Remove always-true comparison, NFC.

Summary:
Looking at r241279, I noticed that UpgradedIntrinsics only gets written
to in the following code:

    if (UpgradeIntrinsicFunction(&F, NewFn))
      UpgradedIntrinsics[&F] = NewFn;

Looking through UpgradeIntrinsicFunction, we always return false OR
NewFn will be set to a different function from our source.

This patch pulls the F != NewFn into UpgradeIntrinsicFunction as an
assert, and removes the check from callers of UpgradeIntrinsicFunction.

Reviewers: rafael, chandlerc

Subscribers: llvm-commits-list

Differential Revision: http://reviews.llvm.org/D10915

llvm-svn: 241369
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
index 70a5518..f1c6ebd 100644
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -229,6 +229,7 @@
 bool llvm::UpgradeIntrinsicFunction(Function *F, Function *&NewFn) {
   NewFn = nullptr;
   bool Upgraded = UpgradeIntrinsicFunction1(F, NewFn);
+  assert(F != NewFn && "Intrinsic function upgraded to the same function");
 
   // Upgrade intrinsic attributes.  This does not change the function.
   if (NewFn)
@@ -710,16 +711,14 @@
   // Upgrade the function and check if it is a totaly new function.
   Function *NewFn;
   if (UpgradeIntrinsicFunction(F, NewFn)) {
-    if (NewFn != F) {
-      // Replace all uses to the old function with the new one if necessary.
-      for (Value::user_iterator UI = F->user_begin(), UE = F->user_end();
-           UI != UE; ) {
-        if (CallInst *CI = dyn_cast<CallInst>(*UI++))
-          UpgradeIntrinsicCall(CI, NewFn);
-      }
-      // Remove old function, no longer used, from the module.
-      F->eraseFromParent();
+    // Replace all uses to the old function with the new one if necessary.
+    for (Value::user_iterator UI = F->user_begin(), UE = F->user_end();
+         UI != UE;) {
+      if (CallInst *CI = dyn_cast<CallInst>(*UI++))
+        UpgradeIntrinsicCall(CI, NewFn);
     }
+    // Remove old function, no longer used, from the module.
+    F->eraseFromParent();
   }
 }