Implement bulk memory's partial failure instantiation semantics

Essentially, table and memory out of bounds errors are no longer link errors,
but traps after linking. This means that the partail writes / inits are visible.

build.rs

@@ -186,7 +186,8 @@ fn ignore(testsuite: &str, testname: &str, strategy: &str) -> bool {
             | ("bulk_memory_operations", "table_init")
             | ("bulk_memory_operations", "elem")
             | ("bulk_memory_operations", "memory_copy")
-            | ("bulk_memory_operations", "memory_fill") => return false,
+            | ("bulk_memory_operations", "memory_fill")
+            | ("bulk_memory_operations", "linking") => return false,
             ("bulk_memory_operations", _) => return true,
 
             _ => {}

crates/api/src/instance.rs

@@ -26,11 +26,15 @@ fn instantiate(
     let mut resolver = SimpleResolver { imports };
     unsafe {
         let instance = compiled_module
-            .instantiate(&mut resolver)
+            .instantiate(
+                config.validating_config.operator_config.enable_bulk_memory,
+                &mut resolver,
+            )
             .map_err(|e| -> Error {
                 match e {
                     InstantiationError::StartTrap(trap) => Trap::from_jit(trap).into(),
-                    e @ InstantiationError::TableOutOfBounds(_) => {
+                    e @ InstantiationError::TableOutOfBounds(_)
+                    | e @ InstantiationError::MemoryOutOfBounds(_) => {
                         let msg = e.to_string();
                         if config.validating_config.operator_config.enable_bulk_memory {
                             Trap::new(msg).into()

crates/api/src/trampoline/create_handle.rs

@@ -42,6 +42,12 @@ pub(crate) fn create_handle(
             &data_initializers,
             signatures.into_boxed_slice(),
             None,
+            store
+                .engine()
+                .config()
+                .validating_config
+                .operator_config
+                .enable_bulk_memory,
             state,
         )?)
     }

crates/jit/src/instantiate.rs

@@ -205,6 +205,7 @@ impl CompiledModule {
     /// See `InstanceHandle::new`
     pub unsafe fn instantiate(
         &self,
+        is_bulk_memory: bool,
         resolver: &mut dyn Resolver,
     ) -> Result<InstanceHandle, InstantiationError> {
         let data_initializers = self
@@ -224,6 +225,7 @@ impl CompiledModule {
             &data_initializers,
             self.signatures.clone(),
             self.dbg_jit_registration.as_ref().map(|r| Rc::clone(&r)),
+            is_bulk_memory,
             Box::new(()),
         )
     }
@@ -277,9 +279,10 @@ pub unsafe fn instantiate(
     data: &[u8],
     resolver: &mut dyn Resolver,
     debug_info: bool,
+    is_bulk_memory: bool,
     profiler: Option<&Arc<Mutex<Box<dyn ProfilingAgent + Send>>>>,
 ) -> Result<InstanceHandle, SetupError> {
-    let instance =
-        CompiledModule::new(compiler, data, debug_info, profiler)?.instantiate(resolver)?;
+    let instance = CompiledModule::new(compiler, data, debug_info, profiler)?
+        .instantiate(is_bulk_memory, resolver)?;
     Ok(instance)
 }

crates/runtime/src/instance.rs

@@ -21,6 +21,7 @@ use more_asserts::assert_lt;
 use std::alloc::{self, Layout};
 use std::any::Any;
 use std::cell::{Cell, RefCell};
+use std::cmp;
 use std::collections::HashMap;
 use std::collections::HashSet;
 use std::convert::TryFrom;
@@ -810,6 +811,7 @@ impl InstanceHandle {
         data_initializers: &[DataInitializer<'_>],
         vmshared_signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>,
         dbg_jit_registration: Option<Rc<GdbJitImageRegistration>>,
+        is_bulk_memory: bool,
         host_state: Box<dyn Any>,
     ) -> Result<Self, InstantiationError> {
         let tables = create_tables(&module);
@@ -904,9 +906,14 @@ impl InstanceHandle {
             VMBuiltinFunctionsArray::initialized(),
         );
 
-        // Check initializer bounds before initializing anything.
+        // Check initializer bounds before initializing anything. Only do this
+        // when bulk memory is disabled, since the bulk memory proposal changes
+        // instantiation such that the intermediate results of failed
+        // initializations are visible.
+        if !is_bulk_memory {
             check_table_init_bounds(instance)?;
             check_memory_init_bounds(instance, data_initializers)?;
+        }
 
