[wasm] Add support for compiling WASM_INTERPRETER_ENTRY stubs

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/isolate-inl.h"
 
@@ skipping 18 matching lines @@
 #include "src/compiler/zone-stats.h"
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/factory.h"
 #include "src/log-inl.h"
 
 #include "src/wasm/function-body-decoder.h"
 #include "src/wasm/wasm-limits.h"
 #include "src/wasm/wasm-module.h"
+#include "src/wasm/wasm-objects.h"
 #include "src/wasm/wasm-opcodes.h"
 #include "src/wasm/wasm-text.h"
 
 // TODO(titzer): pull WASM_64 up to a common header.
 #if !V8_TARGET_ARCH_32_BIT || V8_TARGET_ARCH_X64
 #define WASM_64 1
 #else
 #define WASM_64 0
 #endif
 
@@ skipping 2855 matching lines @@
 
   // Convert the return value back.
   Node* i32_zero = jsgraph()->Int32Constant(0);
   Node* val = sig->return_count() == 0
                   ? i32_zero
                   : FromJS(call, HeapConstant(isolate->native_context()),
                            sig->GetReturn());
   Return(val);
 }
 
+void WasmGraphBuilder::BuildWasmToInterpreter(
+    uint32_t function_index, wasm::FunctionSig* sig,
+    Handle<WasmInstanceObject> instance) {
+  int wasm_count = static_cast<int>(sig->parameter_count());
+  int param_count = jsgraph()->machine()->Is64()
+                        ? wasm_count
+                        : Int64Lowering::GetParameterCountAfterLowering(sig);
+
+  // Build the start and the parameter nodes.
+  Node* start = Start(param_count + 3);
+  *effect_ = start;
+  *control_ = start;
+
+  auto build_runtime_call = [&](Runtime::FunctionId f) -> Node* {
+    Node* parameters[] = {
+        jsgraph()->SmiConstant(function_index),  // function index
+        jsgraph()->HeapConstant(instance),       // wasm instance
+    };
+    return BuildCallToRuntime(
+        f, jsgraph(), jsgraph()->isolate()->native_context(), parameters,
+        arraysize(parameters), effect_, *control_);
+  };
+
+  // Get a buffer to store all parameters.
+  Node* arg_buffer = build_runtime_call(Runtime::kGetWasmInterpreterBuffer);

[titzer, 2017/01/10 19:00:51]

I think we can put this buffer into the stack frame of the caller. We already
have a mechanism to allocate a single stack slot which we could generalize to a
fixed-size buffer. That will also be safer for reentrancy.

[titzer, 2017/01/10 19:02:47]

Actually, now that I think about it, we might be able to use a special call
descriptor to force all the arguments onto the stack, and then the TurboFan
backend will just do all the moves for us.

[Clemens Hammacher, 2017/01/11 15:05:29]

Done: http://crrev.com/2624183002

Using a special call descriptor does not work, since it must be abi-compatible
to WASM_CODE.

+
+  // Now store all our parameters 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_);
+    offset += 1 << ElementSizeLog2Of(param_rep);
+    if (is_i64_as_two_params) {

[titzer, 2017/01/10 19:00:51]

I think this might be backward for big-endian platforms.

[Clemens Hammacher, 2017/01/11 15:05:29]

According to AddParameterNodes (line 2811) and BuildJSToWasmWrapper (line 2776),
the lower word always comes first in the parameters.

+      // 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_);
+      offset += 1 << ElementSizeLog2Of(wasm::kWasmI32);

[titzer, 2017/01/10 19:00:51]

sizeof(int32_t) is also fine.

[Clemens Hammacher, 2017/01/11 15:05:29]

Yes, but this way it is the same expression as 7 lines above.

