; LLVM IR from tangjz/acm-icpc :: 51nod (1069)

; Unoptimized IR (clang -disable-llvm-passes):
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

@n = external dso_local global i32, align 4
@sg = external dso_local global i32, align 4
@x = external dso_local global i32, align 4
@.str = external hidden unnamed_addr constant [3 x i8], align 1
@.str.1 = external hidden unnamed_addr constant [2 x i8], align 1
@.str.2 = external hidden unnamed_addr constant [2 x i8], align 1

; Function Attrs: mustprogress norecurse uwtable
define dso_local noundef i32 @main() #0 {
  %1 = alloca i32, align 4
  store i32 0, ptr %1, align 4
  %2 = call i32 (ptr, ...) @__isoc99_scanf(ptr noundef @.str, ptr noundef @n)
  br label %3

3:                                                ; preds = %7, %0
  %4 = load i32, ptr @n, align 4, !tbaa !5
  %5 = add nsw i32 %4, -1
  store i32 %5, ptr @n, align 4, !tbaa !5
  %6 = icmp ne i32 %4, 0
  br i1 %6, label %7, label %12

7:                                                ; preds = %3
  %8 = call i32 (ptr, ...) @__isoc99_scanf(ptr noundef @.str, ptr noundef @x)
  %9 = load i32, ptr @x, align 4, !tbaa !5
  %10 = load i32, ptr @sg, align 4, !tbaa !5
  %11 = xor i32 %10, %9
  store i32 %11, ptr @sg, align 4, !tbaa !5
  br label %3, !llvm.loop !9

12:                                               ; preds = %3
  %13 = load i32, ptr @sg, align 4, !tbaa !5
  %14 = icmp ne i32 %13, 0
  br i1 %14, label %15, label %16

15:                                               ; preds = %12
  br label %17

16:                                               ; preds = %12
  br label %17

17:                                               ; preds = %16, %15
  %18 = phi ptr [ @.str.1, %15 ], [ @.str.2, %16 ]
  %19 = getelementptr inbounds [2 x i8], ptr %18, i64 0, i64 0
  %20 = call i32 @puts(ptr noundef %19)
  %21 = load i32, ptr %1, align 4
  ret i32 %21
}

declare i32 @__isoc99_scanf(ptr noundef, ...) #1

declare i32 @puts(ptr noundef) #1

attributes #0 = { mustprogress norecurse uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #1 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }

!llvm.module.flags = !{!0, !1, !2, !3}
!llvm.ident = !{!4}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 8, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 2}
!4 = !{!"clang version 19.1.0 (git@github.com:llvm/llvm-project.git a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}


; Optimized IR (opt -passes='default<O3>'):
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

@n = external dso_local global i32, align 4
@sg = external dso_local local_unnamed_addr global i32, align 4
@x = external dso_local global i32, align 4
@.str = external hidden unnamed_addr constant [3 x i8], align 1
@.str.1 = external hidden unnamed_addr constant [2 x i8], align 1
@.str.2 = external hidden unnamed_addr constant [2 x i8], align 1

; Function Attrs: mustprogress nofree norecurse nounwind uwtable
define dso_local noundef i32 @main() local_unnamed_addr #0 {
  %1 = tail call i32 (ptr, ...) @__isoc99_scanf(ptr noundef nonnull @.str, ptr noundef nonnull @n)
  %2 = load i32, ptr @n, align 4, !tbaa !5
  %3 = add nsw i32 %2, -1
  store i32 %3, ptr @n, align 4, !tbaa !5
  %.not2 = icmp eq i32 %2, 0
  br i1 %.not2, label %.._crit_edge_crit_edge, label %.lr.ph

.._crit_edge_crit_edge:                           ; preds = %0
  %.pre = load i32, ptr @sg, align 4, !tbaa !5
  br label %._crit_edge

.lr.ph:                                           ; preds = %0, %.lr.ph
  %4 = tail call i32 (ptr, ...) @__isoc99_scanf(ptr noundef nonnull @.str, ptr noundef nonnull @x)
  %5 = load i32, ptr @x, align 4, !tbaa !5
  %6 = load i32, ptr @sg, align 4, !tbaa !5
  %7 = xor i32 %6, %5
  store i32 %7, ptr @sg, align 4, !tbaa !5
  %8 = load i32, ptr @n, align 4, !tbaa !5
  %9 = add nsw i32 %8, -1
  store i32 %9, ptr @n, align 4, !tbaa !5
  %.not = icmp eq i32 %8, 0
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !9

._crit_edge:                                      ; preds = %.lr.ph, %.._crit_edge_crit_edge
  %10 = phi i32 [ %.pre, %.._crit_edge_crit_edge ], [ %7, %.lr.ph ]
  %.not1 = icmp eq i32 %10, 0
  %.str.1..str.2 = select i1 %.not1, ptr @.str.2, ptr @.str.1
  %11 = tail call i32 @puts(ptr noundef nonnull dereferenceable(1) %.str.1..str.2)
  ret i32 0
}

; Function Attrs: nofree nounwind
declare noundef i32 @__isoc99_scanf(ptr nocapture noundef readonly, ...) local_unnamed_addr #1

; Function Attrs: nofree nounwind
declare noundef i32 @puts(ptr nocapture noundef readonly) local_unnamed_addr #1

attributes #0 = { mustprogress nofree norecurse nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #1 = { nofree nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }

!llvm.module.flags = !{!0, !1, !2, !3}
!llvm.ident = !{!4}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 8, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 2}
!4 = !{!"clang version 19.1.0 (git@github.com:llvm/llvm-project.git a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: EarlyCSEPass,GVNPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass