8301404: Factor out os::malloc with os::realloc common code, so that we only have 1 code path

[gerard-ziemski]

This is the 2nd time I am proposing this (controversial?) change, but this time I do have performance numbers, which indicate no change in speed (using NMTBenchmark from #23786):

proposed:

time:72,642,827[ns]
[samples:807,804] [NMT headers:382,064]
[malloc#:588,703] [realloc#:12,462] [free#:206,639]
memory requested:57,274,288 bytes, allocated:69,004,800 bytes
malloc overhead:4,853,360 bytes [8.47%], NMT headers overhead:6,877,152 bytes [12.01%]
existing code:

time:73,085,446[ns]
[samples:807,804] [NMT headers:382,064]
[malloc#:588,703] [realloc#:12,462] [free#:206,639]
memory requested:57,274,288 bytes, allocated:69,004,800 bytes
malloc overhead:4,853,360 bytes [8.47%], NMT headers overhead:6,877,152 bytes [12.01%]
Note: the NMTBenchmark reports realloc(nullptr) as mallocs(), which is why both versions show the same count for mallocs/reallocs.

The performance is virtually the same where I sampled each test 30 times and took the best (the shortest).

This proposed change factors out the common code and simplifies both os::malloc and os::realloc. We were able to reduce malloc from 44 lines down to 8 (saving of 36 lines) and realloc from 84 to 55 (29 lines).

To me the most important part here is that we reduce the number of times that NMT has to interact with the native allocation code.

---

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-8301404: Factor out os::malloc with os::realloc common code, so that we only have 1 code path (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/24189/head:pull/24189
$ git checkout pull/24189

Update a local copy of the PR:
$ git checkout pull/24189
$ git pull https://git.openjdk.org/jdk.git pull/24189/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 24189

View PR using the GUI difftool:
$ git pr show -t 24189

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/24189.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back gziemski! 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]

@gerard-ziemski The following label will be automatically applied to this pull request:

• hotspot-runtime

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

• 01: Full - Incremental (01470b34)
• 00: Full (abfb5f2c)