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, 2 insertions, 2 deletions

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index b4d7a660688..2b39f2273b3 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -817,7 +817,7 @@ void SlotTracker::processFunction() {
   for(Function::const_arg_iterator AI = TheFunction->arg_begin(),
       AE = TheFunction->arg_end(); AI != AE; ++AI)
     if (!AI->hasName())
-      CreateFunctionSlot(AI);
+      CreateFunctionSlot(&*AI);
 
   ST_DEBUG("Inserting Instructions:\n");
 
@@ -2635,7 +2635,7 @@ void AssemblyWriter::printFunction(const Function *F) {
     Out << " {";
     // Output all of the function's basic blocks.
     for (Function::const_iterator I = F->begin(), E = F->end(); I != E; ++I)
-      printBasicBlock(I);
+      printBasicBlock(&*I);
 
     // Output the function's use-lists.
     printUseLists(F);