llvm-native-core 0.1.16

//! AArch64 SVE2.1 Instruction Selection Table
//!
//! SVE2.1 extends SVE2 with quad-word (128-bit element) operations,
//! multi-vector signed/unsigned extend with 4-vector grouping,
//! interleave/deinterleave, quad-word TBL, FP8 down-convert,
//! floating-point round-to-odd, and PTRUE with pattern predicate.
//!
//! Clean-room behavioural reconstruction from:
//! - Arm Architecture Reference Manual Supplement — SVE2.1
//! - Arm A64 ISA XML descriptions
//! - Black-box oracle interrogation
//! - Zero LLVM source code consultation

use crate::arm::arm_instr_info::ArmOpcode;
use crate::opcode::Opcode;

use super::arm_isel_table::IselPattern;

// ============================================================================
// SVE2.1 ISel Table
// ============================================================================

/// SVE2.1 ISel statistics.
#[derive(Debug, Default, Clone)]
pub struct SVE21IselStats {
    pub total_patterns: usize,
    pub quad_load_store: usize,
    pub multi_vector_extend: usize,
    pub interleave_deinterleave: usize,
    pub quad_tbl: usize,
    pub fp8_ops: usize,
    pub quad_arith: usize,
    pub ptrue_patterns: usize,
    pub frinto_patterns: usize,
}

/// Complete SVE2.1 ISel table.
pub struct SVE21IselTable {
    /// All SVE2.1 ISel patterns.
    pub patterns: Vec<IselPattern>,
    /// ISel statistics.
    pub stats: SVE21IselStats,
}

/// Create the SVE2.1 ISel pattern table.
pub fn sve21_isel_table() -> Vec<IselPattern> {
    let mut table = Vec::new();

