[NFC][DebugInfo] Make some block-start-position methods return iterators (#124287)

As part of the "RemoveDIs" work to eliminate debug intrinsics, we're
replacing methods that use Instruction*'s as positions with iterators. A
number of these (such as getFirstNonPHIOrDbg) are sufficiently
infrequently used that we can just replace the pointer-returning version
with an iterator-returning version, hopefully without much/any
disruption.

Thus this patch has getFirstNonPHIOrDbg and
getFirstNonPHIOrDbgOrLifetime return an iterator, and updates all
call-sites. There are no concerns about the iterators returned being
converted to Instruction*'s and losing the debug-info bit: because the
methods skip debug intrinsics, the iterator head bit is always false
anyway.

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
index c2f7c5d..bcc5620 100644
--- a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -770,7 +770,7 @@ static bool unswitchTrivialSwitch(Loop &L, SwitchInst &SI, DominatorTree &DT,
     // instruction in the block.
     auto *TI = BBToCheck.getTerminator();
     bool isUnreachable = isa<UnreachableInst>(TI);
-    return !isUnreachable || BBToCheck.getFirstNonPHIOrDbg() != TI;
+    return !isUnreachable || &*BBToCheck.getFirstNonPHIOrDbg() != TI;
   };
 
   SmallVector<int, 4> ExitCaseIndices;