RFR (XS) 8184762: ZapStackSegments should use optimized memset

Aleksey Shipilev shade at redhat.com
Mon Jul 17 17:34:54 UTC 2017


fastdebug builds performance is important to minimize testing time.
ZapStackSegments is trueInDebug, and used to zap vm/utilities/stack.* segments
as they get recycled.

However, that zapping uses the handrolled memset, which shows up in profiles
with individual stores. It seems better to use Copy::fill_to_bytes for this,
which will call into platform-specific memset.

Additionally, this would be a good time to introduce its zapped pattern to
globalDefinitions. The choice of 0xCA is arbitrary, and open for discussion.


Testing: hotspot_tier1 (Linux x86_64 / fastdebug)


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