@item @samp{check_stack}
If stack checking cannot be done on your system by probing the stack with
a load or store instruction (@pxref{Stack Checking}), define this pattern
-to perform the needed check and signaling an error if the stack
-has overflowed. The single operand is the location in the stack furthest
-from the current stack pointer that you need to validate. Normally,
-on machines where this pattern is needed, you would obtain the stack
-limit from a global or thread-specific variable or register.
+to perform the needed check and signal an error if the stack has overflowed.
+The single operand is the address in the stack furthest from the current
+stack pointer that you need to validate. Normally, on machines where this
+pattern is needed, you would obtain the stack limit from a global or
+thread-specific variable or register.
+
+@cindex @code{probe_stack} instruction pattern
+@item @samp{probe_stack}
+If stack checking can be done on your system by probing the stack but doing
+it with a load or store instruction is not optimal (@pxref{Stack Checking}),
+define this pattern to do the probing differently and signal an error if
+the stack has overflowed. The single operand is the memory location in the
+stack that needs to be probed.
@cindex @code{nonlocal_goto} instruction pattern
@item @samp{nonlocal_goto}