IR: Remove implicit iterator conversions from lib/IR, NFC

Stop converting implicitly between iterators and pointers/references in
lib/IR.  For convenience, I've added a `getIterator()` accessor to
`ilist_node` so that callers don't need to know how to spell the
iterator class (i.e., they can use `X.getIterator()` instead of
`Function::iterator(X)`).

I'll eventually disallow these implicit conversions entirely, but
there's a lot of code, so it doesn't make sense to do it all in one
patch.  One library or so at a time.

Why?  To root out cases of `getNextNode()` and `getPrevNode()` being
used in iterator logic.  The design of `ilist` makes that invalid when
the current node could be at the back of the list, but it happens to
"work" right now because of a bug where those functions never return
`nullptr` if you're using a half-node sentinel.  Before I can fix the
function, I have to remove uses of it that rely on it misbehaving.
(Maybe the function should just be deleted anyway?  But I don't want
deleting it -- potentially a huge project -- to block fixing
ilist/iplist.)

llvm-svn: 249782

1 files changed, 8 insertions, 7 deletions

diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index 91ac83c10d4..b5a30a4969b 100644
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -28,7 +28,7 @@ Instruction::Instruction(Type *ty, unsigned it, Use *Ops, unsigned NumOps,
   if (InsertBefore) {
     BasicBlock *BB = InsertBefore->getParent();
     assert(BB && "Instruction to insert before is not in a basic block!");
-    BB->getInstList().insert(InsertBefore, this);
+    BB->getInstList().insert(InsertBefore->getIterator(), this);
   }
 }
 
@@ -64,31 +64,32 @@ Module *Instruction::getModule() {
 
 
 void Instruction::removeFromParent() {
-  getParent()->getInstList().remove(this);
+  getParent()->getInstList().remove(getIterator());
 }
 
 iplist<Instruction>::iterator Instruction::eraseFromParent() {
-  return getParent()->getInstList().erase(this);
+  return getParent()->getInstList().erase(getIterator());
 }
 
 /// insertBefore - Insert an unlinked instructions into a basic block
 /// immediately before the specified instruction.
 void Instruction::insertBefore(Instruction *InsertPos) {
-  InsertPos->getParent()->getInstList().insert(InsertPos, this);
+  InsertPos->getParent()->getInstList().insert(InsertPos->getIterator(), this);
 }
 
 /// insertAfter - Insert an unlinked instructions into a basic block
 /// immediately after the specified instruction.
 void Instruction::insertAfter(Instruction *InsertPos) {
-  InsertPos->getParent()->getInstList().insertAfter(InsertPos, this);
+  InsertPos->getParent()->getInstList().insertAfter(InsertPos->getIterator(),
+                                                    this);
 }
 
 /// moveBefore - Unlink this instruction from its current basic block and
 /// insert it into the basic block that MovePos lives in, right before
 /// MovePos.
 void Instruction::moveBefore(Instruction *MovePos) {
-  MovePos->getParent()->getInstList().splice(MovePos,getParent()->getInstList(),
-                                             this);
+  MovePos->getParent()->getInstList().splice(
+      MovePos->getIterator(), getParent()->getInstList(), getIterator());
 }
 
 /// Set or clear the unsafe-algebra flag on this instruction, which must be an