diff --git a/llvm/lib/CodeGen/PeepholeOptimizer.cpp b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
--- a/llvm/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
@@ -616,6 +616,7 @@
   // Attempt to optimize the comparison instruction.
   LLVM_DEBUG(dbgs() << "Attempting to optimize compare: " << MI);
   if (TII->optimizeCompareInstr(MI, SrcReg, SrcReg2, CmpMask, CmpValue, MRI)) {
+    LLVM_DEBUG(dbgs() << "  -> Successfully optimized compare!\n");
     ++NumCmps;
     return true;
   }
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -1183,10 +1183,9 @@
                         return MI.getIterator() == From;
                       }) != To->getParent()->rend());
 
-  // We iterate backward starting \p To until we hit \p From.
-  for (--To; To != From; --To) {
-    const MachineInstr &Instr = *To;
-
+  // We iterate backward starting at \p To until we hit \p From.
+  for (const MachineInstr &Instr :
+       reversedInstructionsWithoutDebug(std::prev(To), From)) {
     if (((AccessToCheck & AK_Write) &&
          Instr.modifiesRegister(AArch64::NZCV, TRI)) ||
         ((AccessToCheck & AK_Read) && Instr.readsRegister(AArch64::NZCV, TRI)))
diff --git a/llvm/test/CodeGen/AArch64/arm64-csel.ll b/llvm/test/CodeGen/AArch64/arm64-csel.ll
--- a/llvm/test/CodeGen/AArch64/arm64-csel.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-csel.ll
@@ -1,4 +1,4 @@
-; RUN: llc -O3 < %s | FileCheck %s
+; RUN: llc -debugify-and-strip-all-safe -O3 < %s | FileCheck %s
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n32:64"
 target triple = "arm64-unknown-unknown"