"This patch adds a virtual call to AbstractLatticeFunction to derive a

type lattice value for an Argument*, giving clients the opportunity to
use something other than Top for it if they choose to."

Patch by John McCall!

llvm-svn: 54589

2 files changed, 10 insertions, 1 deletions

diff --git a/llvm/include/llvm/Analysis/SparsePropagation.h b/llvm/include/llvm/Analysis/SparsePropagation.h
index bc9ae6172b8..a054c76c9bc 100644
--- a/llvm/include/llvm/Analysis/SparsePropagation.h
+++ b/llvm/include/llvm/Analysis/SparsePropagation.h
@@ -24,6 +24,7 @@
 namespace llvm {
   class Value;
   class Constant;
+  class Argument;
   class Instruction;
   class PHINode;
   class TerminatorInst;
@@ -75,6 +76,12 @@ public:
   virtual Constant *GetConstant(LatticeVal LV, Value *Val, SparseSolver &SS) {
     return 0;
   }
+
+  /// ComputeArgument - Given a formal argument value, compute and return a
+  /// lattice value corresponding to the specified argument.
+  virtual LatticeVal ComputeArgument(Argument *I) {
+    return getOverdefinedVal(); // always safe
+  }
   
   /// MergeValues - Compute and return the merge of the two specified lattice
   /// values.  Merging should only move one direction down the lattice to
diff --git a/llvm/lib/Analysis/SparsePropagation.cpp b/llvm/lib/Analysis/SparsePropagation.cpp
index 2fda64c7335..8f042c27839 100644
--- a/llvm/lib/Analysis/SparsePropagation.cpp
+++ b/llvm/lib/Analysis/SparsePropagation.cpp
@@ -57,8 +57,10 @@ SparseSolver::LatticeVal SparseSolver::getOrInitValueState(Value *V) {
     return LatticeFunc->getUntrackedVal();
   else if (Constant *C = dyn_cast<Constant>(V))
     LV = LatticeFunc->ComputeConstant(C);
+  else if (Argument *A = dyn_cast<Argument>(V))
+    LV = LatticeFunc->ComputeArgument(A);
   else if (!isa<Instruction>(V))
-    // Non-instructions (e.g. formal arguments) are overdefined.
+    // All other non-instructions are overdefined.
     LV = LatticeFunc->getOverdefinedVal();
   else
     // All instructions are underdefined by default.