RFR : [XS] 8209942: [epsilon] range function for EpsilonTLABElasticity causes compiler warning

Baesken, Matthias matthias.baesken at sap.com
Wed Sep 5 11:03:05 UTC 2018

Hello,  when compiling    jdk/jdk   on Windows,  (with VS2017 update level 15.8 and not disabling warnings as errors )
I came across  this  warning   leading to build error :

C:/jdk-just-clone/src/hotspot/share/runtime/flags/jvmFlagRangeList.cpp(341): error C2220: warning treated as error - no 'object' file generated
C:/jdk-just-clone/src/hotspot/share/runtime/flags/jvmFlagRangeList.cpp(341): warning C4305: 'argument': truncation from 'const intx' to 'double'

Would have been helpful  to have a compiler flag set  that really   ***shows  the code***  leading to the warning/error  (because it comes from heavy macro expansion).

The following  CR   ,   Reported by ralf.schmelter at sap.com<mailto:ralf.schmelter at sap.com>  , fixes the issue  :

The flag -XX:EpsilonTLABElasticity (epsilon_globals.hpp, line 77) expects a double value, but uses max_intx in the allowed range.
This leads to a truncation warning in the Windows build. If the value should only be guaranteed to be >= 1, then DBL_MAX should have been used instead.

Webrev/bug :



Please review .

Thanks, Matthias

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