On Tue, Dec 22, 2015 at 5:11 AM, Luke Wagner <lwag...@mozilla.com> wrote:
> I think there was also a performance reason: IIUC, the non-zero-cost > exception handling strategy is baked into the Win32 ABI > (https://www.microsoft.com/msj/0197/exception/exception.aspx) and thus > enabling EH has a runtime cost for frames containing auto objects with > destructors (which in modern SM is very common). I vaguely remember > seeing a platform email thread about using EH a while back (>6 years) > that measured the then-overhead in Gecko to be ~10%; I can't find the > thread now. I talked to an engineer who worked on EH optimizations in > MSVC and he said that there have been some 32-bit EH optimizations > more recently but there is still runtime cost to having auto objects > with destructors, so probably this is worth measuring again. Assuming > we're able to move a large percentage of FF users to Win64 builds over > the next year, then it seems like we'd care about this even less. > As I recall, there was a significant performance hit just enabling RTTI, which is a prerequisite for exception handling. I think it was a space problem. Mike Hommey would know more. Rob -- lbir ye,ea yer.tnietoehr rdn rdsme,anea lurpr edna e hnysnenh hhe uresyf toD selthor stor edna siewaoeodm or v sstvr esBa kbvted,t rdsme,aoreseoouoto o l euetiuruewFa kbn e hnystoivateweh uresyf tulsa rehr rdm or rnea lurpr .a war hsrer holsa rodvted,t nenh hneireseoouot.tniesiewaoeivatewt sstvr esn _______________________________________________ dev-tech-js-engine-internals mailing list dev-tech-js-engine-internals@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-tech-js-engine-internals
