eliminate code related to --no-ir-gen

tests_lit/reader_tests/unreachable.ll

 ; Test parsing unreachable instruction.
 
 ; RUN: %p2i -i %s --insts | FileCheck %s
 ; RUN: %if --need=allow_disable_ir_gen --command \
-; RUN:   %p2i -i %s --args -notranslate -timing -no-ir-gen \
+; RUN:   %p2i -i %s --args -notranslate -timing \
 ; RUN: | %if --need=allow_disable_ir_gen --command \
 ; RUN:   FileCheck --check-prefix=NOIR %s
 
 define internal i32 @divide(i32 %num, i32 %den) {
 entry:
   %cmp = icmp ne i32 %den, 0
   br i1 %cmp, label %return, label %abort
 
 abort:                                            ; preds = %entry
   unreachable
 
 return:                                           ; preds = %entry
   %div = sdiv i32 %num, %den
   ret i32 %div
 }
 
 ; CHECK:      define internal i32 @divide(i32 %num, i32 %den) {
 ; CHECK-NEXT: entry:
 ; CHECK-NEXT:   %cmp = icmp ne i32 %den, 0
 ; CHECK-NEXT:   br i1 %cmp, label %return, label %abort
 ; CHECK-NEXT: abort:
 ; CHECK-NEXT:   unreachable
 ; CHECK-NEXT: return:
 ; CHECK-NEXT:   %div = sdiv i32 %num, %den
 ; CHECK-NEXT:   ret i32 %div
 ; CHECK-NEXT: }
 
 ; NOIR: Total across all functions