From e493027984b5961617c867a7003face00a057c92 Mon Sep 17 00:00:00 2001
From: Vadim Chugunov <vadimcn@gmail.com>
Date: Sat, 1 Aug 2015 16:07:38 -0700
Subject: [PATCH] When a `nounwind` function has a personality routine, LLVM
 messes up .seh directives (happens to `rust_try` in optimized builds).  A
 workaround is to give `rust_try` the `uwtable` attribute. Also, make sure
 that the dummy "load from null" instruction inserted by init_function() gets
 cleaned up.

---
 src/librustc_trans/trans/intrinsic.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/librustc_trans/trans/intrinsic.rs b/src/librustc_trans/trans/intrinsic.rs
index e0062493e0a5f..0400771dff15c 100644
--- a/src/librustc_trans/trans/intrinsic.rs
+++ b/src/librustc_trans/trans/intrinsic.rs
@@ -16,6 +16,7 @@ use llvm::{SequentiallyConsistent, Acquire, Release, AtomicXchg, ValueRef, TypeK
 use middle::subst;
 use middle::subst::FnSpace;
 use trans::adt;
+use trans::attributes;
 use trans::base::*;
 use trans::build::*;
 use trans::callee;
@@ -1189,6 +1190,7 @@ fn trans_gnu_try<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
         //      ret ptr
 
         let rust_try = declare::define_internal_rust_fn(ccx, "__rust_try", try_fn_ty);
+        attributes::emit_uwtable(rust_try, true);
         let catch_pers = match bcx.tcx().lang_items.eh_personality_catch() {
             Some(did) => callee::trans_fn_ref(ccx, did, ExprId(0),
                                               bcx.fcx.param_substs).val,
@@ -1219,6 +1221,7 @@ fn trans_gnu_try<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
         AddClause(catch, vals, C_null(Type::i8p(ccx)));
         let ptr = ExtractValue(catch, vals, 0);
         Ret(catch, ptr, dloc);
+        fcx.cleanup();
 
         return rust_try
     });