From c4359e01303da2755fe7e8033826b132eb3659b1 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Tue, 13 Nov 2012 10:55:35 +0100 Subject: math: excess precision fix modf, modff, scalbn, scalbnf old code was correct only if the result was stored (without the excess precision) or musl was compiled with -ffloat-store. now we use STRICT_ASSIGN to work around the issue. (see note 160 in c11 section 6.8.6.4) --- src/math/scalbn.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) (limited to 'src/math/scalbn.c') diff --git a/src/math/scalbn.c b/src/math/scalbn.c index 42a2b294..003141e3 100644 --- a/src/math/scalbn.c +++ b/src/math/scalbn.c @@ -2,8 +2,6 @@ double scalbn(double x, int n) { - /* make sure result is stored as double on overflow or underflow */ - volatile double z; double scale; if (n > 1023) { @@ -13,8 +11,8 @@ double scalbn(double x, int n) x *= 0x1p1023; n -= 1023; if (n > 1023) { - z = x * 0x1p1023; - return z; + STRICT_ASSIGN(double, x, x * 0x1p1023); + return x; } } } else if (n < -1022) { @@ -24,12 +22,12 @@ double scalbn(double x, int n) x *= 0x1p-1022; n += 1022; if (n < -1022) { - z = x * 0x1p-1022; - return z; + STRICT_ASSIGN(double, x, x * 0x1p-1022); + return x; } } } INSERT_WORDS(scale, (uint32_t)(0x3ff+n)<<20, 0); - z = x * scale; - return z; + STRICT_ASSIGN(double, x, x * scale); + return x; } -- cgit v1.2.1