[turbofan] Run everything after representation selection concurrently.

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 478ea193e6383f52c7813442c8429476cc09cd54..a14fdf5b184a324196b06d39472a72fbe601d37d 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -2042,6 +2042,44 @@ static void LeaveArgumentsAdaptorFrame(MacroAssembler* masm) {
   __ PushReturnAddressFrom(rcx);
 }
 
+// static
+void Builtins::Generate_AllocateInNewSpace(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- rdx    : requested object size (untagged)
+  //  -- rsp[0] : return address
+  // -----------------------------------
+  Label runtime;
+  __ Allocate(rdx, rax, rcx, rdi, &runtime, NO_ALLOCATION_FLAGS);
+  __ Ret();
+
+  __ bind(&runtime);
+  __ Integer32ToSmi(rdx, rdx);
+  __ PopReturnAddressTo(rcx);
+  __ Push(rdx);
+  __ PushReturnAddressFrom(rcx);
+  __ Move(rsi, Smi::FromInt(0));
+  __ TailCallRuntime(Runtime::kAllocateInNewSpace);
+}
+
+// static
+void Builtins::Generate_AllocateInOldSpace(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- rdx    : requested object size (untagged)
+  //  -- rsp[0] : return address
+  // -----------------------------------
+  Label runtime;
+  __ Allocate(rdx, rax, rcx, rdi, &runtime, PRETENURE);
+  __ Ret();
+
+  __ bind(&runtime);
+  __ Integer32ToSmi(rdx, rdx);
+  __ PopReturnAddressTo(rcx);
+  __ Push(rdx);
+  __ Push(Smi::FromInt(AllocateTargetSpace::encode(OLD_SPACE)));
+  __ PushReturnAddressFrom(rcx);
+  __ Move(rsi, Smi::FromInt(0));
+  __ TailCallRuntime(Runtime::kAllocateInTargetSpace);
+}
 
 void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
   // ----------- S t a t e -------------