[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, 10 insertions, 10 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 00280db..54de812 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -2726,7 +2726,7 @@ static Instruction *getSuccPad(Instruction *Terminator) {
     UnwindDest = CSI->getUnwindDest();
   else
     UnwindDest = cast<CleanupReturnInst>(Terminator)->getUnwindDest();
-  return UnwindDest->getFirstNonPHI();
+  return &*UnwindDest->getFirstNonPHIIt();
 }
 
 void Verifier::verifySiblingFuncletUnwinds() {
@@ -4585,7 +4585,7 @@ void Verifier::visitCatchPadInst(CatchPadInst &CPI) {
 
   // The catchpad instruction must be the first non-PHI instruction in the
   // block.
-  Check(BB->getFirstNonPHI() == &CPI,
+  Check(&*BB->getFirstNonPHIIt() == &CPI,
         "CatchPadInst not the first non-PHI instruction in the block.", &CPI);
 
   visitEHPadPredecessors(CPI);
@@ -4609,7 +4609,7 @@ void Verifier::visitCleanupPadInst(CleanupPadInst &CPI) {
 
   // The cleanuppad instruction must be the first non-PHI instruction in the
   // block.
-  Check(BB->getFirstNonPHI() == &CPI,
+  Check(&*BB->getFirstNonPHIIt() == &CPI,
         "CleanupPadInst not the first non-PHI instruction in the block.", &CPI);
 
   auto *ParentPad = CPI.getParentPad();
@@ -4664,7 +4664,7 @@ void Verifier::visitFuncletPadInst(FuncletPadInst &FPI) {
       Value *UnwindPad;
       bool ExitsFPI;
       if (UnwindDest) {
-        UnwindPad = UnwindDest->getFirstNonPHI();
+        UnwindPad = &*UnwindDest->getFirstNonPHIIt();
         if (!cast<Instruction>(UnwindPad)->isEHPad())
           continue;
         Value *UnwindParent = getParentPad(UnwindPad);
@@ -4767,7 +4767,7 @@ void Verifier::visitFuncletPadInst(FuncletPadInst &FPI) {
       BasicBlock *SwitchUnwindDest = CatchSwitch->getUnwindDest();
       Value *SwitchUnwindPad;
       if (SwitchUnwindDest)
-        SwitchUnwindPad = SwitchUnwindDest->getFirstNonPHI();
+        SwitchUnwindPad = &*SwitchUnwindDest->getFirstNonPHIIt();
       else
         SwitchUnwindPad = ConstantTokenNone::get(FPI.getContext());
       Check(SwitchUnwindPad == FirstUnwindPad,
@@ -4790,7 +4790,7 @@ void Verifier::visitCatchSwitchInst(CatchSwitchInst &CatchSwitch) {
 
   // The catchswitch instruction must be the first non-PHI instruction in the
   // block.
-  Check(BB->getFirstNonPHI() == &CatchSwitch,
+  Check(&*BB->getFirstNonPHIIt() == &CatchSwitch,
         "CatchSwitchInst not the first non-PHI instruction in the block.",
         &CatchSwitch);
 
@@ -4799,14 +4799,14 @@ void Verifier::visitCatchSwitchInst(CatchSwitchInst &CatchSwitch) {
         "CatchSwitchInst has an invalid parent.", ParentPad);
 
   if (BasicBlock *UnwindDest = CatchSwitch.getUnwindDest()) {
-    Instruction *I = UnwindDest->getFirstNonPHI();
+    BasicBlock::iterator I = UnwindDest->getFirstNonPHIIt();
     Check(I->isEHPad() && !isa<LandingPadInst>(I),
           "CatchSwitchInst must unwind to an EH block which is not a "
           "landingpad.",
           &CatchSwitch);
 
     // Record catchswitch sibling unwinds for verifySiblingFuncletUnwinds
-    if (getParentPad(I) == ParentPad)
+    if (getParentPad(&*I) == ParentPad)
       SiblingFuncletInfo[&CatchSwitch] = &CatchSwitch;
   }
 
@@ -4814,7 +4814,7 @@ void Verifier::visitCatchSwitchInst(CatchSwitchInst &CatchSwitch) {
         "CatchSwitchInst cannot have empty handler list", &CatchSwitch);
 
   for (BasicBlock *Handler : CatchSwitch.handlers()) {
-    Check(isa<CatchPadInst>(Handler->getFirstNonPHI()),
+    Check(isa<CatchPadInst>(Handler->getFirstNonPHIIt()),
           "CatchSwitchInst handlers must be catchpads", &CatchSwitch, Handler);
   }
 
@@ -4828,7 +4828,7 @@ void Verifier::visitCleanupReturnInst(CleanupReturnInst &CRI) {
         CRI.getOperand(0));
 
   if (BasicBlock *UnwindDest = CRI.getUnwindDest()) {
-    Instruction *I = UnwindDest->getFirstNonPHI();
+    BasicBlock::iterator I = UnwindDest->getFirstNonPHIIt();
     Check(I->isEHPad() && !isa<LandingPadInst>(I),
           "CleanupReturnInst must unwind to an EH block which is not a "
           "landingpad.",