Avoid data race in method caching in ocamlrun#11512
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xavierleroy merged 1 commit intoocaml:trunkfrom Sep 19, 2022
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When calling a method with the opcode GETPUBMET, the method address is resolved and possibly cached by modifying a word in the bytecode. If multiple domains execute the same GETPUBMET opcode concurrently, this is technically a data race. However, any integer value in the correct range is a safe value. Therefore we inform the compiler of potential concurrent accesses by using atomic accesses with relaxed memory order.
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xavierleroy
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Aug 25, 2022
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Thanks! Looks good to me. We can wait a few days for a second opinion.
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As a side remark, I kind of remember that the benefit of method caching was pretty limited for bytecode. |
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We got a second opinion (of sorts), so let's merge this PR. We could reconsider the use of method caching in bytecode later. |
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When calling a method with the opcode GETPUBMET, the method address is resolved and possibly cached by modifying a word in the bytecode. If multiple domains execute the same GETPUBMET opcode concurrently, this is technically a data race. However, any integer value in the correct range is a safe value. Therefore we inform the compiler of potential concurrent accesses by using atomic accesses with relaxed memory order. (cherry picked from commit b019062)
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Cherry-picked to 5.0: e4db530 |
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When calling a method with the opcode
GETPUBMET, the method address is resolved and possibly cached by modifying a word in the bytecode. If multiple domains execute the sameGETPUBMETopcode concurrently, this is technically a data race. However, any integer value in the correct range is a safe value. Therefore we inform the compiler of potential concurrent accesses by using atomic accesses with relaxed memory order.