decode fixed-point compare instructions

Cargo.lock

@@ -279,11 +279,13 @@ dependencies = [
  "fayalite",
  "hex-literal",
  "parse_powerisa_pdf",
+ "regex",
  "roxmltree",
  "serde",
  "sha2",
  "simple-mermaid",
  "ureq",
+ "which",
 ]
 
 [[package]]
@@ -359,12 +361,12 @@ checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
 
 [[package]]
 name = "errno"
-version = "0.3.9"
+version = "0.3.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "534c5cf6194dfab3db3242765c03bbe257cf92f22b38f6bc0c58d59108a820ba"
+checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
- "windows-sys 0.52.0",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -630,9 +632,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.159"
+version = "0.2.180"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "561d97a539a36e26a9a5fad1ea11a3039a67714694aaa379433e580854bc3dc5"
+checksum = "bcc35a38544a891a5f7c865aca548a982ccb3b8650a5b06d0fd33a10283c56fc"
 
 [[package]]
 name = "libloading"
@@ -1210,6 +1212,7 @@ checksum = "b4ee928febd44d98f2f459a4a79bd4d928591333a494a10a868418ac1b39cf1f"
 dependencies = [
  "either",
  "home",
+ "regex",
  "rustix",
  "winsafe",
 ]

Cargo.toml

@@ -23,6 +23,7 @@ serde = { version = "1.0.202", features = ["derive"] }
 sha2 = "0.10.9"
 simple-mermaid = "0.2.0"
 ureq = "3.1.4"
+which = { version = "6.0.3", features = ["regex"] }
 
 [profile.dev]
 opt-level = 1

crates/cpu/Cargo.toml

@@ -30,4 +30,6 @@ ureq.workspace = true
 [dev-dependencies]
 base16ct.workspace = true
 hex-literal.workspace = true
+regex = "1.12.2"
 sha2.workspace = true
+which.workspace = true

crates/cpu/src/decoder.rs

@@ -0,0 +1,4 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// See Notices.txt for copyright information
+
+pub mod simple_power_isa;

crates/cpu/src/instruction.rs

@@ -4,7 +4,9 @@ use crate::{unit::UnitMOp, util::range_u32_len};
 use fayalite::{
     expr::{HdlPartialEqImpl, ops::ArrayLiteral},
     intern::Interned,
+    module::wire_with_loc,
     prelude::*,
+    ty::StaticType,
 };
 use std::{borrow::Cow, fmt, marker::PhantomData, ops::Range};
 
@@ -734,6 +736,120 @@ impl<DestReg: Type, SrcRegWidth: Size> LogicalMOp<DestReg, SrcRegWidth> {
     }
 }
 