    // ================================================================
    // SVE2.1 — Quad-word Load/Store (LD1Q/ST1Q)
    // Contiguous load/store with 128-bit element size
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::Load,
        description: "ld1q {z0.q-z3.q}, p0/z, [x0] — SVE2.1 quad-word load 4×128-bit",
        result_opcode: ArmOpcode::LD1Q_SVE,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Load,
        description: "ld1q {z0.q-z1.q}, p0/z, [x0] — SVE2.1 quad-word load 2×128-bit",
        result_opcode: ArmOpcode::LD1Q_SVE,
        priority: 101,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Load,
        description: "ld1q {z0.q}, p0/z, [x0] — SVE2.1 quad-word load 1×128-bit",
        result_opcode: ArmOpcode::LD1Q_SVE,
        priority: 102,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Store,
        description: "st1q {z0.q-z3.q}, p0, [x0] — SVE2.1 quad-word store 4×128-bit",
        result_opcode: ArmOpcode::ST1Q_SVE,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Store,
        description: "st1q {z0.q-z1.q}, p0, [x0] — SVE2.1 quad-word store 2×128-bit",
        result_opcode: ArmOpcode::ST1Q_SVE,
        priority: 101,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Store,
        description: "st1q {z0.q}, p0, [x0] — SVE2.1 quad-word store 1×128-bit",
        result_opcode: ArmOpcode::ST1Q_SVE,
        priority: 102,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Multi-Vector Signed Extend (SUNPK with 4 vectors)
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::SExt,
        description: "sunpk {z0.h-z3.h}, z0.b — SVE2.1 signed unpack 8→16-bit, 4 vectors",
        result_opcode: ArmOpcode::SUNPK_SVE21,
        priority: 100,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::SExt,
        description: "sunpk {z0.s-z3.s}, z0.h — SVE2.1 signed unpack 16→32-bit, 4 vectors",
        result_opcode: ArmOpcode::SUNPK_SVE21,
        priority: 101,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::SExt,
        description: "sunpk {z0.d-z3.d}, z0.s — SVE2.1 signed unpack 32→64-bit, 4 vectors",
        result_opcode: ArmOpcode::SUNPK_SVE21,
        priority: 102,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Multi-Vector Unsigned Extend (UUNPK with 4 vectors)
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::ZExt,
        description: "uunpk {z0.h-z3.h}, z0.b — SVE2.1 unsigned unpack 8→16-bit, 4 vectors",
        result_opcode: ArmOpcode::UUNPK_SVE21,
        priority: 100,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ZExt,
        description: "uunpk {z0.s-z3.s}, z0.h — SVE2.1 unsigned unpack 16→32-bit, 4 vectors",
        result_opcode: ArmOpcode::UUNPK_SVE21,
        priority: 101,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ZExt,
        description: "uunpk {z0.d-z3.d}, z0.s — SVE2.1 unsigned unpack 32→64-bit, 4 vectors",
        result_opcode: ArmOpcode::UUNPK_SVE21,
        priority: 102,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Multi-Vector Signed Extend (2 vectors)
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::SExt,
        description: "sunpk {z0.h-z1.h}, z0.b — SVE2.1 signed unpack 8→16-bit, 2 vectors",
        result_opcode: ArmOpcode::SUNPK_SVE21_2,
        priority: 110,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::SExt,
        description: "sunpk {z0.s-z1.s}, z0.h — SVE2.1 signed unpack 16→32-bit, 2 vectors",
        result_opcode: ArmOpcode::SUNPK_SVE21_2,
        priority: 111,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::SExt,
        description: "sunpk {z0.d-z1.d}, z0.s — SVE2.1 signed unpack 32→64-bit, 2 vectors",
        result_opcode: ArmOpcode::SUNPK_SVE21_2,
        priority: 112,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Multi-Vector Unsigned Extend (2 vectors)
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::ZExt,
        description: "uunpk {z0.h-z1.h}, z0.b — SVE2.1 unsigned unpack 8→16-bit, 2 vectors",
        result_opcode: ArmOpcode::UUNPK_SVE21_2,
        priority: 110,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ZExt,
        description: "uunpk {z0.s-z1.s}, z0.h — SVE2.1 unsigned unpack 16→32-bit, 2 vectors",
        result_opcode: ArmOpcode::UUNPK_SVE21_2,
        priority: 111,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ZExt,
        description: "uunpk {z0.d-z1.d}, z0.s — SVE2.1 unsigned unpack 32→64-bit, 2 vectors",
        result_opcode: ArmOpcode::UUNPK_SVE21_2,
        priority: 112,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Interleave (ZIPQ) with quad-word
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description:
            "zipq1 {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 interleave even quad-word",
        result_opcode: ArmOpcode::ZIPQ1_SVE21,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description:
            "zipq2 {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 interleave odd quad-word",
        result_opcode: ArmOpcode::ZIPQ2_SVE21,
        priority: 101,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description:
            "zipq1 {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 interleave even 2-reg quad-word",
        result_opcode: ArmOpcode::ZIPQ1_SVE21_2,
        priority: 110,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description:
            "zipq2 {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 interleave odd 2-reg quad-word",
        result_opcode: ArmOpcode::ZIPQ2_SVE21_2,
        priority: 111,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Deinterleave (UZPQ) with quad-word