         // Apply the initializers.
         initialize_tables(instance)?;
@@ -1133,9 +1140,9 @@ fn check_memory_init_bounds(
         unsafe {
             let mem_slice = get_memory_slice(init, instance);
             if mem_slice.get_mut(start..start + init.data.len()).is_none() {
-                return Err(InstantiationError::Link(LinkError(
-                    "data segment does not fit".to_owned(),
-                )));
+                return Err(InstantiationError::MemoryOutOfBounds(
+                    "data segment does not fit".into(),
+                ));
             }
         }
     }
@@ -1179,11 +1186,29 @@ fn initialize_tables(instance: &Instance) -> Result<(), InstantiationError> {
         let start = get_table_init_start(init, instance);
         let table = instance.get_table(init.table_index);
 
+        // Even if there aren't any elements being initialized, if its out of
+        // bounds, then we report an error. This is required by the bulk memory
+        // proposal and the way that it uses `table.init` during instantiation.
+        if start > table.size() as usize {
+            return Err(InstantiationError::TableOutOfBounds(
+                "active element segment does not fit in table".into(),
+            ));
+        }
+
         for (i, func_idx) in init.elements.iter().enumerate() {
             let anyfunc = instance.get_caller_checked_anyfunc(*func_idx);
             table
                 .set(u32::try_from(start + i).unwrap(), anyfunc)
-                .unwrap();
+                // Note that when multi-value is disabled, this will never fail
+                // since we bounds check table element initialization before
+                // doing any table slot writes. However when multi-value is
+                // enabled, these become runtime traps and the intermediate
+                // table slot writes are visible.
+                .map_err(|()| {
+                    InstantiationError::TableOutOfBounds(
+                        "active element segment does not fit in table".into(),
+                    )
+                })?;
         }
     }
 
@@ -1239,8 +1264,25 @@ fn initialize_memories(
         let start = get_memory_init_start(init, instance);
         unsafe {
             let mem_slice = get_memory_slice(init, instance);
-            let to_init = &mut mem_slice[start..start + init.data.len()];
-            to_init.copy_from_slice(init.data);
+
+            let end = start.saturating_add(init.data.len());
+            let actual_end = cmp::min(mem_slice.len(), end);
+            let num_uncopied = end - actual_end;
+
+            let to_init = &mut mem_slice[start..actual_end];
+            to_init.copy_from_slice(&init.data[..init.data.len() - num_uncopied]);
+
+            // Note that if bulk memory is disabled, we'll never hit this case
+            // because we did an eager bounds check in
+            // `check_memory_init_bounds`. However when bulk memory is enabled,
+            // we need the incremental writes up to the OOB trap to be visible,
+            // since this is dictated by the updated spec for the bulk memory
+            // proposal.
+            if num_uncopied > 0 {
+                return Err(InstantiationError::MemoryOutOfBounds(
+                    "active data segment does not fit in memory".into(),
+                ));
+            }
         }
     }
 
@@ -1307,6 +1349,13 @@ pub enum InstantiationError {
     #[error("Table out of bounds error: {0}")]
     TableOutOfBounds(String),
 
+    /// A memory out of bounds error.
+    ///
+    /// Depending on whether bulk memory is enabled or not, this is either a
+    /// link error or a trap raised during instantiation.
+    #[error("Memory out of bounds error: {0}")]
+    MemoryOutOfBounds(String),
+
     /// A wasm link error occured.
     #[error("Failed to link module")]
     Link(#[from] LinkError),

tests/instantiate.rs

@@ -24,7 +24,17 @@ fn test_environ_translate() {
     let cache_config = CacheConfig::new_cache_disabled();
     let mut compiler = Compiler::new(isa, CompilationStrategy::Auto, cache_config);
     unsafe {
-        let instance = instantiate(&mut compiler, &data, &mut resolver, false, None);
+        let instance = instantiate(
+            &mut compiler,
+            &data,
+            &mut resolver,
+            // Bulk memory.
+            false,
+            // Debug info.
+            false,
+            // Profiler.
+            None,
+        );
         assert!(instance.is_ok());
     }
 }