MIPS[64]: Reland of `Fix unaligned arguments storage in Wasm-to-interpreter entry`

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/assembler-inl.h"
 #include "src/base/platform/elapsed-timer.h"
@@ skipping 2793 matching lines @@
   }
 
   // The return value is also passed via this buffer:
   DCHECK_GE(wasm::kV8MaxWasmFunctionReturns, sig->return_count());
   // TODO(wasm): Handle multi-value returns.
   DCHECK_EQ(1, wasm::kV8MaxWasmFunctionReturns);
   int return_size_bytes =
       sig->return_count() == 0 ? 0 : 1 << ElementSizeLog2Of(sig->GetReturn(0));
 
   // Get a stack slot for the arguments.
-  Node* arg_buffer = args_size_bytes == 0 && return_size_bytes == 0
-                         ? jsgraph()->IntPtrConstant(0)
-                         : graph()->NewNode(jsgraph()->machine()->StackSlot(
-                               std::max(args_size_bytes, return_size_bytes)));
+  Node* arg_buffer =
+      args_size_bytes == 0 && return_size_bytes == 0
+          ? jsgraph()->IntPtrConstant(0)
+          : graph()->NewNode(jsgraph()->machine()->StackSlot(
+                std::max(args_size_bytes, return_size_bytes), 8));
 
   // Now store all our arguments to the buffer.
   int param_index = 0;
   int offset = 0;
 
   for (int i = 0; i < wasm_count; i++) {
     Node* param = Param(param_index++);
     if (Int64Lowering::IsI64AsTwoParameters(jsgraph()->machine(),
                                             sig->GetParam(i))) {
-      StoreRepresentation store_rep(wasm::kWasmI32,
-                                    WriteBarrierKind::kNoWriteBarrier);
-      *effect_ =
-          graph()->NewNode(jsgraph()->machine()->Store(store_rep), arg_buffer,
-                           Int32Constant(offset + kInt64LowerHalfMemoryOffset),
-                           param, *effect_, *control_);
+      int alignment = offset % (1 << ElementSizeLog2Of(wasm::kWasmI32));
+      bool offset_aligned = (alignment == 0);
 
-      param = Param(param_index++);
-      *effect_ =
-          graph()->NewNode(jsgraph()->machine()->Store(store_rep), arg_buffer,
-                           Int32Constant(offset + kInt64UpperHalfMemoryOffset),
-                           param, *effect_, *control_);
+      if (offset_aligned ||

[Clemens Hammacher, 2017/05/23 12:35:12]

You introduce lots of code duplication here.
Please extract a method like this:

const Operator* GetSafeStoreOperator(MachineOperatorBuilder* machine,
                                     int offset, wasm::ValueType type) {
  int alignment = offset % (1 << ElementSizeLog2Of(type));
  if (alignment == 0 || machine->UnalignedStoreSupported(
                            MachineType::TypeForRepresentation(type), 0)) {
    StoreRepresentation rep(type, WriteBarrierKind::kNoWriteBarrier);
    return machine->Store(rep);
  }
  UnalignedStoreRepresentation rep(type);
  return machine->UnalignedStore(rep);
}

And then just use this to generate the nodes:
*effect_ = graph()->NewNode(
          GetSafeStoreOperator(jsgraph()->machine(), offset, param_rep),
          arg_buffer, ...

[ivica.bogosavljevic, 2017/05/23 13:54:40]