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description:
            "uzpq1 {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 deinterleave even quad-word",
        result_opcode: ArmOpcode::UZPQ1_SVE21,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description:
            "uzpq2 {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 deinterleave odd quad-word",
        result_opcode: ArmOpcode::UZPQ2_SVE21,
        priority: 101,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description: "uzpq1 {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 deinterleave even 2-reg quad-word",
        result_opcode: ArmOpcode::UZPQ1_SVE21_2,
        priority: 110,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description:
            "uzpq2 {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 deinterleave odd 2-reg quad-word",
        result_opcode: ArmOpcode::UZPQ2_SVE21_2,
        priority: 111,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Quad-word Table Lookup (TBLQ)
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description: "tblq {z0.q-z3.q}, {z4.q-z7.q}, {z8.q-z11.q} — SVE2.1 4-reg quad-word TBL",
        result_opcode: ArmOpcode::TBLQ_SVE21,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description: "tblq {z0.q-z1.q}, {z2.q-z3.q}, {z4.q-z5.q} — SVE2.1 2-reg quad-word TBL",
        result_opcode: ArmOpcode::TBLQ_SVE21_2,
        priority: 101,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::ShuffleVector,
        description: "tblq {z0.q}, {z1.q}, {z2.q} — SVE2.1 1-reg quad-word TBL",
        result_opcode: ArmOpcode::TBLQ_SVE21_1,
        priority: 102,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — FP8 Down-Convert (F1CVTL ↔ F2CVTL)
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::FPTrunc,
        description: "f1cvtl z0.h, z1.b — SVE2.1 FP8 down-convert high→low precision (16→8-bit)",
        result_opcode: ArmOpcode::F1CVTL_SVE21,
        priority: 100,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FPExt,
        description: "f2cvtl z0.b, z1.h — SVE2.1 FP8 up-convert low→high precision (8→16-bit)",
        result_opcode: ArmOpcode::F2CVTL_SVE21,
        priority: 100,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FPTrunc,
        description: "f1cvtl z0.s, z1.h — SVE2.1 FP16→FP32 down-convert high→low precision",
        result_opcode: ArmOpcode::F1CVTL_SVE21,
        priority: 101,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FPExt,
        description: "f2cvtl z0.h, z1.s — SVE2.1 FP32→FP16 up-convert low→high precision",
        result_opcode: ArmOpcode::F2CVTL_SVE21,
        priority: 101,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Multi-vector FP8 Down-Convert
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::FPTrunc,
        description: "f1cvtl {z0.h-z3.h}, z0.b — SVE2.1 multi-vector FP8 down-convert 4-reg",
        result_opcode: ArmOpcode::F1CVTL_SVE21_MULTI,
        priority: 110,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FPExt,
        description: "f2cvtl {z0.b-z3.b}, z0.h — SVE2.1 multi-vector FP8 up-convert 4-reg",
        result_opcode: ArmOpcode::F2CVTL_SVE21_MULTI,
        priority: 110,
        num_operands: 2,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Floating-point Round to Odd (FRINTO)
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::FAdd,
        description: "frinto z0.h, p0/m, z1.h — SVE2.1 FP round-to-odd half-precision",
        result_opcode: ArmOpcode::FRINTO_SVE21,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FAdd,
        description: "frinto z0.s, p0/m, z1.s — SVE2.1 FP round-to-odd single-precision",
        result_opcode: ArmOpcode::FRINTO_SVE21,
        priority: 101,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FAdd,
        description: "frinto z0.d, p0/m, z1.d — SVE2.1 FP round-to-odd double-precision",
        result_opcode: ArmOpcode::FRINTO_SVE21,
        priority: 102,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — PTRUE with Pattern Predicate
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, pow2 — SVE2.1 PTRUE with POW2 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 100,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, vl1 — SVE2.1 PTRUE with VL1 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 101,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, vl2 — SVE2.1 PTRUE with VL2 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 102,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, vl3 — SVE2.1 PTRUE with VL3 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 103,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, vl4 — SVE2.1 PTRUE with VL4 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 104,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, vl5 — SVE2.1 PTRUE with VL5 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 105,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, vl6 — SVE2.1 PTRUE with VL6 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 106,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, vl7 — SVE2.1 PTRUE with VL7 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 107,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Call,
        description: "ptrue p0.b, vl8 — SVE2.1 PTRUE with VL8 pattern predicate",
        result_opcode: ArmOpcode::PTRUE_PAT,
        priority: 108,
        num_operands: 1,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — 128-bit Element Operations with Quad-Register Grouping
    // ================================================================

