Here's some pretty pictures of the relative CoreMark performance on a Cortex-A9. Note that in accordance with the CoreMark rules, all results are estimates.
Linaro GCC 4.5 and mainline GCC vs 4.5.2: http://people.linaro.org/~michaelh/incoming/all-o3-vs-gcc-4.5.2.png
Linaro GCC 4.5 releases vs our first: http://people.linaro.org/~michaelh/incoming/releases-o3-vs-gcc-linaro-4.5-20...
Linaro GCC 4.5 builds between 2010.08 and 2010.10: http://people.linaro.org/~michaelh/incoming/releases-o3-vs-gcc-linaro-4.5-20...
The 2.5 % drop in performance for 2010.09 is probably due to r99379. The further 2 % drop in 2010.10 is due to re-syncing with mainline 4.5.2.
Performance has been moving solidly upwards but it has to start from the -4.5 % from these two updates. Chung Lin's unsigned extension changes should be interesting...
-- Michael