[MachineBasicBlock] Add helpers for skipping debug instructions [1/14]

Summary:
These helpers are exercised by follow-up commits in this patch series,
which is all about removing CodeGen differences with vs. without debug
info in the AArch64 backend.

Reviewers: fhahn, aprantl, jpaquette, paquette

Subscribers: kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78260

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 5f46086..57dd8d3 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -1329,8 +1329,8 @@ MachineBasicBlock::findDebugLoc(instr_iterator MBBI) {
 /// instructions.  Return UnknownLoc if there is none.
 DebugLoc MachineBasicBlock::findPrevDebugLoc(instr_iterator MBBI) {
   if (MBBI == instr_begin()) return {};
-  // Skip debug declarations, we don't want a DebugLoc from them.
-  MBBI = skipDebugInstructionsBackward(std::prev(MBBI), instr_begin());
+  // Skip debug instructions, we don't want a DebugLoc from them.
+  MBBI = prev_nodbg(MBBI, instr_begin());
   if (!MBBI->isDebugInstr()) return MBBI->getDebugLoc();
   return {};
 }