CodeGen: Avoid getNodePtrUnchecked() where we need a Value, NFC

`ilist_iterator<NodeTy>::getNodePtrUnchecked()` is documented as being
for internal use only, but CodeGenPrepare was using it anyway.  This
code relies on pulling out the `Value*` pointer even after the lifetime
of the iterator is over.  But having this pointer available in
ilist_iterator depends on UB in the first place.

Instead, safely pull out the `Value*` when the iterator is alive and
stop using the internal-only API.

There should be no functionality change here.

llvm-svn: 261493

1 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index f8bd3f37203..a4e382d9c85 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -1773,13 +1773,14 @@ bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool& ModifiedDT) {
       // Substituting this can cause recursive simplifications, which can
       // invalidate our iterator.  Use a WeakVH to hold onto it in case this
       // happens.
-      WeakVH IterHandle(&*CurInstIterator);
+      Value *CurValue = &*CurInstIterator;
+      WeakVH IterHandle(CurValue);
 
       replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
 
       // If the iterator instruction was recursively deleted, start over at the
       // start of the block.
-      if (IterHandle != CurInstIterator.getNodePtrUnchecked()) {
+      if (IterHandle != CurValue) {
         CurInstIterator = BB->begin();
         SunkAddrs.clear();
       }
@@ -3945,12 +3946,13 @@ bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
   if (Repl->use_empty()) {
     // This can cause recursive deletion, which can invalidate our iterator.
     // Use a WeakVH to hold onto it in case this happens.
-    WeakVH IterHandle(&*CurInstIterator);
+    Value *CurValue = &*CurInstIterator;
+    WeakVH IterHandle(CurValue);
     BasicBlock *BB = CurInstIterator->getParent();
 
     RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
 
-    if (IterHandle != CurInstIterator.getNodePtrUnchecked()) {
+    if (IterHandle != CurValue) {
       // If the iterator instruction was recursively deleted, start over at the
       // start of the block.
       CurInstIterator = BB->begin();