On Friday, 10 January 2020 at 00:02:52 UTC, Johan wrote:
For LDC: ``` double fma(double a, double b, double c) { import ldc.llvmasm; return __irEx!(`declare double @llvm.fma.f64(double %a, double %b, double %c)`, `%r = call double @llvm.fma.f64(double %0, double %1, double %2)ret double %r`, "", double, double, double, double)(a,b,c); } ```
You have to tell LDC that you are compiling for a CPU that has FMA capability (otherwise it will insert a call to a "fma" runtime library function that most likely you are not linking with). For example, "-mattr=fma" or "-mcpu=skylake".
https://d.godbolt.org/z/ddwORl Or you add it only for the "fma" function, using ``` import ldc.attributes; @target("fma") double fma(double a, double b, double c) ... ``` https://d.godbolt.org/z/-X7FnC https://wiki.dlang.org/LDC-specific_language_changes#.40.28ldc.attributes.target.28.22feature.22.29.29 cheers, Johan
