commit fe814e89965ddf9a8b603863bd28259f8dd7be35
author Mathieu Chartier <mathieuc@google.com> Wed Nov 09 14:32:49 2016 -0800
committer Mathieu Chartier <mathieuc@google.com> Thu Nov 10 14:41:28 2016 -0800
tree 32ecc282f176d0e2a98f41f6e4b116d26cf58bee
parent 977919fbcbfbf0c1c3fa97e51490bc678da646d2

Use entrypoint switching to reduce code size of GcRoot read barrier

Set the read barrier mark register entrypoints to null when the GC
is not marking. The compiler uses this to avoid needing to load the
is_gc_marking boolean.

Code size results on ritzperf CC:
arm32: 13439400 -> 13242792 (-1.5%)
arm64: 16380544 -> 16208512 (-1.05%)

Implemented for arm32 and arm64. TODO: Consider implementing on x86.

Bug: 32638713
Bug: 29516974

Test: test-art-host + run ritzperf
Change-Id: I527ca5dc4cd43950ba43b872d0ac81e1eb5791eb