On Thu, 19 Jan 2023 17:27:57 GMT, Justin King <jck...@openjdk.org> wrote:

>> Update MSVC CFlags to be more consistent with other compilers. Also disables 
>> RTTI in a simliar manner to GCC/Clang for the JVM.
>
> Justin King has updated the pull request with a new target base due to a 
> merge or a rebase. The incremental webrev excludes the unrelated changes 
> brought in by the merge/rebase. The pull request contains two additional 
> commits since the last revision:
> 
>  - Merge branch 'openjdk:master' into msvc-cflags
>  - Update MSVC CFlags
>    
>    Signed-off-by: Justin King <jck...@google.com>

Changing the global optimization flags is a pretty big and potentially 
intrusive change. It's quite possible that the current flags need a 
re-evaluation, since they were chosen a long time ago, for a much older version 
of Visual Studio. But, doing that evaluation is going to take some work. What 
is the impact on footprint and performance? How thoroughly have you tested that 
the increased optimization level isn't triggering something in Hotspot? We have 
quite a bit of history of compiler optimizations not working well with certain 
things that are done in the JVM.

My expectation for a change like this is that it would come with a pretty 
extensive report on gains, losses and tradeoffs to motivate it. Then other 
OpenJDK participants would likely want to replicate those findings and verify 
with their own benchmarks and requirements. I don't think making the number 
after the O in the flags match what we use for other compilers is motivation 
enough to warrant a change like this. Different compilers are sure to have 
their optimization levels mean different things.

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

PR: https://git.openjdk.org/jdk/pull/12073

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