buffer: align chunks on 8-byte boundary #1126
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When slicing global pool - ensure that the underlying buffer's data ptr is 8-byte alignment to do not ruin expectations of 3rd party C++ addons. NOTE: 0.10 node.js always returned aligned pointers and io.js should do this too for compatibility.
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Suggested reviewer: @trevnorris @bnoordhuis |
| @@ -157,6 +157,12 @@ function palloc(that, length) { | |||
| var buf = sliceOnto(allocPool, that, start, end); | |||
| poolOffset = end; | |||
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| // Ensure aligned slices | |||
| if (poolOffset & 0x7) { | |||
| poolOffset |= 0x7; | |||
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I'm curious, why is this line needed if the condition already succeeded?
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poolOffset = 1poolOffset & 0x7 === 1poolOffset |= 0x7=>0x7poolOffset++=>0x8- Voila,
poolOffsetis aligned!
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@mscdex in other words, I'm just setting all bits that are lower than alignment value and increment the number to align it.
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A less convoluted way of writing that is poolOffset = (poolOffset & ~7) + 8 :-)
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I used something like this: poolOffset += 8 - poolOffset % 8; :)
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Yeah, I do this to for variable-size alignment or just non-power-of-two.
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LGTM |
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@bnoordhuis thanks! @trevnorris : please put your LGTM here too, just to make sure that I'm not messing up with any performance-critical things here. |
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LGTM |
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lgtm |
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oh, last minute LGTM :) I almost pushed the commit without your name in |
When slicing global pool - ensure that the underlying buffer's data ptr is 8-byte alignment to do not ruin expectations of 3rd party C++ addons. NOTE: 0.10 node.js always returned aligned pointers and io.js should do this too for compatibility. PR-URL: #1126 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-by: Bert Belder <bertbelder@gmail.com>
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Landed in 07c0667, thank you! |
When slicing global pool - ensure that the underlying buffer's data ptr
is 8-byte alignment to do not ruin expectations of 3rd party C++ addons.
NOTE: 0.10 node.js always returned aligned pointers and io.js should do
this to for compatibility.