Integrated: 8297534: Specify the size of MEMFLAGS

[Johan Sjölen]

On Wed, 23 Nov 2022 22:19:52 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

> Hi!
> 
> In MallocHeader we assume that MEMFLAGS can be stored in a uint8_t, see:
> 
> ```c++
> class MallocHeader {
> 
>   NOT_LP64(uint32_t _alt_canary);
>   const size_t _size;
>   const uint32_t _mst_marker;
>   const uint8_t _flags;
>   const uint8_t _unused;
>   uint16_t _canary;
> // SNIP!
>   inline MEMFLAGS flags() const { return (MEMFLAGS)_flags; }
> 
> 
> With C++11 we can specify the underlying type of an `enum class`, so let's just do that. If we generate 257 memflags we'll get a compile error. I don't believe that this would lead to any change in the behavior of the code.
> 
> Testing: Compiled the code. Running tier1 testing right now.

This pull request has now been integrated.

Changeset: 81eb5fbf
Author:    Johan Sjölen <jsjolen at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/81eb5fbff516e7470f7cc29a67047a048b525722
Stats:     7 lines in 3 files changed: 3 ins; 0 del; 4 mod

8297534: Specify the size of MEMFLAGS

Reviewed-by: stuefe, tschatzl

-------------

PR: https://git.openjdk.org/jdk/pull/11336