Initial support for function, table, memory, and global imports.

lib/runtime/src/table.rs

@@ -0,0 +1,61 @@
+//! Memory management for tables.
+//!
+//! `Table` is to WebAssembly tables what `LinearMemory` is to WebAssembly linear memories.
+
+use cranelift_wasm::TableElementType;
+use vmcontext::{VMCallerCheckedAnyfunc, VMTableDefinition};
+use wasmtime_environ::{TablePlan, TableStyle};
+
+/// A table instance.
+#[derive(Debug)]
+pub struct Table {
+    vec: Vec<VMCallerCheckedAnyfunc>,
+    maximum: Option<u32>,
+}
+
+impl Table {
+    /// Create a new table instance with specified minimum and maximum number of elements.
+    pub fn new(plan: &TablePlan) -> Self {
+        match plan.table.ty {
+            TableElementType::Func => (),
+            TableElementType::Val(ty) => {
+                unimplemented!("tables of types other than anyfunc ({})", ty)
+            }
+        };
+
+        match plan.style {
+            TableStyle::CallerChecksSignature => {
+                let mut vec = Vec::new();
+                vec.resize(
+                    plan.table.minimum as usize,
+                    VMCallerCheckedAnyfunc::default(),
+                );
+
+                Self {
+                    vec,
+                    maximum: plan.table.maximum,
+                }
+            }
+        }
+    }
+
+    /// Return a `VMTableDefinition` for exposing the table to JIT code.
+    pub fn vmtable(&mut self) -> VMTableDefinition {
+        VMTableDefinition {
+            base: self.vec.as_mut_ptr() as *mut u8,
+            current_elements: self.vec.len(),
+        }
+    }
+}
+
+impl AsRef<[VMCallerCheckedAnyfunc]> for Table {
+    fn as_ref(&self) -> &[VMCallerCheckedAnyfunc] {
+        self.vec.as_slice()
+    }
+}
+
+impl AsMut<[VMCallerCheckedAnyfunc]> for Table {
+    fn as_mut(&mut self) -> &mut [VMCallerCheckedAnyfunc] {
+        self.vec.as_mut_slice()
+    }
+}