Some minor cleanups/refactorings in components (#4582)

This is a collection of some minor renamings, refactorings, sharing of
code, etc. This was all discovered during my addition of string support
to adapter functions and I figured it'd be best to frontload this and
land it ahead of the full patch since it's getting complex.

Author: alexcrichton

crates/cranelift/src/compiler/component.rs

@@ -8,9 +8,10 @@ use cranelift_codegen::ir::{self, InstBuilder, MemFlags};
 use cranelift_frontend::FunctionBuilder;
 use object::write::Object;
 use std::any::Any;
+use std::ops::Range;
 use wasmtime_environ::component::{
-    AlwaysTrapInfo, CanonicalOptions, Component, ComponentCompiler, ComponentTypes, LowerImport,
-    LoweredIndex, LoweringInfo, RuntimeAlwaysTrapIndex, VMComponentOffsets,
+    AlwaysTrapInfo, CanonicalOptions, Component, ComponentCompiler, ComponentTypes, FunctionInfo,
+    LowerImport, LoweredIndex, RuntimeAlwaysTrapIndex, VMComponentOffsets,
 };
 use wasmtime_environ::{PrimaryMap, SignatureIndex, Trampoline, TrapCode, WasmFuncType};
 
@@ -187,28 +188,29 @@ impl ComponentCompiler for Compiler {
         trampolines: Vec<(SignatureIndex, Box<dyn Any + Send>)>,
         obj: &mut Object<'static>,
     ) -> Result<(
-        PrimaryMap<LoweredIndex, LoweringInfo>,
+        PrimaryMap<LoweredIndex, FunctionInfo>,
         PrimaryMap<RuntimeAlwaysTrapIndex, AlwaysTrapInfo>,
         Vec<Trampoline>,
     )> {
         let module = Default::default();
         let mut text = ModuleTextBuilder::new(obj, &module, &*self.isa);
-        let mut ret = PrimaryMap::new();
-        for (idx, lowering) in lowerings.iter() {
-            let lowering = lowering.downcast_ref::<CompiledFunction>().unwrap();
-            assert!(lowering.traps.is_empty());
-            let (_symbol, range) = text.append_func(
-                false,
-                format!("_wasm_component_lowering_trampoline{}", idx.as_u32()).into_bytes(),
-                &lowering,
-            );
-
-            let i = ret.push(LoweringInfo {
-                start: u32::try_from(range.start).unwrap(),
-                length: u32::try_from(range.end - range.start).unwrap(),
-            });
-            assert_eq!(i, idx);
-        }
+
+        let range2info = |range: Range<u64>| FunctionInfo {
+            start: u32::try_from(range.start).unwrap(),
+            length: u32::try_from(range.end - range.start).unwrap(),
+        };
+        let ret_lowerings = lowerings
+            .iter()
+            .map(|(i, lowering)| {
+                let lowering = lowering.downcast_ref::<CompiledFunction>().unwrap();
+                assert!(lowering.traps.is_empty());
+                let range = text.named_func(
+                    &format!("_wasm_component_lowering_trampoline{}", i.as_u32()),
+                    &lowering,
+                );
+                range2info(range)
+            })
+            .collect();
         let ret_always_trap = always_trap
             .iter()
             .map(|(i, func)| {
@@ -217,11 +219,8 @@ impl ComponentCompiler for Compiler {
                 assert_eq!(func.traps[0].trap_code, TrapCode::AlwaysTrapAdapter);
                 let name = format!("_wasmtime_always_trap{}", i.as_u32());
                 let range = text.named_func(&name, func);
-                let start = u32::try_from(range.start).unwrap();
-                let end = u32::try_from(range.end).unwrap();
                 AlwaysTrapInfo {
-                    start: start,
-                    length: end - start,
+                    info: range2info(range),
                     trap_offset: func.traps[0].code_offset,
                 }
             })
@@ -238,6 +237,6 @@ impl ComponentCompiler for Compiler {
 
         text.finish()?;
 
-        Ok((ret, ret_always_trap, ret_trampolines))
+        Ok((ret_lowerings, ret_always_trap, ret_trampolines))
     }
 }

