5 files changed, 22 insertions, 10 deletions

diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index 0184390185..483bfe3655 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -147,7 +147,7 @@ bool CodeGenPrepare::runOnFunction(Function &F) {
   if (!DisableBranchOpts) {
     MadeChange = false;
     for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
-      MadeChange |= ConstantFoldTerminator(BB);
+      MadeChange |= ConstantFoldTerminator(BB, true);
 
     if (MadeChange)
       ModifiedDT = true;
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index 5a8f4ca192..cf18ff040b 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -706,7 +706,7 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) {
     DEBUG(dbgs() << "  In block '" << BB->getName()
           << "' folding terminator: " << *BB->getTerminator() << '\n');
     ++NumFolds;
-    ConstantFoldTerminator(BB);
+    ConstantFoldTerminator(BB, true);
     return true;
   }
 
diff --git a/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/lib/Transforms/Scalar/SimplifyCFGPass.cpp
index 1137c2b23f..eccafea3aa 100644
--- a/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -163,7 +163,7 @@ static bool MarkAliveBlocks(BasicBlock *BB,
         Changed = true;
       }
 
-    Changed |= ConstantFoldTerminator(BB);
+    Changed |= ConstantFoldTerminator(BB, true);
     for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
       Worklist.push_back(*SI);
   } while (!Worklist.empty());
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 12e15b07c7..f5a8adacd5 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -44,11 +44,14 @@ using namespace llvm;
 //  Local constant propagation.
 //
 
-// ConstantFoldTerminator - If a terminator instruction is predicated on a
-// constant value, convert it into an unconditional branch to the constant
-// destination.
-//
-bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
+/// ConstantFoldTerminator - If a terminator instruction is predicated on a
+/// constant value, convert it into an unconditional branch to the constant
+/// destination.  This is a nontrivial operation because the successors of this
+/// basic block must have their PHI nodes updated.
+/// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch
+/// conditions and indirectbr addresses this might make dead if
+/// DeleteDeadConditions is true.
+bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions) {
   TerminatorInst *T = BB->getTerminator();
   IRBuilder<> Builder(T);
 
@@ -89,7 +92,10 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
 
       // Replace the conditional branch with an unconditional one.
       Builder.CreateBr(Dest1);
+      Value *Cond = BI->getCondition();
       BI->eraseFromParent();
+      if (DeleteDeadConditions)
+        RecursivelyDeleteTriviallyDeadInstructions(Cond);
       return true;
     }
     return false;
@@ -152,7 +158,10 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
       }
 
       // Delete the old switch.
-      BB->getInstList().erase(SI);
+      Value *Cond = SI->getCondition();
+      SI->eraseFromParent();
+      if (DeleteDeadConditions)
+        RecursivelyDeleteTriviallyDeadInstructions(Cond);
       return true;
     }
     
@@ -186,7 +195,10 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
         else
           IBI->getDestination(i)->removePredecessor(IBI->getParent());
       }
+      Value *Address = IBI->getAddress();
       IBI->eraseFromParent();
+      if (DeleteDeadConditions)
+        RecursivelyDeleteTriviallyDeadInstructions(Address);
       
       // If we didn't find our destination in the IBI successor list, then we
       // have undefined behavior.  Replace the unconditional branch with an
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 2c032d5d12..5ab9a2877c 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2651,7 +2651,7 @@ bool SimplifyCFGOpt::run(BasicBlock *BB) {
 
   // Check to see if we can constant propagate this terminator instruction
   // away...
-  Changed |= ConstantFoldTerminator(BB);
+  Changed |= ConstantFoldTerminator(BB, true);
 
   // Check for and eliminate duplicate PHI nodes in this block.
   Changed |= EliminateDuplicatePHINodes(BB);