Hooking up asm-wasm conversion.

src/s390/builtins-s390.cc

Index: src/s390/builtins-s390.cc
diff --git a/src/s390/builtins-s390.cc b/src/s390/builtins-s390.cc
index 4ffd1528c4c4f7fd0ea07e571b2d76b37929ed33..f722d16288d5b48b984c9c758d60caeb4ca32f59 100644
--- a/src/s390/builtins-s390.cc
+++ b/src/s390/builtins-s390.cc
@@ -1396,6 +1396,43 @@ void Builtins::Generate_CompileOptimizedConcurrent(MacroAssembler* masm) {
   GenerateTailCallToReturnedCode(masm, Runtime::kCompileOptimized_Concurrent);
 }
 
+void Builtins::Generate_InstantiateAsmJs(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- r2 : argument count (preserved for callee)
+  //  -- r3 : new target (preserved for callee)
+  //  -- r5 : target function (preserved for callee)
+  // -----------------------------------
+  Label failed;
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    // Push a copy of the target function and the new target.
+    __ SmiTag(r2);
+    // Push another copy as a parameter to the runtime call.
+    __ Push(r2, r3, r5, r3);
+
+    // Copy arguments from caller (stdlib, foreign, heap).
+    for (int i = 2; i >= 0; --i) {
+      __ LoadP(r4, MemOperand(fp, StandardFrameConstants::kCallerSPOffset +
+                                      i * kPointerSize));
+      __ push(r4);
+    }
+    // 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(r2, &failed);
+    scope.GenerateLeaveFrame();
+    __ Drop(4);
+    __ Ret();
+
+    __ bind(&failed);
+    // Restore target function and new target.
+    __ Pop(r2, r3, r5);
+    __ SmiUntag(r2);
+  }
+  // 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
   // garbage collection which allows us to save/restore the registers without