Make the InsertBefore argument to FindInsertedValue optional, so you can find an inserted value without modifying the code.

llvm-svn: 52319

llvm/include/llvm/Analysis/ValueTracking.h

@@ -55,10 +55,13 @@ namespace llvm {
   /// FindScalarValue - Given an aggregrate and an sequence of indices, see if the
   /// scalar value indexed is already around as a register, for example if it were
   /// inserted directly into the aggregrate.
+  ///
+  /// If InsertBefore is not null, this function will duplicate (modified)
+  /// insertvalues when a part of a nested struct is extracted.
   Value *FindInsertedValue(Value *V,
                          const unsigned *idx_begin,
                          const unsigned *idx_end,
-                         Instruction *InsertBefore);
+                         Instruction *InsertBefore = 0);
 } // end namespace llvm
 
 #endif

llvm/lib/Analysis/ValueTracking.cpp

@@ -805,6 +805,7 @@ Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
 // Any inserted instructions are inserted before InsertBefore
 Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
                          const unsigned *idx_end, Instruction *InsertBefore) {
+  assert(InsertBefore && "Must have someplace to insert!");
   const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
                                                              idx_begin,
                                                              idx_end);
@@ -851,9 +852,13 @@ Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
     for (const unsigned *i = I->idx_begin(), *e = I->idx_end();
          i != e; ++i, ++req_idx) {
       if (req_idx == idx_end)
+        if (InsertBefore)
           // The requested index is a part of a nested aggregate. Handle this
           // specially.
           return BuildSubAggregate(V, idx_begin, req_idx, InsertBefore);
+        else
+          // We can't handle this without inserting insertvalues
+          return 0;
       
       // This insert value inserts something else than what we are looking for.
       // See if the (aggregrate) value inserted into has the value we are