作为一种解决方法，我添加了__gnu_h2f_ieee来自https://gist.github.com/whchung/25875271922806e58ac21ad7d707e3cd的代码：
#ifdef __x86_64__
#include <limits.h>
#include <stdint.h>
typedef uint16_t src_t;
typedef uint16_t src_rep_t;
#define SRC_REP_C UINT16_C
static const int srcSigBits = 10;
#define src_rep_t_clz __builtin_clz
typedef float dst_t;
typedef uint32_t dst_rep_t;
#define DST_REP_C UINT32_C
static const int dstSigBits = 23;
// End of specialization parameters. Two helper routines for conversion to and
// from the representation of floating-point data as integer values follow.
static __inline src_rep_t srcToRep(src_t x) {
const union { src_t f; src_rep_t i; } rep = {.f = x};
return rep.i;
}
static __inline dst_t dstFromRep(dst_rep_t x) {
const union { dst_t f; dst_rep_t i; } rep = {.i = x};
return rep.f;
}
// End helper routines. Conversion implementation follows.
static __inline dst_t __extendXfYf2__(src_t a) {
// Various constants whose values follow from the type parameters.
// Any reasonable optimizer will fold and propagate all of these.
const int srcBits = sizeof(src_t)*CHAR_BIT;
const int srcExpBits = srcBits - srcSigBits - 1;
const int srcInfExp = (1 << srcExpBits) - 1;
const int srcExpBias = srcInfExp >> 1;
const src_rep_t srcMinNormal = SRC_REP_C(1) << srcSigBits;
const src_rep_t srcInfinity = (src_rep_t)srcInfExp << srcSigBits;
const src_rep_t srcSignMask = SRC_REP_C(1) << (srcSigBits + srcExpBits);
const src_rep_t srcAbsMask = srcSignMask - 1;
const src_rep_t srcQNaN = SRC_REP_C(1) << (srcSigBits - 1);
const src_rep_t srcNaNCode = srcQNaN - 1;
const int dstBits = sizeof(dst_t)*CHAR_BIT;
const int dstExpBits = dstBits - dstSigBits - 1;
const int dstInfExp = (1 << dstExpBits) - 1;
const int dstExpBias = dstInfExp >> 1;
const dst_rep_t dstMinNormal = DST_REP_C(1) << dstSigBits;
// Break a into a sign and representation of the absolute value
const src_rep_t aRep = srcToRep(a);
const src_rep_t aAbs = aRep & srcAbsMask;
const src_rep_t sign = aRep & srcSignMask;
dst_rep_t absResult;
// If sizeof(src_rep_t) < sizeof(int), the subtraction result is promoted
// to (signed) int. To avoid that, explicitly cast to src_rep_t.
if ((src_rep_t)(aAbs - srcMinNormal) < srcInfinity - srcMinNormal) {
// a is a normal number.
// Extend to the destination type by shifting the significand and
// exponent into the proper position and rebiasing the exponent.
absResult = (dst_rep_t)aAbs << (dstSigBits - srcSigBits);
absResult += (dst_rep_t)(dstExpBias - srcExpBias) << dstSigBits;
}
else if (aAbs >= srcInfinity) {
// a is NaN or infinity.
// Conjure the result by beginning with infinity, then setting the qNaN
// bit (if needed) and right-aligning the rest of the trailing NaN
// payload field.
absResult = (dst_rep_t)dstInfExp << dstSigBits;
absResult |= (dst_rep_t)(aAbs & srcQNaN) << (dstSigBits - srcSigBits);
absResult |= (dst_rep_t)(aAbs & srcNaNCode) << (dstSigBits - srcSigBits);
}
else if (aAbs) {
// a is denormal.
// renormalize the significand and clear the leading bit, then insert
// the correct adjusted exponent in the destination type.
const int scale = src_rep_t_clz(aAbs) - src_rep_t_clz(srcMinNormal);
absResult = (dst_rep_t)aAbs << (dstSigBits - srcSigBits + scale);
absResult ^= dstMinNormal;
const int resultExponent = dstExpBias - srcExpBias - scale + 1;
absResult |= (dst_rep_t)resultExponent << dstSigBits;
}
else {
// a is zero.
absResult = 0;
}
// Apply the signbit to (dst_t)abs(a).
const dst_rep_t result = absResult | (dst_rep_t)sign << (dstBits - srcBits);
return dstFromRep(result);
}
// Use a forwarding definition and noinline to implement a poor man's alias,
// as there isn't a good cross-platform way of defining one.
__attribute__((noinline)) float __extendhfsf2(uint16_t a) {
return __extendXfYf2__(a);
}
extern "C" float __gnu_h2f_ieee(uint16_t a) {
return __extendhfsf2(a);
}
#endif
在一个单独的源文件中（#ifdef因为在 ARM 上应该定义这个函数）。