lt.md

lt (less than)

Takes 2 operands from the stack of the same numeric type and compares them.

Places an i32 on the stack representing the result of the comparison: either 1 if the first operand is less than the second, or 0 otherwise ^{1 2 3}.

For integer types, there are two opcodes per type, to indicate whether to treat the operands as signed or unsigned for the comparison ⁴.

$$ T.\mathsf{lt}_s^? \enspace (a: T, b: T) \to \begin{cases} 1_\mathsf{i32} &\text{if } a < b \\ 0_\mathsf{i32} &\text{if } a \ge b \end{cases} $$

Instructions

Opcode	Instruction	Stack Arity
0x48	i32.lt_s	$[ \mathsf{i32}, \mathsf{i32} ] \to [ \mathsf{i32} ]$
0x49	i32.lt_u	$[ \mathsf{i32}, \mathsf{i32} ] \to [ \mathsf{i32} ]$
0x56	i64.lt_s	$[ \mathsf{i64}, \mathsf{i64} ] \to [ \mathsf{i32} ]$
0x57	i64.lt_u	$[ \mathsf{i64}, \mathsf{i64} ] \to [ \mathsf{i32} ]$
0x5D	f32.lt	$[ \mathsf{f32}, \mathsf{f32} ] \to [ \mathsf{i32} ]$
0x63	f64.lt	$[ \mathsf{f64}, \mathsf{f64} ] \to [ \mathsf{i32} ]$

WAT Examples

todo

References

WebAssembly Core Specification

Footnotes

1. Execution, Numerics, Integer Operations, ilt_u - https://www.w3.org/TR/wasm-core-2/exec/numerics.html#op-ilt-u ↩

2. Execution, Numerics, Integer Operations, ilt_s - https://www.w3.org/TR/wasm-core-2/exec/numerics.html#op-ilt-s ↩

3. Execution, Numerics, Floating-Point Operations, flt - https://www.w3.org/TR/wasm-core-2/exec/numerics.html#op-flt ↩

4. Structure, Numeric Instructions - https://www.w3.org/TR/wasm-core-2/syntax/instructions.html#numeric-instructions ↩