xbolva00 added inline comments.
================
Comment at: lib/Sema/SemaChecking.cpp:110
+/// are usually useless
+static unsigned AdjustPrecision(unsigned precision) {
+ return (precision * 59 + 195) / 196;
----------------
craig.topper wrote:
> scanon wrote:
> > erichkeane wrote:
> > > Hmm.... I don't terribly understand how this function works. Also,
> > > comment above needs to end in a period.
> > >
> > > Can you elaborate further as to how this works? Those are 3 pretty
> > > suspect looking magic numbers...
> > It's attempting to compute the number of good base-10 digits (59/196 ~=
> > log2(10)). We should really just make APFloat print the shortest
> > round-trippable digit sequence instead. Yes, this is tricky to implement,
> > but we don't need to implement it. There are two recent high-quality
> > implementations available, which are both significantly faster than
> > previous algorithms: Ryu and Swift's
> > (https://github.com/apple/swift/blob/master/stdlib/public/runtime/SwiftDtoa.cpp).
> > Swift's has the virtue of already being used in LLVM-family languages and
> > having a tidy single-file implementation, but either would be perfectly
> > usable, I think.
> >
> > Neither supports float128 yet, but we could simply drop them in for float,
> > double, and float80.
> Function names should start with lower case I think?
float80 has precision = 64 so we can put MAX value of unsigned long long into
it with no issues, or?
https://reviews.llvm.org/D52835
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