On Thu, Jun 20, 2013 at 3:05 PM, Eli Friedman <[email protected]>wrote:
> On Thu, Jun 20, 2013 at 2:39 PM, Michael Gottesman > <[email protected]>wrote: > >> >> On Jun 20, 2013, at 2:16 PM, Eli Friedman <[email protected]> wrote: >> >> On Tue, Jun 18, 2013 at 3:11 PM, Michael Gottesman <[email protected]> >> wrote: >> >>> Hello cfe commits! >>> >>> The attached patch adds checked-arithmetic builtins to ameliorate such >>> code in security critical applications (for instance webkit). It simply >>> exposes {u,s}{add,sub,mul}. >>> >>> *NOTE* The u{add,sub} overlaps with the multi precision built-ins. I >>> decided to add in the additional builtin since users are going to see >>> s{add,sub} and look for u{add,sub}. We could add in a Builtins.h header >>> where I could implement the checked arithmetic with the multi precision >>> arithmetic builtins but I felt that was a bigger change than this. >>> >>> >> It looks like you copy-pasted some stuff you didn't mean to in the >> changes to LanguageExtensions.rst. >> >> >> = /. Fixed. >> >> >> + return RValue::get(Builder.CreateZExt(Carry, X->getType())); >> >> These builtins all return bool, right? Why are you zero-extending here? >> (You might be able to get away with this in C because of integer >> promotions, but I'm pretty sure it'll explode in C++.) >> >> >> = /. Fixed. The reason I was zero extending was that I was basing this >> off of the multiprecision builtin code and forgot to remove it. >> >> >> IIRC, we don't actually support CodeGen of llvm.smul.with.overflow with >> 64-bit operands on x86-32; it would be nice to print a proper error message >> instead of crashing. (At least, we didn't at one point; I don't recall if >> it ever got fixed.) >> >> >> I just codegened my test file on OS X with -arch i386 and it codegened >> fine. So it looks like it was fixed. >> >> Hows this look: >> > > > LGTM. > Oh, one more thing I forgot: please put a note into the release notes. -Eli
_______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
