[PR #1204] Reduce fdiv's into fmul's #1767

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claunia · 2026-01-29T20:55:42Z

claunia commented

2026-01-29 20:55:42 +00:00

Original Pull Request: https://github.com/google/brotli/pull/1204

State: closed
Merged: Yes

Provides small speedup on microarchitectures where the floating point divide is slower than the floating point multiply.

As measured on an Ampere Altra, I see about +0.5% depending on the input.

$ ./brotli.old -fvk -w 0 enwik8.xhtml
Compressed [enwik8.xhtml]: 95.367 MiB -> 24.549 MiB in 237.92 sec

$ ./brotli.new -fvk -w 0 enwik8.xhtml
Compressed [enwik8.xhtml]: 95.367 MiB -> 24.549 MiB in 236.72 sec

**Original Pull Request:** https://github.com/google/brotli/pull/1204 **State:** closed **Merged:** Yes --- Provides small speedup on microarchitectures where the floating point divide is slower than the floating point multiply. As measured on an Ampere Altra, I see about +0.5% depending on the input. ``` $ ./brotli.old -fvk -w 0 enwik8.xhtml Compressed [enwik8.xhtml]: 95.367 MiB -> 24.549 MiB in 237.92 sec $ ./brotli.new -fvk -w 0 enwik8.xhtml Compressed [enwik8.xhtml]: 95.367 MiB -> 24.549 MiB in 236.72 sec ```

claunia added the pull-request label 2026-01-29 20:55:42 +00:00

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Reference: starred/brotli#1767