[llvm] r266550 - Revert "use range loop, try to make comments more meaningful; NFCI"

[Duncan P. N. Exon Smith via llvm-commits]

Author: dexonsmith
Date: Sat Apr 16 22:59:37 2016
New Revision: 266550

URL: http://llvm.org/viewvc/llvm-project?rev=266550&view=rev
Log:
Revert "use range loop, try to make comments more meaningful; NFCI"

This reverts commit r266541 since it introduces a use-after-free:
  http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/11471

Modified:
    llvm/trunk/lib/IR/AutoUpgrade.cpp

Modified: llvm/trunk/lib/IR/AutoUpgrade.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/AutoUpgrade.cpp?rev=266550&r1=266549&r2=266550&view=diff
==============================================================================
--- llvm/trunk/lib/IR/AutoUpgrade.cpp (original)
+++ llvm/trunk/lib/IR/AutoUpgrade.cpp Sat Apr 16 22:59:37 2016
@@ -802,18 +802,21 @@ void llvm::UpgradeIntrinsicCall(CallInst
   }
 }
 
-void llvm::UpgradeCallsToIntrinsic(Function *F) {
+// This tests each Function to determine if it needs upgrading. When we find
+// one we are interested in, we then upgrade all calls to reflect the new
+// function.
+void llvm::UpgradeCallsToIntrinsic(Function* F) {
   assert(F && "Illegal attempt to upgrade a non-existent intrinsic.");
 
-  // Check if this function should be upgraded and get the replacement function
-  // if there is one.
+  // Upgrade the function and check if it is a totaly new function.
   Function *NewFn;
   if (UpgradeIntrinsicFunction(F, NewFn)) {
-    // Replace all users of the old function with the new function or new IR.
-    for (User *U : F->users())
-      if (CallInst *CI = dyn_cast<CallInst>(U))
+    // 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();
   }