fix double-processing of DT_RELR relocations in ldso relocating itself

[musl] / src / math / __rem_pio2f.c

diff --git a/src/math/__rem_pio2f.c b/src/math/__rem_pio2f.c
index 4473c1c..e676564 100644 (file)
--- a/src/math/__rem_pio2f.c
+++ b/src/math/__rem_pio2f.c
@@ -35,6 +35,7 @@
  */
 static const double
 toint   = 1.5/EPS,
+pio4    = 0x1.921fb6p-1,
 invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
 pio2_1  = 1.57079631090164184570e+00, /* 0x3FF921FB, 0x50000000 */
 pio2_1t = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */
@@ -50,10 +51,20 @@ int __rem_pio2f(float x, double *y)
        ix = u.i & 0x7fffffff;
        /* 25+53 bit pi is good enough for medium size */
        if (ix < 0x4dc90fdb) {  /* |x| ~< 2^28*(pi/2), medium size */
-               /* Use a specialized rint() to get fn.  Assume round-to-nearest. */
+               /* Use a specialized rint() to get fn. */
                fn = (double_t)x*invpio2 + toint - toint;
                n  = (int32_t)fn;
                *y = x - fn*pio2_1 - fn*pio2_1t;
+               /* Matters with directed rounding. */
+               if (predict_false(*y < -pio4)) {
+                       n--;
+                       fn--;
+                       *y = x - fn*pio2_1 - fn*pio2_1t;
+               } else if (predict_false(*y > pio4)) {
+                       n++;
+                       fn++;
+                       *y = x - fn*pio2_1 - fn*pio2_1t;
+               }
                return n;
        }
        if(ix>=0x7f800000) {  /* x is inf or NaN */