[9] RFR (M): 8011858: Use Compile::live_nodes() instead of Compile::unique() in appropriate places (original) (raw)

Vlad Ureche vlad.ureche at gmail.com
Fri Jul 17 22:47:15 UTC 2015

Hi,

Please review the following patch for JDK-8011858. Big thanks to Vladimir Kozlov for his patient guidance while working on this!

Bug: https://bugs.openjdk.java.net/browse/JDK-8011858

Problem: Throughout C2, local stacks are used to prevent recursive calls from blowing up the system stack. These are sized based on the total number of nodes in the compilation run (e.g. C->unique()). Instead, they should be sized based on the live node count (C->live_nodes()).

Now, with the increased difference between live_nodes (limited at LiveNodeCountInliningCutoff, set to 40K) and unique nodes (which can go up to 240K), it is important to not over-estimate the size of stacks.

Solution: This patch mirrors a patch written by Vladimir Kozlov for JDK8u. It replaces the initial sizes from C->unique() to C->live_nodes(), preserving any shifts (divisions) and offsets. For example, in the compile.cpp patch <http://cr.openjdk.java.net/~kvn/8011858/webrev/src/share/vm/opto/compile.cpp.patch> :

There is an issue described at https://bugs.openjdk.java.net/browse/JDK-8131702 where I took the workaround from Vladimir’s patch.

Webrev: http://cr.openjdk.java.net/~kvn/8011858/webrev/ or http://vladureche.ro/webrev/8011858 (updated, includes a link to bug 8121702)

Tests: Running jtreg with the compiler, runtime and gc tests on the dev <http://hg.openjdk.java.net/jdk9/dev> branch shows the same status before and after the patch: 808 tests passed, 16 failed and 6 errors <http://vladureche.ro/webrev/8011858/JTreport/html/index.html>. What would be a stable point where all tests are expected to pass, so I can test the patch there? Maybe jdk9 <http://hg.openjdk.java.net/jdk9/jdk9>?

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