From 771a1d8e0ad4e6702aaab91cb5e58adbf3ec3708 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eduardo=20S=C3=A1nchez=20Mu=C3=B1oz?= <esm@eduardosm.net>
Date: Wed, 24 Jun 2020 18:17:27 +0200
Subject: [PATCH] Make `std::panicking::panic_count::is_zero` inline and move
 the slow path into a separate cold function.

---
 src/libstd/panicking.rs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/libstd/panicking.rs b/src/libstd/panicking.rs
index 46196960e718b..9a5d5e2b5ae9f 100644
--- a/src/libstd/panicking.rs
+++ b/src/libstd/panicking.rs
@@ -258,6 +258,7 @@ pub mod panic_count {
         LOCAL_PANIC_COUNT.with(|c| c.get())
     }
 
+    #[inline]
     pub fn is_zero() -> bool {
         if GLOBAL_PANIC_COUNT.load(Ordering::Relaxed) == 0 {
             // Fast path: if `GLOBAL_PANIC_COUNT` is zero, all threads
@@ -265,9 +266,17 @@ pub mod panic_count {
             // equal to zero, so TLS access can be avoided.
             true
         } else {
-            LOCAL_PANIC_COUNT.with(|c| c.get() == 0)
+            is_zero_slow_path()
         }
     }
+
+    // Slow path is in a separate function to reduce the amount of code
+    // inlined from `is_zero`.
+    #[inline(never)]
+    #[cold]
+    fn is_zero_slow_path() -> bool {
+        LOCAL_PANIC_COUNT.with(|c| c.get() == 0)
+    }
 }
 
 #[cfg(test)]
@@ -350,6 +359,7 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
 }
 
 /// Determines whether the current thread is unwinding because of panic.
+#[inline]
 pub fn panicking() -> bool {
     !panic_count::is_zero()
 }