[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, 3 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 94cf118..d5cf62e 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -2108,7 +2108,7 @@ insertDbgVariableRecordsForPHIs(BasicBlock *BB,
   for (auto PHI : InsertedPHIs) {
     BasicBlock *Parent = PHI->getParent();
     // Avoid inserting a debug-info record into an EH block.
-    if (Parent->getFirstNonPHI()->isEHPad())
+    if (Parent->getFirstNonPHIIt()->isEHPad())
       continue;
     for (auto VI : PHI->operand_values()) {
       auto V = DbgValueMap.find(VI);
@@ -2174,7 +2174,7 @@ void llvm::insertDebugValuesForPHIs(BasicBlock *BB,
   for (auto *PHI : InsertedPHIs) {
     BasicBlock *Parent = PHI->getParent();
     // Avoid inserting an intrinsic into an EH block.
-    if (Parent->getFirstNonPHI()->isEHPad())
+    if (Parent->getFirstNonPHIIt()->isEHPad())
       continue;
     for (auto *VI : PHI->operand_values()) {
       auto V = DbgValueMap.find(VI);
@@ -3206,7 +3206,7 @@ static bool markAliveBlocks(Function &F,
         BasicBlock *HandlerBB = *I;
         if (DTU)
           ++NumPerSuccessorCases[HandlerBB];
-        auto *CatchPad = cast<CatchPadInst>(HandlerBB->getFirstNonPHI());
+        auto *CatchPad = cast<CatchPadInst>(HandlerBB->getFirstNonPHIIt());
         if (!HandlerSet.insert({CatchPad, Empty}).second) {
           if (DTU)
             --NumPerSuccessorCases[HandlerBB];