# `lvxl` — Load Vector Indexed LRU > **Category:** [Memory](../categories/memory.md) · **Form:** [X](../forms/X.md) · **Opcode:** `0x7c0002ce` ## Assembler Mnemonics | Mnemonic | XML entry | Flags | Description | | --- | --- | --- | --- | | `lvxl` | `lvxl` | — | Load Vector Indexed LRU | | `lvxl128` | `lvxl128` | — | Load Vector Indexed LRU 128 | ## Syntax ```asm lvslx [VD], [RA0], [RB] lvxl128 [VD], [RA0], [RB] ``` ## Encoding ### `lvxl` — form `X` - **Opcode word:** `0x7c0002ce` - **Primary opcode (bits 0–5):** `31` - **Extended opcode:** `359` - **Synchronising:** no | Bits | Field | Meaning | | --- | --- | --- | | 0–5 | `OPCD` | primary opcode | | 6–10 | `RT/FRT/VRT` | destination | | 11–15 | `RA/FRA/VRA` | source A | | 16–20 | `RB/FRB/VRB` | source B | | 21–30 | `XO` | extended opcode (10 bits) | | 31 | `Rc` | record-form flag | ### `lvxl128` — form `VX128_1` - **Opcode word:** `0x100002c3` - **Primary opcode (bits 0–5):** `4` - **Extended opcode:** `707` - **Synchronising:** no | Bits | Field | Meaning | | --- | --- | --- | | 0–5 | `OPCD` | primary opcode (4) | | 6–10 | `VD128l` | destination low 5 bits | | 11–15 | `RA` | address register | | 16–20 | `RB` | offset register | | 21–27 | `XO` | extended opcode | | 28–29 | `VD128h` | destination high 2 bits | | 30–31 | `—` | reserved | ## Operands | Field | Role | Description | | --- | --- | --- | | `RA0` | lvxl: read; lvxl128: read | Source GPR; when the encoded register number is 0 the operand is the literal 64-bit zero, **not** `r0`. | | `RB` | lvxl: read; lvxl128: read | Source GPR. | | `VD` | lvxl: write; lvxl128: write | Destination vector register. | ## Register Effects ### `lvxl` - **Reads (always):** `RA0`, `RB` - **Reads (conditional):** _none_ - **Writes (always):** `VD` - **Writes (conditional):** _none_ ### `lvxl128` - **Reads (always):** `RA0`, `RB` - **Reads (conditional):** _none_ - **Writes (always):** `VD` - **Writes (conditional):** _none_ ## Status-Register Effects _No condition-register or status-register effects._ ## Operation (pseudocode) ``` ; Pseudocode derives directly from the xenia-rs interpreter ; arm (see Implementation References). Operation semantics: ; - Read source operands from the fields listed under Operands. ; - Apply the arithmetic / logical / memory action described ; in the Description field above. ; - Write results to the destination register(s); update any ; status bits enumerated under Status-Register Effects. ; Consult the IBM AIX reference link under IBM Reference for ; canonical PPC-style pseudocode where xenia's expression is ; terse. ``` ## C Translation Example ```c /* C translation: the xenia-rs interpreter arm below in */ /* Implementation References is the authoritative semantic */ /* snapshot. Translate it line-by-line: */ /* - ctx.gpr[N] -> r[N] (or f[]/v[] for FPRs/VRs) */ /* - mem.read_u*/write_u* -> mem_read_u*_be / mem_write_u*_be */ /* - ctx.update_cr_signed(fld, v) -> update_cr_signed(fld, v) */ /* - ctx.xer_ca / xer_ov / xer_so -> xer.CA / xer.OV / xer.SO */ /* The Register Effects and Status-Register Effects tables above */ /* enumerate every side effect a faithful translation must emit. */ ``` ## Implementation References **`lvxl`** - xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="lvxl"`](../../xenia-canary/tools/ppc-instructions.xml) - xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_altivec.cc:145`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_altivec.cc#L145) - xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:47`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L47) - xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:802`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L802) - xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:1960-1969`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L1960-L1969)
xenia-rs interpreter body (frozen snapshot) ```rust PpcOpcode::lvxl | PpcOpcode::lvxl128 => { // Same as lvx but with cache hint (ignored) let ea = if instr.ra() == 0 { 0u64 } else { ctx.gpr[instr.ra()] }; let ea = (ea.wrapping_add(ctx.gpr[instr.rb()]) & !0xF) as u32; let mut bytes = [0u8; 16]; for i in 0..16 { bytes[i] = mem.read_u8(ea + i as u32); } let vd = if matches!