src/hotspot/cpu/x86/macroAssembler_x86.cpp

@@ -6368,19 +6368,22 @@
 
 int MacroAssembler::shuffle_value_args(bool is_packing, bool receiver_only, int extra_stack_offset,
                                        BasicType* sig_bt, const GrowableArray<SigEntry>* sig_cc,
                                        int args_passed, int args_on_stack, VMRegPair* regs,            // from
                                        int args_passed_to, int args_on_stack_to, VMRegPair* regs_to) { // to
-  // Check if we need to extend the stack for unpacking
+  // Check if we need to extend the stack for packing/unpacking
   int sp_inc = (args_on_stack_to - args_on_stack) * VMRegImpl::stack_slot_size;
   if (sp_inc > 0) {
+    sp_inc = align_up(sp_inc, StackAlignmentInBytes);
+    if (!is_packing) {
     // Save the return address, adjust the stack (make sure it is properly
     // 16-byte aligned) and copy the return address to the new top of the stack.
+      // (Note: C1 does this in C1_MacroAssembler::scalarized_entry).
     pop(r13);
-    sp_inc = align_up(sp_inc, StackAlignmentInBytes);
     subptr(rsp, sp_inc);
     push(r13);
+    }
   } else {
     // The scalarized calling convention needs less stack space than the unscalarized one.
     // No need to extend the stack, the caller will take care of these adjustments.
     sp_inc = 0;
   }