JDK-7074017 : Introduce MemBarAcquireLock/MemBarReleaseLock nodes for monitor enter/exit code paths
- Type: Bug
- Component: hotspot
- Sub-Component: compiler
- Affected Version: hs21,hs22
- Priority: P4
- Status: Closed
- Resolution: Fixed
- OS: generic,linux
- CPU: generic,arm
- Submitted: 2011-08-02
- Updated: 2011-11-25
- Resolved: 2011-09-30
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| JDK 7 | Other |
|---|---|
7u2Fixed  |
hs22Fixed |
Description
To implement the java memory model, on a monitor operation, c2 currently adds a MemBarAcquire/MemBarRelease node after/before the monitor enter/exit. No membar instruction is emitted for these MemBarAcquire/MemBarRelease: in the ad file, Matcher::prior_fast_lock()/Matcher::post_fast_unlock() is used to detect a MemBarAcquire/MemBarRelease associated with a monitor enter/exit and to use an empty encoding. Matcher::post_fast_unlock() is broken with UseOptoBiasInlining: it never returns true. This CR covers the replacement of MemBarAcquire/MemBarRelease nodes on the monitor enter/exit code paths with new MemBarAcquireLock/MemBarReleaseLock nodes. It makes it straightforward to distinguish between MemBarAcquire/MemBarRelease on the monitor enter/exit code paths and other code paths without the need for the MemBarAcquire/MemBarRelease machinery.
Comments
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