diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -2141,6 +2141,14 @@
   if (NewOpC == -1)
     return false;
 
+  // This transformation should not be performed if `nsw` is missing and is not
+  // `equalityOnly` comparison. Since if there is overflow, sub_lt, sub_gt in
+  // CRReg do not reflect correct order. If `equalityOnly` is true, sub_eq in
+  // CRReg can reflect if compared values are equal, this optz is still valid.
+  if (!equalityOnly && (NewOpC == PPC::SUBF_rec || NewOpC == PPC::SUBF8_rec) &&
+      Sub && !Sub->getFlag(MachineInstr::NoSWrap))
+    return false;
+
   // If we have SUB(r1, r2) and CMP(r2, r1), the condition code based on CMP
   // needs to be updated to be based on SUB.  Push the condition code
   // operands to OperandsToUpdate.  If it is safe to remove CmpInstr, the
diff --git a/llvm/test/CodeGen/PowerPC/pr47830.ll b/llvm/test/CodeGen/PowerPC/pr47830.ll
--- a/llvm/test/CodeGen/PowerPC/pr47830.ll
+++ b/llvm/test/CodeGen/PowerPC/pr47830.ll
@@ -5,8 +5,9 @@
 define i64 @f(i64 %a, i64 %b) {
 ; CHECK-LABEL: f:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    sub. r3, r3, r4
-; CHECK-NEXT:    isellt r3, 0, r3
+; CHECK-NEXT:    sub r5, r3, r4
+; CHECK-NEXT:    cmpd r3, r4
+; CHECK-NEXT:    isellt r3, 0, r5
 ; CHECK-NEXT:    blr
   %c = icmp slt i64 %a, %b
   %d = sub i64 %a, %b