241416 2022-06-08 06:48:24 -0700 [meta] IPC encoders could be simplified / sped-up 2022-06-08 17:12:35 -0700 1 1 1 Unclassified WebKit WebKit2 Other Unspecified Unspecified NEW https://bugs.webkit.org/show_bug.cgi?id=241407 InRadar P2 Normal --- 1 jean-yves.avenard webkit-unassigned cdumez fujii kkinnunen webkit-bug-importer oldest_to_newest 1874710 0 jean-yves.avenard 2022-06-08 06:48:24 -0700 As seen with bug 241407. The vast majority of IPC encoders/decoders do the following: Considering a struct of type T: ``` template<class Encoder> inline void T::encode(T& encoder) const { encoder << param1 << param2 << param3 << param4; } ``` followed by something like: ``` template<class Decoder> std::optional<T> T::decode(Decoder& decoder) { Param1 param1; if (!decoder.decode(param1)) return { }; Param1 param2; if (!decoder.decode(param2)) return { }; Param1 param3; if (!decoder.decode(param3)) return { }; Param1 param4; if (!decoder.decode(param4)) return { }; return T { WTFMove(param1), WTFMove(param2), WTFMove(param3), WTFMove(param4) } } ``` after every deserialisation a test is performed when it's unlikely to ever be false. Instead we could do something like: ``` { auto param1 = decoder.decode<Param1>(); auto param2 = decoder.decode<Param2>(); auto param3 = decoder.decode<Param3>(); auto param4 = decoder.decode<Param4>(); if (UNLIKELY(!decoder.isValid())) return std::nullopt; return T { WTFMove(*param1), WTFMove(*param2), WTFMove(*param3), WTFMove(*param4 }; } ``` it makes the core more readable and allows to only test once for the unlikely case where we have an error. 1874711 1 webkit-bug-importer 2022-06-08 06:48:44 -0700 <rdar://problem/94629221>