[PATCHv2] new target hook for loop unrolling adjustment

[Andreas Krebbel]

>> 2010-02-01  Christian Borntraeger  <borntraeger@de.ibm.com>
>>             Wolfgang Gellerich  <gellerich@de.ibm.com>
>>
>>         Implement target hook for loop unrolling
>>         * target.h (loop_unroll_adjust): Add a new target hook function.
>>         * target-def.h (TARGET_LOOP_UNROLL_ADJUST): Likewise.
>>         * doc/tm.texi (TARGET_LOOP_UNROLL_ADJUST): Document it.
>>         * config/s390/s390.c (TARGET_LOOP_UNROLL_ADJUST): Define it.
>>         (s390_loop_unroll_adjust): Implement the new target hook for 
>> s390.
>>         * loop-unroll.c (decide_unroll_runtime_iterations): Call loop 
>> unroll target hook
>>         (decide_unroll_stupid): Likewise.

Committed to mainline. Thanks!

Bye,

-Andreas-