(0.47) JIT: Detect in-place redefinition based on J9JITRedefinedClass #20065
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Previously, the redefinition hook would determine the relationship between the old/new and stale/fresh status of redefined classes by checking for TR_EnableHCR. This was a proxy for debug mode, in which fast HCR is off because redefinition will OSR and discard the entire code cache. Until recently, this determination was accurate because in debug mode the VM would always redefine classes out-of-place to allow for "extended HCR." However, extended HCR is now being deprecated, and as of 704a781, by default it's off and redefinition is in-place. If a class was redefined in-place unexpectedly, the hook would mix up the old and the new class, which would result in an incorrect CH table state. Rather than try to predict whether redefinition is supposed to be done in-place, the hook will now detect whether it was in fact done in-place.
…N modes" This reverts commit f6a5b16.
pshipton
approved these changes
Aug 27, 2024
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Backport of #19824