Update for new async ABI changes

This commit updates to account for WebAssembly/component-model#520. This
is a large-ish change to the semantics from a runtime perspective and
needed a number of changes:

* The `sync_prepare_call` and `async_prepare_call` libcalls were merged
  together. The previous async version statically took two arguments but
  now it's taking a variable number of arguments which looked quite a
  lot like `sync_prepare_call` so they're now merged into one.

* Lots of little updates were made to `fact/signatures.rs` to account
  for ABI changes.

* Tests with handwritten signatures were all updated to the new ABI.

* The `CallerInfo::Async` structure which "buffers" a call was updated
  to have a `Vec<ValRaw>` for the incoming parameters. This is a
  particularly inefficient way to store parameters but it's in theory
  workable for now.

* The `Storage` abstraction in host calls was refactored and updated to
  account for async and how lifting parameters could be either flat or
  indirect. Similar updates were made to the dynamic path as well

Author: alexcrichton

Cargo.lock

@@ -594,21 +594,21 @@ lto = true
 
 # TODO: remove this once we've switched to a wasm-tools/wit-bindgen release:
 [patch.crates-io]
-# wasmparser = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wat = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wast = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wasmprinter = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wasm-encoder = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wasm-smith = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wasm-mutate = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wit-parser = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wit-component = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wasm-wave = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wasm-compose = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wasm-metadata = { git = "https://github.com/bytecodealliance/wasm-tools" }
-# wit-bindgen = { git = "https://github.com/alexcrichton/wit-bindgen", branch = 'fix-a-tpyo' }
-# wit-bindgen-rt = { git = "https://github.com/alexcrichton/wit-bindgen", branch = 'fix-a-tpyo' }
-# wit-bindgen-rust-macro = { git = "https://github.com/alexcrichton/wit-bindgen", branch = 'fix-a-tpyo' }
+wasmparser = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wat = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wast = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wasmprinter = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wasm-encoder = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wasm-smith = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wasm-mutate = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wit-parser = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wit-component = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wasm-wave = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wasm-compose = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wasm-metadata = { git = "https://github.com/alexcrichton/wasm-tools", branch = 'new-async-abi' }
+wit-bindgen = { git = "https://github.com/alexcrichton/wit-bindgen", branch = 'new-async-abi' }
+wit-bindgen-rt = { git = "https://github.com/alexcrichton/wit-bindgen", branch = 'new-async-abi' }
+wit-bindgen-rust-macro = { git = "https://github.com/alexcrichton/wit-bindgen", branch = 'new-async-abi' }
 
 # wasmparser = { path = '../wasm-tools/crates/wasmparser' }
 # wat = { path = '../wasm-tools/crates/wat' }

Cargo.toml

@@ -6,7 +6,7 @@ use cranelift_codegen::ir::condcodes::IntCC;
 use cranelift_codegen::ir::{self, InstBuilder, MemFlags, Value};
 use cranelift_codegen::isa::{CallConv, TargetIsa};
 use cranelift_frontend::FunctionBuilder;
-use wasmtime_environ::fact::SYNC_PREPARE_FIXED_PARAMS;
+use wasmtime_environ::fact::PREPARE_CALL_FIXED_PARAMS;
 use wasmtime_environ::{CompiledFunctionBody, component::*};
 use wasmtime_environ::{
     HostCall, ModuleInternedTypeIndex, PtrSize, TrapSentinel, Tunables, WasmFuncType, WasmValType,
@@ -255,9 +255,8 @@ impl<'a> TrampolineCompiler<'a> {
                     me.raise_if_host_trapped(rets.pop().unwrap());
                 })
             }
-            Trampoline::SyncPrepareCall { memory } => self.translate_sync_prepare(*memory),
+            Trampoline::PrepareCall { memory } => self.translate_prepare(*memory),
             Trampoline::SyncStartCall { callback } => self.translate_sync_start(*callback),
-            Trampoline::AsyncPrepareCall { memory } => self.translate_async_prepare(*memory),
             Trampoline::AsyncStartCall {
                 callback,
                 post_return,
@@ -471,7 +470,7 @@ impl<'a> TrampolineCompiler<'a> {
         );
     }
 
-    fn translate_sync_prepare(&mut self, memory: Option<RuntimeMemoryIndex>) {
+    fn translate_prepare(&mut self, memory: Option<RuntimeMemoryIndex>) {
         match self.abi {
             Abi::Wasm => {}
 
@@ -489,8 +488,8 @@ impl<'a> TrampolineCompiler<'a> {
         let pointer_type = self.isa.pointer_type();
         let wasm_func_ty = &self.types[self.signature].unwrap_func();
 
-        let param_offset = SYNC_PREPARE_FIXED_PARAMS.len();
-        let spill_offset = param_offset + 2;
+        let param_offset = PREPARE_CALL_FIXED_PARAMS.len();
+        let spill_offset = param_offset + 2; // skip caller/callee vmctx
 
         let (values_vec_ptr, len) = self.compiler.allocate_stack_array_and_spill_args(
             &WasmFuncType::new(
@@ -517,7 +516,7 @@ impl<'a> TrampolineCompiler<'a> {
 
         self.translate_intrinsic_libcall(
             vmctx,
-            host::sync_prepare,
+            host::prepare_call,
             &callee_args,
             TrapSentinel::Falsy,
         );
@@ -572,34 +571,6 @@ impl<'a> TrampolineCompiler<'a> {
         self.builder.ins().return_(&results);
     }
 