I like this approach better, consider it done

+          jsgraph()->machine()->UnalignedStoreSupported(
+              MachineType::TypeForRepresentation(wasm::kWasmI32), 0)) {
+        StoreRepresentation store_rep(wasm::kWasmI32,
+                                      WriteBarrierKind::kNoWriteBarrier);
+
+        *effect_ = graph()->NewNode(
+            jsgraph()->machine()->Store(store_rep), arg_buffer,
+            Int32Constant(offset + kInt64LowerHalfMemoryOffset), param,
+            *effect_, *control_);
+
+        param = Param(param_index++);
+        *effect_ = graph()->NewNode(
+            jsgraph()->machine()->Store(store_rep), arg_buffer,
+            Int32Constant(offset + kInt64UpperHalfMemoryOffset), param,
+            *effect_, *control_);
+      } else {
+        UnalignedStoreRepresentation store_rep(wasm::kWasmI32);
+
+        *effect_ = graph()->NewNode(
+            jsgraph()->machine()->UnalignedStore(store_rep), arg_buffer,
+            Int32Constant(offset + kInt64LowerHalfMemoryOffset), param,
+            *effect_, *control_);
+
+        param = Param(param_index++);
+        *effect_ = graph()->NewNode(
+            jsgraph()->machine()->UnalignedStore(store_rep), arg_buffer,
+            Int32Constant(offset + kInt64UpperHalfMemoryOffset), param,
+            *effect_, *control_);
+      }
       offset += 8;
 
     } else {
       MachineRepresentation param_rep = sig->GetParam(i);
-      StoreRepresentation store_rep(param_rep,
-                                    WriteBarrierKind::kNoWriteBarrier);
-      *effect_ =
-          graph()->NewNode(jsgraph()->machine()->Store(store_rep), arg_buffer,
-                           Int32Constant(offset), param, *effect_, *control_);
+      int alignment = offset % (1 << ElementSizeLog2Of(param_rep));
+      bool offset_aligned = (alignment == 0);
+
+      if (offset_aligned ||
+          jsgraph()->machine()->UnalignedStoreSupported(
+              MachineType::TypeForRepresentation(param_rep), 0)) {
+        StoreRepresentation store_rep(param_rep,
+                                      WriteBarrierKind::kNoWriteBarrier);
+        *effect_ =
+            graph()->NewNode(jsgraph()->machine()->Store(store_rep), arg_buffer,
+                             Int32Constant(offset), param, *effect_, *control_);
+
+      } else {
+        UnalignedStoreRepresentation store_rep(param_rep);
+        *effect_ = graph()->NewNode(
+            jsgraph()->machine()->UnalignedStore(store_rep), arg_buffer,
+            Int32Constant(offset), param, *effect_, *control_);
+      }
       offset += 1 << ElementSizeLog2Of(param_rep);
     }
   }
   DCHECK_EQ(param_count, param_index);
   DCHECK_EQ(args_size_bytes, offset);
 
   // We are passing the raw arg_buffer here. To the GC and other parts, it looks
   // like a Smi (lowest bit not set). In the runtime function however, don't
   // call Smi::value on it, but just cast it to a byte pointer.
   Node* parameters[] = {
@@ skipping 976 matching lines @@
 
 Handle<Code> CompileWasmInterpreterEntry(Isolate* isolate, uint32_t func_index,
                                          wasm::FunctionSig* sig,
                                          Handle<WasmInstanceObject> instance) {
   //----------------------------------------------------------------------------
   // Create the Graph
   //----------------------------------------------------------------------------
   Zone zone(isolate->allocator(), ZONE_NAME);
   Graph graph(&zone);
   CommonOperatorBuilder common(&zone);
-  MachineOperatorBuilder machine(&zone);
+  MachineOperatorBuilder machine(
+      &zone, MachineType::PointerRepresentation(),
+      InstructionSelector::SupportedMachineOperatorFlags(),
+      InstructionSelector::AlignmentRequirements());
   JSGraph jsgraph(isolate, &graph, &common, nullptr, nullptr, &machine);
 
   Node* control = nullptr;
   Node* effect = nullptr;
 
   WasmGraphBuilder builder(nullptr, &zone, &jsgraph, sig);
   builder.set_control_ptr(&control);
   builder.set_effect_ptr(&effect);
   builder.BuildWasmInterpreterEntry(func_index, sig, instance);
 
@@ skipping 273 matching lines @@
     wasm::ModuleBytesEnv* module_env, const wasm::WasmFunction* function) {
   WasmCompilationUnit unit(isolate, module_env, function);
   unit.InitializeHandles();
   unit.ExecuteCompilation();
   return unit.FinishCompilation(thrower);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8