    // Multi-vector FADD (128-bit)
    table.push(IselPattern {
        ir_opcode: Opcode::FAdd,
        description: "fadd {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word FP add",
        result_opcode: ArmOpcode::FADD_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FSub,
        description: "fsub {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word FP sub",
        result_opcode: ArmOpcode::FSUB_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FMul,
        description: "fmul {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word FP mul",
        result_opcode: ArmOpcode::FMUL_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });

    // Multi-vector integer ADD/SUB with 128-bit elements
    table.push(IselPattern {
        ir_opcode: Opcode::Add,
        description: "add {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word int add",
        result_opcode: ArmOpcode::ADD_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Sub,
        description: "sub {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word int sub",
        result_opcode: ArmOpcode::SUB_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });

    // Multi-vector LSL/LSR with 128-bit elements
    table.push(IselPattern {
        ir_opcode: Opcode::Shl,
        description:
            "lsl {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word shift left",
        result_opcode: ArmOpcode::LSL_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::LShr,
        description: "lsr {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word logical shift right",
        result_opcode: ArmOpcode::LSR_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::AShr,
        description: "asr {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word arithmetic shift right",
        result_opcode: ArmOpcode::ASR_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });

    // Multi-vector bitwise operations
    table.push(IselPattern {
        ir_opcode: Opcode::And,
        description: "and {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word and",
        result_opcode: ArmOpcode::AND_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Or,
        description: "orr {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word orr",
        result_opcode: ArmOpcode::ORR_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Xor,
        description: "eor {z0.q-z3.q}, {z0.q-z3.q}, {z4.q-z7.q} — SVE2.1 4-reg quad-word eor",
        result_opcode: ArmOpcode::EOR_SVE21_QUAD,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — 2-Register Quad-Word variants
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::FAdd,
        description: "fadd {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 2-reg quad-word FP add",
        result_opcode: ArmOpcode::FADD_SVE21_QUAD_2,
        priority: 200,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FSub,
        description: "fsub {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 2-reg quad-word FP sub",
        result_opcode: ArmOpcode::FSUB_SVE21_QUAD_2,
        priority: 200,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FMul,
        description: "fmul {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 2-reg quad-word FP mul",
        result_opcode: ArmOpcode::FMUL_SVE21_QUAD_2,
        priority: 200,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Add,
        description: "add {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 2-reg quad-word int add",
        result_opcode: ArmOpcode::ADD_SVE21_QUAD_2,
        priority: 200,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::Mul,
        description: "mul {z0.q-z1.q}, {z0.q-z1.q}, {z2.q-z3.q} — SVE2.1 2-reg quad-word int mul",
        result_opcode: ArmOpcode::MUL_SVE21_QUAD_2,
        priority: 200,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_quad"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — FP8 mixed-format operations
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::FAdd,
        description: "fadd{z0.b-z3.b}, {z0.b-z3.b}, {z4.b-z7.b} — SVE2.1 4-reg FP8 packed add",
        result_opcode: ArmOpcode::FADD_SVE21_FP8,
        priority: 300,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FSub,
        description: "fsub{z0.b-z3.b}, {z0.b-z3.b}, {z4.b-z7.b} — SVE2.1 4-reg FP8 packed sub",
        result_opcode: ArmOpcode::FSUB_SVE21_FP8,
        priority: 300,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FMul,
        description: "fmul{z0.b-z3.b}, {z0.b-z3.b}, {z4.b-z7.b} — SVE2.1 4-reg FP8 packed mul",
        result_opcode: ArmOpcode::FMUL_SVE21_FP8,
        priority: 300,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });

    // ================================================================
    // SVE2.1 — Multi-vector dot product with FP8 accumulation
    // ================================================================
    table.push(IselPattern {
        ir_opcode: Opcode::FAdd,
        description:
            "fdot {z0.s-z3.s}, {z0.b-z3.b}, {z4.b-z7.b} — SVE2.1 4-reg FP8→FP32 dot product",
        result_opcode: ArmOpcode::FDOT_SVE21,
        priority: 100,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });
    table.push(IselPattern {
        ir_opcode: Opcode::FMul,
        description:
            "fdot {z0.s-z3.s}, {z0.b-z3.b}, {z4.b-z7.b} — SVE2.1 4-reg FP8 fresh dot product",
        result_opcode: ArmOpcode::FDOT_SVE21,
        priority: 110,
        num_operands: 3,
        imm_constraint: None,
        is_two_address: false,
        required_feature: Some("sve2p1_fp8"),
        cond: None,
    });

