From 759bafb906ba3addc5ab470ca41455ef452f30ab Mon Sep 17 00:00:00 2001
From: Alon Zakai <alonzakai@gmail.com>
Date: Sat, 23 Apr 2016 18:10:05 -0700
Subject: vacuum dead code after unconditional brs

---
 src/passes/Vacuum.cpp | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/passes/Vacuum.cpp b/src/passes/Vacuum.cpp
index 863d78f14..ed868f2f9 100644
--- a/src/passes/Vacuum.cpp
+++ b/src/passes/Vacuum.cpp
@@ -32,14 +32,25 @@ struct Vacuum : public WalkerPass<PostWalker<Vacuum, Visitor<Vacuum>>> {
     int skip = 0;
     auto& list = curr->list;
     size_t size = list.size();
+    bool needResize = false;
     for (size_t z = 0; z < size; z++) {
       if (list[z]->is<Nop>()) {
         skip++;
-      } else if (skip > 0) {
-        list[z - skip] = list[z];
+        needResize = true;
+      } else {
+        if (skip > 0) {
+          list[z - skip] = list[z];
+        }
+        // if this is an unconditional br, the rest is dead code
+        Break* br = list[z - skip]->dynCast<Break>();
+        if (br && !br->condition) {
+          list.resize(z - skip + 1);
+          needResize = false;
+          break;
+        }
       }
     }
-    if (skip > 0) {
+    if (needResize) {
       list.resize(size - skip);
     }
     if (!curr->name.is()) {
-- 
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