[PATCH] optimization docs part 6

[Jerome L Quinn <jlquinn at us dot ibm dot com>]

In this last patch, I reworked the -0 descriptions some.  The -O2 flag
needed it as it
was incorrect.  The remainder I thought was more readable.

2002-08-30 Jerry Quinn <jlquinn@us.ibm.com>
      * gcc/gcc/doc/invoke.texi (Optimization Options): Clean up -O flag
descriptions.


--- gcc/gcc/doc/invoke.texi.safe           2002-08-25 01:40:52.000000000
-0400
+++ gcc/gcc/doc/invoke.texi          2002-08-25 01:41:43.000000000 -0400
@@ -3175,7 +3175,23 @@
 @cindex optimize options
 @cindex options, optimization

-These options control various sorts of optimizations:
+These options control various sorts of optimizations.
+
+Without any optimization option, the compiler's goal is to reduce the
+cost of compilation and to make debugging produce the expected
+results.  Statements are independent: if you stop the program with a
+breakpoint between statements, you can then assign a new value to any
+variable or change the program counter to any other statement in the
+function and get exactly the results you would expect from the source
+code.
+
+Turning on optimization flags makes the compiler attempt to improve
+the performance and/or code size at the expense of compilation time
+and possibly the ability to debug the program.
+
+Not all optimizations are controlled directly by a flag.  Only
+optimizations that have a flag are listed.
+

 @table @gcctabopt
 @item -O
@@ -3185,13 +3201,6 @@
 Optimize.  Optimizing compilation takes somewhat more time, and a lot
 more memory for a large function.

-Without @option{-O}, the compiler's goal is to reduce the cost of
-compilation and to make debugging produce the expected results.
-Statements are independent: if you stop the program with a breakpoint
-between statements, you can then assign a new value to any variable or
-change the program counter to any other statement in the function and
-get exactly the results you would expect from the source code.
-
 With @option{-O}, the compiler tries to reduce code size and execution
 time, without performing any optimizations that take a great deal of
 compilation time.
@@ -3269,20 +3278,20 @@

 Options of the form @option{-f@var{flag}} specify machine-independent
 flags.  Most flags have both positive and negative forms; the negative
-form of @option{-ffoo} would be @option{-fno-foo}.  In the table below,
-only one of the forms is listed---the one which is not the default.
-You can figure out the other form by either removing @samp{no-} or
-adding it.
+form of @option{-ffoo} would be @option{-fno-foo}.  In the table
+below, only one of the forms is listed---the one you typically will
+use.  You can figure out the other form by either removing @samp{no-}
+or adding it.
+
+The following options control specific optimizations.  They are either
+activated by @option{-O} options or are related to ones that are.  You
+can use the following flags in the rare cases when ``fine-tuning'' of
+optimizations to be performed is desired.

-@table @gcctabopt
-@item -fno-default-inline
-@opindex fno-default-inline
-Do not make member functions inline by default merely because they are
-defined inside the class scope (C++ only).  Otherwise, when you specify
-@w{@option{-O}}, member functions defined inside class scope are compiled
-inline by default; i.e., you don't need to add @samp{inline} in front of
-the member function name.
+Not all of the optimizations performed by GCC have @option{-f} options
+to control them.

+@table @gcctabopt
 @item -fno-defer-pop
 @opindex fno-defer-pop
 Always pop the arguments to each function call as soon as that function
@@ -3335,6 +3344,14 @@

 Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.

+@item -fno-default-inline
+@opindex fno-default-inline
+Do not make member functions inline by default merely because they are
+defined inside the class scope (C++ only).  Otherwise, when you specify
+@w{@option{-O}}, member functions defined inside class scope are compiled
+inline by default; i.e., you don't need to add @samp{inline} in front of
+the member function name.
+
 @item -fno-inline
 @opindex fno-inline
 Don't pay attention to the @code{inline} keyword.  Normally this option
@@ -3431,21 +3448,7 @@
 assumptions based on that.

 The default is @option{-fzero-initialized-in-bss}.
-@end table
-
-The following options control specific optimizations.  The @option{-O2}
-option turns on all of these optimizations except @option{-funroll-loops}
-and @option{-funroll-all-loops}.  On most machines, the @option{-O} option
-turns on the @option{-fthread-jumps} and @option{-fdelayed-branch}
options,
-but specific machines may handle it differently.
-
-You can use the following flags in the rare cases when ``fine-tuning''
-of optimizations to be performed is desired.

-Not all of the optimizations performed by GCC have @option{-f} options
-to control them.
-
-@table @gcctabopt
 @item -fstrength-reduce
 @opindex fstrength-reduce
 Perform the optimizations of loop strength reduction and