    table
}

/// Build the SVE2.1 ISel table with statistics.
pub fn build_sve21_isel_table() -> SVE21IselTable {
    let patterns = sve21_isel_table();
    let total = patterns.len();
    let quad_load_store = patterns
        .iter()
        .filter(|p| matches!(p.result_opcode, ArmOpcode::LD1Q_SVE | ArmOpcode::ST1Q_SVE))
        .count();
    let extend = patterns
        .iter()
        .filter(|p| {
            matches!(
                p.result_opcode,
                ArmOpcode::SUNPK_SVE21
                    | ArmOpcode::UUNPK_SVE21
                    | ArmOpcode::SUNPK_SVE21_2
                    | ArmOpcode::UUNPK_SVE21_2
            )
        })
        .count();
    let interleave = patterns
        .iter()
        .filter(|p| {
            matches!(
                p.result_opcode,
                ArmOpcode::ZIPQ1_SVE21
                    | ArmOpcode::ZIPQ2_SVE21
                    | ArmOpcode::ZIPQ1_SVE21_2
                    | ArmOpcode::ZIPQ2_SVE21_2
                    | ArmOpcode::UZPQ1_SVE21
                    | ArmOpcode::UZPQ2_SVE21
                    | ArmOpcode::UZPQ1_SVE21_2
                    | ArmOpcode::UZPQ2_SVE21_2
            )
        })
        .count();
    let tblq = patterns
        .iter()
        .filter(|p| {
            matches!(
                p.result_opcode,
                ArmOpcode::TBLQ_SVE21 | ArmOpcode::TBLQ_SVE21_2 | ArmOpcode::TBLQ_SVE21_1
            )
        })
        .count();
    let fp8 = patterns
        .iter()
        .filter(|p| {
            matches!(
                p.result_opcode,
                ArmOpcode::F1CVTL_SVE21
                    | ArmOpcode::F2CVTL_SVE21
                    | ArmOpcode::F1CVTL_SVE21_MULTI
                    | ArmOpcode::F2CVTL_SVE21_MULTI
                    | ArmOpcode::FADD_SVE21_FP8
                    | ArmOpcode::FSUB_SVE21_FP8
                    | ArmOpcode::FMUL_SVE21_FP8
                    | ArmOpcode::FDOT_SVE21
            )
        })
        .count();
    let quad_ops = patterns
        .iter()
        .filter(|p| {
            matches!(
                p.result_opcode,
                ArmOpcode::FADD_SVE21_QUAD
                    | ArmOpcode::FSUB_SVE21_QUAD
                    | ArmOpcode::FMUL_SVE21_QUAD
                    | ArmOpcode::ADD_SVE21_QUAD
                    | ArmOpcode::SUB_SVE21_QUAD
                    | ArmOpcode::LSL_SVE21_QUAD
                    | ArmOpcode::LSR_SVE21_QUAD
                    | ArmOpcode::ASR_SVE21_QUAD
                    | ArmOpcode::AND_SVE21_QUAD
                    | ArmOpcode::ORR_SVE21_QUAD
                    | ArmOpcode::EOR_SVE21_QUAD
                    | ArmOpcode::FADD_SVE21_QUAD_2
                    | ArmOpcode::FSUB_SVE21_QUAD_2
                    | ArmOpcode::FMUL_SVE21_QUAD_2
                    | ArmOpcode::ADD_SVE21_QUAD_2
                    | ArmOpcode::MUL_SVE21_QUAD_2
            )
        })
        .count();
    let ptrue = patterns
        .iter()
        .filter(|p| matches!(p.result_opcode, ArmOpcode::PTRUE_PAT))
        .count();
    let frinto = patterns
        .iter()
        .filter(|p| matches!(p.result_opcode, ArmOpcode::FRINTO_SVE21))
        .count();

    SVE21IselTable {
        patterns,
        stats: SVE21IselStats {
            total_patterns: total,
            quad_load_store,
            multi_vector_extend: extend,
            interleave_deinterleave: interleave,
            quad_tbl: tblq,
            fp8_ops: fp8,
            quad_arith: quad_ops,
            ptrue_patterns: ptrue,
            frinto_patterns: frinto,
        },
    }
}

/// SVE2.1 ISel engine.
pub struct SVE21IselEngine {
    pub table: SVE21IselTable,
    pub features: SVE21Features,
}

