[InstSimplify] Add pre-commit tests. NFC.

Author: dtcxzyw

llvm/test/Transforms/InstSimplify/select-icmp.ll

@@ -244,3 +244,21 @@ cond.true:                                        ; preds = %entry
 cond.end:                                         ; preds = %entry, %cond.true
   ret i8 0
 }
+
+define ptr @icmp_ptr_eq_replace(ptr %a, ptr %b) {
+; CHECK-LABEL: @icmp_ptr_eq_replace(
+; CHECK-NEXT:    ret ptr [[B:%.*]]
+;
+  %cmp = icmp eq ptr %a, %b
+  %sel = select i1 %cmp, ptr %a, ptr %b
+  ret ptr %sel
+}
+
+define ptr @icmp_ptr_eq_replace_null(ptr %a) {
+; CHECK-LABEL: @icmp_ptr_eq_replace_null(
+; CHECK-NEXT:    ret ptr [[A:%.*]]
+;
+  %cmp = icmp eq ptr %a, null
+  %sel = select i1 %cmp, ptr null, ptr %a
+  ret ptr %sel
+}