Prevent repeated registration of frames on Linux.

This commit calls `__register_frame` once for the entire frame table on
Linux.

On macOS, it still manually walks the frame table and registers each frame with
`__register_frame`.

crates/jit/src/unwind/systemv.rs

@@ -99,22 +99,32 @@ impl UnwindRegistry {
     }
 
     unsafe fn register_frames(&mut self) {
-        let start = self.frame_table.as_ptr();
-        let end = start.add(self.frame_table.len());
-        let mut current = start;
-
-        // Walk all of the entries in the frame table and register them
-        while current < end {
-            let len = std::ptr::read::<u32>(current as *const u32) as usize;
-
-            // Skip over the CIE
-            if current != start {
-                __register_frame(current);
-                self.registrations.push(current as usize);
+        cfg_if::cfg_if! {
+            if #[cfg(target_os = "macos")] {
+                // On macOS, `__register_frame` takes a pointer to a single FDE
+                let start = self.frame_table.as_ptr();
+                let end = start.add(self.frame_table.len());
+                let mut current = start;
+
+                // Walk all of the entries in the frame table and register them
+                while current < end {
+                    let len = std::ptr::read::<u32>(current as *const u32) as usize;
+
+                    // Skip over the CIE
+                    if current != start {
+                        __register_frame(current);
+                        self.registrations.push(current as usize);
+                    }
+
+                    // Move to the next table entry (+4 because the length itself is not inclusive)
+                    current = current.add(len + 4);
+                }
+            } else {
+                // On other platforms, `__register_frame` will walk the FDEs until an entry of length 0
+                let ptr = self.frame_table.as_ptr();
+                __register_frame(ptr);
+                self.registrations.push(ptr as usize);
             }
-
-            // Move to the next table entry (+4 because the length itself is not inclusive)
-            current = current.add(len + 4);
         }
     }
 }