Function check_long_double_representation

numpy/core/setup_common.py:223–268

(cmd)

# Code to detect long double representation taken from MPFR m4 macro
def check_long_double_representation(cmd):
    cmd._check_compiler()
    body = LONG_DOUBLE_REPRESENTATION_SRC % {'type': 'long double'}

    # Disable whole program optimization (the default on vs2015, with python 3.5+)
    # which generates intermediary object files and prevents checking the
    # float representation.
    if sys.platform == "win32" and not mingw32():
        try:
            cmd.compiler.compile_options.remove("/GL")
        except (AttributeError, ValueError):
            pass

    # Disable multi-file interprocedural optimization in the Intel compiler on Linux
    # which generates intermediary object files and prevents checking the
    # float representation.
    elif (sys.platform != "win32"
            and cmd.compiler.compiler_type.startswith('intel')
            and '-ipo' in cmd.compiler.cc_exe):
        newcompiler = cmd.compiler.cc_exe.replace(' -ipo', '')
        cmd.compiler.set_executables(
            compiler=newcompiler,
            compiler_so=newcompiler,
            compiler_cxx=newcompiler,
            linker_exe=newcompiler,
            linker_so=newcompiler + ' -shared'
        )

    # We need to use _compile because we need the object filename
    src, obj = cmd._compile(body, None, None, 'c')
    try:
        ltype = long_double_representation(pyod(obj))
        return ltype
    except ValueError:
        # try linking to support CC="gcc -flto" or icc -ipo
        # struct needs to be volatile so it isn't optimized away
        # additionally "clang -flto" requires the foo struct to be used
        body = body.replace('struct', 'volatile struct')
        body += "int main(void) { return foo.before[0]; }\n"
        src, obj = cmd._compile(body, None, None, 'c')
        cmd.temp_files.append("_configtest")
        cmd.compiler.link_executable([obj], "_configtest")
        ltype = long_double_representation(pyod("_configtest"))
        return ltype
    finally:
        cmd._clean()

LONG_DOUBLE_REPRESENTATION_SRC = r"""
/* "before" is 16 bytes to ensure there's no padding between it and "x".