fixes, additions

book.tex

@@ -7743,9 +7743,12 @@ The \code{IndirectCallq} instruction should be treated like
 \code{Callq} regarding its written locations $W$, in that they should
 include all the caller-saved registers. Recall that the reason for
 that is to force call-live variables to be assigned to callee-saved
-registers or to be spilled to the stack. Also, the arity field of
-\code{IndirectCallq} determines how many of the argument-passing
-registers should be considered in the set of read locations $R$.
+registers or to be spilled to the stack.
+
+Regarding the set of read locations $R$ the arity field of
+\code{TailJmp} and \code{IndirectCallq} determines how many of the
+argument-passing registers should be considered as read by those
+instructions.
 
 \section{Build Interference Graph}