+#[hdl]
+pub enum CompareMode {
+    U64,
+    S64,
+    U32,
+    S32,
+    U16,
+    S16,
+    U8,
+    S8,
+    /// compare one ranged byte -- like the PowerISA `cmprb _, 0, ..` instruction
+    CmpRBOne,
+    /// compare two ranged bytes -- like the PowerISA `cmprb _, 1, ..` instruction
+    CmpRBTwo,
+    /// like the PowerISA `cmpeqb` instruction
+    CmpEqB,
+}
+
+impl HdlPartialEqImpl<Self> for CompareMode {
+    #[track_caller]
+    fn cmp_value_eq(
+        lhs: Self,
+        lhs_value: Cow<'_, Self::SimValue>,
+        rhs: Self,
+        rhs_value: Cow<'_, Self::SimValue>,
+    ) -> bool {
+        SimValue::opaque(&SimValue::from_value(lhs, lhs_value.into_owned()))
+            == SimValue::opaque(&SimValue::from_value(rhs, rhs_value.into_owned()))
+    }
+
+    #[track_caller]
+    fn cmp_sim_value_eq(
+        lhs: Cow<'_, SimValue<Self>>,
+        rhs: Cow<'_, SimValue<Self>>,
+    ) -> SimValue<Bool> {
+        (SimValue::opaque(&lhs) == SimValue::opaque(&rhs)).to_sim_value()
+    }
+
+    #[track_caller]
+    fn cmp_sim_value_ne(
+        lhs: Cow<'_, SimValue<Self>>,
+        rhs: Cow<'_, SimValue<Self>>,
+    ) -> SimValue<Bool> {
+        (SimValue::opaque(&lhs) != SimValue::opaque(&rhs)).to_sim_value()
+    }
+
+    #[track_caller]
+    fn cmp_expr_eq(lhs: Expr<Self>, rhs: Expr<Self>) -> Expr<Bool> {
+        lhs.cast_to_bits().cmp_eq(rhs.cast_to_bits())
+    }
+}
+
+common_mop_struct! {
+    #[mapped(<NewDestReg, NewSrcRegWidth> CompareMOp<NewDestReg, NewSrcRegWidth, SrcCount>)]
+    #[hdl(cmp_eq)]
+    pub struct CompareMOp<DestReg: Type, SrcRegWidth: Size, SrcCount: KnownSize> {
+        #[common]
+        pub alu_common: AluCommonMOp<DestReg, SrcRegWidth, SrcCount>,
+        pub compare_mode: CompareMode,
+    }
+}
+
+impl<DestReg: Type, SrcRegWidth: Size> CompareMOp<DestReg, SrcRegWidth, ConstUsize<2>> {
+    #[hdl]
+    pub fn compare<Target: MOpTrait>(
+        dest: impl ToExpr<Type = DestReg>,
+        src: impl ToExpr<Type = Array<UIntType<SrcRegWidth>, 2>>,
+        imm: impl ToExpr<Type = SInt<{ COMMON_MOP_2_IMM_WIDTH }>>,
+        output_integer_mode: impl ToExpr<Type = OutputIntegerMode>,
+        compare_mode: impl ToExpr<Type = CompareMode>,
+    ) -> Expr<Target>
+    where
+        Self: MOpInto<Target>,
+    {
+        MOpInto::mop_into(
+            #[hdl]
+            CompareMOp {
+                alu_common: #[hdl]
+                AluCommonMOp {
+                    common: CommonMOp::new(0_hdl_u0, dest, src, Expr::as_dyn_int(imm.to_expr())),
+                    output_integer_mode,
+                },
+                compare_mode,
+            },
+        )
+    }
+}
+
+impl<DestReg: Type, SrcRegWidth: Size> CompareMOp<DestReg, SrcRegWidth, ConstUsize<1>> {
+    #[hdl]
+    pub fn compare_i<Target: MOpTrait>(
+        dest: impl ToExpr<Type = DestReg>,
+        src: impl ToExpr<Type = Array<UIntType<SrcRegWidth>, 1>>,
+        imm: impl ToExpr<Type = SInt<{ COMMON_MOP_1_IMM_WIDTH }>>,
+        output_integer_mode: impl ToExpr<Type = OutputIntegerMode>,
+        compare_mode: impl ToExpr<Type = CompareMode>,
+    ) -> Expr<Target>
+    where
+        Self: MOpInto<Target>,
+    {
+        MOpInto::mop_into(
+            #[hdl]
+            CompareMOp {
+                alu_common: #[hdl]
+                AluCommonMOp {
+                    common: CommonMOp::new(0_hdl_u0, dest, src, Expr::as_dyn_int(imm.to_expr())),
+                    output_integer_mode,
+                },
+                compare_mode,
+            },
+        )
+    }
+}
+
 common_mop_struct! {
     #[mapped(<NewDestReg, NewSrcRegWidth> BranchMOp<NewDestReg, NewSrcRegWidth>)]
     #[hdl(cmp_eq)]
@@ -751,6 +867,8 @@ mop_enum! {
         AddSub(AddSubMOp<DestReg, SrcRegWidth, ConstUsize<3>>),
         AddSubI(AddSubMOp<DestReg, SrcRegWidth, ConstUsize<2>>),
         Logical(LogicalMOp<DestReg, SrcRegWidth>),
+        Compare(CompareMOp<DestReg, SrcRegWidth, ConstUsize<2>>),
+        CompareI(CompareMOp<DestReg, SrcRegWidth, ConstUsize<1>>),
     }
 }
 
@@ -947,6 +1065,87 @@ pub struct MOpDestReg {
     pub flag_regs: Array<HdlOption<()>, { range_u32_len(&MOpRegNum::FLAG_REG_NUMS) }>,
 }
 
