Implement tables and call_indirect (#12)

* Implement tables and call_indirect

* Restore comment about sig checking.

* Widen callee index on 64bit platforms.

filetests/call_indirect.wat

@@ -0,0 +1,50 @@
+(module
+  (type $indirect_sig (func (param i64) (result i64)))
+
+  (func $assert (param i32)
+    (block $ok
+      (br_if $ok
+        (get_local 0)
+      )
+      (unreachable)
+    )
+  )
+
+  (func $plus_1 (param i64) (result i64)
+    get_local 0
+    i64.const 1
+    i64.add
+  )
+  (func $minus_1 (param i64) (result i64)
+    get_local 0
+    i64.const 1
+    i64.sub
+  )
+
+  (func $main 
+    (call $call_indirect
+      (i32.const 0)
+      (i64.const 2)
+    )
+    (call $call_indirect
+      (i32.const 1)
+      (i64.const 0)
+    )
+  )
+
+  (func $call_indirect (param $func i32) (param $expected i64)
+    (call $assert
+      (i64.eq
+        (call_indirect (type $indirect_sig)
+          (i64.const 1)
+          (get_local $func)
+        )
+        (get_local $expected)
+      )
+    )
+  )
+  (start $main)
+
+  (table 2 2 anyfunc)
+  (elem (i32.const 0) $plus_1 $minus_1)
+)

lib/environ/src/environ.rs

@@ -1,6 +1,6 @@
 use cranelift_codegen::cursor::FuncCursor;
 use cranelift_codegen::ir;
-use cranelift_codegen::ir::immediates::Offset32;
+use cranelift_codegen::ir::immediates::{Imm64, Offset32};
 use cranelift_codegen::ir::types::*;
 use cranelift_codegen::ir::{
     AbiParam, ArgumentPurpose, ExtFuncData, ExternalName, FuncRef, Function, InstBuilder, Signature,
@@ -312,8 +312,29 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
         })
     }
 
-    fn make_table(&mut self, _func: &mut ir::Function, _index: TableIndex) -> ir::Table {
-        unimplemented!("make_table");
+    fn make_table(&mut self, func: &mut ir::Function, _index: TableIndex) -> ir::Table {
+        let pointer_bytes = self.pointer_bytes();
+        let base_gv_addr = func.create_global_value(ir::GlobalValueData::VMContext {
+            offset: Offset32::new(pointer_bytes as i32 * 2),
+        });
+        let base_gv = func.create_global_value(ir::GlobalValueData::Deref {
+            base: base_gv_addr,
+            offset: 0.into(),
+        });
+        let bound_gv_addr = func.create_global_value(ir::GlobalValueData::VMContext {
+            offset: Offset32::new(pointer_bytes as i32 * 3),
+        });
+        let bound_gv = func.create_global_value(ir::GlobalValueData::Deref {
+            base: bound_gv_addr,
+            offset: 0.into(),
+        });
+
+        func.create_table(ir::TableData {
+            base_gv,
+            min_size: Imm64::new(0),
+            bound_gv,
+            element_size: Imm64::new(i64::from(self.pointer_bytes() as i64)),
+        })
     }
 
     fn make_indirect_sig(&mut self, func: &mut ir::Function, index: SignatureIndex) -> ir::SigRef {
@@ -338,17 +359,38 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
         &mut self,
         mut pos: FuncCursor,
         table_index: TableIndex,
-        _table: ir::Table,
+        table: ir::Table,
         _sig_index: SignatureIndex,
         sig_ref: ir::SigRef,
         callee: ir::Value,
         call_args: &[ir::Value],
     ) -> WasmResult<ir::Inst> {
-        // TODO: Cranelift's call_indirect doesn't implement bounds checking
-        // or signature checking, so we need to implement it ourselves.
+        // TODO: Cranelift's call_indirect doesn't implement signature checking,
+        // so we need to implement it ourselves.
         debug_assert_eq!(table_index, 0, "non-default tables not supported yet");
+
+        let callee_ty = pos.func.dfg.value_type(callee);
+        debug_assert_eq!(callee_ty, I32, "wasm call indirect index should be I32");
+        let callee = if self.pointer_type() == I64 {
+            // The current limitation of `table_addr` is that the index should be
+            // the same type as `self.pointer_type()`. So we just extend the given
+            // index to 64-bit here.
+            pos.ins().uextend(I64, callee)
+        } else {
+            callee
+        };
+        let table_entry_addr = pos.ins().table_addr(I64, table, callee, 0);
+
+        // Dereference table_entry_addr to get the function address.
+        let mut mem_flags = ir::MemFlags::new();
+        mem_flags.set_notrap();
+        mem_flags.set_aligned();
+        let func_addr = pos
+            .ins()
+            .load(self.pointer_type(), mem_flags, table_entry_addr, 0);
+
         let real_call_args = FuncEnvironment::get_real_call_args(pos.func, call_args);
-        Ok(pos.ins().call_indirect(sig_ref, callee, &real_call_args))
+        Ok(pos.ins().call_indirect(sig_ref, func_addr, &real_call_args))
     }
 
