tree 1a04d214dd6223423abd442d8d9b0b61a3db2336
parent bae88c0759d48acf29b58d960ad2665e3462dfda
author Mathieu Chartier <mathieuc@google.com> 1566848026 -0700
committer Mathieu Chartier <mathieuc@google.com> 1567094752 +0000

Prevent overflow for AOT hotness counters

Previous, the addition did not have a check for overflow and might wrap
around since the counter is only 16 bits.

Modified the test to exercise this.

The slowdown from fixing the overflow is 2% average on golem arm32/64.
Overall this brings the slowdown from the counter to ~15% from ~13%.

The benchmarks that regress the most are loopy ones that I would
consider non-representative. Code size increases by 0.6%.

Bug: 139883463
Test: test/run-test --host --64 --prebuild 674-hotness-compiled
Test: test/run-test --host --prebuild 674-hotness-compiled
Test: test/run-test --64 --prebuild 674-hotness-compiled
Test: test/run-test ---prebuild 674-hotness-compiled

Change-Id: Icf0ab2aedbc40ab10c9d952ce0f9c7b5e5feaf15