+and @code{COMPLEX} variables with a quiet NaN. For a signalling NaN
+use @option{-finit-real=snan}; note, however, that compile-time
+optimizations may convert them into quiet NaN and that trapping
+needs to be enabled (e.g. via @option{-ffpe-trap}).
+
+Finally, note that enabling any of the @option{-finit-*} options will
+silence warnings that would have been emitted by @option{-Wuninitialized}
+for the affected local variables.
+
+@item -falign-commons
+@opindex @code{falign-commons}
+@cindex alignment of @code{COMMON} blocks
+By default, @command{gfortran} enforces proper alignment of all variables in a
+@code{COMMON} block by padding them as needed. On certain platforms this is mandatory,
+on others it increases performance. If a @code{COMMON} block is not declared with
+consistent data types everywhere, this padding can cause trouble, and
+@option{-fno-align-commons} can be used to disable automatic alignment. The
+same form of this option should be used for all files that share a @code{COMMON} block.
+To avoid potential alignment issues in @code{COMMON} blocks, it is recommended to order
+objects from largest to smallest.
+
+@item -fno-protect-parens
+@opindex @code{fno-protect-parens}
+@cindex re-association of parenthesized expressions
+By default the parentheses in expression are honored for all optimization
+levels such that the compiler does not do any re-association. Using
+@option{-fno-protect-parens} allows the compiler to reorder @code{REAL} and
+@code{COMPLEX} expressions to produce faster code. Note that for the re-association
+optimization @option{-fno-signed-zeros} and @option{-fno-trapping-math}
+need to be in effect. The parentheses protection is enabled by default, unless
+@option{-Ofast} is given.
+
+@item -frealloc-lhs
+@opindex @code{frealloc-lhs}
+@cindex Reallocate the LHS in assignments
+An allocatable left-hand side of an intrinsic assignment is automatically
+(re)allocated if it is either unallocated or has a different shape. The
+option is enabled by default except when @option{-std=f95} is given.
+
+@item -faggressive-function-elimination
+@opindex @code{faggressive-function-elimination}
+@cindex Elimination of functions with identical argument lists
+Functions with identical argument lists are eliminated within
+statements, regardless of whether these functions are marked
+@code{PURE} or not. For example, in
+@smallexample
+ a = f(b,c) + f(b,c)
+@end smallexample
+there will only be a single call to @code{f}. This option only works
+if @option{-ffrontend-optimize} is in effect.
+
+@item -ffrontend-optimize
+@opindex @code{frontend-optimize}
+@cindex Front-end optimization
+This option performs front-end optimization, based on manipulating
+parts the Fortran parse tree. Enabled by default by any @option{-O}
+option. Optimizations enabled by this option include elimination of
+identical function calls within expressions, removing unnecessary
+calls to @code{TRIM} in comparisons and assignments and replacing
+@code{TRIM(a)} with @code{a(1:LEN_TRIM(a))}.
+It can be deselected by specifying @option{-fno-frontend-optimize}.