RFR: 8171855: Move package name transformations during module bootstrap into VM

Claes Redestad claes.redestad at oracle.com
Mon Jan 2 23:21:48 UTC 2017

Hi Rémi,

are you confusing package names with module names?

 From the linked specification:

"Package names referenced from the Module attribute are stored in
CONSTANT_Package_info entries in the constant pool. Such entries wrap
CONSTANT_Utf8_info entries which represent package names encoded in
internal form."

This still appears necessary since loading the module establishes the
symbol entries representing the referenced packages.



On 2017-01-03 00:06, Remi Forax wrote:
> Hi Claes,
> the whole replace dance should not be needed anymore with the latest revision of the spec,
> module names are not stored in internal form anymore.
> see http://cr.openjdk.java.net/~mr/jigsaw/spec/lang-vm.html#jigsaw-2.1
> Rémi
> ----- Mail original -----
>> De: "Claes Redestad" <claes.redestad at oracle.com>
>> À: "jigsaw-dev" <jigsaw-dev at openjdk.java.net>, hotspot-runtime-dev at openjdk.java.net
>> Envoyé: Lundi 2 Janvier 2017 19:27:43
>> Objet: RFR: 8171855: Move package name transformations during module	bootstrap into VM
>> Hi,
>> during jigsaw bootstrap, package names - represented in external form,
>> "java.lang" - are transformed into VM internal form, "java/lang",
>> before calling into the VM.
>> This, however, can effectively be moved into the VM, which removes the
>> need to generate a lot of short-lived strings during bootstrap and heat
>> up various String.replace-related methods.  This has a noticeable impact
>> on startup metrics.
>> Webrev: http://cr.openjdk.java.net/~redestad/8171855/
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8171855
>> JPRT -testset hotspot pass, and I've prepared to push this into jdk9/hs
>> if there are no objections.
>> Char-based replace on a UTF-8 source should be correct as long as the
>> from and to chars are ASCII (0x00 through 0x7F).  A more general method
>> would be needed to safely deal with char values above 0x7F, so adding
>> some asserts to that effect should be considered.
>> Thanks!
>> /Claes

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