From: Nick Lewycky <nicholas@mxc.ca>
Date: Sat, 19 Sep 2009 18:33:36 +0000 (+0000)
Subject: Lett users of sparse propagation do their own thing with phi nodes if they want
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=875646f376f6c83bf8426fdb44e1dbf312cf784e;p=oota-llvm.git

Lett users of sparse propagation do their own thing with phi nodes if they want
to. This can be combined with LCSSA or SSI form to store more information on a
PHINode than can be computed by looking at its incoming values.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82317 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/Analysis/SparsePropagation.h b/include/llvm/Analysis/SparsePropagation.h
index cc655aa85fd..820e1bd1e43 100644
--- a/include/llvm/Analysis/SparsePropagation.h
+++ b/include/llvm/Analysis/SparsePropagation.h
@@ -72,6 +72,12 @@ public:
   virtual LatticeVal ComputeConstant(Constant *C) {
     return getOverdefinedVal(); // always safe
   }
+
+  /// IsSpecialCasedPHI - Given a PHI node, determine whether this PHI node is
+  /// one that the we want to handle through ComputeInstructionState.
+  virtual bool IsSpecialCasedPHI(PHINode *PN) {
+    return false;
+  }
   
   /// GetConstant - If the specified lattice value is representable as an LLVM
   /// constant value, return it.  Otherwise return null.  The returned value
diff --git a/lib/Analysis/SparsePropagation.cpp b/lib/Analysis/SparsePropagation.cpp
index 17bb73f991e..8a74745dd3f 100644
--- a/lib/Analysis/SparsePropagation.cpp
+++ b/lib/Analysis/SparsePropagation.cpp
@@ -223,6 +223,13 @@ void SparseSolver::visitTerminatorInst(TerminatorInst &TI) {
 }
 
 void SparseSolver::visitPHINode(PHINode &PN) {
+  if (LatticeFunc->IsSpecialCasedPHI(&PN)) {
+    LatticeVal IV = LatticeFunc->ComputeInstructionState(PN, *this);
+    if (IV != LatticeFunc->getUntrackedVal())
+      UpdateState(PN, IV);
+    return;
+  }
+
   LatticeVal PNIV = getOrInitValueState(&PN);
   LatticeVal Overdefined = LatticeFunc->getOverdefinedVal();