[PowerPC] Add test case for pr47830. NFC.

llvm/test/CodeGen/PowerPC/pr47830.ll

@@ -0,0 +1,27 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -ppc-asm-full-reg-names -verify-machineinstrs \
+; RUN:   -mtriple=powerpc64le-linux-gnu < %s | FileCheck %s
+
+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:    blr
+  %c = icmp slt i64 %a, %b
+  %d = sub i64 %a, %b
+  %e = select i1 %c, i64 0, i64 %d
+  ret i64 %e
+}
+
+define i64 @g(i64 %a, i64 %b) {
+; CHECK-LABEL: g:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    sub. r3, r3, r4
+; CHECK-NEXT:    isellt r3, 0, r3
+; CHECK-NEXT:    blr
+  %c = icmp slt i64 %a, %b
+  %d = sub nsw i64 %a, %b
+  %e = select i1 %c, i64 0, i64 %d
+  ret i64 %e
+}