From e1d1cd191f6601b0ed2219beb7a4fb00f25b6667 Mon Sep 17 00:00:00 2001
From: Christian Poveda <christianpoveda@protonmail.com>
Date: Thu, 8 Aug 2019 15:22:34 -0500
Subject: [PATCH] Use ldexp from cmath instead

---
 src/shims/foreign_items.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/shims/foreign_items.rs b/src/shims/foreign_items.rs
index 37e5fe42c3d..ba9b7ca27eb 100644
--- a/src/shims/foreign_items.rs
+++ b/src/shims/foreign_items.rs
@@ -594,8 +594,10 @@ fn emulate_foreign_item(
                 // FIXME: Using host floats.
                 let x = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
                 let exp = this.read_scalar(args[1])?.to_i32()?;
-                // FIXME: We should use cmath if there are any imprecisions.
-                let n = x * 2.0f64.powi(exp);
+                extern {
+                    fn ldexp(x: f64, n: i32) -> f64;
+                }
+                let n = unsafe { ldexp(x, exp) };
                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
             }