RFR: JDK-8217909: Make unused r12 register (without compressed oops) available to regalloc in C2

Andrew Dinn adinn at redhat.com
Wed Feb 13 13:37:46 UTC 2019

On 13/02/2019 11:26, Roman Kennke wrote:
> I started a version based on Dean's approach:
> http://cr.openjdk.java.net/~rkennke/JDK-8217909/webrev.01/
> Unfortunately it barks on ptr_reg class:
> assert fails
> /home/rkennke/src/openjdk/jdk-jdk/src/hotspot/share/adlc/formsopt.hpp
> 246: User defined register classes are not allowed to spill to the stack.
> Interestingly, it doesn't do that when I only handle any_reg class.
> However, I am not sure what that means or how to fix it. Any hints?
You could maybe use reg_class_dynamic to do this. See the AArch64 ad
file for an example.


Andrew Dinn
Senior Principal Software Engineer
Red Hat UK Ltd
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