crates/environ/src/component/compiler.rs

@@ -10,7 +10,7 @@ use std::any::Any;
 /// Description of where a trampoline is located in the text section of a
 /// compiled image.
 #[derive(Serialize, Deserialize)]
-pub struct LoweringInfo {
+pub struct FunctionInfo {
     /// The byte offset from the start of the text section where this trampoline
     /// starts.
     pub start: u32,
@@ -22,11 +22,8 @@ pub struct LoweringInfo {
 /// `ComponentCompiler::compile_always_trap`.
 #[derive(Serialize, Deserialize)]
 pub struct AlwaysTrapInfo {
-    /// The byte offset from the start of the text section where this trampoline
-    /// starts.
-    pub start: u32,
-    /// The byte length of this trampoline's function body.
-    pub length: u32,
+    /// Information about the extent of this generated function.
+    pub info: FunctionInfo,
     /// The offset from `start` of where the trapping instruction is located.
     pub trap_offset: u32,
 }
@@ -79,7 +76,7 @@ pub trait ComponentCompiler: Send + Sync {
         tramplines: Vec<(SignatureIndex, Box<dyn Any + Send>)>,
         obj: &mut Object<'static>,
     ) -> Result<(
-        PrimaryMap<LoweredIndex, LoweringInfo>,
+        PrimaryMap<LoweredIndex, FunctionInfo>,
         PrimaryMap<RuntimeAlwaysTrapIndex, AlwaysTrapInfo>,
         Vec<Trampoline>,
     )>;

crates/runtime/src/component.rs

@@ -244,27 +244,22 @@ impl ComponentInstance {
     /// This can only be called after `idx` has been initialized at runtime
     /// during the instantiation process of a component.
     pub fn lowering_anyfunc(&self, idx: LoweredIndex) -> NonNull<VMCallerCheckedAnyfunc> {
-        unsafe {
-            let ret = self
-                .vmctx_plus_offset::<VMCallerCheckedAnyfunc>(self.offsets.lowering_anyfunc(idx));
-            debug_assert!((*ret).func_ptr.as_ptr() as usize != INVALID_PTR);
-            debug_assert!((*ret).vmctx as usize != INVALID_PTR);
-            NonNull::new(ret).unwrap()
-        }
+        unsafe { self.anyfunc(self.offsets.lowering_anyfunc(idx)) }
     }
 
     /// Same as `lowering_anyfunc` except for the functions that always trap.
     pub fn always_trap_anyfunc(
         &self,
         idx: RuntimeAlwaysTrapIndex,
     ) -> NonNull<VMCallerCheckedAnyfunc> {
-        unsafe {
-            let ret = self
-                .vmctx_plus_offset::<VMCallerCheckedAnyfunc>(self.offsets.always_trap_anyfunc(idx));
-            debug_assert!((*ret).func_ptr.as_ptr() as usize != INVALID_PTR);
-            debug_assert!((*ret).vmctx as usize != INVALID_PTR);
-            NonNull::new(ret).unwrap()
-        }
+        unsafe { self.anyfunc(self.offsets.always_trap_anyfunc(idx)) }
+    }
+
+    unsafe fn anyfunc(&self, offset: u32) -> NonNull<VMCallerCheckedAnyfunc> {
+        let ret = self.vmctx_plus_offset::<VMCallerCheckedAnyfunc>(offset);
+        debug_assert!((*ret).func_ptr.as_ptr() as usize != INVALID_PTR);
+        debug_assert!((*ret).vmctx as usize != INVALID_PTR);
+        NonNull::new(ret).unwrap()
     }
 
     /// Stores the runtime memory pointer at the index specified.
@@ -335,16 +330,12 @@ impl ComponentInstance {
             debug_assert!(
                 *self.vmctx_plus_offset::<usize>(self.offsets.lowering_data(idx)) == INVALID_PTR
             );
-            debug_assert!(
-                *self.vmctx_plus_offset::<usize>(self.offsets.lowering_anyfunc(idx)) == INVALID_PTR
-            );
             *self.vmctx_plus_offset(self.offsets.lowering(idx)) = lowering;
-            let vmctx = self.vmctx();
-            *self.vmctx_plus_offset(self.offsets.lowering_anyfunc(idx)) = VMCallerCheckedAnyfunc {
-                func_ptr: anyfunc_func_ptr,
-                type_index: anyfunc_type_index,
-                vmctx: VMOpaqueContext::from_vmcomponent(vmctx),
-            };
+            self.set_anyfunc(
+                self.offsets.lowering_anyfunc(idx),
+                anyfunc_func_ptr,
+                anyfunc_type_index,
+            );
         }
     }
 
