Patch forthcoming. <rdar://problem/16122966>
Created attachment 227605 [details] the patch
Comment on attachment 227605 [details] the patch r=me
Comment on attachment 227605 [details] the patch This causes a v8-raytrace regression in FTL. I'm investigating.
Found the issue. FTL::OSRExitCompiler was unintentionally relying on numLocals() to be aligned. Nobody else makes such an assumption. And FTL::OSRExitCompiler only relied on it because its round-up was done by rounding the stack size in bytes up to stackAlignmentRegisters() [sic]. Changing that the stackAlignmentBytes() fixes the bug. I will land with this fix.
Landed in http://trac.webkit.org/changeset/166142