+impl MOpDestReg {
+    #[hdl]
+    #[track_caller]
+    pub fn new_sim(normal_regs: &[u32], flag_regs: &[u32]) -> SimValue<Self> {
+        let zero_reg = MOpRegNum::const_zero().to_sim_value();
+        let mut normal_regs_sim = std::array::from_fn(|_| zero_reg.clone());
+        for (i, reg) in normal_regs.iter().copied().enumerate() {
+            let Some(normal_reg_sim) = normal_regs_sim.get_mut(i) else {
+                panic!("too many normal regs");
+            };
+            if reg >= 1 << MOpRegNum::WIDTH {
+                panic!("normal reg number out of range");
+            }
+            *normal_reg_sim.value = reg.cast_to_static::<UInt<_>>();
+        }
+        let mut flag_regs_sim = std::array::from_fn(|_| {
+            #[hdl(sim)]
+            HdlNone()
+        });
+        for &flag_reg in flag_regs {
+            let Some(index) = { MOpRegNum::FLAG_REG_NUMS }.position(|v| flag_reg == v) else {
+                panic!(
+                    "flag reg number {flag_reg} is out of range, supported range is: {:?}",
+                    MOpRegNum::FLAG_REG_NUMS
+                );
+            };
+            flag_regs_sim[index] = #[hdl(sim)]
+            HdlSome(());
+        }
+        #[hdl(sim)]
+        Self {
+            normal_regs: normal_regs_sim,
+            flag_regs: flag_regs_sim,
+        }
+    }
+    #[hdl]
+    #[track_caller]
+    pub fn new(
+        normal_regs: impl IntoIterator<Item = Expr<MOpRegNum>>,
+        flag_regs: impl IntoIterator<Item = (u32, Expr<Bool>)>,
+    ) -> Expr<Self> {
+        let mut normal_regs_array = [MOpRegNum::const_zero(); Self::NORMAL_REG_COUNT];
+        const FLAG_REG_COUNT: usize = range_u32_len(&MOpRegNum::FLAG_REG_NUMS);
+        let mut used_flag_regs = [false; FLAG_REG_COUNT];
+        let mut flag_regs_array = [HdlNone(); FLAG_REG_COUNT];
+        for (i, normal_reg) in normal_regs.into_iter().enumerate() {
+            assert!(i < Self::NORMAL_REG_COUNT, "too many normal regs");
+            normal_regs_array[i] = normal_reg;
+        }
+        for (flag_reg_num, flag_reg_enabled) in flag_regs {
+            let Some(index) = { MOpRegNum::FLAG_REG_NUMS }.position(|v| flag_reg_num == v) else {
+                panic!(
+                    "flag reg number {flag_reg_num} is out of range, supported range is: {:?}",
+                    MOpRegNum::FLAG_REG_NUMS
+                );
+            };
+            assert!(
+                !used_flag_regs[index],
+                "duplicate flag reg number {flag_reg_num}"
+            );
+            used_flag_regs[index] = true;
+            let wire = wire_with_loc(
+                &format!("flag_reg_{index}"),
+                SourceLocation::caller(),
+                StaticType::TYPE,
+            );
+            connect(wire, HdlNone());
+            #[hdl]
+            if flag_reg_enabled {
+                connect(wire, HdlSome(()));
+            }
+            flag_regs_array[index] = wire;
+        }
+        #[hdl]
+        Self {
+            normal_regs: normal_regs_array,
+            flag_regs: flag_regs_array,
+        }
+    }
+}
+
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
 pub enum RenameTableName {
     /// the large rename table for normal registers (has less read/write ports)

crates/cpu/src/instruction/power_isa.rs

@@ -29,24 +29,150 @@ impl MOpRegNum {
     pub const POWER_ISA_LR_REG_NUM: u32 = 1;
     pub const POWER_ISA_CTR_REG_NUM: u32 = 2;
     pub const POWER_ISA_TAR_REG_NUM: u32 = 3;
-    /// XER bits are stored in [`PRegValue.flags`], bits that don't exist in [`PRegValue.flags`] are stored in [`PRegValue.int_fp`]
+
+    /// SO, OV, and OV32 XER bits -- in [`PRegValue.flags`]
     ///
     /// [`PRegValue.flags`]: struct@crate::register::PRegValue
-    /// [`PRegValue.int_fp`]: struct@crate::register::PRegValue
+    pub const POWER_ISA_XER_SO_OV_OV32_REG_NUM: u32 =
-    pub const POWER_ISA_XER_REG_NUM: u32 = 4;
+        range_u32_nth_or_panic(&Self::FLAG_REG_NUMS, 0);
+    /// CA and CA32 XER bits -- in [`PRegValue.flags`]
+    ///
+    /// [`PRegValue.flags`]: struct@crate::register::PRegValue
+    pub const POWER_ISA_XER_CA_CA32_REG_NUM: u32 = 4;
+    /// only the XER bits that don't exist in [`PRegValue.flags`]
+    ///
+    /// [`PRegValue.flags`]: struct@crate::register::PRegValue
+    pub const POWER_ISA_XER_OTHER_REG_NUM: u32 = 5;
 
