From 5ee4fdcd15cc404f6d195027b11c24bdb0905204 Mon Sep 17 00:00:00 2001
From: Oliver Schneider <git-spam-no-reply9815368754983@oli-obk.de>
Date: Fri, 23 Jun 2017 13:31:00 +0200
Subject: [PATCH] fetch_tls_dtor "read" an `Undef` as nonzero

---
 src/eval_context.rs | 6 +++++-
 src/memory.rs       | 8 ++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/eval_context.rs b/src/eval_context.rs
index 0a2bce922df5..7052a411f7e2 100644
--- a/src/eval_context.rs
+++ b/src/eval_context.rs
@@ -362,7 +362,11 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
             StackPopCleanup::None => {},
             StackPopCleanup::Tls(key) => {
                 // either fetch the next dtor or start new from the beginning, if any are left with a non-null data
-                if let Some((instance, ptr, key)) = self.memory.fetch_tls_dtor(key).or_else(|| self.memory.fetch_tls_dtor(None)) {
+                let dtor = match self.memory.fetch_tls_dtor(key)? {
+                    dtor @ Some(_) => dtor,
+                    None => self.memory.fetch_tls_dtor(None)?,
+                };
+                if let Some((instance, ptr, key)) = dtor {
                     trace!("Running TLS dtor {:?} on {:?}", instance, ptr);
                     // TODO: Potentially, this has to support all the other possible instances? See eval_fn_call in terminator/mod.rs
                     let mir = self.load_mir(instance.def)?;
diff --git a/src/memory.rs b/src/memory.rs
index e34737f464de..5794dc783cfe 100644
--- a/src/memory.rs
+++ b/src/memory.rs
@@ -404,22 +404,22 @@ impl<'a, 'tcx> Memory<'a, 'tcx> {
     /// with associated destructors, implementations may stop calling destructors,
     /// or they may continue calling destructors until no non-NULL values with
     /// associated destructors exist, even though this might result in an infinite loop.
-    pub(crate) fn fetch_tls_dtor(&mut self, key: Option<TlsKey>) -> Option<(ty::Instance<'tcx>, PrimVal, TlsKey)> {
+    pub(crate) fn fetch_tls_dtor(&mut self, key: Option<TlsKey>) -> EvalResult<'tcx, Option<(ty::Instance<'tcx>, PrimVal, TlsKey)>> {
         use std::collections::Bound::*;
         let start = match key {
             Some(key) => Excluded(key),
             None => Unbounded,
         };
         for (&key, &mut TlsEntry { ref mut data, dtor }) in self.thread_local.range_mut((start, Unbounded)) {
-            if *data != PrimVal::Bytes(0) {
+            if !data.is_null()? {
                 if let Some(dtor) = dtor {
                     let ret = Some((dtor, *data, key));
                     *data = PrimVal::Bytes(0);
-                    return ret;
+                    return Ok(ret);
                 }
             }
         }
-        return None;
+        return Ok(None);
     }
 }