/// SVE2.1 feature flags.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct SVE21Features {
    pub has_sve2p1: bool,
    pub has_sve2p1_fp8: bool,
    pub has_sve2p1_quad: bool,
    pub allowed_quad_regs: u8, // 1, 2, or 4
}

impl Default for SVE21Features {
    fn default() -> Self {
        Self {
            has_sve2p1: false,
            has_sve2p1_fp8: false,
            has_sve2p1_quad: false,
            allowed_quad_regs: 1,
        }
    }
}

impl SVE21Features {
    /// Full SVE2.1 with all sub-features enabled.
    pub fn sve21_full() -> Self {
        Self {
            has_sve2p1: true,
            has_sve2p1_fp8: true,
            has_sve2p1_quad: true,
            allowed_quad_regs: 4,
        }
    }

    /// Check if a feature string is available.
    pub fn has_feature(&self, feat: &str) -> bool {
        match feat {
            "sve2p1" => self.has_sve2p1,
            "sve2p1_fp8" => self.has_sve2p1_fp8,
            "sve2p1_quad" => self.has_sve2p1_quad,
            _ => false,
        }
    }
}

impl SVE21IselEngine {
    /// Create a new SVE2.1 ISel engine.
    pub fn new(features: SVE21Features) -> Self {
        let table = build_sve21_isel_table();
        Self { table, features }
    }

    /// Check whether a pattern is applicable.
    pub fn is_pattern_applicable(&self, pattern: &IselPattern) -> bool {
        match pattern.required_feature {
            Some("sve2p1") => self.features.has_sve2p1,
            Some("sve2p1_fp8") => self.features.has_sve2p1_fp8,
            Some("sve2p1_quad") => self.features.has_sve2p1_quad,
            _ => true,
        }
    }

    /// Select the best pattern for a given IR opcode.
    pub fn select_pattern(&self, ir_opcodes: &[Opcode]) -> Option<&IselPattern> {
        let mut best: Option<&IselPattern> = None;
        for p in &self.table.patterns {
            if ir_opcodes.contains(&p.ir_opcode) && self.is_pattern_applicable(p) {
                match best {
                    None => best = Some(p),
                    Some(b) if p.priority < b.priority => best = Some(p),
                    _ => {}
                }
            }
        }
        best
    }

    /// Get statistics about the SVE2.1 ISel table.
    pub fn stats(&self) -> String {
        format!(
            "SVE2.1 ISel: {} patterns (quad load/store: {}, extend: {}, interleave: {}, TBLQ: {}, FP8: {}, quad arith: {}, PTRUE: {}, FRINTO: {})",
            self.table.stats.total_patterns,
            self.table.stats.quad_load_store,
            self.table.stats.multi_vector_extend,
            self.table.stats.interleave_deinterleave,
            self.table.stats.quad_tbl,
            self.table.stats.fp8_ops,
            self.table.stats.quad_arith,
            self.table.stats.ptrue_patterns,
            self.table.stats.frinto_patterns,
        )
    }
}

// ============================================================================
// SVE2.1 Opcode Extensions for ArmOpcode
// ============================================================================

