RFR: 8259894: refactor parts of jvm.h into jvm_io.h and jvm_constants.h [v2]

[Coleen Phillimore]

On Thu, 21 Jan 2021 03:09:13 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> jvm.h is over 1000 lines long. It is included by 940 out of 1000 HotSpot .o files. However, most of the HotSpot source files just use a small fraction of jvm.h:
>> 
>> - the jio_xxxprintf() functions
>> - the JVM_RECOGNIZED_XXX_MODIFIERS defines
>> 
>> We should move these two parts into jvm_io.h and jvm_constants.h. This reduces the files that include jvm.h to about 82 files. Build time of HotSpot is reduced by about 0.4%.
>> 
>> Testing: mach5: tier1, builds-tier2, builds-tier3, builds-tier4 and builds-tier5. Also locally: aarch64, arm, ppc64, s390, x86, and zero.
>
> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
> 
>   David Holmes comments

Looks good to me.

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Marked as reviewed by coleenp (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/2154