llvm/compiler-rt/lib/builtins/fp_lib.h

//===-- lib/fp_lib.h - Floating-point utilities -------------------*- C -*-===//
//
// 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 is a configuration header for soft-float routines in compiler-rt.
// This file does not provide any part of the compiler-rt interface, but defines
// many useful constants and utility routines that are used in the
// implementation of the soft-float routines in compiler-rt.
//
// Assumes that float, double and long double correspond to the IEEE-754
// binary32, binary64 and binary 128 types, respectively, and that integer
// endianness matches floating point endianness on the target platform.
//
//===----------------------------------------------------------------------===//

#ifndef FP_LIB_HEADER
#define FP_LIB_HEADER

#include "int_lib.h"
#include "int_math.h"
#include "int_types.h"
#include <limits.h>
#include <stdbool.h>
#include <stdint.h>

#if defined SINGLE_PRECISION

typedef uint16_t half_rep_t;
typedef uint32_t rep_t;
typedef uint64_t twice_rep_t;
typedef int32_t srep_t;
typedef float fp_t;
#define HALF_REP_C
#define REP_C
#define significandBits

static __inline int rep_clz(rep_t a) { return clzsi(a); }

// 32x32 --> 64 bit multiply
static __inline void wideMultiply(rep_t a, rep_t b, rep_t *hi, rep_t *lo) {
  const uint64_t product = (uint64_t)a * b;
  *hi = (rep_t)(product >> 32);
  *lo = (rep_t)product;
}
COMPILER_RT_ABI fp_t __addsf3(fp_t a, fp_t b);

#elif defined DOUBLE_PRECISION

half_rep_t;
rep_t;
srep_t;
fp_t;
#define HALF_REP_C
#define REP_C
#define significandBits

static inline int rep_clz(rep_t a) {}

#define loWord
#define hiWord

// 64x64 -> 128 wide multiply for platforms that don't have such an operation;
// many 64-bit platforms have this operation, but they tend to have hardware
// floating-point, so we don't bother with a special case for them here.
static __inline void wideMultiply(rep_t a, rep_t b, rep_t *hi, rep_t *lo) {}
#undef loWord
#undef hiWord

COMPILER_RT_ABI fp_t __adddf3(fp_t a, fp_t b);

#elif defined QUAD_PRECISION
#if defined(CRT_HAS_F128) && defined(CRT_HAS_128BIT)
typedef uint64_t half_rep_t;
typedef __uint128_t rep_t;
typedef __int128_t srep_t;
typedef tf_float fp_t;
#define HALF_REP_C
#define REP_C
#if defined(CRT_HAS_IEEE_TF)
// Note: Since there is no explicit way to tell compiler the constant is a
// 128-bit integer, we let the constant be casted to 128-bit integer
#define significandBits
#define TF_MANT_DIG

static __inline int rep_clz(rep_t a) {
  const union {
    __uint128_t ll;
#if _YUGA_BIG_ENDIAN
    struct {
      uint64_t high, low;
    } s;
#else
    struct {
      uint64_t low, high;
    } s;
#endif
  } uu = {.ll = a};

  uint64_t word;
  uint64_t add;

  if (uu.s.high) {
    word = uu.s.high;
    add = 0;
  } else {
    word = uu.s.low;
    add = 64;
  }
  return __builtin_clzll(word) + add;
}

#define Word_LoMask
#define Word_HiMask
#define Word_FullMask
#define Word_1
#define Word_2
#define Word_3
#define Word_4

// 128x128 -> 256 wide multiply for platforms that don't have such an operation;
// many 64-bit platforms have this operation, but they tend to have hardware
// floating-point, so we don't bother with a special case for them here.
static __inline void wideMultiply(rep_t a, rep_t b, rep_t *hi, rep_t *lo) {

  const uint64_t product11 = Word_1(a) * Word_1(b);
  const uint64_t product12 = Word_1(a) * Word_2(b);
  const uint64_t product13 = Word_1(a) * Word_3(b);
  const uint64_t product14 = Word_1(a) * Word_4(b);
  const uint64_t product21 = Word_2(a) * Word_1(b);
  const uint64_t product22 = Word_2(a) * Word_2(b);
  const uint64_t product23 = Word_2(a) * Word_3(b);
  const uint64_t product24 = Word_2(a) * Word_4(b);
  const uint64_t product31 = Word_3(a) * Word_1(b);
  const uint64_t product32 = Word_3(a) * Word_2(b);
  const uint64_t product33 = Word_3(a) * Word_3(b);
  const uint64_t product34 = Word_3(a) * Word_4(b);
  const uint64_t product41 = Word_4(a) * Word_1(b);
  const uint64_t product42 = Word_4(a) * Word_2(b);
  const uint64_t product43 = Word_4(a) * Word_3(b);
  const uint64_t product44 = Word_4(a) * Word_4(b);

  const __uint128_t sum0 = (__uint128_t)product44;
  const __uint128_t sum1 = (__uint128_t)product34 + (__uint128_t)product43;
  const __uint128_t sum2 =
      (__uint128_t)product24 + (__uint128_t)product33 + (__uint128_t)product42;
  const __uint128_t sum3 = (__uint128_t)product14 + (__uint128_t)product23 +
                           (__uint128_t)product32 + (__uint128_t)product41;
  const __uint128_t sum4 =
      (__uint128_t)product13 + (__uint128_t)product22 + (__uint128_t)product31;
  const __uint128_t sum5 = (__uint128_t)product12 + (__uint128_t)product21;
  const __uint128_t sum6 = (__uint128_t)product11;

  const __uint128_t r0 = (sum0 & Word_FullMask) + ((sum1 & Word_LoMask) << 32);
  const __uint128_t r1 = (sum0 >> 64) + ((sum1 >> 32) & Word_FullMask) +
                         (sum2 & Word_FullMask) + ((sum3 << 32) & Word_HiMask);

