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authoriximeow <me@iximeow.net>2022-12-03 15:03:13 -0800
committeriximeow <me@iximeow.net>2022-12-03 15:03:13 -0800
commit8eef2114ece0b4a96866f075e87f195a804d61cb (patch)
treef4cdbf7303d88df14e35f678f1bca8c00b8f0630 /CHANGELOG
parent64abb4e439230c8b4b8a6534989784e362efb12d (diff)
describe optimizations included in 1.1.5opts
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## 1.1.5
+* optimizations (mostly code motion) for hot codepaths
+ - large `match`-based decode tables have been outlined to 256-entry arrays.
+ this makes for slicely nicer inlining in `read_with_annotations`.
+ - vex/evex decoding in 64-bit decoding now shares more code. this seems to
+ aid code cache friendliness when prefixes must be read.
+ - added a fast path for operand reading for the more-likely cases of
+ [64-bit]: {0x66,rex}{<opcode>,0x0f-<opcode>}
+ [32-bit]: {0x66}{<opcode>,0x0f-<opcode>}
+ [16-bit]: {0x66}{<opcode>,0x0f-<opcode>}
+
+ in particular, this avoids checking for instruction length overflows and
+ some bounds checks when we aren't handling a pessimal case of many-prefixed
+ instructions. if an instruction has multiple prefixes, decoders fall back
+ to normal read-in-a-loop-until-length-limit-reached decoding.
* `Makefile` at the crate root now exercises `yaxpeax-x86` builds and tests under:
- default features (fmt, std)
- no-std + fmt