thanks for the heads-up. Did you keep the bit_casts in fletch for non-pointer types?
On Thu, Dec 3, 2015 at 2:34 PM 'Erik Corry' via v8-dev < [email protected]> wrote: > Slava points out that I am writing about use of bit_cast for pointer types > (eg casting an Object** to a Class**), but ignoring the other use of > bit_cast (eg casting a float to a uint32_t). It's only the pointer types > that are problematic, I think. > > On 3 December 2015 at 13:37, Erik Corry <[email protected]> wrote: > >> Some investigation by ager and some asking around has resulted in the >> conclusion that bit_cast only serves to prevent warnings. It doesn't >> actually fix the program's use of undefined behaviour. Mads was able to >> get gcc to generate broken code for a function with strict aliasing issues >> both with and without bit_cast. >> >> We have ripped bit_cast out of Fletch, replacing it with reinterpret_cast >> everywhere. >> >> We have also added the -fno-strict-aliasing, since there's no sensible >> way to fix a GC and a runtime for a dynamic language so it doesn't alias >> pointers. (The only way I can think of involves getting rid of the C++ >> "Object" class and treating the heap as a char array, which would be >> horrible beyond belief). This flag is available on both Clang and gcc, and >> is the default behaviour for MSVC. If you add the same flag to V8 you may >> see a small performance regression on Linux, but not on Mac and Windows >> where I think it already is the default. >> >> -- >> Erik Corry >> >> Google Denmark ApS >> Frederiksborggade 20B, 1 sal >> 1360 København K >> Denmark >> CVR nr. 28 86 69 84 >> > > > > -- > Erik Corry > > Google Denmark ApS > Frederiksborggade 20B, 1 sal > 1360 København K > Denmark > CVR nr. 28 86 69 84 > > -- > -- > v8-dev mailing list > [email protected] > http://groups.google.com/group/v8-dev > --- > You received this message because you are subscribed to the Google Groups > "v8-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
