[llvm-dev] compiler-rt uses non-existent macro: __SOFT_FP__

[Nasser, Salim via llvm-dev]

A handful of files in compiler-rt/builtins use the macro "__SOFT_FP__". All the uses are along the same lines. Here's a representative example from compiler-rt/lib/builtins/fixdfdi.c:


#ifndef __SOFT_FP__

// Support for systems that have hardware floating-point; can set the invalid

// flag as a side-effect of computation.

...

#else

// Support for systems that don't have hardware floating-point; there are no

// flags to set, and we don't want to code-gen to an unknown soft-float

// implementation.

...

#endif

My question is : when - if ever - should __SOFT_FP__ be defined?

The obvious answer is "when compiling for a soft-float target".

However: __SOFT_FP__ is never set by the compiler (neither clang nor GCC).

Nor (as far as I can tell) does it appear in any compiler-rt header file, build script, or Makefile. In fact the only occurrences of this macro anywhere in the llvm-project and GCC source trees are the aforementioned uses under compiler-rt/builtins.

On the other hand both clang and GCC *do* set an alarmingly similar looking macro - "__SOFTFP__" (no middle underscore) -  when compiling for soft-float.

Since we need to build compiler-rt libraries for a couple of our soft-float targets at Wind River, we want to make sure we're building them in the "right" way. Currently we do *not* define __SOFT_FP__ for soft-float targets (and our tests pass!).

Regards,
Salim

Salim Nasser | Compilers | Wind River


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