-    fn translate_async_prepare(&mut self, memory: Option<RuntimeMemoryIndex>) {
-        match self.abi {
-            Abi::Wasm => {}
-
-            Abi::Array => {
-                // This code can only be called from (FACT-generated) Wasm, so
-                // we don't need to support the array ABI.
-                self.builder.ins().trap(TRAP_INTERNAL_ASSERT);
-                return;
-            }
-        }
-
-        let args = self.builder.func.dfg.block_params(self.block0).to_vec();
-        let vmctx = args[0];
-
-        let mut callee_args = vec![vmctx, self.load_optional_memory(vmctx, memory)];
-
-        // remaining parameters
-        callee_args.extend(args[2..].iter().copied());
-
-        self.translate_intrinsic_libcall(
-            vmctx,
-            host::async_prepare,
-            &callee_args,
-            TrapSentinel::Falsy,
-        );
-    }
-
     fn translate_async_start(
         &mut self,
         callback: Option<RuntimeCallbackIndex>,

crates/cranelift/src/compiler/component.rs

@@ -32,11 +32,26 @@
 /// for transferring parameters.
 pub const MAX_FLAT_PARAMS: usize = 16;
 
+/// Similar to `MAX_FLAT_PARAMS`, but used for async-lowered imports instead of
+/// sync ones.
+pub const MAX_FLAT_ASYNC_PARAMS: usize = 4;
+
 /// Canonical ABI-defined constant for the maximum number of "flat" results.
 /// This number of results are returned directly from wasm and otherwise results
 /// are transferred through memory.
 pub const MAX_FLAT_RESULTS: usize = 1;
 
+/// Sentinel value in `result_count_or_max_if_async` as part of the
+/// `prepare_call` libcall which indicates that preparation is being done for an
+/// async function that produces no result, aka there is no return pointer.
+pub const PREPARE_ASYNC_NO_RESULT: u32 = u32::MAX;
+
+/// Sentinel value in `result_count_or_max_if_async` as part of the
+/// `prepare_call` libcall which indicates that preparation is being done for an
+/// async function that produces at least one result, aka there is a return
+/// pointer.
+pub const PREPARE_ASYNC_WITH_RESULT: u32 = u32::MAX - 1;
+
 mod artifacts;
 mod info;
 mod names;
@@ -106,12 +121,22 @@ macro_rules! foreach_builtin_component_function {
             #[cfg(feature = "component-model-async")]
             subtask_cancel(vmctx: vmctx, caller_instance: u32, async_: u8, task_id: u32) -> u64;
             #[cfg(feature = "component-model-async")]
-            sync_prepare(vmctx: vmctx, memory: ptr_u8, start: ptr_u8, return_: ptr_u8, caller_instance: u32, callee_instance: u32, task_return_type: u32, string_encoding: u32, result_count: u32, storage: ptr_u8, storage_len: size) -> bool;
+            prepare_call(
+                vmctx: vmctx,
+                memory: ptr_u8,
+                start: ptr_u8,
+                return_: ptr_u8,
+                caller_instance: u32,
+                callee_instance: u32,
+                task_return_type: u32,
+                string_encoding: u32,
+                result_count_or_max_if_async: u32,
+                storage: ptr_u8,
+                torage_len: size
+            ) -> bool;
             #[cfg(feature = "component-model-async")]
             sync_start(vmctx: vmctx, callback: ptr_u8, callee: ptr_u8, param_count: u32, storage: ptr_u8, storage_len: size) -> bool;
             #[cfg(feature = "component-model-async")]
-            async_prepare(vmctx: vmctx, memory: ptr_u8, start: ptr_u8, return_: ptr_u8, caller_instance: u32, callee_instance: u32, task_return_type: u32, string_encoding: u32, params: u32, results: u32) -> bool;
-            #[cfg(feature = "component-model-async")]
             async_start(vmctx: vmctx, callback: ptr_u8, post_return: ptr_u8, callee: ptr_u8, param_count: u32, result_count: u32, flags: u32) -> u64;
             #[cfg(feature = "component-model-async")]
             future_new(vmctx: vmctx, ty: u32) -> u64;

crates/environ/src/component.rs

@@ -383,15 +383,12 @@ pub enum Trampoline {
     ResourceTransferBorrow,
     ResourceEnterCall,
     ResourceExitCall,
-    SyncPrepareCall {
+    PrepareCall {
         memory: Option<MemoryId>,
     },
     SyncStartCall {
         callback: Option<CallbackId>,
     },
-    AsyncPrepareCall {
-        memory: Option<MemoryId>,
-    },
     AsyncStartCall {
         callback: Option<CallbackId>,
         post_return: Option<PostReturnId>,
@@ -895,15 +892,12 @@ impl LinearizeDfg<'_> {
             Trampoline::ResourceTransferBorrow => info::Trampoline::ResourceTransferBorrow,
             Trampoline::ResourceEnterCall => info::Trampoline::ResourceEnterCall,
             Trampoline::ResourceExitCall => info::Trampoline::ResourceExitCall,
-            Trampoline::SyncPrepareCall { memory } => info::Trampoline::SyncPrepareCall {
+            Trampoline::PrepareCall { memory } => info::Trampoline::PrepareCall {
                 memory: memory.map(|v| self.runtime_memory(v)),
             },
             Trampoline::SyncStartCall { callback } => info::Trampoline::SyncStartCall {
                 callback: callback.map(|v| self.runtime_callback(v)),
             },
-            Trampoline::AsyncPrepareCall { memory } => info::Trampoline::AsyncPrepareCall {
-                memory: memory.map(|v| self.runtime_memory(v)),
-            },
             Trampoline::AsyncStartCall {
                 callback,
                 post_return,