  *lo = r0 + (r1 << 64);
  *hi = (r1 >> 64) + (sum1 >> 96) + (sum2 >> 64) + (sum3 >> 32) + sum4 +
        (sum5 << 32) + (sum6 << 64);
}
#undef Word_1
#undef Word_2
#undef Word_3
#undef Word_4
#undef Word_HiMask
#undef Word_LoMask
#undef Word_FullMask
#endif // defined(CRT_HAS_IEEE_TF)
#else
typedef long double fp_t;
#endif // defined(CRT_HAS_F128) && defined(CRT_HAS_128BIT)
#else
#error SINGLE_PRECISION, DOUBLE_PRECISION or QUAD_PRECISION must be defined.
#endif

#if defined(SINGLE_PRECISION) || defined(DOUBLE_PRECISION) ||                  \
    (defined(QUAD_PRECISION) && defined(CRT_HAS_TF_MODE))
#define typeWidth

static __inline rep_t toRep(fp_t x) {}

static __inline fp_t fromRep(rep_t x) {}

#if !defined(QUAD_PRECISION) || defined(CRT_HAS_IEEE_TF)
#define exponentBits
#define maxExponent
#define exponentBias

#define implicitBit
#define significandMask
#define signBit
#define absMask
#define exponentMask
#define oneRep
#define infRep
#define quietBit
#define qnanRep

static __inline int normalize(rep_t *significand) {}

static __inline void wideLeftShift(rep_t *hi, rep_t *lo, unsigned int count) {}

static __inline void wideRightShiftWithSticky(rep_t *hi, rep_t *lo,
                                              unsigned int count) {}

// Implements logb methods (logb, logbf, logbl) for IEEE-754. This avoids
// pulling in a libm dependency from compiler-rt, but is not meant to replace
// it (i.e. code calling logb() should get the one from libm, not this), hence
// the __compiler_rt prefix.
static __inline fp_t __compiler_rt_logbX(fp_t x) {}

// Avoid using scalbn from libm. Unlike libc/libm scalbn, this function never
// sets errno on underflow/overflow.
static __inline fp_t __compiler_rt_scalbnX(fp_t x, int y) {}

#endif // !defined(QUAD_PRECISION) || defined(CRT_HAS_IEEE_TF)

// Avoid using fmax from libm.
static __inline fp_t __compiler_rt_fmaxX(fp_t x, fp_t y) {}

#endif

#if defined(SINGLE_PRECISION)

static __inline fp_t __compiler_rt_logbf(fp_t x) {
  return __compiler_rt_logbX(x);
}
static __inline fp_t __compiler_rt_scalbnf(fp_t x, int y) {
  return __compiler_rt_scalbnX(x, y);
}

#elif defined(DOUBLE_PRECISION)

static __inline fp_t __compiler_rt_logb(fp_t x) {}
static __inline fp_t __compiler_rt_scalbn(fp_t x, int y) {}
static __inline fp_t __compiler_rt_fmax(fp_t x, fp_t y) {}

#elif defined(QUAD_PRECISION) && defined(CRT_HAS_TF_MODE)
// The generic implementation only works for ieee754 floating point. For other
// floating point types, continue to rely on the libm implementation for now.
#if defined(CRT_HAS_IEEE_TF)
static __inline tf_float __compiler_rt_logbtf(tf_float x) {
  return __compiler_rt_logbX(x);
}
static __inline tf_float __compiler_rt_scalbntf(tf_float x, int y) {
  return __compiler_rt_scalbnX(x, y);
}
static __inline tf_float __compiler_rt_fmaxtf(tf_float x, tf_float y) {
  return __compiler_rt_fmaxX(x, y);
}
#define __compiler_rt_logbl
#define __compiler_rt_scalbnl
#define __compiler_rt_fmaxl
#define crt_fabstf
#define crt_copysigntf
#elif defined(CRT_LDBL_128BIT)
static __inline tf_float __compiler_rt_logbtf(tf_float x) {
  return crt_logbl(x);
}
static __inline tf_float __compiler_rt_scalbntf(tf_float x, int y) {
  return crt_scalbnl(x, y);
}
static __inline tf_float __compiler_rt_fmaxtf(tf_float x, tf_float y) {
  return crt_fmaxl(x, y);
}
#define __compiler_rt_logbl
#define __compiler_rt_scalbnl
#define __compiler_rt_fmaxl
#define crt_fabstf
#define crt_copysigntf
#else
#error Unsupported TF mode type
#endif

#endif // *_PRECISION

#endif // FP_LIB_HEADER