RFR (S): 8233702: Introduce helper function to clamp value to range

[Kim Barrett]

> On Nov 13, 2019, at 10:23 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
>  I re-added the assert, and re-checked in our CI with hs-tier1-5. For some reason there were some failures I thought I had fixed already. Sorry :(
> 
> Here are new webrevs:
> 
> http://cr.openjdk.java.net/~tschatzl/8233702/webrev.0_to_1/ (diff)
> http://cr.openjdk.java.net/~tschatzl/8233702/webrev.1/ (full)
> 
> Thanks,
>  Thomas

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src/hotspot/share/compiler/compilerDefinitions.cpp
 355         FLAG_SET_DEFAULT(MetaspaceSize, clamp(MetaspaceSize, 12*M, MaxMetaspaceSize));

I've not found anything that guarantees MaxMetaspaceSize >= 12*M.

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src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp
 254   // We can't use clamp() here because min_size() and max_size() because some

s/here because min_size()/here between min_size()/

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src/hotspot/share/runtime/globals.hpp
1408   product(intx,  AllocatePrefetchDistance, -1,                              \
1409           "Distance to prefetch ahead of allocation pointer. "              \
1410           "-1: use system-specific value (automatically determined")        \
1411           range(-1, 512)                                                    \
1412           constraint(AllocatePrefetchDistanceConstraintFunc,AfterMemoryInit)\

With the addition of the range restriction, is the constraint function
still needed?  I don't remember whether a range restriction is applied
to assignments such as are being done in various vm_version_<cpu>.cpp
files.

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