-    pub const POWER_ISA_CR_REG_NUMS: Range<u32> = 8..16;
+    /// SO, OV, and OV32 XER bits -- in [`PRegValue.flags`]
+    ///
+    /// [`PRegValue.flags`]: struct@crate::register::PRegValue
+    #[hdl]
+    pub fn power_isa_xer_so_ov_ov32_reg() -> Expr<Self> {
+        #[hdl]
+        Self {
+            value: Self::POWER_ISA_XER_SO_OV_OV32_REG_NUM.cast_to_static::<UInt<_>>(),
+        }
+    }
+    /// CA and CA32 XER bits -- in [`PRegValue.flags`]
+    ///
+    /// [`PRegValue.flags`]: struct@crate::register::PRegValue
+    #[hdl]
+    pub fn power_isa_xer_ca_ca32_reg() -> Expr<Self> {
+        #[hdl]
+        Self {
+            value: Self::POWER_ISA_XER_CA_CA32_REG_NUM.cast_to_static::<UInt<_>>(),
+        }
+    }
+    /// only the XER bits that don't exist in [`PRegValue.flags`]
+    ///
+    /// [`PRegValue.flags`]: struct@crate::register::PRegValue
+    #[hdl]
+    pub fn power_isa_xer_other_reg() -> Expr<Self> {
+        #[hdl]
+        Self {
+            value: Self::POWER_ISA_XER_OTHER_REG_NUM.cast_to_static::<UInt<_>>(),
+        }
+    }
+
+    pub const POWER_ISA_CR_0_REG_NUM: u32 = range_u32_nth_or_panic(&Self::FLAG_REG_NUMS, 1);
+    pub const POWER_ISA_CR_1_THRU_7_REG_NUMS: Range<u32> = 9..16;
     pub const fn power_isa_cr_reg_num(index: usize) -> u32 {
-        range_u32_nth_or_panic(&Self::POWER_ISA_CR_REG_NUMS, index)
+        if index == 0 {
+            Self::POWER_ISA_CR_0_REG_NUM
+        } else {
+            range_u32_nth_or_panic(&Self::POWER_ISA_CR_1_THRU_7_REG_NUMS, index - 1)
+        }
+    }
+    #[hdl]
+    pub fn power_isa_cr_reg(field_num: Expr<UInt<3>>) -> Expr<Self> {
+        #[hdl]
+        let power_isa_cr_reg: Self = wire();
+        #[hdl]
+        if field_num.cmp_eq(0u8) {
+            connect_any(power_isa_cr_reg.value, Self::POWER_ISA_CR_0_REG_NUM);
+        } else {
+            connect_any(
+                power_isa_cr_reg.value,
+                Self::POWER_ISA_CR_1_THRU_7_REG_NUMS.start - 1 + field_num,
+            );
+        }
+        power_isa_cr_reg
+    }
+    #[hdl]
+    pub fn power_isa_cr_reg_sim(field_num: &SimValue<UInt<3>>) -> SimValue<Self> {
+        #[hdl(sim)]
+        Self {
+            value: Self::power_isa_cr_reg_num(
+                field_num.cast_to_static::<UInt<8>>().as_int() as usize
+            )
+            .cast_to_static::<UInt<_>>(),
+        }
     }
 
     pub const POWER_ISA_GPR_REG_NUMS: Range<u32> = 32..64;
     pub const fn power_isa_gpr_reg_num(index: usize) -> u32 {
         range_u32_nth_or_panic(&Self::POWER_ISA_GPR_REG_NUMS, index)
     }
+    #[hdl]
+    pub fn power_isa_gpr_reg(reg_num: Expr<UInt<5>>) -> Expr<Self> {
+        #[hdl]
+        Self {
+            value: (Self::POWER_ISA_GPR_REG_NUMS.start + reg_num).cast_to_static::<UInt<_>>(),
+        }
+    }
+    #[hdl]
+    pub fn power_isa_gpr_reg_sim(reg_num: &SimValue<UInt<5>>) -> SimValue<Self> {
+        #[hdl(sim)]
+        Self {
+            value: (Self::POWER_ISA_GPR_REG_NUMS.start + reg_num).cast_to_static::<UInt<_>>(),
+        }
+    }
+    pub const fn power_isa_gpr_or_zero_reg_num(index: usize) -> u32 {
+        if index == 0 {
+            Self::CONST_ZERO_REG_NUM
+        } else {
+            Self::power_isa_gpr_reg_num(index)
+        }
+    }
+    #[hdl]
+    pub fn power_isa_gpr_or_zero_reg(reg_num: Expr<UInt<5>>) -> Expr<Self> {
+        #[hdl]
+        let power_isa_gpr_or_zero_reg: Self = wire();
+        connect(power_isa_gpr_or_zero_reg, Self::power_isa_gpr_reg(reg_num));
+        #[hdl]
+        if reg_num.cmp_eq(0u8) {
+            connect(power_isa_gpr_or_zero_reg, Self::const_zero());
+        }
+        power_isa_gpr_or_zero_reg
+    }
+    #[hdl]
+    pub fn power_isa_gpr_or_zero_reg_sim(reg_num: &SimValue<UInt<5>>) -> SimValue<Self> {
+        #[hdl(sim)]
+        Self {
+            value: Self::power_isa_gpr_or_zero_reg_num(
+                reg_num.cast_to_static::<UInt<8>>().as_int() as usize,
+            )
+            .cast_to_static::<UInt<_>>(),
+        }
+    }
 
