-
-If you want a variable to be unaltered by @code{longjmp}, and you don't
-want to write @code{volatile} because old C compilers don't accept it,
-just take the address of the variable. If a variable's address is ever
-taken, even if just to compute it and ignore it, then the variable cannot
-go in a register:
-
-@example
-@{
- int careful;
- &careful;
- @dots{}
-@}
-@end example
-
-@cindex arithmetic libraries
-@cindex math libraries
-@opindex msoft-float
-Code compiled with GCC may call certain library routines. Most of
-them handle arithmetic for which there are no instructions. This
-includes multiply and divide on some machines, and floating point
-operations on any machine for which floating point support is disabled
-with @option{-msoft-float}. Some standard parts of the C library, such as
-@code{bcopy} or @code{memcpy}, are also called automatically. The usual
-function call interface is used for calling the library routines.
-
-Some of these routines can be defined in mostly machine-independent C;
-they appear in @file{libgcc2.c}. Others must be hand-written in
-assembly language for each processor. Wherever they are defined, they
-are compiled into the support library, @file{libgcc.a}, which is
-automatically searched when you link programs with GCC@.