Optimize binary syntax for little-endian segments #10126
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Break out code for binary construction and matching that do not depend on the architecture (x86_64 or AArch64).
In Erlang/OTP 26 (in erlang#6031), the JIT learned to optimize binary construction such as: <<A:16/big, B:32/big, C:16/big>> The optimization is done on the native-code level, but the idea behind it can be illustrated in Erlang by rewriting the construction as follows: Acc0 = A, Acc1 = (Acc0 bsl 32) bor B, Acc = (Acc1 bsl 16) bor C, <<Acc:64/big>> When done in native code, the values of the segments is accumulated into a CPU register, which is then written to memory. This is faster than writing each segment to memory one at a time, especially if the sizes are not byte-sized as in the following example: <<A:6, B:6, C:6, D:6>> This commit introduces a similar optimization for little-endian integer segments. Example: <<A:16/little, B:32/little, C:16/little>> This expression can be rewritten as follows: Acc0 = C, Acc1 = (Acc0 bsl 32) bor B, Acc = (Acc1 bsl 16) bor A, <<Acc:64/little>> Note that this rewriting is only safe if all segments except the last one are byte-sized.
Multiple little-endians segments were handled one at a time. It turns out that it is safe to match out multiple little-endian segments at once, or even any mix of big and little endian segments at once.
bjorng
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CT Test Results 3 files 142 suites 49m 46s ⏱️ Results for commit 24e5b6c. ♻️ This comment has been updated with latest results. To speed up review, make sure that you have read Contributing to Erlang/OTP and that all checks pass. See the TESTING and DEVELOPMENT HowTo guides for details about how to run test locally. Artifacts// Erlang/OTP Github Action Bot |
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This pull request optimizes both construction and matching of little-endian integer segments. See the commit messages for details.