8377895: Create sizeof_auto, to reduce narrowing conversions

[lkorinth]

sizeof_auto is created so that we can reduce the amount of casting and thus make the code more type safe. The normal sizeof will return a size_t although the size of most stuff can be represented in a uint8_t. sizeof_auto will return the size in an as small unsigned type as is possible. The result is that expressions that uses sizeof_auto can convert to most integral types, and no explicit narrowing cast will be needed.

The change in cpCache.hpp is an example where we would get an implicit narrowing warning (if we had those enabled) using normal sizeof, but where sizeof_auto will not make the expression a size_t .

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8377895: Create sizeof_auto, to reduce narrowing conversions (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/29716/head:pull/29716
$ git checkout pull/29716

Update a local copy of the PR:
$ git checkout pull/29716
$ git pull https://git.openjdk.org/jdk.git pull/29716/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 29716

View PR using the GUI difftool:
$ git pr show -t 29716

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/29716.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back lkorinth! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

@lkorinth The following label will be automatically applied to this pull request:

• hotspot

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 00: Full (aa7bfa0a)

[stefank]

I think the change looks good. The gtests doesn't compile everywhere so that needs to be fixed.