RFR: Add support for ARMv6 to ARM JIT

[Andrew Hughes]

----- Original Message -----
> Hi,
> 
> The following patch adds support for ARMv6 to the ARM JIT (previously known
> as the Thumb2 JIT).
> 
> http://openjdk.linaro.org/arm32jit/patches/6046.patch
> 
> The following ARM architectures are now supported
> 
> ARMv6 - Vanilla ARMv6 as on Raspberry PI (No Thumb2, No LDREXD/STREXD)
> ARMv6K - ARMv6 with MP support (No Thumb2, but has LDREXD/STREXD)
> ARMV6T2 - ARMv6 with Thumb2 and LDREXD/STREXD
> ARMV7 - all variants supported
> ARMV8 - all variants supported (in AARCH32 mode)
> 
> Note, because of the lack of properly working double/long atomic primitives
> on vanilla ARMv6 only non MP is supported on this. The Raspberry PI is
> single core so this is not a problem, it just uses LDM/STM or LDRD/STRD.
> 
> I have based the patches on the icedtea7 tree at
> http://icedtea.classpath.org/hg/icedtea7-forest/hotspot Is this the correct
> location for the tip of the icedtea7 development?
> 
> Because of the size of the changes I have introduced a new file arm32JIT.cpp
> rather than modifying the existing thumb2.cpp. This is switched on a symbol
> ARM32JIT. By default it will continue to build the Thumb2 JIT. To change it
> to build the ARM32 JIT by default add -DARM32JIT to CFLAGS in zeroshark.make
> as in the following patch.
> 
> http://openjdk.linaro.org/arm32jit/patches/6047.patch
> 
> I have put an image at
> 
> http://openjdk.linaro.org/arm32jit/images/arm32jit.tgz
> 
> I would be grateful if people could try out this image, especially on
> Raspberry PI.
> 
> Some influential environment variables are
> 
> T2_COMPILE_ARM
> 
> Force it to compile for ARM32. By default it still compiles for Thumb2 on
> Thumb2 capable cores, setting this variable will force it to compile for
> ARM.
> 
> T2_PRINT_STATISTICS
> 
> Print some compilation statistics as it compiles
> 
> T2_PRINT_COMPILATION (or -XX:+PrintCompilation)
> 
> Print the name of each method as it compiles
> 
> T2_PRINT_DISASS (or -XX:+UnlockDiagnosticVMOptions -XX:+PrintAssembly)
> 
> Disassemble each method as it compiles.
> 
> I have tested the original Thumb2 JIT and the new ARM v6 JIT with hotspot and
> langtools tests from JTreg. Here are the results I get:-
> 
> Original Thumb2 JIT
> 
> Hotspot: Test results: passed: 265; failed: 13; error: 7
> Langtools: Test results: passed: 1,957; failed: 1; error: 9
> 
> ARMv6 JIT
> 
> Hotspot: Test results: passed: 266; failed: 8; error: 11
> Langtools: Test results: passed: 1,957; failed: 1; error: 9
> 
> All comments welcome!
> Ed.
> 
> 
> 

You're more than welcome to commit this. Now would be a good time
to do so while things are still relatively quiet, before our
next release cycle in April.

I've opened a bug to track this:

http://icedtea.classpath.org/bugzilla/show_bug.cgi?id=2228

If you include the text 'PR2228' in the commit message when pushing
to http://icedtea.classpath.org/hg/icedtea7-forest/hotspot, the commit
will be recorded on the bug.

Thanks,
-- 
Andrew :)

Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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