     pub const POWER_ISA_FPR_REG_NUMS: Range<u32> = 64..96;
     pub const fn power_isa_fpr_reg_num(index: usize) -> u32 {
         range_u32_nth_or_panic(&Self::POWER_ISA_FPR_REG_NUMS, index)
     }
+    #[hdl]
+    pub fn power_isa_fpr_reg(reg_num: Expr<UInt<5>>) -> Expr<Self> {
+        #[hdl]
+        Self {
+            value: (Self::POWER_ISA_FPR_REG_NUMS.start + reg_num).cast_to_static::<UInt<_>>(),
+        }
+    }
+    #[hdl]
+    pub fn power_isa_fpr_reg_sim(reg_num: &SimValue<UInt<5>>) -> SimValue<Self> {
+        #[hdl(sim)]
+        Self {
+            value: (Self::POWER_ISA_FPR_REG_NUMS.start + reg_num).cast_to_static::<UInt<_>>(),
+        }
+    }
 }

crates/cpu/src/lib.rs

@@ -1,9 +1,10 @@
 // SPDX-License-Identifier: LGPL-3.0-or-later
 // See Notices.txt for copyright information
 pub mod config;
+pub mod decoder;
 pub mod instruction;
 pub mod next_pc;
-pub mod powerisa;
+pub mod powerisa_instructions_xml;
 pub mod reg_alloc;
 pub mod register;
 pub mod unit;

crates/cpu/src/unit/alu_branch.rs

@@ -4,8 +4,8 @@
 use crate::{
     config::CpuConfig,
     instruction::{
-        AddSubMOp, AluBranchMOp, AluCommonMOp, COMMON_MOP_SRC_LEN, CommonMOp, LogicalMOp, MOpTrait,
+        AddSubMOp, AluBranchMOp, AluCommonMOp, COMMON_MOP_SRC_LEN, CommonMOp, CompareMOp,
-        OutputIntegerMode, RenamedMOp, UnitOutRegNum,
+        LogicalMOp, MOpTrait, OutputIntegerMode, RenamedMOp, UnitOutRegNum,
     },
     register::{FlagsMode, PRegFlagsPowerISA, PRegFlagsX86, PRegValue},
     unit::{
@@ -244,6 +244,20 @@ fn logical(
     }
 }
 
+#[hdl]
+fn compare<SrcCount: KnownSize>(
+    mop: Expr<CompareMOp<UnitOutRegNum<DynSize>, DynSize, SrcCount>>,
+    flags_mode: Expr<FlagsMode>,
+    src_values: Expr<Array<PRegValue, { COMMON_MOP_SRC_LEN }>>,
+) -> Expr<UnitResultCompleted<()>> {
+    // TODO: finish
+    #[hdl]
+    UnitResultCompleted::<_> {
+        value: PRegValue::zeroed(),
+        extra_out: (),
+    }
+}
+
 #[hdl_module]
 pub fn alu_branch(config: &CpuConfig, unit_index: usize) {
     #[hdl]
@@ -336,6 +350,40 @@ pub fn alu_branch(config: &CpuConfig, unit_index: usize) {
                     },
                 ),
             ),
+            AluBranchMOp::<_, _>::Compare(mop) => connect(
+                unit_base.execute_end,
+                HdlSome(
+                    #[hdl]
+                    ExecuteEnd::<_, _> {
+                        unit_output: #[hdl]
+                        UnitOutput::<_, _> {
+                            which: MOpTrait::dest_reg(mop),
+                            result: UnitResult[()].Completed(compare(
+                                mop,
+                                global_state.flags_mode,
+                                src_values,
+                            )),
+                        },
+                    },
+                ),
+            ),
+            AluBranchMOp::<_, _>::CompareI(mop) => connect(
+                unit_base.execute_end,
+                HdlSome(
+                    #[hdl]
+                    ExecuteEnd::<_, _> {
+                        unit_output: #[hdl]
+                        UnitOutput::<_, _> {
+                            which: MOpTrait::dest_reg(mop),
+                            result: UnitResult[()].Completed(compare(
+                                mop,
+                                global_state.flags_mode,
+                                src_values,
+                            )),
+                        },
+                    },
+                ),
+            ),
         }
     }
 }

