From a171ac0380a22f992d9c57a4189ddfc834d0e022 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Wed, 9 Aug 2017 17:15:02 +0000 Subject: compiler: handle >32bit exponent in Ldexp Libgo's implementation of math.Ldexp declared the libc "ldexp" as taking an 'int' exponent argument, which is not quite right for 64-bit platforms (exp arg is always int32); this could yield incorrect results for exponent values outside the range of Minint32/Maxint32. Fix by upating the type for the libc version of ldexp, and adding guards to screen for out-of-range exponents. Fixes #21323. Reviewed-on: https://go-review.googlesource.com/54250 From-SVN: r250992 --- libgo/go/math/ldexp.go | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'libgo') diff --git a/libgo/go/math/ldexp.go b/libgo/go/math/ldexp.go index 2898f5d..e91a090c 100644 --- a/libgo/go/math/ldexp.go +++ b/libgo/go/math/ldexp.go @@ -13,10 +13,15 @@ package math // Ldexp(NaN, exp) = NaN //extern ldexp -func libc_ldexp(float64, int) float64 +func libc_ldexp(float64, int32) float64 func Ldexp(frac float64, exp int) float64 { - r := libc_ldexp(frac, exp) + if exp > MaxInt32 { + exp = MaxInt32 + } else if exp < MinInt32 { + exp = MinInt32 + } + r := libc_ldexp(frac, int32(exp)) return r } -- cgit v1.1