[V8][Wasm] Wasm throws.

src/compiler/wasm-compiler.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/wasm-compiler.h"
 
 #include <memory>
 
 #include "src/isolate-inl.h"
 
@@ skipping 1685 matching lines @@
   Node* result = BuildChangeSmiToInt32(call);
 
   result = check_input_range.Phi(MachineRepresentation::kWord32, result,
                                  jsgraph()->Int32Constant(-1));
   *effect_ = graph()->NewNode(jsgraph()->common()->EffectPhi(2), call, *effect_,
                               check_input_range.merge);
   *control_ = check_input_range.merge;
   return result;
 }
 
+Node* WasmGraphBuilder::Throw(Node* input) {
+  MachineOperatorBuilder* machine = jsgraph()->machine();
+
+  // Pass the thrown value as two SMIs:

[titzer, 2016/09/15 12:53:28]

Please leave a TODO here, since I think we all agreed this was sad :(

[John, 2016/09/15 14:03:08]

Done.

+  //
+  // upper = static_cast<uint32_t>(input) >> 16;
+  // lower = input & 0xFFFF;
+  Node* upper = BuildChangeInt32ToSmi(
+      graph()->NewNode(machine->Word32Shr(), input, Int32Constant(16)));
+  Node* lower = BuildChangeInt32ToSmi(
+      graph()->NewNode(machine->Word32And(), input, Int32Constant(0xFFFFu)));
+
+  Node* parameters[] = {lower, upper};  // thrown value
+  return BuildCallToRuntime(Runtime::kWasmThrow, jsgraph(),
+                            module_->instance->context, parameters,
+                            arraysize(parameters), effect_, *control_);
+}
+
 Node* WasmGraphBuilder::BuildI32DivS(Node* left, Node* right,
                                      wasm::WasmCodePosition position) {
   MachineOperatorBuilder* m = jsgraph()->machine();
   trap_->ZeroCheck32(wasm::kTrapDivByZero, right, position);
   Node* before = *control_;
   Node* denom_is_m1;
   Node* denom_is_not_m1;
   Branch(
       graph()->NewNode(m->Word32Equal(), right, jsgraph()->Int32Constant(-1)),
       &denom_is_m1, &denom_is_not_m1);
@@ skipping 1563 matching lines @@
                             function_->code_start_offset),
            compile_ms);
   }
 
   return code;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8