RFR: 8301404: Replace os::malloc with os::realloc, so we only have 1 code path

[Thomas Stuefe]

On Fri, 17 Feb 2023 16:56:12 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> Please review this enhancement, which eliminates a duplicate and almost identical path we have for malloc() and realloc(), and collapses  them down to only one codepath, by taking advantage of fact that `malloc() == realloc(NULL)`
>> 
>> Tested with MACH5 tier1,2,3,4,5
>
> src/hotspot/share/services/mallocHeader.hpp line 125:
> 
>> 123:     const size_t size;
>> 124:     const MEMFLAGS flags;
>> 125:     const uint32_t mst_marker;
> 
> I need help with this part. I'm not familiar with C++ enough to make my change work while keeping these fields `const`
> 
> Can someone suggest a better approach here, or is it OK to drop the `const` modifier off?

Its a warning sign that something is off. From first glance, a FreeInfo should be immutable; there should be no reason to modify it once its created.

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PR: https://git.openjdk.org/jdk/pull/12621