$NetBSD$

--- gcc/doc/md.texi.orig	Tue Dec 15 18:36:44 2009
+++ gcc/doc/md.texi
@@ -4503,8 +4503,9 @@ byte by byte in lexicographic order starting at the be
 string.  The instruction is not allowed to prefetch more than one byte
 at a time since either string may end in the first byte and reading past
 that may access an invalid page or segment and cause a fault.  The
-effect of the instruction is to store a value in operand 0 whose sign
-indicates the result of the comparison.
+comparison terminates early if the fetched bytes are different or if
+they are equal to zero.  The effect of the instruction is to store a
+value in operand 0 whose sign indicates the result of the comparison.
 
 @cindex @code{cmpstr@var{m}} instruction pattern
 @item @samp{cmpstr@var{m}}
@@ -4522,8 +4523,10 @@ The two memory blocks specified are compared byte by b
 order starting at the beginning of each string.  The instruction is not allowed
 to prefetch more than one byte at a time since either string may end in the
 first byte and reading past that may access an invalid page or segment and
-cause a fault.  The effect of the instruction is to store a value in operand 0
-whose sign indicates the result of the comparison.
+cause a fault.  The comparison will terminate when the fetched bytes
+are different or if they are equal to zero.  The effect of the
+instruction is to store a value in operand 0 whose sign indicates the
+result of the comparison.
 
 @cindex @code{cmpmem@var{m}} instruction pattern
 @item @samp{cmpmem@var{m}}
@@ -4531,9 +4534,10 @@ Block compare instruction, with five operands like the
 of @samp{cmpstr@var{m}}.  The two memory blocks specified are compared
 byte by byte in lexicographic order starting at the beginning of each
 block.  Unlike @samp{cmpstr@var{m}} the instruction can prefetch
-any bytes in the two memory blocks.  The effect of the instruction is
-to store a value in operand 0 whose sign indicates the result of the
-comparison.
+any bytes in the two memory blocks.  Also unlike @samp{cmpstr@var{m}}
+the comparison will not stop if both bytes are zero.  The effect of
+the instruction is to store a value in operand 0 whose sign indicates
+the result of the comparison.
 
 @cindex @code{strlen@var{m}} instruction pattern
 @item @samp{strlen@var{m}}