@@ -355,19 +346,22 @@ impl ComponentInstance {
         func_ptr: NonNull<VMFunctionBody>,
         type_index: VMSharedSignatureIndex,
     ) {
-        unsafe {
-            debug_assert!(
-                *self.vmctx_plus_offset::<usize>(self.offsets.always_trap_anyfunc(idx))
-                    == INVALID_PTR
-            );
-            let vmctx = self.vmctx();
-            *self.vmctx_plus_offset(self.offsets.always_trap_anyfunc(idx)) =
-                VMCallerCheckedAnyfunc {
-                    func_ptr,
-                    type_index,
-                    vmctx: VMOpaqueContext::from_vmcomponent(vmctx),
-                };
-        }
+        unsafe { self.set_anyfunc(self.offsets.always_trap_anyfunc(idx), func_ptr, type_index) }
+    }
+
+    unsafe fn set_anyfunc(
+        &mut self,
+        offset: u32,
+        func_ptr: NonNull<VMFunctionBody>,
+        type_index: VMSharedSignatureIndex,
+    ) {
+        debug_assert!(*self.vmctx_plus_offset::<usize>(offset) == INVALID_PTR);
+        let vmctx = self.vmctx();
+        *self.vmctx_plus_offset(offset) = VMCallerCheckedAnyfunc {
+            func_ptr,
+            type_index,
+            vmctx: VMOpaqueContext::from_vmcomponent(vmctx),
+        };
     }
 
     unsafe fn initialize_vmctx(&mut self, store: *mut dyn Store) {

crates/wasmtime/src/component/component.rs

@@ -10,7 +10,7 @@ use std::path::Path;
 use std::ptr::NonNull;
 use std::sync::Arc;
 use wasmtime_environ::component::{
-    AlwaysTrapInfo, ComponentTypes, GlobalInitializer, LoweredIndex, LoweringInfo,
+    AlwaysTrapInfo, ComponentTypes, FunctionInfo, GlobalInitializer, LoweredIndex,
     RuntimeAlwaysTrapIndex, StaticModuleIndex, Translator,
 };
 use wasmtime_environ::{PrimaryMap, ScopeVec, SignatureIndex, Trampoline, TrapCode};
@@ -56,7 +56,7 @@ struct ComponentInner {
     /// These trampolines are the function pointer within the
     /// `VMCallerCheckedAnyfunc` and will delegate indirectly to a host function
     /// pointer when called.
-    lowerings: PrimaryMap<LoweredIndex, LoweringInfo>,
+    lowerings: PrimaryMap<LoweredIndex, FunctionInfo>,
 
     /// Where the "always trap" functions are located within the `text` section
     /// of `trampoline_obj`.
@@ -205,7 +205,7 @@ impl Component {
             .values()
             .as_slice()
             .windows(2)
-            .all(|window| { window[0].start < window[1].start }));
+            .all(|window| { window[0].info.start < window[1].info.start }));
 
         crate::module::register_component(code.text, &always_trap);
         Ok(Component {
@@ -229,7 +229,7 @@ impl Component {
         types: &ComponentTypes,
         provided_trampolines: &HashSet<SignatureIndex>,
     ) -> Result<(
-        PrimaryMap<LoweredIndex, LoweringInfo>,
+        PrimaryMap<LoweredIndex, FunctionInfo>,
         PrimaryMap<RuntimeAlwaysTrapIndex, AlwaysTrapInfo>,
         Vec<Trampoline>,
         wasmtime_runtime::MmapVec,
@@ -368,17 +368,17 @@ impl Component {
 
     pub(crate) fn lowering_ptr(&self, index: LoweredIndex) -> NonNull<VMFunctionBody> {
         let info = &self.inner.lowerings[index];
-        self.func(info.start, info.length)
+        self.func(info)
     }
 
     pub(crate) fn always_trap_ptr(&self, index: RuntimeAlwaysTrapIndex) -> NonNull<VMFunctionBody> {
         let info = &self.inner.always_trap[index];
-        self.func(info.start, info.length)
+        self.func(&info.info)
     }
 
-    fn func(&self, start: u32, len: u32) -> NonNull<VMFunctionBody> {
+    fn func(&self, info: &FunctionInfo) -> NonNull<VMFunctionBody> {
         let text = self.text();
-        let trampoline = &text[start as usize..][..len as usize];
+        let trampoline = &text[info.start as usize..][..info.length as usize];
         NonNull::new(trampoline.as_ptr() as *mut VMFunctionBody).unwrap()
     }
 
@@ -393,7 +393,7 @@ impl Component {
             .always_trap
             .values()
             .as_slice()
-            .binary_search_by_key(&offset, |info| info.start + info.trap_offset)
+            .binary_search_by_key(&offset, |info| info.info.start + info.trap_offset)
         {
             Ok(_) => Some(TrapCode::AlwaysTrapAdapter),
             Err(_) => None,

crates/wasmtime/src/module/registry.rs

@@ -287,7 +287,7 @@ pub fn register_component(text: &[u8], traps: &PrimaryMap<RuntimeAlwaysTrapIndex
     let info = Arc::new(
         traps
             .iter()
-            .map(|(_, info)| info.start + info.trap_offset)
+            .map(|(_, info)| info.info.start + info.trap_offset)
             .collect::<Vec<_>>(),
     );
     let prev = GLOBAL_MODULES