1 files changed, 49 insertions, 0 deletions
diff --git a/library/std/src/sys/mod.rs b/library/std/src/sys/mod.rs
index c72be13804d..a9ea5f0de89 100644
--- a/library/std/src/sys/mod.rs
+++ b/library/std/src/sys/mod.rs
@@ -60,3 +60,52 @@ cfg_if::cfg_if! {
         pub const FULL_BACKTRACE_DEFAULT: bool = false;
     }
 }
+
+#[cfg(not(test))]
+cfg_if::cfg_if! {
+    if #[cfg(target_os = "android")] {
+        pub use self::android::log2f32;
+        pub use self::android::log2f64;
+    } else {
+        #[inline]
+        pub fn log2f32(n: f32) -> f32 {
+            unsafe { crate::intrinsics::log2f32(n) }
+        }
+
+        #[inline]
+        pub fn log2f64(n: f64) -> f64 {
+            unsafe { crate::intrinsics::log2f64(n) }
+        }
+    }
+}
+
+// Solaris/Illumos requires a wrapper around log, log2, and log10 functions
+// because of their non-standard behavior (e.g., log(-n) returns -Inf instead
+// of expected NaN).
+#[cfg(not(test))]
+#[cfg(any(target_os = "solaris", target_os = "illumos"))]
+#[inline]
+pub fn log_wrapper<F: Fn(f64) -> f64>(n: f64, log_fn: F) -> f64 {
+    if n.is_finite() {
+        if n > 0.0 {
+            log_fn(n)
+        } else if n == 0.0 {
+            f64::NEG_INFINITY // log(0) = -Inf
+        } else {
+            f64::NAN // log(-n) = NaN
+        }
+    } else if n.is_nan() {
+        n // log(NaN) = NaN
+    } else if n > 0.0 {
+        n // log(Inf) = Inf
+    } else {
+        f64::NAN // log(-Inf) = NaN
+    }
+}
+
+#[cfg(not(test))]
+#[cfg(not(any(target_os = "solaris", target_os = "illumos")))]
+#[inline]
+pub fn log_wrapper<F: Fn(f64) -> f64>(n: f64, log_fn: F) -> f64 {
+    log_fn(n)
+}