+    }
+  }
+  DCHECK_EQ(param_count, param_index);
+
+  build_runtime_call(Runtime::kWasmRunInterpreter);
+
+  // Read back the return value.
+  if (jsgraph()->machine()->Is32() && sig->return_count() > 0 &&
+      sig->GetReturn() == wasm::kWasmI64) {
+    MachineType load_rep = wasm::WasmOpcodes::MachineTypeFor(wasm::kWasmI32);
+    Node* lower =
+        graph()->NewNode(jsgraph()->machine()->Load(load_rep), arg_buffer,
+                         Int32Constant(0), *effect_, *control_);
+    Node* upper =
+        graph()->NewNode(jsgraph()->machine()->Load(load_rep), arg_buffer,
+                         Int32Constant(4), *effect_, *control_);
+    Return(upper, lower);
+  } else {
+    Node* val;
+    if (sig->return_count() == 0) {
+      val = Int32Constant(0);
+    } else {
+      MachineType load_rep =
+          wasm::WasmOpcodes::MachineTypeFor(sig->GetReturn());
+      val = graph()->NewNode(jsgraph()->machine()->Load(load_rep), arg_buffer,
+                             Int32Constant(0), *effect_, *control_);
+    }
+    Return(val);
+  }
+}
+
 Node* WasmGraphBuilder::MemBuffer(uint32_t offset) {
   DCHECK(module_ && module_->instance);
   if (offset == 0) {
     if (!mem_buffer_) {
       mem_buffer_ = jsgraph()->RelocatableIntPtrConstant(
           reinterpret_cast<uintptr_t>(module_->instance->mem_start),
           RelocInfo::WASM_MEMORY_REFERENCE);
     }
     return mem_buffer_;
   } else {
@@ skipping 555 matching lines @@
     }
     RecordFunctionCompilation(
         CodeEventListener::FUNCTION_TAG, isolate, code, "wasm-to-js", index,
         {module_name->ToCString().get(), module_name->length()},
         {function_name, function_name_size});
   }
 
   return code;
 }
 
+Handle<Code> CompileWasmToInterpreter(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);
+  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.BuildWasmToInterpreter(func_index, sig, instance);
+
+  Handle<Code> code = Handle<Code>::null();
+  {
+    if (FLAG_trace_turbo_graph) {  // Simple textual RPO.
+      OFStream os(stdout);
+      os << "-- Wasm to interpreter graph -- " << std::endl;
+      os << AsRPO(graph);
+    }
+
+    // Schedule and compile to machine code.
+    CallDescriptor* incoming =
+        wasm::ModuleEnv::GetWasmCallDescriptor(&zone, sig);
+    if (machine.Is32()) {
+      incoming = wasm::ModuleEnv::GetI32WasmCallDescriptor(&zone, incoming);
+    }
+    Code::Flags flags = Code::ComputeFlags(Code::WASM_TO_INTERPRETER);
+    EmbeddedVector<char, 32> debug_name;
+    int name_len = SNPrintF(debug_name, "wasm-to-interpreter#%d", func_index);
+    DCHECK(name_len > 0 && name_len < debug_name.length());
+    debug_name.Truncate(name_len);
+    DCHECK_EQ('\0', debug_name.start()[debug_name.length()]);
+
+    CompilationInfo info(debug_name, isolate, &zone, flags);
+    code = Pipeline::GenerateCodeForTesting(&info, incoming, &graph, nullptr);
+#ifdef ENABLE_DISASSEMBLER
+    if (FLAG_print_opt_code && !code.is_null()) {
+      OFStream os(stdout);
+      code->Disassemble(debug_name.start(), os);
+    }
+#endif
+
+    if (isolate->logger()->is_logging_code_events() ||
+        isolate->is_profiling()) {
+      RecordFunctionCompilation(CodeEventListener::FUNCTION_TAG, isolate, code,
+                                "wasm-to-interpreter", func_index,
+                                wasm::WasmName("module"), debug_name);
+    }
+  }
+
+  Handle<FixedArray> deopt_data = isolate->factory()->NewFixedArray(1, TENURED);
+  Handle<WeakCell> weak_instance = isolate->factory()->NewWeakCell(instance);
+  deopt_data->set(0, *weak_instance);
+  code->set_deoptimization_data(*deopt_data);
+
+  return code;
+}
+
 SourcePositionTable* WasmCompilationUnit::BuildGraphForWasmFunction(
     double* decode_ms) {
   base::ElapsedTimer decode_timer;
   if (FLAG_trace_wasm_decode_time) {
     decode_timer.Start();
   }
   // Create a TF graph during decoding.
 
   Graph* graph = jsgraph_->graph();
   CommonOperatorBuilder* common = jsgraph_->common();
@@ skipping 187 matching lines @@
                       Smi::FromInt(instruction.instr_offset));
     fn_protected->set(Code::kTrapDataSize * i + Code::kTrapLandingOffset,
                       Smi::FromInt(instruction.landing_offset));
   }
   return fn_protected;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8