crates/cpu/tests/simple_power_isa_decoder.rs

@@ -0,0 +1,831 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// See Notices.txt for copyright information
+
+use cpu::{
+    decoder::simple_power_isa::decode_one_insn,
+    instruction::{
+        AddSubMOp, CompareMOp, CompareMode, MOp, MOpDestReg, MOpRegNum, OutputIntegerMode,
+    },
+    util::array_vec::ArrayVec,
+};
+use fayalite::{prelude::*, sim::vcd::VcdWriterDecls, util::RcWriter};
+use std::{
+    fmt::{self, Write as _},
+    io::Write,
+    process::Command,
+};
+
+struct TestCase {
+    mnemonic: &'static str,
+    first_input: u32,
+    second_input: Option<u32>,
+    output: SimValue<ArrayVec<MOp, ConstUsize<2>>>,
+    loc: &'static std::panic::Location<'static>,
+}
+
+impl fmt::Debug for TestCase {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let Self {
+            mnemonic,
+            first_input,
+            second_input,
+            output,
+            loc,
+        } = self;
+        let mut debug_struct = f.debug_struct("TestCase");
+        debug_struct
+            .field("mnemonic", mnemonic)
+            .field("first_input", &format_args!("0x{first_input:08x}"));
+        if let Some(second_input) = second_input {
+            debug_struct.field("second_input", &format_args!("0x{second_input:08x}"));
+        } else {
+            debug_struct.field("second_input", &format_args!("None"));
+        }
+        debug_struct
+            .field("output", &ArrayVec::elements_sim_ref(output))
+            .field("loc", &format_args!("{loc}"))
+            .finish()
+    }
+}
+
+#[hdl]
+fn test_cases() -> Vec<TestCase> {
+    let mut retval = Vec::new();
+    #[track_caller]
+    fn insn_single(
+        mnemonic: &'static str,
+        first_input: u32,
+        second_input: Option<u32>,
+        output: impl ToSimValue<Type = MOp>,
+    ) -> TestCase {
+        let zero_mop = UInt::new_dyn(MOp.canonical().bit_width())
+            .zero()
+            .cast_bits_to(MOp);
+        let mut single_storage = ArrayVec::new_sim(ArrayVec[MOp][ConstUsize], &zero_mop);
+        ArrayVec::try_push_sim(&mut single_storage, zero_mop).expect("known to have space");
+        ArrayVec::elements_sim_mut(&mut single_storage)[0] = output.to_sim_value();
+        TestCase {
+            mnemonic,
+            first_input,
+            second_input,
+            output: single_storage.clone(),
+            loc: std::panic::Location::caller(),
+        }
+    }
+    retval.push(insn_single(
+        "addi 3, 4, 0x1234",
+        0x38641234,
+        None,
+        AddSubMOp::add_sub_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_gpr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0x1234.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            false,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "paddi 3, 4, 0x123456789, 0",
+        0x06012345,
+        Some(0x38646789),
+        AddSubMOp::add_sub_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_gpr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0x123456789i64.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            false,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "paddi 3, 0, 0x123456789, 1",
+        0x06112345,
+        Some(0x38606789),
+        AddSubMOp::add_sub_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_gpr_reg_num(3)], &[]),
+            [MOpRegNum::const_zero().value, MOpRegNum::const_zero().value],
+            0x123456789i64.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            false,
+            false,
+            true,
+        ),
+    ));
+    retval.push(insn_single(
+        "addis 3, 4, 0x1234",
+        0x3C641234,
+        None,
+        AddSubMOp::add_sub_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_gpr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0x12340000.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            false,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "addpcis 3, 0x1234",
+        0x4c7a1204,
+        None,
+        AddSubMOp::add_sub_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_gpr_reg_num(3)], &[]),
+            [MOpRegNum::const_zero().value; _],
+            0x12340004.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            false,
+            false,
+            true,
+        ),
+    ));
+    retval.push(insn_single(
+        "add. 3, 4, 5",
+        0x7c642a15,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[MOpRegNum::power_isa_gpr_reg_num(3)],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            false,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "addic. 3, 4, 0x1234",
+        0x34641234,
+        None,
+        AddSubMOp::add_sub_i(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0x1234.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            false,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "subf. 3, 4, 5",
+        0x7c642851,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[MOpRegNum::power_isa_gpr_reg_num(3)],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            true,
+            false,
+            true,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "subfic 3, 4, 0x1234",
+        0x20641234,
+        None,
+        AddSubMOp::add_sub_i(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0x1234.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            true,
+            false,
+            true,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "addc. 3, 4, 5",
