[wasm] Use Param and Return methods consistently

Also, provide a variadic template Return function for easier use, and
refactor the underlying Return function to not use the Buffer, since
that might still be needed later (for example if trap code is generated
during CallIndirect, and the arguments to the call are stored in the
buffer).

R=titzer@chromium.org

Review-Url: https://codereview.chromium.org/2591903003
Cr-Commit-Position: refs/heads/master@{#41888}

src/compiler/wasm-compiler.cc

@@ -301,7 +301,6 @@ class WasmTrapHelper : public ZoneObject {
   }
 
   void BuildTrapCode(Node* reason_node, Node* position_node) {
-    Node* end;
     Node** control_ptr = builder_->control_;
     Node** effect_ptr = builder_->effect_;
     wasm::ModuleEnv* module = builder_->module_;
@@ -332,16 +331,12 @@ class WasmTrapHelper : public ZoneObject {
       Node* thrw =
           graph()->NewNode(common()->Throw(), jsgraph()->ZeroConstant(),
                            *effect_ptr, *control_ptr);
-      end = thrw;
+      MergeControlToEnd(jsgraph(), thrw);
     } else {
       // End the control flow with returning 0xdeadbeef
       Node* ret_value = GetTrapValue(builder_->GetFunctionSignature());
-      end = graph()->NewNode(jsgraph()->common()->Return(),
-                             jsgraph()->Int32Constant(0), ret_value,
-                             *effect_ptr, *control_ptr);
+      builder_->Return(ret_value);
     }
-
-    MergeControlToEnd(jsgraph(), end);
   }
 };
 
@@ -374,7 +369,7 @@ Node* WasmGraphBuilder::Start(unsigned params) {
   return start;
 }
 
-Node* WasmGraphBuilder::Param(unsigned index, wasm::LocalType type) {
+Node* WasmGraphBuilder::Param(unsigned index) {
   return graph()->NewNode(jsgraph()->common()->Parameter(index),
                           graph()->start());
 }
@@ -1099,9 +1094,18 @@ Node* WasmGraphBuilder::Return(unsigned count, Node** vals) {
   DCHECK_NOT_NULL(*control_);
   DCHECK_NOT_NULL(*effect_);
 
-  Node** buf = Realloc(vals, count, count + 3);
-  memmove(buf + 1, buf, sizeof(void*) * count);
+  static const int kStackAllocatedNodeBufferSize = 8;
+  Node* stack_buffer[kStackAllocatedNodeBufferSize];
+  std::vector<Node*> heap_buffer;
+
+  Node** buf = stack_buffer;
+  if (count + 3 > kStackAllocatedNodeBufferSize) {
+    heap_buffer.resize(count + 3);
+    buf = heap_buffer.data();
+  }
+
   buf[0] = jsgraph()->Int32Constant(0);
+  memcpy(buf + 1, vals, sizeof(void*) * count);
   buf[count + 1] = *effect_;
   buf[count + 2] = *control_;
   Node* ret =
@@ -2763,8 +2767,7 @@ void WasmGraphBuilder::BuildJSToWasmWrapper(Handle<Code> wasm_code,
 
   // Convert JS parameters to WASM numbers.
   for (int i = 0; i < wasm_count; ++i) {
-    Node* param =
-        graph()->NewNode(jsgraph()->common()->Parameter(i + 1), start);
+    Node* param = Param(i + 1);
     Node* wasm_param = FromJS(param, context, sig->GetParam(i));
     args[pos++] = wasm_param;
     if (jsgraph()->machine()->Is32() && sig->GetParam(i) == wasm::kAstI64) {
@@ -2784,6 +2787,7 @@ void WasmGraphBuilder::BuildJSToWasmWrapper(Handle<Code> wasm_code,
     desc = wasm::ModuleEnv::GetI32WasmCallDescriptor(jsgraph()->zone(), desc);
   }
   Node* call = graph()->NewNode(jsgraph()->common()->Call(desc), count, args);
+  *effect_ = call;
   Node* retval = call;
   if (jsgraph()->machine()->Is32() && sig->return_count() > 0 &&
       sig->GetReturn(0) == wasm::kAstI64) {
@@ -2793,10 +2797,7 @@ void WasmGraphBuilder::BuildJSToWasmWrapper(Handle<Code> wasm_code,
   }
   Node* jsval = ToJS(
       retval, sig->return_count() == 0 ? wasm::kAstStmt : sig->GetReturn());
-  Node* ret = graph()->NewNode(jsgraph()->common()->Return(),
-                               jsgraph()->Int32Constant(0), jsval, call, start);
-
-  MergeControlToEnd(jsgraph(), ret);
+  Return(jsval);
 }
 
 int WasmGraphBuilder::AddParameterNodes(Node** args, int pos, int param_count,
@@ -2804,8 +2805,7 @@ int WasmGraphBuilder::AddParameterNodes(Node** args, int pos, int param_count,
   // Convert WASM numbers to JS values.
   int param_index = 0;
   for (int i = 0; i < param_count; ++i) {
-    Node* param = graph()->NewNode(
-        jsgraph()->common()->Parameter(param_index++), graph()->start());
+    Node* param = Param(param_index++);
     args[pos++] = ToJS(param, sig->GetParam(i));
     if (jsgraph()->machine()->Is32() && sig->GetParam(i) == wasm::kAstI64) {
       // On 32 bit platforms we have to skip the high word of int64
@@ -2909,10 +2909,7 @@ void WasmGraphBuilder::BuildWasmToJSWrapper(Handle<JSReceiver> target,
                   ? i32_zero
                   : FromJS(call, HeapConstant(isolate->native_context()),
                            sig->GetReturn());
-  Node* ret = graph()->NewNode(jsgraph()->common()->Return(), i32_zero, val,
-                               *effect_, start);
-
-  MergeControlToEnd(jsgraph(), ret);
+  Return(val);
 }
 
 Node* WasmGraphBuilder::MemBuffer(uint32_t offset) {

src/compiler/wasm-compiler.h

@@ -127,7 +127,7 @@ class WasmGraphBuilder {
   //-----------------------------------------------------------------------
   Node* Error();
   Node* Start(unsigned params);
-  Node* Param(unsigned index, wasm::LocalType type);
+  Node* Param(unsigned index);
   Node* Loop(Node* entry);
   Node* Terminate(Node* effect, Node* control);
   Node* Merge(unsigned count, Node** controls);
@@ -166,7 +166,12 @@ class WasmGraphBuilder {
   Node* Switch(unsigned count, Node* key);
   Node* IfValue(int32_t value, Node* sw);
   Node* IfDefault(Node* sw);
-  Node* Return(unsigned count, Node** vals);
+  Node* Return(unsigned count, Node** nodes);
+  template <typename... Nodes>
+  Node* Return(Node* fst, Nodes*... more) {
+    Node* arr[] = {fst, more...};
+    return Return(arraysize(arr), arr);
+  }
   Node* ReturnVoid();
   Node* Unreachable(wasm::WasmCodePosition position);
 

src/wasm/ast-decoder.cc

@@ -524,7 +524,7 @@ class WasmFullDecoder : public WasmDecoder {
       // Initialize local variables.
       uint32_t index = 0;
       while (index < sig_->parameter_count()) {
-        ssa_env->locals[index] = builder_->Param(index, local_type_vec_[index]);
+        ssa_env->locals[index] = builder_->Param(index);
         index++;
       }
       while (index < local_type_vec_.size()) {