Gate debug builtins behind a Cargo feature (#7305)

This doesn't shave off much but can help tidy up some symbols from
exported objects if they aren't needed.

Cargo.toml

@@ -302,6 +302,7 @@ default = [
   "profiling",
   "coredump",
   "addr2line",
+  "debug-builtins",
 ]
 
 # ========================================
@@ -339,6 +340,7 @@ cranelift = ["wasmtime-cli-flags/cranelift", "dep:wasmtime-cranelift"]
 profiling = ["wasmtime/profiling"]
 coredump = ["wasmtime-cli-flags/coredump"]
 addr2line = ["wasmtime/addr2line"]
+debug-builtins = ["wasmtime/debug-builtins"]
 
 # CLI subcommands for the `wasmtime` executable. See `wasmtime $cmd --help`
 # for more information on each subcommand.

crates/runtime/Cargo.toml

@@ -58,10 +58,7 @@ wasmtime-versioned-export-macros = { workspace = true }
 
 [features]
 async = ["wasmtime-fiber"]
-
-# Enables support for the pooling instance allocator
 pooling-allocator = []
-
 component-model = ["wasmtime-environ/component-model", "dep:encoding_rs"]
-
 wmemcheck = []
+debug-builtins = []

crates/runtime/src/lib.rs

@@ -29,6 +29,7 @@ mod table;
 mod traphandlers;
 mod vmcontext;
 
+#[cfg(feature = "debug-builtins")]
 pub mod debug_builtins;
 pub mod libcalls;
 pub mod mpk;

crates/wasmtime/Cargo.toml

@@ -84,6 +84,7 @@ default = [
   'demangle',
   'addr2line',
   'coredump',
+  'debug-builtins',
 ]
 
 # An on-by-default feature enabling runtime compilation of WebAssembly modules
@@ -154,3 +155,7 @@ coredump = ["dep:wasm-encoder"]
 # Support address-to-file/line information in traps when wasm files have DWARF
 # debugging information.
 addr2line = ["wasmtime-jit/addr2line"]
+
+# Export some symbols from the final binary to assist in debugging
+# Cranelift-generated code with native debuggers like GDB and LLDB.
+debug-builtins = ["wasmtime-runtime/debug-builtins"]

crates/wasmtime/src/engine.rs

@@ -14,7 +14,7 @@ use wasmtime_cache::CacheConfig;
 use wasmtime_environ::obj;
 use wasmtime_environ::{FlagValue, ObjectKind};
 use wasmtime_jit::{profiling::ProfilingAgent, CodeMemory};
-use wasmtime_runtime::{debug_builtins, CompiledModuleIdAllocator, InstanceAllocator, MmapVec};
+use wasmtime_runtime::{CompiledModuleIdAllocator, InstanceAllocator, MmapVec};
 
 mod serialization;
 
@@ -78,7 +78,8 @@ impl Engine {
         // is the per-program initialization required for handling traps, such
         // as configuring signals, vectored exception handlers, etc.
         wasmtime_runtime::init_traps(crate::module::is_wasm_trap_pc, config.macos_use_mach_ports);
-        debug_builtins::ensure_exported();
+        #[cfg(feature = "debug-builtins")]
+        wasmtime_runtime::debug_builtins::ensure_exported();
 
         let registry = SignatureRegistry::new();
         let config = config.clone();