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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
This commit is contained in:
Duncan P. N. Exon Smith 2016-02-21 19:37:45 +00:00
parent 1b936c0f59
commit 7b269642d2
1 changed files with 6 additions and 4 deletions
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10
llvm/lib/CodeGen/CodeGenPrepare.cpp
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@ -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();