src: make base64 decoding 10-15% faster #2193
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mscdex
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| @@ -150,62 +150,83 @@ static const int unbase64_table[] = | |||
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, | |||
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 | |||
| }; | |||
| #define unbase64(x) unbase64_table[(uint8_t)(x)] | |||
| #define unbase64(x) \ | |||
| static_cast<uint8_t>(unbase64_table[static_cast<uint8_t>(x)]) | |||
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very minor nit. Is four spaces here, okay?
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Should we really cast the result to uint8_t when the actual data is int8_t?
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Yes. The alternative was to change the type of the list elements to uint8_t but then I'd also have to change all the -1 to 255 to squelch compiler warnings. It would make the diff a lot noisier for no reason; conversion from signed to unsigned is well-defined.
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Is four spaces here, okay?
I don't think we really have a convention for that but I'll change it to two spaces before landing.
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Incorporated feedback, PTAL. @trevnorris Good suggestion about force-flattening the string first. I'm confident saying now that it's actually 50% faster. :-) |
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LGTM |
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@bnoordhuis then I guess you can rename this PR :) great job! |
Make the inner loop execute fewer compare-and-branch executions per
processed byte, resulting in a 50% or more speedup.
This coincidentally fixes an out-of-bounds read:
while (unbase64(*src) < 0 && src < srcEnd)
Should have read:
while (src < srcEnd && unbase64(*src) < 0)
But this commit removes the offending code altogether.
Fixes: nodejs#2166
PR-URL: nodejs#2193
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
parallel/test-buffer called `Buffer.prototype.toString()` on a buffer with uninitialized memory. Call `Buffer.prototype.fill()` on it first. PR-URL: nodejs#2193 Reviewed-By: Trevor Norris <trev.norris@gmail.com>
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Landed in 8fd3ce1 and ac70bc8 with hex values, thanks everyone. I only added @trevnorris in the Reviewed-By because he was the only one to formally LGTM it. |
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Is it going to be in 2.5.0, 3.0 or both? |
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@YuriSolovyov 2.5.0+ (both) :) |
Make the inner loop execute fewer compare-and-branch executions per
processed byte, resulting in a 10-15% speedup.
This coincidentally fixes an out-of-bounds read:
Should have read:
But this commit removes the offending code altogether.
Fixes: #2166
R=@trevnorris?
CI: https://jenkins-iojs.nodesource.com/view/iojs/job/iojs+any-pr+multi/155/