(instr.opcode, PpcOpcode::lvxl128) { instr.vd128() } else { instr.rd() }; ctx.vr[vd] = xenia_types::Vec128::from_bytes(bytes); ctx.pc += 4; } ```
**`lvxl128`** - xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="lvxl128"`](../../xenia-canary/tools/ppc-instructions.xml) - xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_altivec.cc:148`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_altivec.cc#L148) - xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:47`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L47) - xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:418`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L418) - xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:1960-1969`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L1960-L1969)
xenia-rs interpreter body (frozen snapshot) ```rust PpcOpcode::lvxl | PpcOpcode::lvxl128 => { // Same as lvx but with cache hint (ignored) let ea = if instr.ra() == 0 { 0u64 } else { ctx.gpr[instr.ra()] }; let ea = (ea.wrapping_add(ctx.gpr[instr.rb()]) & !0xF) as u32; let mut bytes = [0u8; 16]; for i in 0..16 { bytes[i] = mem.read_u8(ea + i as u32); } let vd = if matches!(instr.opcode, PpcOpcode::lvxl128) { instr.vd128() } else { instr.rd() }; ctx.vr[vd] = xenia_types::Vec128::from_bytes(bytes); ctx.pc += 4; } ```
## Special Cases & Edge Conditions - **Same data effect as [`lvx`](lvx.md), but with cache hint.** Loads 16 bytes from `EA & ~0xF` into `VD`. The `l` suffix signals to the cache hardware that the line is **least-recently-used** — a hint that the line will not be reused soon, allowing the cache to evict it preferentially under pressure. Useful in streaming reads (e.g. once-through vertex transforms, decode passes). - **Hint ignored under emulation.** Xenia's snapshot comment is explicit: "Same as lvx but with cache hint (ignored)". The functional behaviour is identical to `lvx` — only real hardware acts on the hint. - **Alignment is forced, not checked.** Like `lvx`, the low four bits of `EA` are masked. Unaligned `EA` silently rounds down to the 16-byte boundary. - **Big-endian lane layout.** Byte at the aligned base goes into lane 0; byte at base+15 into lane 15. - **`RA0` semantics.** `RA = 0` selects literal zero. - **No update form.** `lvxl` has no `u`-suffix variant. - **VMX128 sibling (`lvxl128`).** Identical semantics; the only difference is the operand encoding using the split-field 7-bit register index addressing `v0..v127`. Xenia's snapshot dispatches on the opcode to decide which decode helper to use. - **Note: assembler typo.** The Syntax block above shows `lvslx` for the non-128 variant — that is a transcription artefact of the source XML. The real mnemonic is `lvxl`. ## Related Instructions - [`lvx`](lvx.md), [`lvx128`](lvx.md) — same load without the LRU hint. - [`stvxl`](stvxl.md), [`stvxl128`](stvxl.md) — symmetric "store last" variants. - [`stvx`](stvx.md) — non-hint store. - [`dcbt`](dcbt.md), [`dcbtst`](dcbtst.md) — explicit prefetch hints (the hint family). ## IBM Reference - [AIX 7.3 — `lvxl` (Load Vector Indexed LRU)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-lvxl-load-vector-indexed-last-instruction) - `PowerISA v2.07B Book I` "Vector Facility" for canonical hint semantics.