From 9178d0792f6ea29bb285eb548e7246c1a57071e5 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Mon, 16 Aug 2010 14:41:14 +0000
Subject: [PATCH] Instead, teach SimplifyCFG to trim non-address-taken blocks
 from indirectbr destination lists.

llvm-svn: 111122
---
 lib/Transforms/Utils/SimplifyCFG.cpp      |  5 +++--
 test/Transforms/SimplifyCFG/indirectbr.ll | 13 +++++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index db719a0ce4d..28d7afbf1c3 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2057,12 +2057,13 @@ bool SimplifyCFGOpt::run(BasicBlock *BB) {
         return true;
       }
     }
-  } else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(BB->getTerminator())) {
+  } else if (IndirectBrInst *IBI =
+               dyn_cast<IndirectBrInst>(BB->getTerminator())) {
     // Eliminate redundant destinations.
     SmallPtrSet<Value *, 8> Succs;
     for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) {
       BasicBlock *Dest = IBI->getDestination(i);
-      if (!Succs.insert(Dest)) {
+      if (!Dest->hasAddressTaken() || !Succs.insert(Dest)) {
         Dest->removePredecessor(BB);
         IBI->removeDestination(i);
         --i; --e;
diff --git a/test/Transforms/SimplifyCFG/indirectbr.ll b/test/Transforms/SimplifyCFG/indirectbr.ll
index b13433ce306..de4f5b60755 100644
--- a/test/Transforms/SimplifyCFG/indirectbr.ll
+++ b/test/Transforms/SimplifyCFG/indirectbr.ll
@@ -49,3 +49,16 @@ BB0:
   ret void
 }
 
+; SimplifyCFG should notice that BB0 does not have its address taken and
+; remove it from entry's successor list.
+
+; CHECK: indbrtest2
+; CHECK: entry:
+; CHECK-NEXT: unreachable
+
+define void @indbrtest2(i8* %t) {
+entry:
+  indirectbr i8* %t, [label %BB0, label %BB0]
+BB0:
+  ret void
+}