Move trap information to a section of the compiled image (#3241)

This commit moves the `traps` field of `FunctionInfo` into a section of
the compiled artifact produced by Cranelift. This section is quite large
and when previously encoded/decoded with `bincode` this can take quite
some time to process. Traps are expected to be relatively rare and it's
not necessarily the right tradeoff to spend so much time
serializing/deserializing this data, so this commit offloads the section
into a custom-encoded binary format located elsewhere in the compiled image.

This is similar to #3240 in its goal which is to move very large pieces
of metadata to their own sections to avoid decoding anything when we
load a precompiled modules. This also has a small benefit that it's
slightly more efficient storage for the trap information too, but that's
a negligible benefit.

This is part of #3230 to make loading modules fast.

crates/environ/src/compilation.rs

@@ -20,64 +20,10 @@ use thiserror::Error;
 #[derive(Serialize, Deserialize, Clone, Default)]
 #[allow(missing_docs)]
 pub struct FunctionInfo {
-    pub traps: Vec<TrapInformation>,
     pub start_srcloc: FilePos,
     pub stack_maps: Vec<StackMapInformation>,
 }
 
-/// Information about trap.
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
-pub struct TrapInformation {
-    /// The offset of the trapping instruction in native code. It is relative to the beginning of the function.
-    pub code_offset: u32,
-    /// Code of the trap.
-    pub trap_code: TrapCode,
-}
-
-/// A trap code describing the reason for a trap.
-///
-/// All trap instructions have an explicit trap code.
-#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash, Serialize, Deserialize)]
-pub enum TrapCode {
-    /// The current stack space was exhausted.
-    StackOverflow,
-
-    /// A `heap_addr` instruction detected an out-of-bounds error.
-    ///
-    /// Note that not all out-of-bounds heap accesses are reported this way;
-    /// some are detected by a segmentation fault on the heap unmapped or
-    /// offset-guard pages.
-    HeapOutOfBounds,
-
-    /// A wasm atomic operation was presented with a not-naturally-aligned linear-memory address.
-    HeapMisaligned,
-
-    /// A `table_addr` instruction detected an out-of-bounds error.
-    TableOutOfBounds,
-
-    /// Indirect call to a null table entry.
-    IndirectCallToNull,
-
-    /// Signature mismatch on indirect call.
-    BadSignature,
-
-    /// An integer arithmetic operation caused an overflow.
-    IntegerOverflow,
-
-    /// An integer division by zero.
-    IntegerDivisionByZero,
-
-    /// Failed float-to-int conversion.
-    BadConversionToInteger,
-
-    /// Code that was supposed to have been unreachable was reached.
-    UnreachableCodeReached,
-
-    /// Execution has potentially run too long and may be interrupted.
-    /// This trap is resumable.
-    Interrupt,
-}
-
 /// The offset within a function of a GC safepoint, and its associated stack
 /// map.
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]