Define Instruction Set.

This commit is contained in:
Sergey Pepyakin 2018-06-12 16:09:31 +03:00
parent f91dc92119
commit 4b7c3c0c94
2 changed files with 242 additions and 0 deletions

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src/instructions.rs Normal file
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/// Enumeration of instruction set used by wasmi.
///
/// The instruction set is mostly derived from Wasm. However,
/// there is a substantial difference.
///
/// # Structured Stack Machine vs Traditional One
///
/// Wasm is a structured stack machine. Wasm encodes control flow in structures
/// similar to that commonly found in a programming languages
/// such as if, while. That contrasts to a traditional stack machine which
/// encodes all control flow with goto-like instructions.
///
/// Structured stack machine code aligns well with goals of Wasm,
/// namely providing fast validation of Wasm code and compilation to native code.
///
/// Unfortunately, the downside of structured stack machine code is
/// that it is less convenient to interpret. For example, let's look at
/// the following example in hypothetical structured stack machine:
///
/// ```
/// loop
/// ...
/// if_true_jump_to_end
/// ...
/// end
/// ```
///
/// To execute `if_true_jump_to_end` , the interpreter needs to skip all instructions
/// until it reaches the *matching* `end`. That's quite inefficient compared
/// to a plain goto to the specific position.
///
/// # Differences from Wasm
///
/// - There is no `nop` instruction.
/// - All control flow strucutres are flattened to plain gotos.
/// - Implicit returns via reaching function scope `End` are replaced with an explicit `return` instruction.
/// - Locals live on the value stack now.
enum Instruction {
/// Keep the specified amount of operands and then
/// drop the rest.
DropKeep {
drop: u32,
keep: u32,
},
/// Push a local variable or an argument from the specified depth.
GetLocal {
depth: u32
},
/// Pop a value and put it in at the specified depth.
SetLocal {
depth: u32
},
/// Copy a value to the specified depth.
TeeLocal(u32),
/// Similar to the Wasm ones, but instead of a label depth
/// they specify direct PC.
Br(u32),
BrIf(u32),
BrTable(Box<[u32]>, u32),
Unreachable,
Return,
Call(u32),
CallIndirect(u32, u8),
Drop,
Select,
GetGlobal(u32),
SetGlobal(u32),
// All store/load instructions operate with 'memory immediates'
// which represented here as (flag, offset) tuple
I32Load(u32, u32),
I64Load(u32, u32),
F32Load(u32, u32),
F64Load(u32, u32),
I32Load8S(u32, u32),
I32Load8U(u32, u32),
I32Load16S(u32, u32),
I32Load16U(u32, u32),
I64Load8S(u32, u32),
I64Load8U(u32, u32),
I64Load16S(u32, u32),
I64Load16U(u32, u32),
I64Load32S(u32, u32),
I64Load32U(u32, u32),
I32Store(u32, u32),
I64Store(u32, u32),
F32Store(u32, u32),
F64Store(u32, u32),
I32Store8(u32, u32),
I32Store16(u32, u32),
I64Store8(u32, u32),
I64Store16(u32, u32),
I64Store32(u32, u32),
CurrentMemory(u8),
GrowMemory(u8),
I32Const(i32),
I64Const(i64),
F32Const(u32),
F64Const(u64),
I32Eqz,
I32Eq,
I32Ne,
I32LtS,
I32LtU,
I32GtS,
I32GtU,
I32LeS,
I32LeU,
I32GeS,
I32GeU,
I64Eqz,
I64Eq,
I64Ne,
I64LtS,
I64LtU,
I64GtS,
I64GtU,
I64LeS,
I64LeU,
I64GeS,
I64GeU,
F32Eq,
F32Ne,
F32Lt,
F32Gt,
F32Le,
F32Ge,
F64Eq,
F64Ne,
F64Lt,
F64Gt,
F64Le,
F64Ge,
I32Clz,
I32Ctz,
I32Popcnt,
I32Add,
I32Sub,
I32Mul,
I32DivS,
I32DivU,
I32RemS,
I32RemU,
I32And,
I32Or,
I32Xor,
I32Shl,
I32ShrS,
I32ShrU,
I32Rotl,
I32Rotr,
I64Clz,
I64Ctz,
I64Popcnt,
I64Add,
I64Sub,
I64Mul,
I64DivS,
I64DivU,
I64RemS,
I64RemU,
I64And,
I64Or,
I64Xor,
I64Shl,
I64ShrS,
I64ShrU,
I64Rotl,
I64Rotr,
F32Abs,
F32Neg,
F32Ceil,
F32Floor,
F32Trunc,
F32Nearest,
F32Sqrt,
F32Add,
F32Sub,
F32Mul,
F32Div,
F32Min,
F32Max,
F32Copysign,
F64Abs,
F64Neg,
F64Ceil,
F64Floor,
F64Trunc,
F64Nearest,
F64Sqrt,
F64Add,
F64Sub,
F64Mul,
F64Div,
F64Min,
F64Max,
F64Copysign,
I32WrapI64,
I32TruncSF32,
I32TruncUF32,
I32TruncSF64,
I32TruncUF64,
I64ExtendSI32,
I64ExtendUI32,
I64TruncSF32,
I64TruncUF32,
I64TruncSF64,
I64TruncUF64,
F32ConvertSI32,
F32ConvertUI32,
F32ConvertSI64,
F32ConvertUI64,
F32DemoteF64,
F64ConvertSI32,
F64ConvertUI32,
F64ConvertSI64,
F64ConvertUI64,
F64PromoteF32,
I32ReinterpretF32,
I64ReinterpretF64,
F32ReinterpretI32,
F64ReinterpretI64,
}

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@ -356,6 +356,7 @@ mod imports;
mod global; mod global;
mod func; mod func;
mod types; mod types;
mod instructions;
#[cfg(test)] #[cfg(test)]
mod tests; mod tests;