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?
> 

Yes, this is correct. This will branched for 2.6.0 around the time of the u80
release upstream.

> 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 guess we need to make a decision as to whether to turn it on by default now
or wait until it's been in a release as the non-default option.

> 

Thanks for the contribution!
-- 
Andrew :)

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

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