Set min jump table entries when compiling interpreter #20908
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OpenXL on PPC has been known to have some issues with branch tables/indirect branch prediction before, which, when compiling OpenJ9 on AIX with OpenXL, resulted in a ~15% performance regression from before (i.e.: when building with xlC). To eliminate this degredation, the compiler flags "-mllvm -ppc-min-jump-table-entries=512" can be used on the souce files containing the interpreter loop. Signed-off-by: midronij <[email protected]>
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Looks like: with this change, variable CMAKE_C_COMPILER_IS_OPENXL is needed for cmake after all (I have impression that Keith requested it to be removed from cmake). |
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OpenXL on PPC has been known to have some issues with branch tables/indirect branch prediction before, which, when compiling OpenJ9 on AIX with OpenXL, resulted in a ~15% performance regression from before (i.e.: when building with xlC). To eliminate this degredation, the compiler flags
-mllvm -ppc-min-jump-table-entries=512can be used on the souce files containing the interpreter loop.