MIPS[64]: 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 2958 matching lines @@
 
   // 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++);
     bool is_i64_as_two_params =
         jsgraph()->machine()->Is32() && sig->GetParam(i) == wasm::kWasmI64;
     MachineRepresentation param_rep =
         is_i64_as_two_params ? wasm::kWasmI32 : 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));

[titzer, 2017/02/23 20:44:46]

What about just aligning all arguments to 64-bits?

[ivica.bogosavljevic, 2017/02/24 09:37:56]

Pfiffig!

+    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);
+
     // TODO(clemensh): Respect endianess here. Might need to swap upper and
     // lower word.
     if (is_i64_as_two_params) {
       // Also store the upper half.
       param = Param(param_index++);
-      StoreRepresentation store_rep(wasm::kWasmI32,
-                                    WriteBarrierKind::kNoWriteBarrier);
-      *effect_ =
-          graph()->NewNode(jsgraph()->machine()->Store(store_rep), arg_buffer,
-                           Int32Constant(offset), param, *effect_, *control_);
+
+      alignment = offset % (1 << ElementSizeLog2Of(wasm::kWasmI32));
+      offset_aligned = (alignment == 0);
+
+      if (offset_aligned ||
+          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), param, *effect_, *control_);
+      } else {
+        UnalignedStoreRepresentation store_rep(wasm::kWasmI32);
+        *effect_ = graph()->NewNode(
+            jsgraph()->machine()->UnalignedStore(store_rep), arg_buffer,
+            Int32Constant(offset), param, *effect_, *control_);
+      }
       offset += 1 << ElementSizeLog2Of(wasm::kWasmI32);
     }
   }
   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 883 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 235 matching lines @@
                             function_->code_start_offset),
            compile_ms);
   }
 
   return code;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8