strange dependancy generation bug?

[Dave Jones]

Recently (about the same time that the V=0 stuff was changed over
in kbuild), I noticed that the dependancy generation stuff seems to be
executed more often.

An example:

(davej@halogen:linux-2.5)$ make arch/i386/kernel/cpu/cpufreq/powernow-k7.o V=1
make -f scripts/Makefile.build obj=scripts
make -f scripts/Makefile.build obj=scripts/genksyms
make -f scripts/Makefile.build obj=arch/i386/kernel/cpu/cpufreq arch/i386/kernel/cpu/cpufreq/powernow-k7.o
  gcc -Wp,-MD,arch/i386/kernel/cpu/cpufreq/.powernow-k7.o.d -D__KERNEL__ -Iinclude -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fno-strict-aliasing -fno-common -pipe -mpreferred-stack-boundary=2 -march=i686 -Iinclude/asm-i386/mach-default -nostdinc -iwithprefix include    -DKBUILD_BASENAME=powernow_k7 -DKBUILD_MODNAME=powernow_k7 -c -o arch/i386/kernel/cpu/cpufreq/.tmp_powernow-k7.o arch/i386/kernel/cpu/cpufreq/powernow-k7.c
scripts/fixdep arch/i386/kernel/cpu/cpufreq/.powernow-k7.o.d arch/i386/kernel/cpu/cpufreq/powernow-k7.o 'gcc -Wp,-MD,arch/i386/kernel/cpu/cpufreq/.powernow-k7.o.d -D__KERNEL__ -Iinclude -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fno-strict-aliasing -fno-common -pipe -mpreferred-stack-boundary=2 -march=i686 -Iinclude/asm-i386/mach-default -nostdinc -iwithprefix include    -DKBUILD_BASENAME=powernow_k7 -DKBUILD_MODNAME=powernow_k7 -c -o arch/i386/kernel/cpu/cpufreq/.tmp_powernow-k7.o arch/i386/kernel/cpu/cpufreq/powernow-k7.c' > arch/i386/kernel/cpu/cpufreq/.powernow-k7.o.tmp; rm -f arch/i386/kernel/cpu/cpufreq/.powernow-k7.o.d; mv -f arch/i386/kernel/cpu/cpufreq/.powernow-k7.o.tmp arch/i386/kernel/cpu/cpufreq/.powernow-k7.o.cmd

First question that springs to mind, is why does the fixdep stuff get run _after_ doing the compile ?
Second, is why does this always happen? Even on subsequent builds.

		Dave