Move Value::getUnderlyingObject to be a standalone

function so that it can live in Analysis instead of
VMCore.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121885 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 0 deletions

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index a612f130d1..d1b75c3f9f 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -1426,3 +1426,23 @@ uint64_t llvm::GetStringLength(Value *V) {
   // an empty string as a length.
   return Len == ~0ULL ? 1 : Len;
 }
+
+Value *llvm::GetUnderlyingObject(Value *V, unsigned MaxLookup) {
+  if (!V->getType()->isPointerTy())
+    return V;
+  for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
+    if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
+      V = GEP->getPointerOperand();
+    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
+      V = cast<Operator>(V)->getOperand(0);
+    } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
+      if (GA->mayBeOverridden())
+        return V;
+      V = GA->getAliasee();
+    } else {
+      return V;
+    }
+    assert(V->getType()->isPointerTy() && "Unexpected operand type!");
+  }
+  return V;
+}