Merge #1681

1681: Fix warning about zero-sized FDEs. r=nlewycky a=nlewycky # Description The LLVM implementation of libunwind API will emit a warning when `__register_frame` is called with a zero-size FDE. There's usually only one at the end of a CIE, but just skip any that come up. # Review - [ ] Add a short description of the the change to the CHANGELOG.md file Co-authored-by: Nick Lewycky <[email protected]> Co-authored-by: nlewycky <[email protected]>
wasmerio · Oct 5, 2020 · 63ec921 · 63ec921
2 parents 1b90a8f + 852a898
commit 63ec921
Showing 1 changed file with 3 additions and 5 deletions.
diff --git a/lib/engine-jit/src/unwind/systemv.rs b/lib/engine-jit/src/unwind/systemv.rs
@@ -81,11 +81,9 @@ impl UnwindRegistry {
             while current < end {
                 let len = std::ptr::read::<u32>(current as *const u32) as usize;
 
-                // Skip over the CIE
-                if current != start {
-                    // If len == 0, __register_frame will be a no-op.
-                    // So rather than skip it here, we just let __register_frame
-                    // deal with empty FDEs the way they want.
+                // Skip over the CIE and zero-length FDEs.
+                // LLVM's libunwind emits a warning on zero-length FDEs.
+                if current != start && len != 0 {
                     __register_frame(current);
                     self.registrations.push(current as usize);
                 }