[wasm] Add stack checks at the beginning of each function.

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 af4ee67c4391ca94e33728a8174543d37068a07d..976568af5178748a9a4b7aed2129e098aa0f0a10 100644
--- a/src/compiler/wasm-compiler.cc
+++ b/src/compiler/wasm-compiler.cc
@@ -388,6 +388,40 @@ Node* WasmGraphBuilder::Int64Constant(int64_t value) {
   return jsgraph()->Int64Constant(value);
 }
 
+void WasmGraphBuilder::StackCheck(wasm::WasmCodePosition position) {
+  // We do not generate stack checks for cctests.
+  if (module_ && !module_->instance->context.is_null()) {
+    Node* limit = graph()->NewNode(
+        jsgraph()->machine()->Load(MachineType::Pointer()),
+        jsgraph()->ExternalConstant(
+            ExternalReference::address_of_stack_limit(jsgraph()->isolate())),
+        jsgraph()->IntPtrConstant(0), *effect_, *control_);
+    Node* pointer = graph()->NewNode(jsgraph()->machine()->LoadStackPointer());
+
+    Node* check =
+        graph()->NewNode(jsgraph()->machine()->UintLessThan(), limit, pointer);
+
+    Diamond stack_check(graph(), jsgraph()->common(), check, BranchHint::kTrue);
+
+    Node* effect_true = *effect_;
+
+    Node* effect_false;
+    // Generate a call to the runtime if there is a stack check failure.
+    {
+      Node* node = BuildCallToRuntime(Runtime::kStackGuard, jsgraph(),
+                                      module_->instance->context, nullptr, 0,
+                                      effect_, control_);

[Michael Starzinger, 2016/08/18 17:22:48]

This should be s/control_/diamond.if_false/ here, otherwise it is pure luck that
the runtime call is scheduled inside the else branch. Unconditionally calling
the runtime would be a valid schedule too.

[ahaas, 2016/08/19 07:13:42]

Thanks for noticing this. I fixed it now.

+      effect_false = node;
+    }
+
+    Node* ephi = graph()->NewNode(jsgraph()->common()->EffectPhi(2),
+                                  effect_true, effect_false, stack_check.merge);
+
+    *control_ = stack_check.merge;
+    *effect_ = ephi;
+  }
+}
+
 Node* WasmGraphBuilder::Binop(wasm::WasmOpcode opcode, Node* left, Node* right,
                               wasm::WasmCodePosition position) {
   const Operator* op;