[wasm] Initial signal handler

src/compiler/wasm-compiler.cc

Index: src/compiler/wasm-compiler.cc
diff --git a/src/compiler/wasm-compiler.cc b/src/compiler/wasm-compiler.cc
index b461e2fab7c90eca9823f5180241620a856b53fb..2cf75e15de15000d7f3b644ce546fbd0bba647b4 100644
--- a/src/compiler/wasm-compiler.cc
+++ b/src/compiler/wasm-compiler.cc
@@ -2807,6 +2807,13 @@ void WasmGraphBuilder::BuildJSToWasmWrapper(Handle<Code> wasm_code,
     args[pos++] = wasm_param;
   }
 
+  // Set the ThreadInWasm flag before we do the actual call.
+  if (trap_handler::ShouldEnableTrapHandler()) {
+    BuildCallToRuntime(Runtime::kSetThreadInWasm, jsgraph(),

[ahaas, 2017/02/20 09:27:23]

I wonder if we could set this flag without a runtime call. I think we should
make calls from JavaScript to WebAssembly as fast as possible. I think this is
critical to support the use case of providing WebAssembly libraries for
JavaScript. Could you add a TODO for this?

[titzer, 2017/02/20 09:50:08]

+1. I think you can embed a store directly to a location in the isolate (later
TLS) that sets the ThreadInWasm flag.

[Eric Holk, 2017/02/23 02:16:55]

TODO is added.

+                       jsgraph()->isolate()->native_context(), nullptr, 0,
+                       effect_, *control_);
+  }
+
   args[pos++] = *effect_;
   args[pos++] = *control_;
 
@@ -2816,6 +2823,14 @@ void WasmGraphBuilder::BuildJSToWasmWrapper(Handle<Code> wasm_code,
 
   Node* call = graph()->NewNode(jsgraph()->common()->Call(desc), count, args);
   *effect_ = call;
+
+  // Clear the ThreadInWasmFlag
+  if (trap_handler::ShouldEnableTrapHandler()) {
+    BuildCallToRuntime(Runtime::kClearThreadInWasm, jsgraph(),

[ahaas, 2017/02/20 09:27:24]

Is this runtime function called when WebAssembly throws a trap, e.g. division by
zero?

[Eric Holk, 2017/02/23 02:16:55]

The changes in isolate.cc will clear the flag when unwinding out of a Wasm
frame, which should handle this case.

+                       jsgraph()->isolate()->native_context(), nullptr, 0,
+                       effect_, *control_);
+  }
+
   Node* retval = call;
   Node* jsval = ToJS(
       retval, sig->return_count() == 0 ? wasm::kWasmStmt : sig->GetReturn());
@@ -2860,6 +2875,12 @@ void WasmGraphBuilder::BuildWasmToJSWrapper(Handle<JSReceiver> target,
   Node* call;
   bool direct_call = false;
 
+  if (trap_handler::ShouldEnableTrapHandler()) {
+    BuildCallToRuntime(Runtime::kClearThreadInWasm, jsgraph(),
+                       jsgraph()->isolate()->native_context(), nullptr, 0,
+                       effect_, *control_);
+  }
+
   if (target->IsJSFunction()) {
     Handle<JSFunction> function = Handle<JSFunction>::cast(target);
     if (function->shared()->internal_formal_parameter_count() == wasm_count) {
@@ -2924,6 +2945,12 @@ void WasmGraphBuilder::BuildWasmToJSWrapper(Handle<JSReceiver> target,
   *effect_ = call;
   SetSourcePosition(call, 0);
 
+  if (trap_handler::ShouldEnableTrapHandler()) {
+    BuildCallToRuntime(Runtime::kSetThreadInWasm, jsgraph(),
+                       jsgraph()->isolate()->native_context(), nullptr, 0,
+                       effect_, *control_);
+  }
+
   // Convert the return value back.
   Node* i32_zero = jsgraph()->Int32Constant(0);
   Node* val = sig->return_count() == 0