FRET.RA

assembly

[
  "FRET.RA [RegDst0 ~ RegDstn], sp!, uimm"
]

block

[]

catalog_indices

[
  64
]

catalog_records

[
  {
    "asm": "FRET.RA [RegDst0 ~ RegDstn], sp!, uimm",
    "constraints": [
      {
        "field": "DstBegin",
        "operator": "one-of",
        "values": [
          2,
          3,
          4,
          5,
          6,
          7,
          8,
          9,
          10,
          11,
          12,
          13,
          14,
          15,
          16,
          17,
          18,
          19,
          20,
          21,
          22,
          23
        ]
      },
      {
        "field": "DstEnd",
        "operator": "one-of",
        "values": [
          2,
          3,
          4,
          5,
          6,
          7,
          8,
          9,
          10,
          11,
          12,
          13,
          14,
          15,
          16,
          17,
          18,
          19,
          20,
          21,
          22,
          23
        ]
      }
    ],
    "encoding": [
      {
        "index": 0,
        "mask": "0x0000707f",
        "match": "0x00002041",
        "width_bits": 32
      }
    ],
    "encoding_kind": "L32",
    "fields": [
      {
        "name": "DstBegin",
        "pieces": [
          {
            "instruction_lsb": 15,
            "value_lsb": 0,
            "width": 5
          }
        ],
        "signedness": "encoding-defined",
        "width": 5
      },
      {
        "name": "DstEnd",
        "pieces": [
          {
            "instruction_lsb": 20,
            "value_lsb": 0,
            "width": 5
          }
        ],
        "signedness": "encoding-defined",
        "width": 5
      },
      {
        "name": "uimm",
        "pieces": [
          {
            "instruction_lsb": 25,
            "value_lsb": 3,
            "width": 7
          },
          {
            "instruction_lsb": 7,
            "value_lsb": 10,
            "width": 5
          }
        ],
        "signedness": "unsigned",
        "width": 15
      }
    ],
    "form_id": "fret_ra_32_659c886221c1",
    "length_bits": 32,
    "mnemonic": "FRET.RA",
    "semantic_family": "CMD",
    "semantic_group": "Bundle Split",
    "semantic_handler": "ExecuteFrameReturnAddress",
    "semantic_summary": "Restores a restartable stack frame and returns through the pre-restore architectural return address.",
    "status": "accepted"
  }
]

classification

[
  "lifecycle"
]

contract

{
  "block_composition": [
    "none"
  ],
  "canonical_assembly": [
    "FRET.RA [RegDst0 ~ RegDstn], sp!, uimm"
  ],
  "defaults": [
    "The inclusive register range is the ring R2..R23. Singleton, full-ring, and wraparound ranges are assigned.",
    "uimm is always present and represents a byte count in multiples of eight; encoded zero is real zero and is illegal because every assigned range contains at least one register.",
    "The return target is the architectural ra value snapshotted before any restored register can overwrite ra."
  ],
  "encoding_class": "standalone-encoded",
  "examples": [
    "FRET.RA [RegDst0 ~ RegDstn], sp!, uimm"
  ],
  "exceptions": [
    "Reserved endpoints or an insufficient frame size raise Fault_IllegalInstruction before sp, register, memory, target, progress, or TPC effects.",
    "Each eight-byte stack access is a restart boundary. A recoverable access fault preserves earlier committed events and retries exactly the first uncommitted event from trap-preserved template state.",
    "An odd pre-restore ra raises Fault_InstructionPC before sp, memory, destination, frame, or return effects."
  ],
  "field_contracts": {},
  "field_zero_meanings": {
    "DstBegin": "Encoded zero is outside the callee-save ring and is reserved.",
    "DstEnd": "Encoded zero is outside the callee-save ring and is reserved.",
    "uimm": "Encoded zero is a real zero-byte frame size and is illegal for every nonempty range."
  },
  "legality": [
    "DstBegin and DstEnd select the inclusive R2..R23 callee-save ring; every endpoint outside 2..23 is reserved before effects.",
    "If the range contains N registers, uimm must be at least 8*N bytes. The encoding supplies only multiples of eight."
  ],
  "memory_effects": [
    "Load one aligned eight-byte value per selected destination using the same restartable frame-slot order as FEXIT."
  ],
  "operands": [
    {
      "field": "DstBegin",
      "role": "first register in the inclusive R2..R23 ring range"
    },
    {
      "field": "DstEnd",
      "role": "last register in the inclusive R2..R23 ring range"
    },
    {
      "field": "uimm",
      "role": "frame byte count, encoded in multiples of eight"
    }
  ],
  "ordering": [
    "Snapshot and validate the pre-restore return target, add uimm to sp, then restore descending slots in register-ring order.",
    "After the final restore, publish the snapshotted target to TPC; the command does not perform a sequential TPC increment."
  ],
  "standalone_opcode": true,
  "state_effects": [
    "Restoring a range that contains ra updates the architectural ra value without changing the already snapshotted return target.",
    "Completion decrements nonzero frame depth, publishes the last-frame tuple, clears progress, and transfers to the validated target."
  ]
}

depends_on

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

id

PTO-BLOCK-FRET-RA

mnemonic

FRET.RA

summary

Restores a restartable stack frame and returns through the pre-restore architectural return address.

surface

block

{
  "classification": [
    "lifecycle"
  ],
  "documentation": "docs/block/lifecycle/FRET.RA.md",
  "id": "PTO-BLOCK-FRET-RA",
  "instruction_contract": {
    "artifact": "spec/evidence/instruction-contract-closure.json",
    "mnemonic": "FRET.RA",
    "ndf_clause": "PTO-INST-BLOCK-FRET-RA"
  },
  "mnemonic": "FRET.RA",
  "readiness_subjects": [
    "ADR-0032",
    "ADR-0052",
    "ADR-0059",
    "ADR-0084"
  ],
  "semantic_tests": [
    "PTO-AVS-BLOCK-FRET-RA-ACCESS-RECOVERY-002",
    "PTO-AVS-BLOCK-FRET-RA-TARGET-001"
  ],
  "source": "asl/block/lifecycle/FRET.RA.asl",
  "surface": "block",
  "tests": [
    "PTO-AVS-BLOCK-FRET-RA-ACCESS-RECOVERY-002",
    "PTO-AVS-BLOCK-FRET-RA-DECODE-001",
    "PTO-AVS-BLOCK-FRET-RA-TARGET-001"
  ]
}