llvm/compiler-rt/lib/builtins/fp_extend_impl.inc

//=-lib/fp_extend_impl.inc - low precision -> high precision conversion -*-- -//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements a fairly generic conversion from a narrower to a wider
// IEEE-754 floating-point type.  The constants and types defined following the
// includes below parameterize the conversion.
//
// It does not support types that don't use the usual IEEE-754 interchange
// formats; specifically, some work would be needed to adapt it to
// (for example) the Intel 80-bit format or PowerPC double-double format.
//
// Note please, however, that this implementation is only intended to support
// *widening* operations; if you need to convert to a *narrower* floating-point
// type (e.g. double -> float), then this routine will not do what you want it
// to.
//
// It also requires that integer types at least as large as both formats
// are available on the target platform; this may pose a problem when trying
// to add support for quad on some 32-bit systems, for example.  You also may
// run into trouble finding an appropriate CLZ function for wide source types;
// you will likely need to roll your own on some platforms.
//
// Finally, the following assumptions are made:
//
// 1. Floating-point types and integer types have the same endianness on the
//    target platform.
//
// 2. Quiet NaNs, if supported, are indicated by the leading bit of the
//    significand field being set.
//
//===----------------------------------------------------------------------===//

#include "fp_extend.h"

// The source type may use a usual IEEE-754 interchange format or Intel 80-bit
// format. In particular, for the source type srcSigFracBits may be not equal to
// srcSigBits. The destination type is assumed to be one of IEEE-754 standard
// types.
static __inline dst_t __extendXfYf2__(src_t a) { … }