[NFC][DebugInfo] Use iterator-flavour getFirstNonPHI at many call-sites (#123737)

As part of the "RemoveDIs" project, BasicBlock::iterator now carries a
debug-info bit that's needed when getFirstNonPHI and similar feed into
instruction insertion positions. Call-sites where that's necessary were
updated a year ago; but to ensure some type safety however, we'd like to
have all calls to getFirstNonPHI use the iterator-returning version.

This patch changes a bunch of call-sites calling getFirstNonPHI to use
getFirstNonPHIIt, which returns an iterator. All these call sites are
where it's obviously safe to fetch the iterator then dereference it. A
follow-up patch will contain less-obviously-safe changes.

We'll eventually deprecate and remove the instruction-pointer
getFirstNonPHI, but not before adding concise documentation of what
considerations are needed (very few).

---------

Co-authored-by: Stephen Tozer <Melamoto@gmail.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopSimplify.cpp b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
index b3f9f76..61ffb49 100644
--- a/llvm/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
@@ -382,7 +382,7 @@ static BasicBlock *insertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader,
   BasicBlock *BEBlock = BasicBlock::Create(Header->getContext(),
                                            Header->getName() + ".backedge", F);
   BranchInst *BETerminator = BranchInst::Create(Header, BEBlock);
-  BETerminator->setDebugLoc(Header->getFirstNonPHI()->getDebugLoc());
+  BETerminator->setDebugLoc(Header->getFirstNonPHIIt()->getDebugLoc());
 
   LLVM_DEBUG(dbgs() << "LoopSimplify: Inserting unique backedge block "
                     << BEBlock->getName() << "\n");