Move native signatures out of Module (#2362)

After compilation there's actually no need to hold onto the native
signature for a wasm function type, so this commit moves out the
`ir::Signature` value from a `Module` into a separate field that's
deallocated when compilation is finished. This simplifies the
`SignatureRegistry` because it only needs to track wasm functino types
and it also means less work is done for `Func::wrap`.

crates/wasmtime/src/func.rs

@@ -541,7 +541,7 @@ impl Func {
         // Signatures should always be registered in the store's registry of
         // shared signatures, so we should be able to unwrap safely here.
         let signatures = self.instance.store.signatures().borrow();
-        let (wft, _, _) = signatures
+        let (wft, _) = signatures
             .lookup_shared(self.sig_index())
             .expect("signature should be registered");
 
@@ -554,7 +554,7 @@ impl Func {
     /// Returns the number of parameters that this function takes.
     pub fn param_arity(&self) -> usize {
         let signatures = self.instance.store.signatures().borrow();
-        let (sig, _, _) = signatures
+        let (sig, _) = signatures
             .lookup_shared(self.sig_index())
             .expect("signature should be registered");
         sig.params.len()
@@ -563,7 +563,7 @@ impl Func {
     /// Returns the number of results this function produces.
     pub fn result_arity(&self) -> usize {
         let signatures = self.instance.store.signatures().borrow();
-        let (sig, _, _) = signatures
+        let (sig, _) = signatures
             .lookup_shared(self.sig_index())
             .expect("signature should be registered");
         sig.returns.len()
@@ -657,7 +657,7 @@ impl Func {
             .borrow()
             .lookup_shared(unsafe { export.anyfunc.as_ref().type_index })
             .expect("failed to retrieve trampoline from module")
-            .2;
+            .1;
 
         Func {
             instance,

crates/wasmtime/src/instance.rs

@@ -293,7 +293,7 @@ fn with_imports<R>(
                 let ty = store
                     .signatures()
                     .borrow()
-                    .lookup(&m.signatures[m.functions[i]].0)
+                    .lookup(&m.signatures[m.functions[i]])
                     .ok_or_else(|| anyhow!("function types incompatible"))?;
                 if !func.matches_expected(ty) {
                     bail!("function types incompatible");

crates/wasmtime/src/runtime.rs

@@ -915,10 +915,9 @@ impl Store {
         module: &'a wasmtime_environ::Module,
     ) -> impl Fn(wasm::SignatureIndex) -> VMSharedSignatureIndex + 'a {
         move |index| {
-            let (wasm, _native) = &module.signatures[index];
             self.signatures()
                 .borrow()
-                .lookup(wasm)
+                .lookup(&module.signatures[index])
                 .expect("signature not previously registered")
         }
     }
@@ -993,8 +992,8 @@ impl Store {
         let trampolines = module.compiled_module().trampolines();
         let module = module.compiled_module().module();
         let mut signatures = self.signatures().borrow_mut();
-        for (index, (wasm, native)) in module.signatures.iter() {
-            signatures.register(wasm, native, trampolines[index]);
+        for (index, wasm) in module.signatures.iter() {
+            signatures.register(wasm, trampolines[index]);
         }
     }
 

crates/wasmtime/src/sig_registry.rs

@@ -3,7 +3,7 @@
 
 use std::collections::{hash_map, HashMap};
 use std::convert::TryFrom;
-use wasmtime_environ::{ir, wasm::WasmFuncType};
+use wasmtime_environ::wasm::WasmFuncType;
 use wasmtime_runtime::{VMSharedSignatureIndex, VMTrampoline};
 
