[wasm] [interpreter] Fix interpreter-to-wasm calls

When calling the CWasmEntry in order to call from the interpreter to a
wasm function, the given buffer must hold the arguments, and must also
have enough space to hold the return values. We were missing the second
part, hence we failed when there are no parameters, but a return.

R=ahaas@chromium.org

Bug: chromium:784125
Change-Id: I08d417cae60eea64fda8a72e898dbed9f3e88148
Reviewed-on: https://chromium-review.googlesource.com/771633
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49402}

src/wasm/wasm-interpreter.cc

@@ -2338,6 +2338,16 @@ class ThreadImpl {
       offset += param_size;
     }
 
+    // Ensure that there is enough space in the arg_buffer to hold the return
+    // value(s).
+    uint32_t return_size = 0;
+    for (ValueType t : sig->returns()) {
+      return_size += 1 << ElementSizeLog2Of(t);
+    }
+    if (arg_buffer.size() < return_size) {
+      arg_buffer.resize(return_size);
+    }
+
     // Wrap the arg_buffer data pointer in a handle. As this is an aligned
     // pointer, to the GC it will look like a Smi.
     Handle<Object> arg_buffer_obj(reinterpret_cast<Object*>(arg_buffer.data()),

test/mjsunit/wasm/interpreter.js

@@ -22,6 +22,7 @@ function checkStack(stack, expected_lines) {
 }
 
 (function testCallImported() {
+  print(arguments.callee.name);
   var stack;
   let func = () => stack = new Error('test imported stack').stack;
 
@@ -47,6 +48,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testCallImportedWithParameters() {
+  print(arguments.callee.name);
   var stack;
   var passed_args = [];
   let func1 = (i, j) => (passed_args.push(i, j), 2 * i + j);
@@ -80,6 +82,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testTrap() {
+  print(arguments.callee.name);
   var builder = new WasmModuleBuilder();
   var foo_idx = builder.addFunction('foo', kSig_v_v)
                     .addBody([kExprNop, kExprNop, kExprUnreachable])
@@ -110,6 +113,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testThrowFromImport() {
+  print(arguments.callee.name);
   function func() {
     throw new Error('thrown from imported function');
   }
@@ -141,6 +145,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testGlobals() {
+  print(arguments.callee.name);
   var builder = new WasmModuleBuilder();
   builder.addGlobal(kWasmI32, true);  // 0
   builder.addGlobal(kWasmI64, true);  // 1
@@ -190,6 +195,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testReentrantInterpreter() {
+  print(arguments.callee.name);
   var stacks;
   var instance;
   function func(i) {
@@ -227,6 +233,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testIndirectImports() {
+  print(arguments.callee.name);
   var builder = new WasmModuleBuilder();
 
   var sig_i_ii = builder.addType(kSig_i_ii);
@@ -260,6 +267,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testIllegalImports() {
+  print(arguments.callee.name);
   var builder = new WasmModuleBuilder();
 
   var sig_l_v = builder.addType(kSig_l_v);
@@ -311,6 +319,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testInfiniteRecursion() {
+  print(arguments.callee.name);
   var builder = new WasmModuleBuilder();
 
   var direct = builder.addFunction('main', kSig_v_v)
@@ -331,6 +340,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testUnwindSingleActivation() {
+  print(arguments.callee.name);
   // Create two activations and unwind just the top one.
   var builder = new WasmModuleBuilder();
 
@@ -367,6 +377,7 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testInterpreterGC() {
+  print(arguments.callee.name);
   function run(f) {
     // wrap the creation in a closure so that the only thing returned is
     // the module (i.e. the underlying array buffer of wasm wire bytes dies).
@@ -400,10 +411,11 @@ function checkStack(stack, expected_lines) {
 })();
 
 (function testImportThrowsOnToNumber() {
+  print(arguments.callee.name);
   const builder = new WasmModuleBuilder();
-  builder.addImport('mod', 'func', kSig_i_v);
+  const imp_idx = builder.addImport('mod', 'func', kSig_i_v);
   builder.addFunction('main', kSig_i_v)
-      .addBody([kExprCallFunction, 0])
+      .addBody([kExprCallFunction, imp_idx])
       .exportFunc();
   var num_callback_calls = 0;
   const callback = () => {
@@ -421,3 +433,19 @@ function checkStack(stack, expected_lines) {
     assertEquals(i + 1, num_callback_calls);
   }
 })();
+
+(function testCallWithMoreReturnsThenParams() {
+  print(arguments.callee.name);
+  const builder1 = new WasmModuleBuilder();
+  builder1.addFunction('exp', kSig_l_v)
+      .addBody([kExprI64Const, 23])
+      .exportFunc();
+  const exp = builder1.instantiate().exports.exp;
+  const builder2 = new WasmModuleBuilder();
+  const imp_idx = builder2.addImport('imp', 'func', kSig_l_v);
+  builder2.addFunction('main', kSig_i_v)
+      .addBody([kExprCallFunction, imp_idx, kExprI32ConvertI64])
+      .exportFunc();
+  const instance = builder2.instantiate({imp: {func: exp}});
+  assertEquals(23, instance.exports.main());
+})();