AArch64 drreg failure in drcachesim: "failed to restore reg" on stolen reg value #4461
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derekbruening
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Do not try to get the application value of the stolen register on the jump barrier used for drreg parity in filtered drcachesim instrumentation. Enable thread filtering on non-x86: there is no missing support there. Tested by locally enabling the tool.drcacheoff.burst_threadfilter test (it is disabled for AArch64 because of the #2007 link failure in some toolchains), working around #4468 with "-steal_register 25", and confirming that the drreg failure disappears with the fix here. This is needed for the forthcoming new global filter for drcachesim (#4462), in addition to the thread filter feature. An enabled-on-AArch64 test should be added as part of that feature to serve as a regression test here, if #2007 has not been resolved by then to enable the thread filter test. Issue: #4461, #4462 Fixes #4461
derekbruening
added a commit
that referenced
this issue
Oct 2, 2020
Do not try to get the application value of the stolen register on the jump barrier used for drreg parity in filtered drcachesim instrumentation. Enable thread filtering on non-x86: there is no missing support there. Tested by locally enabling the tool.drcacheoff.burst_threadfilter test (it is disabled for AArch64 because of the #2007 link failure in some toolchains), working around #4468 with "-steal_register 25", and confirming that the drreg failure disappears with the fix here. This is needed for the forthcoming new global filter for drcachesim (#4462), in addition to the thread filter feature. An enabled-on-AArch64 test should be added as part of that feature to serve as a regression test here, if #2007 has not been resolved by then to enable the thread filter test. Issue: #4461, #4462 Fixes #4461
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Running drcachesim on AArch64 with a thread filter hits a drreg failure: "failed to restore reg" on the stolen reg value.
Looks like it calls drreg_get_app_value() on the stolen register. Probably it should just skip for that reg since it won't be a scratch reg?
Why didn't the test suite hit this? Looks like the tool.drcacheoff.burst_threadfilter test is disabled (along with many similar tests) on AArch64 due to #2007 :(
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