[DWARFLinkerParallel] Fix incorrect uses of compare_exchange_weak #138129
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The documentation for compare_exchange_weak says that it is allowed to spuriously fail. If compare_exchange_weak is called in a loop, spurious failures usually are benign - but in these cases, a spurious failure would give incorrect behaviour. E.g. in TypePool::getOrCreateTypeEntryBody, we assume that if the compare_exchange call returned false, we had been preempted by another thread and that DIE is non-null. This fixes running the dsymutil tests on Windows on aarch64 (built with a mingw toolchain with libc++).
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LGTM. Thanks for catching this!
IanWood1
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May 6, 2025
…vm#138129) The documentation for compare_exchange_weak says that it is allowed to spuriously fail. If compare_exchange_weak is called in a loop, spurious failures usually are benign - but in these cases, a spurious failure would give incorrect behaviour. E.g. in TypePool::getOrCreateTypeEntryBody, we assume that if the compare_exchange call returned false, we had been preempted by another thread and that DIE is non-null. This fixes running the dsymutil tests on Windows on aarch64 (built with a mingw toolchain with libc++).
GeorgeARM
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May 7, 2025
…vm#138129) The documentation for compare_exchange_weak says that it is allowed to spuriously fail. If compare_exchange_weak is called in a loop, spurious failures usually are benign - but in these cases, a spurious failure would give incorrect behaviour. E.g. in TypePool::getOrCreateTypeEntryBody, we assume that if the compare_exchange call returned false, we had been preempted by another thread and that DIE is non-null. This fixes running the dsymutil tests on Windows on aarch64 (built with a mingw toolchain with libc++).
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The documentation for compare_exchange_weak says that it is allowed to spuriously fail. If compare_exchange_weak is called in a loop, spurious failures usually are benign - but in these cases, a spurious failure would give incorrect behaviour.
E.g. in TypePool::getOrCreateTypeEntryBody, we assume that if the compare_exchange call returned false, we had been preempted by another thread and that DIE is non-null.
This fixes running the dsymutil tests on Windows on aarch64 (built with a mingw toolchain with libc++).