 /// WebAssembly requires that the caller and callee signatures in an indirect
@@ -25,8 +25,6 @@ pub struct SignatureRegistry {
 struct Entry {
     // The WebAssembly type signature, using wasm types.
     wasm: WasmFuncType,
-    // The native signature we're using for this wasm type signature.
-    native: ir::Signature,
     // The native trampoline used to invoke this type signature from `Func`.
     // Note that the code memory for this trampoline is not owned by this
     // type, but instead it's expected to be owned by the store that this
@@ -39,7 +37,6 @@ impl SignatureRegistry {
     pub fn register(
         &mut self,
         wasm: &WasmFuncType,
-        native: &ir::Signature,
         trampoline: VMTrampoline,
     ) -> VMSharedSignatureIndex {
         let len = self.wasm2index.len();
@@ -57,7 +54,6 @@ impl SignatureRegistry {
                 let index = VMSharedSignatureIndex::new(u32::try_from(len).unwrap());
                 self.index_map.push(Entry {
                     wasm: wasm.clone(),
-                    native: native.clone(),
                     trampoline,
                 });
                 entry.insert(index);
@@ -78,9 +74,9 @@ impl SignatureRegistry {
     pub fn lookup_shared(
         &self,
         idx: VMSharedSignatureIndex,
-    ) -> Option<(&WasmFuncType, &ir::Signature, VMTrampoline)> {
+    ) -> Option<(&WasmFuncType, VMTrampoline)> {
         self.index_map
             .get(idx.bits() as usize)
-            .map(|e| (&e.wasm, &e.native, e.trampoline))
+            .map(|e| (&e.wasm, e.trampoline))
     }
 }

crates/wasmtime/src/trampoline/func.rs

@@ -223,7 +223,7 @@ pub fn create_handle_with_function(
 
     // First up we manufacture a trampoline which has the ABI specified by `ft`
     // and calls into `stub_fn`...
-    let sig_id = module.signatures.push((wft.clone(), sig.clone()));
+    let sig_id = module.signatures.push(wft.clone());
     let func_id = module.functions.push(sig_id);
     module
         .exports
@@ -241,10 +241,7 @@ pub fn create_handle_with_function(
         &sig,
         mem::size_of::<u128>(),
     )?;
-    store
-        .signatures()
-        .borrow_mut()
-        .register(&wft, &sig, trampoline);
+    store.signatures().borrow_mut().register(&wft, trampoline);
 
     // Next up we wrap everything up into an `InstanceHandle` by publishing our
     // code memory (makes it executable) and ensuring all our various bits of
@@ -268,23 +265,18 @@ pub unsafe fn create_handle_with_raw_function(
     store: &Store,
     state: Box<dyn Any>,
 ) -> Result<StoreInstanceHandle> {
-    let pointer_type = store.engine().compiler().isa().pointer_type();
-    let sig = ft.get_wasmtime_signature(pointer_type);
     let wft = ft.to_wasm_func_type();
 
     let mut module = Module::new();
     let mut finished_functions = PrimaryMap::new();
 
-    let sig_id = module.signatures.push((wft.clone(), sig.clone()));
+    let sig_id = module.signatures.push(wft.clone());
     let func_id = module.functions.push(sig_id);
     module
         .exports
         .insert(String::new(), EntityIndex::Function(func_id));
     finished_functions.push(func);
-    store
-        .signatures()
-        .borrow_mut()
-        .register(&wft, &sig, trampoline);
+    store.signatures().borrow_mut().register(&wft, trampoline);
 
     create_handle(module, store, finished_functions, state, &[])
 }

crates/wasmtime/src/trampoline/global.rs

@@ -37,10 +37,10 @@ pub fn create_global(store: &Store, gt: &GlobalType, val: Val) -> Result<StoreIn
                 // our global with a `ref.func` to grab that imported function.
                 let signatures = store.signatures().borrow();
                 let shared_sig_index = f.sig_index();
-                let (wasm, native, _) = signatures
+                let (wasm, _) = signatures
                     .lookup_shared(shared_sig_index)
                     .expect("signature not registered");
-                let local_sig_index = module.signatures.push((wasm.clone(), native.clone()));
+                let local_sig_index = module.signatures.push(wasm.clone());
                 let func_index = module.functions.push(local_sig_index);
                 module.num_imported_funcs = 1;
                 module