+        0x7c642815,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            false,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "subfc. 3, 4, 5",
+        0x7c642811,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            true,
+            false,
+            true,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "adde. 3, 4, 5",
+        0x7c642915,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_xer_ca_ca32_reg().value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            true,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "subfe. 3, 4, 5",
+        0x7c642911,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_xer_ca_ca32_reg().value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            true,
+            true,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "addme. 3, 4",
+        0x7c6401d5,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_xer_ca_ca32_reg().value,
+                MOpRegNum::const_zero().value,
+            ],
+            (-1i8).cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            true,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "subfme. 3, 4",
+        0x7c6401d1,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_xer_ca_ca32_reg().value,
+                MOpRegNum::const_zero().value,
+            ],
+            (-1i8).cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            true,
+            true,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "addze. 3, 4",
+        0x7c640195,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_xer_ca_ca32_reg().value,
+                MOpRegNum::const_zero().value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            false,
+            true,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "subfze. 3, 4",
+        0x7c640191,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[
+                    MOpRegNum::power_isa_gpr_reg_num(3),
+                    MOpRegNum::POWER_ISA_XER_CA_CA32_REG_NUM,
+                ],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_xer_ca_ca32_reg().value,
+                MOpRegNum::const_zero().value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            true,
+            true,
+            false,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "neg. 3, 4",
+        0x7c6400d1,
+        None,
+        AddSubMOp::add_sub(
+            MOpDestReg::new_sim(
+                &[MOpRegNum::power_isa_gpr_reg_num(3)],
+                &[MOpRegNum::POWER_ISA_CR_0_REG_NUM],
+            ),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::const_zero().value,
+                MOpRegNum::const_zero().value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            true,
+            false,
+            true,
+            false,
+        ),
+    ));
+    retval.push(insn_single(
+        "cmpi 3, 0, 4, 0x1234",
+        0x2d841234,
+        None,
+        CompareMOp::compare_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value],
+            0x1234.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::S32(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmpi 3, 1, 4, -0x7655",
+        0x2da489ab,
+        None,
+        CompareMOp::compare_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value],
+            (0x89abu16 as i16).cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::S64(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmp 3, 0, 4, 5",
+        0x7d842800,
+        None,
+        CompareMOp::compare(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::S32(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmp 3, 1, 4, 5",
+        0x7da42800,
+        None,
+        CompareMOp::compare(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::S64(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmpli 3, 0, 4, 0x1234",
+        0x29841234,
+        None,
+        CompareMOp::compare_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value],
+            0x1234.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::U32(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmpli 3, 1, 4, 0x89ab",
+        0x29a489ab,
+        None,
+        CompareMOp::compare_i(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value],
+            0x89ab.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::U64(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmpl 3, 0, 4, 5",
+        0x7d842840,
+        None,
+        CompareMOp::compare(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::U32(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmpl 3, 1, 4, 5",
+        0x7da42840,
+        None,
+        CompareMOp::compare(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::U64(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmprb 3, 0, 4, 5",
+        0x7d842980,
+        None,
+        CompareMOp::compare(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::CmpRBOne(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmprb 3, 1, 4, 5",
+        0x7da42980,
+        None,
+        CompareMOp::compare(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::CmpRBTwo(),
+        ),
+    ));
+    retval.push(insn_single(
+        "cmpeqb 3, 4, 5",
+        0x7d8429c0,
+        None,
+        CompareMOp::compare(
+            MOpDestReg::new_sim(&[MOpRegNum::power_isa_cr_reg_num(3)], &[]),
+            [
+                MOpRegNum::power_isa_gpr_reg(4_hdl_u5).value,
+                MOpRegNum::power_isa_gpr_reg(5_hdl_u5).value,
+            ],