/// Extend the ArmOpcode enum with SVE2.1-specific opcodes.
/// These are new variants that must be added to the ArmOpcode enum
/// in `arm_instr_info.rs` for full ISel support.
///
/// This module documents the required opcode additions.
pub mod sve21_opcodes {
    /// SVE2.1 opcode extensions that need to be added to ArmOpcode.
    #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
    pub enum SVE21ExtensionOpcode {
        // Quad-word load/store
        LD1Q_SVE,
        ST1Q_SVE,
        // Multi-vector signed/unsigned extend
        SUNPK_SVE21,
        UUNPK_SVE21,
        SUNPK_SVE21_2,
        UUNPK_SVE21_2,
        // Interleave/deinterleave
        ZIPQ1_SVE21,
        ZIPQ2_SVE21,
        ZIPQ1_SVE21_2,
        ZIPQ2_SVE21_2,
        UZPQ1_SVE21,
        UZPQ2_SVE21,
        UZPQ1_SVE21_2,
        UZPQ2_SVE21_2,
        // Quad-word TBL
        TBLQ_SVE21,
        TBLQ_SVE21_2,
        TBLQ_SVE21_1,
        // FP8 convert
        F1CVTL_SVE21,
        F2CVTL_SVE21,
        F1CVTL_SVE21_MULTI,
        F2CVTL_SVE21_MULTI,
        // Round-to-odd
        FRINTO_SVE21,
        // PTRUE with pattern
        PTRUE_PAT,
        // Quad-word arithmetic
        FADD_SVE21_QUAD,
        FSUB_SVE21_QUAD,
        FMUL_SVE21_QUAD,
        ADD_SVE21_QUAD,
        SUB_SVE21_QUAD,
        LSL_SVE21_QUAD,
        LSR_SVE21_QUAD,
        ASR_SVE21_QUAD,
        AND_SVE21_QUAD,
        ORR_SVE21_QUAD,
        EOR_SVE21_QUAD,
        FADD_SVE21_QUAD_2,
        FSUB_SVE21_QUAD_2,
        FMUL_SVE21_QUAD_2,
        ADD_SVE21_QUAD_2,
        MUL_SVE21_QUAD_2,
        // FP8 pack ops
        FADD_SVE21_FP8,
        FSUB_SVE21_FP8,
        FMUL_SVE21_FP8,
        FDOT_SVE21,
    }

    /// Map extension opcode to the canonical ArmOpcode.
    /// These are placeholders until the ArmOpcode enum is extended.
    pub fn map_to_arm_opcode(_op: SVE21ExtensionOpcode) -> Option<String> {
        // In a full implementation, this would return the ArmOpcode discriminant.
        None
    }
}

// ============================================================================
// SVE2.1 Vector Length Management
// ============================================================================

/// SVE2.1 vector length configuration.
/// The actual vector length in bits is implementation-defined (128 to 2048),
/// and SVE2.1 operations adapt to the hardware vector length.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SVE21VectorLength {
    VL128,
    VL256,
    VL512,
    VL1024,
    VL2048,
}

impl SVE21VectorLength {
    /// Convert to bits.
    pub fn to_bits(&self) -> u32 {
        match self {
            SVE21VectorLength::VL128 => 128,
            SVE21VectorLength::VL256 => 256,
            SVE21VectorLength::VL512 => 512,
            SVE21VectorLength::VL1024 => 1024,
            SVE21VectorLength::VL2048 => 2048,
        }
    }

    /// Convert to bytes.
    pub fn to_bytes(&self) -> u32 {
        self.to_bits() / 8
    }

    /// Number of quad-word (128-bit) elements per vector.
    pub fn quad_words_per_vector(&self) -> u32 {
        self.to_bits() / 128
    }

    /// Check if multi-vector operations with 4 registers are supported.
    /// Multi-vector ops require VLEN ≥ 128.
    pub fn supports_multi_vector_4(&self) -> bool {
        matches!(
            self,
            SVE21VectorLength::VL128
                | SVE21VectorLength::VL256
                | SVE21VectorLength::VL512
                | SVE21VectorLength::VL1024
                | SVE21VectorLength::VL2048
        )
    }

    /// Check if this VL supports quad-word tiling (VLEN ≥ 256).
    pub fn supports_quad_tiling(&self) -> bool {
        self.to_bits() >= 256
    }
}

/// SVE2.1 operation cost model based on vector length.
#[derive(Debug, Clone)]
pub struct SVE21CostModel {
    /// Current vector length.
    pub vl: SVE21VectorLength,
}

impl SVE21CostModel {
    /// Create a new cost model for a given VL.
    pub fn new(vl: SVE21VectorLength) -> Self {
        Self { vl }
    }

    /// Estimate cycles for a quad-word load (LD1Q with 4 registers).
    pub fn ld1q_4reg_cycles(&self) -> u32 {
        // Rough estimate: 1 cycle per quad-word
        self.vl.quad_words_per_vector()
    }

    /// Estimate cycles for a quad-word arithmetic operation.
    pub fn quad_arith_cycles(&self) -> u32 {
        // Rough estimate: 2 cycles per quad-word operation
        self.vl.quad_words_per_vector() * 2
    }

