Hooking up asm-wasm conversion.

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index 45dea848b50a2bc6d0db6db8c1901da6739ece34..d32f14447870813e3eb894da294bfe2def449d84 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -92,7 +92,6 @@ static void GenerateTailCallToReturnedCode(MacroAssembler* masm,
   __ jmp(rbx);
 }
 
-
 void Builtins::Generate_InOptimizationQueue(MacroAssembler* masm) {
   // Checking whether the queued function is ready for install is optional,
   // since we come across interrupts and stack checks elsewhere.  However,
@@ -1073,6 +1072,46 @@ void Builtins::Generate_CompileOptimizedConcurrent(MacroAssembler* masm) {
   GenerateTailCallToReturnedCode(masm, Runtime::kCompileOptimized_Concurrent);
 }
 
+void Builtins::Generate_InstantiateAsmJs(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- rax : argument count (preserved for callee)
+  //  -- rdx : new target (preserved for callee)
+  //  -- rdi : target function (preserved for callee)
+  // -----------------------------------
+  Label failed;
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    // Push the number of arguments to the callee.
+    __ Integer32ToSmi(rax, rax);
+    __ Push(rax);
+    // Push a copy of the target function and the new target.
+    __ Push(rdi);
+    __ Push(rdx);
+
+    // The function.
+    __ Push(rdi);
+    // Copy arguments from caller (stdlib, foreign, heap).
+    for (int i = 2; i >= 0; --i) {
+      __ Push(Operand(
+          rbp, StandardFrameConstants::kCallerSPOffset + i * kPointerSize));
+    }
+    // Call runtime, on success unwind frame, and parent frame.
+    __ CallRuntime(Runtime::kInstantiateAsmJs, 4);
+    // A smi 0 is returned on failure, an object on success.
+    __ JumpIfSmi(rax, &failed, Label::kNear);
+    scope.GenerateLeaveFrame();
+    __ ret(4 * kPointerSize);
+
+    __ bind(&failed);
+    // Restore target function and new target.
+    __ Pop(rdx);
+    __ Pop(rdi);
+    __ Pop(rax);
+    __ SmiToInteger32(rax, rax);
+  }
+  // On failure, tail call back to regular js.
+  GenerateTailCallToReturnedCode(masm, Runtime::kCompileLazy);
+}
 
 static void GenerateMakeCodeYoungAgainCommon(MacroAssembler* masm) {
   // For now, we are relying on the fact that make_code_young doesn't do any