refactor(ir): use u64 directly instead of spans for instructions

crates/ir/src/lib.rs

@@ -1,4 +1,4 @@
-use std::{num::NonZeroUsize, ops::RangeInclusive};
+use std::num::NonZeroUsize;
 
 use instruction::SocketCount;
 use serde::{Deserialize, Serialize};
@@ -268,26 +268,6 @@ impl<'ir> Instruction<'ir> {
     }
 }
 
-/// Some part referred to in source code.
-#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
-pub struct Span {
-    // would love to use an actual [`std::ops::RangeInclusive`], but those don't implement
-    // `PartialOrd` and `Ord` unfortunately
-    /// At which byte this span starts, inclusively.
-    pub from: usize,
-    /// At which byte this span ends, inclusively.
-    pub to: usize,
-}
-
-impl From<RangeInclusive<usize>> for Span {
-    fn from(range: RangeInclusive<usize>) -> Self {
-        Self {
-            from: *range.start(),
-            to: *range.end(),
-        }
-    }
-}
-
 /// Constructs an [`id::Socket`] a bit more tersely.
 fn socket(id: &id::Instruction, idx: u16) -> id::Socket {
     id::Socket {