    /// Estimate cycles for FP8 down-convert.
    pub fn fp8_convert_cycles(&self) -> u32 {
        // FP8 conversions are ~4 cycles
        4
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_sve21_isel_table_builds() {
        let table = build_sve21_isel_table();
        assert!(table.stats.total_patterns > 30);
        assert!(table.stats.quad_load_store > 0);
        assert!(table.stats.multi_vector_extend > 0);
        assert!(table.stats.interleave_deinterleave > 0);
        assert!(table.stats.quad_tbl > 0);
        assert!(table.stats.fp8_ops > 0);
        assert!(table.stats.ptrue_patterns > 0);
        assert!(table.stats.frinto_patterns > 0);
        assert!(table.stats.quad_arith > 0);
    }

    #[test]
    fn test_sve21_feature_flags() {
        let f = SVE21Features::default();
        assert!(!f.has_sve2p1);
        assert!(!f.has_feature("sve2p1"));

        let f = SVE21Features::sve21_full();
        assert!(f.has_sve2p1);
        assert!(f.has_feature("sve2p1"));
        assert!(f.has_feature("sve2p1_fp8"));
        assert!(f.has_feature("sve2p1_quad"));
        assert_eq!(f.allowed_quad_regs, 4);
    }

    #[test]
    fn test_sve21_isel_engine_select() {
        let engine = SVE21IselEngine::new(SVE21Features::sve21_full());
        let pat = engine.select_pattern(&[Opcode::Load]);
        assert!(pat.is_some());
    }

    #[test]
    fn test_sve21_isel_engine_pattern_applicable() {
        let engine = SVE21IselEngine::new(SVE21Features::sve21_full());
        // LD1Q pattern should be applicable
        let ld1q_pattern = IselPattern {
            ir_opcode: Opcode::Load,
            description: "test",
            result_opcode: ArmOpcode::LD1Q_SVE,
            priority: 100,
            num_operands: 3,
            imm_constraint: None,
            is_two_address: false,
            required_feature: Some("sve2p1"),
            cond: None,
        };
        assert!(engine.is_pattern_applicable(&ld1q_pattern));

        // FP8 pattern should be applicable
        let fp8_pattern = IselPattern {
            ir_opcode: Opcode::FPTrunc,
            description: "test",
            result_opcode: ArmOpcode::F1CVTL_SVE21,
            priority: 100,
            num_operands: 2,
            imm_constraint: None,
            is_two_address: false,
            required_feature: Some("sve2p1_fp8"),
            cond: None,
        };
        assert!(engine.is_pattern_applicable(&fp8_pattern));

        // Quad pattern should be applicable
        let quad_pattern = IselPattern {
            ir_opcode: Opcode::FAdd,
            description: "test",
            result_opcode: ArmOpcode::FADD_SVE21_QUAD,
            priority: 100,
            num_operands: 3,
            imm_constraint: None,
            is_two_address: false,
            required_feature: Some("sve2p1_quad"),
            cond: None,
        };
        assert!(engine.is_pattern_applicable(&quad_pattern));
    }

    #[test]
    fn test_sve21_isel_pattern_disabled_features() {
        let engine = SVE21IselEngine::new(SVE21Features::default());
        let fp8_pattern = IselPattern {
            ir_opcode: Opcode::FPTrunc,
            description: "test",
            result_opcode: ArmOpcode::F1CVTL_SVE21,
            priority: 100,
            num_operands: 2,
            imm_constraint: None,
            is_two_address: false,
            required_feature: Some("sve2p1_fp8"),
            cond: None,
        };
        assert!(!engine.is_pattern_applicable(&fp8_pattern));
    }

    #[test]
    fn test_sve21_quad_regs_limited() {
        let mut features = SVE21Features::sve21_full();
        features.allowed_quad_regs = 2;
        let engine = SVE21IselEngine::new(features);
        // Still applicable, but engine can check allowed_quad_regs
        let pat = engine.select_pattern(&[Opcode::FAdd]);
        assert!(pat.is_some());
    }
}