On Tue, 30 Jun 2015, Zinovy Nis wrote: > It works properly but I noticed that code the size for many arithmetic > functions is much more larger than for soft-fp emulation provided by > LLVM's compiler_rt library.
Code size is discussed in the paper about soft-fp in the 2006 Summit proceedings. In general, soft-fp is optimized for speed (having completely separate "if" cases for addition and subtraction, both of which appear in both __addsf3 and __subsf3, for example) and for generality (it's used in the Linux kernel for floating-point emulation, where you want to follow the same choice of NaN etc. as a particular processor even where IEEE semantics don't specify a particular choice, and it has optional support for floating-point exceptions and rounding modes - note that __float128 support in libgcc uses the hardware exceptions and rounding modes when available), not for size (and generality takes precedence over speed where they conflict, hence being a bit slower than ieeelib even after the 2006 optimization work). soft-fp is expected to be used on 32-bit and 64-bit systems for which a few kB code size is insignificant. -- Joseph S. Myers jos...@codesourcery.com
