[Bug middle-end/39976] [4.5 Regression] Big sixtrack degradation on powerpc 32/64 after revision r146817

[luisgpm at linux dot vnet dot ibm dot com]

------- Comment #17 from luisgpm at linux dot vnet dot ibm dot com  2009-05-15 02:16 -------
Actually, 64-bit is affected too, but not with the "power6x" tuning i was
using. With "-mcpu=power6" i can reproduce the problem.

The problem seems to be a couple load instructions that are being pushed up
from a different basic block, and this results in a Load-hit-store hazard,
since we've pushed the load too close to a store to the same address.

I'm not sure this is a direct consequence of changes in the gimple code. Would
you know Matz?

I'll continue digging...

Luis


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39976