commit 838b97edfaf7470941d0e89ef3b9ed8867c93fc4
author Cameron Zwarich <zwarich@apple.com> Tue Mar 15 07:41:25 2011 +0000
committer Cameron Zwarich <zwarich@apple.com> Tue Mar 15 07:41:25 2011 +0000
tree ea450fb4a9b80b6c8409babb2b2974a014722e39
parent 42e72ca3d00dbe073fbb39e181caa7f0c4c171b7

Do not add PHIs with no users when creating LCSSA form. Patch by Andrew Clinton.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127674 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/LCSSA.cpp

diff --git a/lib/Transforms/Utils/LCSSA.cpp b/lib/Transforms/Utils/LCSSA.cpp
index b2e5fa6..ade4a43 100644
--- a/lib/Transforms/Utils/LCSSA.cpp
+++ b/lib/Transforms/Utils/LCSSA.cpp
@@ -207,6 +207,8 @@
 
   DomTreeNode *DomNode = DT->getNode(DomBB);
 
+  SmallVector<PHINode*, 16> AddedPHIs;
+
   SSAUpdater SSAUpdate;
   SSAUpdate.Initialize(Inst->getType(), Inst->getName());
   
@@ -236,6 +238,8 @@
           &PN->getOperandUse(
             PN->getOperandNumForIncomingValue(PN->getNumIncomingValues()-1)));
     }
+
+    AddedPHIs.push_back(PN);
     
     // Remember that this phi makes the value alive in this block.
     SSAUpdate.AddAvailableValue(ExitBB, PN);
@@ -262,6 +266,12 @@
     // Otherwise, do full PHI insertion.
     SSAUpdate.RewriteUse(*UsesToRewrite[i]);
   }
+
+  // Remove PHI nodes that did not have any uses rewritten.
+  for (unsigned i = 0, e = AddedPHIs.size(); i != e; ++i) {
+    if (!AddedPHIs[i]->hasNUsesOrMore(1))
+      AddedPHIs[i]->eraseFromParent();
+  }
   
   return true;
 }