Node: Prefer Automatic Uninitialized Variables, Next: Avoid f2c Compatibility, Previous: Aligned Data, Up: Faster Programs
If you're using
-fno-automatic already, you probably
should change your code to allow compilation with
(the default), to allow the program to run faster.
Similarly, you should be able to use
(the default) instead of
This is because it is rare that every variable affected by these
options in a given program actually needs to
be so affected.
-fno-automatic, which effectively
every local non-automatic variable and array, affects even things like
variables, which rarely need to be
SAVEd, and this often reduces
-fno-init-local-zero forces such
variables to be initialized to zero--when
SAVEd (such as when
-fno-automatic), this by itself generally affects only
startup time for a program, but when not
it can slow down the procedure every time it is called.
See Overly Convenient Command-Line Options,
for information on the
-finit-local-zero options and how to convert
their use into selective changes in your own code.