src: improve windows1252 decoding speed #61120
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nodejs-github-bot added c++ 
ChALkeR force-pushed the chalker/decoder/single-byte/2 branch from 5b3053e to 7b11e38 Compare 
Comment on lines +425 to +432
| if (!tWindows1252x2) { | ||
| tWindows1252x2 = (uint32_t *) malloc(256 * 256 * 4); // 256 KiB | ||
| for (uint16_t i = 0; i < 256; i++) { | ||
| for (uint16_t j = 0; j < 256; j++) { | ||
| tWindows1252x2[(i << 8) + j] = (((uint32_t) table[i]) << 16) + table[j]; | ||
| } | ||
| } | ||
| } |
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We’re allocating this table (tWindows1252x2) here for the first time, but we never free it anywhere
This could lead to unnecessary memory usage in long-running processes
I think we should add a cleanup hook right after the allocation, so the table gets freed automatically when the environment shuts down
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this PR is a crude concept demo
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Tracking: #61041
This builds on top of #61093 and #61118 and gives an additional ~1.4x improvement by using iteration in pairs for this single encoding, as it's commonly used (it's aliased as
latin1)Combined, this is ~114x faster than
mainon ASCII (due to #61093 + #61118) and ~71x faster thanmainon non-ASCIIThis could be improved further with latin1 checks and by moving ascii checks to prefixes instead, but let #61119 land first
I'm not sure if this even makes sense at this point, it comes at a cost of 128 KiB cache (even though allocated at the first large use)
Perhaps there is some other way or we could ignore this
Warning
Very crude, just a concept demonstration at this point
See #61118 for previous benchmarks