+            0.cast_to_static::<SInt<_>>(),
+            #[hdl(sim)]
+            OutputIntegerMode::Full64(),
+            #[hdl(sim)]
+            CompareMode::CmpEqB(),
+        ),
+    ));
+    retval
+}
+
+#[test]
+fn test_test_cases_assembly() -> std::io::Result<()> {
+    let llvm_mc_regex = regex::Regex::new(r"llvm-mc(-\d+)?$").expect("known to be a valid regex");
+    let llvm_mc = which::which_re(llvm_mc_regex)
+        .expect("can't find llvm-mc or llvm-mc-<num> in path")
+        .next()
+        .expect("can't find llvm-mc or llvm-mc-<num> in path");
+    let test_cases = test_cases();
+    let mut assembly = String::new();
+    for TestCase {
+        mnemonic,
+        first_input: _,
+        second_input: _,
+        output: _,
+        loc: _,
+    } in &test_cases
+    {
+        writeln!(assembly, "{mnemonic}").unwrap();
+    }
+    let (reader, mut writer) = std::io::pipe()?;
+    let thread = std::thread::spawn(move || writer.write_all(assembly.as_bytes()));
+    let std::process::Output {
+        status,
+        stdout,
+        stderr,
+    } = Command::new(&llvm_mc)
+        .arg("--triple=powerpc64le-linux-gnu")
+        .arg("--assemble")
+        .arg("--filetype=asm")
+        .arg("--show-encoding")
+        .arg("-")
+        .stdin(reader)
+        .output()?;
+    let _ = thread.join();
+    let stderr = String::from_utf8_lossy(&stderr);
+    eprint!("{stderr}");
+    if !status.success() {
+        panic!("{} failed: {status}", llvm_mc.display());
+    }
+    let stdout = String::from_utf8_lossy(&stdout);
+    print!("{stdout}");
+    let mut lines = stdout.lines();
+    let text_line = lines.next();
+    assert_eq!(text_line, Some("\t.text"));
+    for test_case @ TestCase {
+        mnemonic: _,
+        first_input,
+        second_input,
+        output: _,
+        loc: _,
+    } in test_cases
+    {
+        let Some(line) = lines.next() else {
+            panic!("output missing line for: {test_case:?}");
+        };
+        let Some((_, comment)) = line.split_once('#') else {
+            panic!("output line missing comment. test_case={test_case:?}\nline:\n{line}");
+        };
+        let [b0, b1, b2, b3] = first_input.to_le_bytes();
+        let expected_comment = if let Some(second_input) = second_input {
+            let [b4, b5, b6, b7] = second_input.to_le_bytes();
+            format!(
+                " encoding: [0x{b0:02x},0x{b1:02x},0x{b2:02x},0x{b3:02x},0x{b4:02x},0x{b5:02x},0x{b6:02x},0x{b7:02x}]"
+            )
+        } else {
+            format!(" encoding: [0x{b0:02x},0x{b1:02x},0x{b2:02x},0x{b3:02x}]")
+        };
+        assert_eq!(
+            comment, expected_comment,
+            "test_case={test_case:?}\nline:\n{line}"
+        );
+    }
+    for line in lines {
+        assert!(line.trim().is_empty(), "bad trailing output line: {line:?}");
+    }
+    Ok(())
+}
+
+#[hdl]
+#[test]
+fn test_decode_insn() {
+    let _n = SourceLocation::normalize_files_for_tests();
+    let m = decode_one_insn();
+    let mut sim = Simulation::new(m);
+    let writer = RcWriter::default();
+    sim.add_trace_writer(VcdWriterDecls::new(writer.clone()));
+    struct DumpVcdOnDrop {
+        writer: Option<RcWriter>,
+    }
+    impl Drop for DumpVcdOnDrop {
+        fn drop(&mut self) {
+            if let Some(mut writer) = self.writer.take() {
+                let vcd = String::from_utf8(writer.take()).unwrap();
+                println!("####### VCD:\n{vcd}\n#######");
+            }
+        }
+    }
+    let mut writer = DumpVcdOnDrop {
+        writer: Some(writer),
+    };
+    for test_case @ TestCase {
+        mnemonic: _,
+        first_input,
+        second_input,
+        output: _,
+        loc: _,
+    } in test_cases()
+    {
+        sim.write(sim.io().first_input, first_input);
+        sim.write(
+            sim.io().second_input,
+            if let Some(v) = second_input {
+                #[hdl(sim)]
+                HdlSome(v)
+            } else {
+                #[hdl(sim)]
+                HdlNone()
+            },
+        );
+        sim.advance_time(SimDuration::from_micros(1));
+        let second_input_used = sim.read_bool(sim.io().second_input_used);
+        let is_illegal = sim.read_bool(sim.io().is_illegal);
+        let output = sim.read(sim.io().output);
+        #[derive(Debug)]
+        #[expect(dead_code, reason = "used only for Debug formatting")]
+        struct FormattedOutput<'a> {
+            insns: &'a [SimValue<MOp>],
+            second_input_used: bool,
+            is_illegal: bool,
+        }
+        let expected = format!(
+            "{:#?}",
+            FormattedOutput {
+                insns: ArrayVec::elements_sim_ref(&test_case.output),
+                second_input_used: second_input.is_some(),
+                is_illegal: false,
+            },
+        );
+        let output = format!(
+            "{:#?}",
+            FormattedOutput {
+                insns: ArrayVec::elements_sim_ref(&output),
+                second_input_used,
+                is_illegal,
+            },
+        );
+        assert!(
+            expected == output,
+            "test_case={test_case:#?}\noutput={output}\nexpected={expected}"
+        );
+    }
+    let vcd = String::from_utf8(writer.writer.take().unwrap().take()).unwrap();
+    println!("####### VCD:\n{vcd}\n#######");
+    if vcd != include_str!("expected/decode_one_insn.vcd") {
+        panic!();
+    }
+}
+
+#[hdl]
+#[test]
+fn test_simple_power_isa_decoder() {
+    // TODO
+}