Clarify non-volatile register usage

Colin Robertson · web-flow · commit a09b0003190a · 2017-03-13T21:07:28.000-07:00
diff --git a/docs/build/function-types.md b/docs/build/function-types.md
@@ -37,7 +37,7 @@ There are basically two types of functions. A function that requires a stack fra
   
  If a frame function does not call another function then it is not required to align the stack (referenced in Section [Stack Allocation](../build/stack-allocation.md)).  
   
- A leaf function is one that does not require a function table entry. It cannot call any functions, allocate space, or save any nonvolatile registers. It is allowed to leave the stack unaligned while it executes.  
+ A leaf function is one that does not require a function table entry. It can't make changes to any nonvolatile registers, including RSP, which means that it can't call any functions or allocate stack space. It is allowed to leave the stack unaligned while it executes.  
   
 ## See Also  
- [Stack Usage](../build/stack-usage.md)
+ [Stack Usage](../build/stack-usage.md)