     fn translate_call(

lib/execute/src/execute.rs

@@ -5,7 +5,7 @@ use memory::LinearMemory;
 use region::protect;
 use region::Protection;
 use std::mem::transmute;
-use std::ptr::write_unaligned;
+use std::ptr::{self, write_unaligned};
 use wasmtime_environ::{
     compile_module, Compilation, Module, ModuleTranslation, Relocation, RelocationTarget,
 };
@@ -66,7 +66,7 @@ fn relocate(compilation: &mut Compilation, relocations: &[Vec<Relocation>]) {
 
 extern "C" fn grow_memory(size: u32, vmctx: *mut *mut u8) -> u32 {
     unsafe {
-        let instance = (*vmctx.offset(2)) as *mut Instance;
+        let instance = (*vmctx.offset(4)) as *mut Instance;
         (*instance)
             .memory_mut(0)
             .grow(size)
@@ -76,18 +76,32 @@ extern "C" fn grow_memory(size: u32, vmctx: *mut *mut u8) -> u32 {
 
 extern "C" fn current_memory(vmctx: *mut *mut u8) -> u32 {
     unsafe {
-        let instance = (*vmctx.offset(2)) as *mut Instance;
+        let instance = (*vmctx.offset(4)) as *mut Instance;
         (*instance).memory_mut(0).current_size()
     }
 }
 
 /// Create the VmCtx data structure for the JIT'd code to use. This must
 /// match the VmCtx layout in the environment.
 fn make_vmctx(instance: &mut Instance, mem_base_addrs: &mut [*mut u8]) -> Vec<*mut u8> {
+    debug_assert!(
+        instance.tables.len() <= 1,
+        "non-default tables is not supported"
+    );
+
+    let (default_table_ptr, default_table_len) = instance
+        .tables
+        .get_mut(0)
+        .map(|table| (table.as_mut_ptr() as *mut u8, table.len()))
+        .unwrap_or((ptr::null_mut(), 0));
+
     let mut vmctx = Vec::new();
     vmctx.push(instance.globals.as_mut_ptr());
     vmctx.push(mem_base_addrs.as_mut_ptr() as *mut u8);
+    vmctx.push(default_table_ptr);
+    vmctx.push(default_table_len as *mut u8);
     vmctx.push(instance as *mut Instance as *mut u8);
+
     vmctx
 }
 

lib/execute/src/instance.rs

@@ -4,7 +4,7 @@
 use cranelift_codegen::ir;
 use cranelift_wasm::GlobalIndex;
 use memory::LinearMemory;
-use wasmtime_environ::{DataInitializer, Module, TableElements};
+use wasmtime_environ::{Compilation, DataInitializer, Module, TableElements};
 
 /// An Instance of a WebAssemby module.
 #[derive(Debug)]
@@ -21,20 +21,29 @@ pub struct Instance {
 
 impl Instance {
     /// Create a new `Instance`.
-    pub fn new(module: &Module, data_initializers: &[DataInitializer]) -> Self {
+    pub fn new(
+        module: &Module,
+        compilation: &Compilation,
+        data_initializers: &[DataInitializer],
+    ) -> Self {
         let mut result = Self {
             tables: Vec::new(),
             memories: Vec::new(),
             globals: Vec::new(),
         };
-        result.instantiate_tables(module, &module.table_elements);
+        result.instantiate_tables(module, compilation, &module.table_elements);
         result.instantiate_memories(module, data_initializers);
         result.instantiate_globals(module);
         result
     }
 
     /// Allocate memory in `self` for just the tables of the current module.
-    fn instantiate_tables(&mut self, module: &Module, table_initializers: &[TableElements]) {
+    fn instantiate_tables(
+        &mut self,
+        module: &Module,
+        compilation: &Compilation,
+        table_initializers: &[TableElements],
+    ) {
         debug_assert!(self.tables.is_empty());
         self.tables.reserve_exact(module.tables.len());
         for table in &module.tables {
@@ -47,7 +56,10 @@ impl Instance {
             debug_assert!(init.base.is_none(), "globalvar base not supported yet");
             let to_init =
                 &mut self.tables[init.table_index][init.offset..init.offset + init.elements.len()];
-            to_init.copy_from_slice(&init.elements);
+            for (i, func_idx) in init.elements.iter().enumerate() {
+                let code_buf = &compilation.functions[*func_idx];
+                to_init[i] = code_buf.as_ptr() as usize;
+            }
         }
     }
 

src/main.rs

@@ -133,8 +133,11 @@ fn handle_module(args: &Args, path: PathBuf, isa: &TargetIsa) -> Result<(), Stri
     let translation = environ.translate(&data).map_err(|e| e.to_string())?;
     let instance = match compile_and_link_module(isa, &translation) {
         Ok(compilation) => {
-            let mut instance =
-                Instance::new(translation.module, &translation.lazy.data_initializers);
+            let mut instance = Instance::new(
+                translation.module,
+                &compilation,
+                &translation.lazy.data_initializers,
+            );
             execute(&translation.module, &compilation, &mut instance)?;
             instance
         }