Eliminate redundant register swapping in JIT #384
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ChinYikMing
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Mar 13, 2024
jserv
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Mar 13, 2024
jserv
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Mar 13, 2024
jserv
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Mar 13, 2024
qwe661234
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Mar 13, 2024
qwe661234
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Mar 16, 2024
vacantron
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Mar 16, 2024
jserv
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Mar 16, 2024
In the current register allocation of JIT, we save the host registers before using to keep the consistency of the content between the vm and the host register, even it had not been changed by any other operation after loaded from the stack. This generates lots of redundant `store` related instructions on the host and reduces the performance of vm. In this patch, we introduce the `dirty` flag to record the status of the host register. Once the content of the host register is changed by an operation, the flag is set to 1. The register swapping will only be invoked when the register is dirty in next allocation. The performance improvement after this patch is shown below: * x86-64 | Metric | Original | Improved | SpeedUp | |-----------+----------+----------+---------| | dhrystone | 0.623 s | 0.463 s | +25.6% | | miniz | 3.437 s | 2.837 s | +17.5% | | primes | 4.435 s | 3.205 s | +27.7% | | sha512 | 3.212 s | 3.024 s | +5.9% | | aes | 1.708 s | 1.545 s | +9.5% | | qsort | 5.236 s | 5.219 s | +0.3% | * aarch64 | Metric | Original | Improved | SpeedUp | |-----------+----------+----------+---------| | dhrystone | 1.003 s | 0.897 s | +10.6% | | miniz | 4.312 s | 4.107 s | +4.8% | | primes | 9.605 s | 8.879 s | +7.6% | | sha512 | 5.902 s | 5.796 s | +1.8% | | aes | 2.932 s | 2.891 s | +1.4% | | qsort | 6.123 s | 5.988 s | +2.2% | Close sysprog21#330
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Thank @vacantron for contributing! |
vestata
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Jan 24, 2025
Eliminate redundant register swapping in JIT
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In the current register allocation of JIT, we save the host registers before using to keep the consistency of the content between the vm and the host register, even it had not been changed by any other operation after loaded from the stack. This generates lots of redundant
storerelated instructions on the host and reduces the performance of vm.In this patch, we introduce the
dirtyflag to record the status of the host register. Once the content of the host register is changed by an operation, the flag is set to 1. The register swapping will only be invoked when the register is dirty in next allocation.The performance improvement after this patch is shown below: