[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/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 3e89b18..33c6341 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -250,7 +250,7 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
     // Don't create MachineBasicBlocks for imaginary EH pad blocks. These blocks
     // are really data, and no instructions can live here.
     if (BB.isEHPad()) {
-      const Instruction *PadInst = BB.getFirstNonPHI();
+      BasicBlock::const_iterator PadInst = BB.getFirstNonPHIIt();
       // If this is a non-landingpad EH pad, mark this function as using
       // funclets.
       // FIXME: SEH catchpads do not create EH scope/funclets, so we could avoid
@@ -261,13 +261,13 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
         MF->getFrameInfo().setHasOpaqueSPAdjustment(true);
       }
       if (isa<CatchSwitchInst>(PadInst)) {
-        assert(&*BB.begin() == PadInst &&
+        assert(BB.begin() == PadInst &&
                "WinEHPrepare failed to remove PHIs from imaginary BBs");
         continue;
       }
       if (isa<FuncletPadInst>(PadInst) &&
           Personality != EHPersonality::Wasm_CXX)
-        assert(&*BB.begin() == PadInst && "WinEHPrepare failed to demote PHIs");
+        assert(BB.begin() == PadInst && "WinEHPrepare failed to demote PHIs");
     }
 
     MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(&BB);