Please review the following change that switches to clang-style warning
disabling on AIX, and adjusts the warning disabling to current needs .
Recently the jdk/jdk build on AIX switched to xlc16/xlclang.
This means we can now use the standard clang-style warning disabling (the old
legacy qsuppress warning disablings from legacy xlc
might not fully work any more).
I think we are pretty close in reducing the compiler warnings to 0 on AIX,
which would make it possible to build with warnings as errors at some point in
the future .
In a first step I would disable these warnings in HS for xlc16/xlclang :
tautological-compare : (seen in os_aix.cpp)
/jdk/src/hotspot/os/aix/os_aix.cpp:2400:15: warning: comparison of unsigned
expression >= 0 is always true [-Wtautological-compare]
if (bytes >= Use64KPagesThreshold) {
~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~
/jdk/src/hotspot/os/aix/os_aix.cpp:2607:15: warning: comparison of unsigned
expression >= 0 is always true [-Wtautological-compare]
if (bytes >= Use64KPagesThreshold) {
In the product build the "Use64KPagesThreshold" is a constant so clang
complains . However in the (fast)debug builds one can set
Use64KPagesThreshold with an -XX setting.
So I think it is best to disable the warning.
shift-negative-value : (seen in c1_LIRGenerator_ppc.cpp)
/jdk/src/hotspot/cpu/ppc/c1_LIRGenerator_ppc.cpp:429:97: warning: shifting a
negative signed value is undefined [-Wshift-negative-value]
(x->op() == Bytecodes::_lsub &&
right.value()->type()->as_LongConstant()->value() == ((-1)<<15)) ) {
~~~~^
/jdk/src/hotspot/cpu/ppc/c1_LIRGenerator_ppc.cpp:483:96: warning: shifting a
negative signed value is undefined [-Wshift-negative-value]
(x->op() == Bytecodes::_isub &&
right.value()->type()->as_IntConstant()->value() == ((-1)<<15)) ) {
We could probably replace the -1 shift by a constant but I think it is nicely
readable .
Bug/webrev :
https://bugs.openjdk.java.net/browse/JDK-8228426
http://cr.openjdk.java.net/~mbaesken/webrevs/8228426.0/
Thanks, Matthias
