review for 6796786: invalid FP identity transform - (a - b) -> b - a

[Christian Thalinger]

On May 2, 2011, at 11:25 PM, Tom Rodriguez wrote:
> http://cr.openjdk.java.net/~never/6796786
> 
> 6796786: invalid FP identity transform - (a - b) -> b - a
> Reviewed-by:
> 
> C2 is transforming the idiom - (a - b) into b - a which produces the
> wrong sign if a == b.  The fix is to eliminate that optimization.
> Tested with test from report.

Looks good.  -- Christian