[wasm] Provide better stack traces for asm.js code

src/asmjs/asm-wasm-builder.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/v8.h"
 
 // Required to get M_E etc. in MSVC.
 #if defined(_WIN32)
 #define _USE_MATH_DEFINES
 #endif
@@ skipping 1341 matching lines @@
             sig.AddReturn(return_type);
           } else {
             returns_value = false;
           }
           for (int i = 0; i < args->length(); ++i) {
             sig.AddParam(TypeOf(args->at(i)));
           }
           uint32_t index = imported_function_table_.LookupOrInsertImport(
               vp->var(), sig.Build());
           VisitCallArgs(expr);
+          current_function_builder_->AddAsmWasmOffset(expr->position());
           current_function_builder_->Emit(kExprCallFunction);
           current_function_builder_->EmitVarInt(index);
         } else {
           WasmFunctionBuilder* function = LookupOrInsertFunction(vp->var());
           VisitCallArgs(expr);
+          current_function_builder_->AddAsmWasmOffset(expr->position());
           current_function_builder_->Emit(kExprCallFunction);
           current_function_builder_->EmitDirectCallIndex(
               function->func_index());
           returns_value = function->signature()->return_count() > 0;
         }
         break;
       }
       case Call::KEYED_PROPERTY_CALL: {
         DCHECK_EQ(kFuncScope, scope_);
         Property* p = expr->expression()->AsProperty();
         DCHECK_NOT_NULL(p);
         VariableProxy* var = p->obj()->AsVariableProxy();
         DCHECK_NOT_NULL(var);
         FunctionTableIndices* indices = LookupFunctionTable(var->var());
         Visit(p->key());  // TODO(titzer): should use RECURSE()
 
         // We have to use a temporary for the correct order of evaluation.
         current_function_builder_->EmitI32Const(indices->start_index);
         current_function_builder_->Emit(kExprI32Add);
         WasmTemporary tmp(current_function_builder_, kAstI32);
         current_function_builder_->EmitSetLocal(tmp.index());
 
         VisitCallArgs(expr);
 
         current_function_builder_->EmitGetLocal(tmp.index());
+        current_function_builder_->AddAsmWasmOffset(expr->position());
         current_function_builder_->Emit(kExprCallIndirect);
         current_function_builder_->EmitVarInt(indices->signature_index);
         returns_value =
             builder_->GetSignature(indices->signature_index)->return_count() >
             0;
         break;
       }
       default:
         UNREACHABLE();
     }
@@ skipping 461 matching lines @@
  private:
   DISALLOW_COPY_AND_ASSIGN(AsmWasmBuilderImpl);
 };
 
 AsmWasmBuilder::AsmWasmBuilder(Isolate* isolate, Zone* zone,
                                FunctionLiteral* literal, AsmTyper* typer)
     : isolate_(isolate), zone_(zone), literal_(literal), typer_(typer) {}
 
 // TODO(aseemgarg): probably should take zone (to write wasm to) as input so
 // that zone in constructor may be thrown away once wasm module is written.
-ZoneBuffer* AsmWasmBuilder::Run(i::Handle<i::FixedArray>* foreign_args) {
+AsmWasmBuilder::Result AsmWasmBuilder::Run(
+    i::Handle<i::FixedArray>* foreign_args) {
   AsmWasmBuilderImpl impl(isolate_, zone_, literal_, typer_);
   impl.Build();
   *foreign_args = impl.GetForeignArgs();
-  ZoneBuffer* buffer = new (zone_) ZoneBuffer(zone_);
-  impl.builder_->WriteTo(*buffer);
-  return buffer;
+  ZoneBuffer* module_buffer = new (zone_) ZoneBuffer(zone_);
+  impl.builder_->WriteTo(*module_buffer);
+  ZoneBuffer* asm_offsets_buffer = new (zone_) ZoneBuffer(zone_);
+  impl.builder_->WriteAsmJsOffsetTable(*asm_offsets_buffer);
+  return {module_buffer, asm_offsets_buffer};
 }
 
 const char* AsmWasmBuilder::foreign_init_name = "__foreign_init__";
 const char* AsmWasmBuilder::single_function_name = "__single_function__";
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8