Use non-generic inner function for pointer formatting

Author: jam1garner

library/core/src/fmt/mod.rs

@@ -2186,28 +2186,34 @@ impl Display for char {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Pointer for *const T {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
-        let old_width = f.width;
-        let old_flags = f.flags;
-
-        // The alternate flag is already treated by LowerHex as being special-
-        // it denotes whether to prefix with 0x. We use it to work out whether
-        // or not to zero extend, and then unconditionally set it to get the
-        // prefix.
-        if f.alternate() {
-            f.flags |= 1 << (FlagV1::SignAwareZeroPad as u32);
-
-            if f.width.is_none() {
-                f.width = Some((usize::BITS / 4) as usize + 2);
+        /// Since the formatting will be identical for all pointer types, use a non-monomorphized
+        /// implementation for the actual formatting to reduce the amount of codegen work needed
+        fn inner(ptr: *const (), f: &mut Formatter<'_>) -> Result {
+            let old_width = f.width;
+            let old_flags = f.flags;
+
+            // The alternate flag is already treated by LowerHex as being special-
+            // it denotes whether to prefix with 0x. We use it to work out whether
+            // or not to zero extend, and then unconditionally set it to get the
+            // prefix.
+            if f.alternate() {
+                f.flags |= 1 << (FlagV1::SignAwareZeroPad as u32);
+
+                if f.width.is_none() {
+                    f.width = Some((usize::BITS / 4) as usize + 2);
+                }
             }
-        }
-        f.flags |= 1 << (FlagV1::Alternate as u32);
+            f.flags |= 1 << (FlagV1::Alternate as u32);
+
+            let ret = LowerHex::fmt(&(ptr as usize), f);
 
-        let ret = LowerHex::fmt(&(*self as *const () as usize), f);
+            f.width = old_width;
+            f.flags = old_flags;
 
-        f.width = old_width;
-        f.flags = old_flags;
+            ret
+        }
 
-        ret
+        inner(*self as *const (), f)
     }
 }