Summary:
* Investigate automotive benchmark.
* Linaro gcc 4.6 release
Details:
1. Automotive benchmark performance analysis for different branch cost
for Cortex-A9.
* Debug function WriteOut, which is called 12 times on average,
leads common performance issue since the IF-THEN in the function is
converted to IT block, which TRUE probability is less than 4%.
* Identify the root cause of performance regression with IT block
for bitmnp01, rspeed01, pntrch01 and ttsprk01. Overall,
- The performance of a taken bpl is better than an ITTT. If this
is a common sense, for IF-THEN, we'd set branch-cost to 1.
- For IF-THEN-ELSE, we'd take branch probability into account when
converting it to IT block.
- ifcvt might generate useless IT block.
2. Try to do Linaro GCC release. But meet several issues:
* Can not branch a clean lp:gcc-linaro/4.7. As a workaround, I had
downloaded a clean bzr tree from other site. For next release, I can
use the local tree to create the release tarball.
* All a9hf-builder ubutests fail due to test environment issue.
Plan:
* Investigate more benchmarks for different branch costs.
Planed leaves:
* Feb. 9 - 15: Chinese Spring Festival.
Best Regards!
-Zhenqiang
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