donat.nagy added inline comments.
================ Comment at: lib/StaticAnalyzer/Checkers/ConversionChecker.cpp:164 + // double and possibly long double on some systems + RepresentsUntilExp = 53; break; + case 32: ---------------- xazax.hun wrote: > A link to the source of these number would be useful. How are these > calculated. Also, as far as I know the current C++ standard does not require > anything about how floating points are represented in an implementation. So > it would be great to somehow refer to the representation used by clang rather > than hardcoding these values. (Note that I am perfectly fine with warning for > implementation defined behavior as the original version also warn for such in > case of integers.) I took these magic numbers from the IEEE 754 standard; I completely agree that their introduction is far from being elegant. Unfortunately it seems that referring to the representation used by clang seems to be somewhat difficult, see e.g. this old [[ https://stackoverflow.com/questions/13780931/how-do-i-get-llvm-types-from-clang | stackoverflow answer ]]. In the Z3 solver a similar problem was solved by defining a static function ([[ https://clang.llvm.org/doxygen/Z3ConstraintManager_8cpp_source.html#l00269 | getFloatSemantics() ]]) which uses a switch to translate the bit width of a floating point type into an llvm::fltSemantics value (which contains the precision value as a field). I could imagine three solutions: - reimplementing the logic getFloatSemantics, - moving getFloatSemantics to some utility library and using it from there, - keeping the current code, with comments describing my assumptions and referencing the IEEE standard. Which of these is the best? Note: According to the documentation [[ https://releases.llvm.org/2.5/docs/LangRef.html#t_floating | the floating point types ]] supported by the LLVM IR are just float, double and some high precision extension types (which are handled by the `default:` branch of my code). Unfortunately, I do not know what happens to the [[ https://clang.llvm.org/docs/LanguageExtensions.html#half-precision-floating-point | `_Float16` ]] half-width float type. Repository: rC Clang https://reviews.llvm.org/D52730 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
