Name: Eliminate Unused Functions
Author: Rusty Russell
Status: Tested on 2.5.70-bk16

GCC 3.3 has the ability to eliminate unused static functions.  This includes
code like this:

static int unusedfunc(void) { ... };
int otherfunc(void)
{
         (void)unusedfunc;
 ...

This means that macros can suppress the "unused" warning on functions
without preventing the function elimination.  This should allow us to
remove a number of #ifdefs around unused functions.

Unfortunately, this elimination is only performed if
-finline-functions is used.  In order to prevent GCC automatically
inlining anything, we also specify "--param max-inline-insns-auto=0".

Earlier compilers don't understand this parameter, so we test for
it at build time.

Results:
  gcc 3.3 without patch:
      -rwxrwxr-x    1 rusty    rusty     5115166 Jun 13 09:17 vmlinux
  gcc 3.3 with patch:
      -rwxrwxr-x    1 rusty    rusty     5115166 Jun 13 09:58 vmlinux
  gcc 3.3 without patch (small unused function added):
      -rwxrwxr-x    1 rusty    rusty     5115195 Jun 13 10:14 vmlinux
  gcc 3.3 with patch (small unused function added):
      -rwxrwxr-x    1 rusty    rusty     5115166 Jun 13 10:15 vmlinux

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal working-2.5.70-bk16-check_region/Makefile working-2.5.70-bk16-check_region-inline/Makefile
--- working-2.5.70-bk16-check_region/Makefile	2003-06-12 09:57:39.000000000 +1000
+++ working-2.5.70-bk16-check_region-inline/Makefile	2003-06-12 21:34:40.000000000 +1000
@@ -213,10 +213,12 @@ CFLAGS_KERNEL	=
 AFLAGS_KERNEL	=
 
 NOSTDINC_FLAGS  = -nostdinc -iwithprefix include
+# Needs gcc 3.3 or above to understand max-inline-insns-auto.
+INLINE_OPTS	:= $(shell $(CC) -o /non/existent/file -c --param max-inline-insns-auto=0 -xc /dev/null 2>&1 | grep /non/existent/file >/dev/null && echo -finline-functions --param max-inline-insns-auto=0)
 
 CPPFLAGS	:= -D__KERNEL__ -Iinclude
 CFLAGS 		:= $(CPPFLAGS) -Wall -Wstrict-prototypes -Wno-trigraphs -O2 \
-	  	   -fno-strict-aliasing -fno-common
+	  	   $(INLINE_OPTS) -fno-strict-aliasing -fno-common
 AFLAGS		:= -D__ASSEMBLY__ $(CPPFLAGS)
 
 export	VERSION PATCHLEVEL SUBLEVEL EXTRAVERSION KERNELRELEASE ARCH \