruction_contract": {
    "artifact": "spec/evidence/instruction-contract-closure.json",
    "mnemonic": "BSTART.MGATHER.CAS",
    "ndf_clause": "PTO-INST-BLOCK-BSTART-MGATHER-CAS"
  },
  "mnemonic": "BSTART.MGATHER.CAS",
  "readiness_subjects": [
    "ADR-0020",
    "ADR-0032",
    "ADR-0033",
    "ADR-0052",
    "ADR-0055",
    "ADR-0056",
    "ADR-0059",
    "ADR-0078"
  ],
  "semantic_tests": [
    "PTO-AVS-BLOCK-MGATHER-CAS-DUP-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-EXEC-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-FAULT-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-PACKED-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-SCHEMA-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-ZERO-001"
  ],
  "source": "asl/block/execution/BSTART.MGATHER.CAS.asl",
  "surface": "block",
  "tests": [
    "PTO-AVS-BLOCK-BSTART-MGATHER-CAS-DECODE-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-DUP-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-EXEC-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-FAULT-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-PACKED-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-SCHEMA-001",
    "PTO-AVS-BLOCK-MGATHER-CAS-ZERO-001"
  ]
}