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794e7d1ab2
In GH-2866, _Py_Bit_Length() was added to pymath.h for lack of a better location. GH-20518 added a more appropriate header file for bit utilities. It also shows how to properly use intrinsics. This allows reconsidering bpo-29782. * Move the function to the new header. * Changed return type to match __builtin_clzl() and reviewed usage. * Use intrinsics where available. * Pick a fallback implementation suitable for inlining.
82 lines
1.6 KiB
C
82 lines
1.6 KiB
C
#include "Python.h"
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#ifdef X87_DOUBLE_ROUNDING
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/* On x86 platforms using an x87 FPU, this function is called from the
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Py_FORCE_DOUBLE macro (defined in pymath.h) to force a floating-point
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number out of an 80-bit x87 FPU register and into a 64-bit memory location,
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thus rounding from extended precision to double precision. */
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double _Py_force_double(double x)
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{
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volatile double y;
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y = x;
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return y;
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}
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#endif
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#ifdef HAVE_GCC_ASM_FOR_X87
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/* inline assembly for getting and setting the 387 FPU control word on
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gcc/x86 */
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#ifdef _Py_MEMORY_SANITIZER
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__attribute__((no_sanitize_memory))
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#endif
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unsigned short _Py_get_387controlword(void) {
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unsigned short cw;
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__asm__ __volatile__ ("fnstcw %0" : "=m" (cw));
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return cw;
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}
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void _Py_set_387controlword(unsigned short cw) {
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__asm__ __volatile__ ("fldcw %0" : : "m" (cw));
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}
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#endif
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#ifndef HAVE_HYPOT
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double hypot(double x, double y)
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{
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double yx;
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x = fabs(x);
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y = fabs(y);
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if (x < y) {
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double temp = x;
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x = y;
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y = temp;
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}
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if (x == 0.)
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return 0.;
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else {
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yx = y/x;
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return x*sqrt(1.+yx*yx);
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}
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}
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#endif /* HAVE_HYPOT */
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#ifndef HAVE_COPYSIGN
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double
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copysign(double x, double y)
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{
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/* use atan2 to distinguish -0. from 0. */
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if (y > 0. || (y == 0. && atan2(y, -1.) > 0.)) {
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return fabs(x);
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} else {
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return -fabs(x);
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}
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}
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#endif /* HAVE_COPYSIGN */
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#ifndef HAVE_ROUND
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double
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round(double x)
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{
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double absx, y;
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absx = fabs(x);
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y = floor(absx);
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if (absx - y >= 0.5)
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y += 1.0;
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return copysign(y, x);
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}
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#endif /* HAVE_ROUND */
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