; LLVM IR from tangjz/acm-icpc :: luogu/1019.ll (Z3dfsii)

; 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
@f = external dso_local global [21 x [21 x i32]], align 16
@used = external dso_local global [21 x i32], align 16
@ans = external dso_local global i32, align 4

; Function Attrs: mustprogress uwtable
define dso_local void @_Z3dfsii(i32 noundef %0, i32 noundef %1) #0 {
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  store i32 %1, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  store i32 1, ptr %5, align 4, !tbaa !5
  br label %6

6:                                                ; preds = %48, %2
  %7 = load i32, ptr %5, align 4, !tbaa !5
  %8 = load i32, ptr @n, align 4, !tbaa !5
  %9 = icmp sle i32 %7, %8
  br i1 %9, label %11, label %10

10:                                               ; preds = %6
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  br label %51

11:                                               ; preds = %6
  %12 = load i32, ptr %5, align 4, !tbaa !5
  %13 = sext i32 %12 to i64
  %14 = getelementptr inbounds [21 x i32], ptr @used, i64 0, i64 %13
  %15 = load i32, ptr %14, align 4, !tbaa !5
  %16 = icmp slt i32 %15, 2
  br i1 %16, label %17, label %47

17:                                               ; preds = %11
  %18 = load i32, ptr %3, align 4, !tbaa !5
  %19 = sext i32 %18 to i64
  %20 = getelementptr inbounds [21 x [21 x i32]], ptr @f, i64 0, i64 %19
  %21 = load i32, ptr %5, align 4, !tbaa !5
  %22 = sext i32 %21 to i64
  %23 = getelementptr inbounds [21 x i32], ptr %20, i64 0, i64 %22
  %24 = load i32, ptr %23, align 4, !tbaa !5
  %25 = icmp ne i32 %24, 0
  br i1 %25, label %26, label %47

26:                                               ; preds = %17
  %27 = load i32, ptr %5, align 4, !tbaa !5
  %28 = sext i32 %27 to i64
  %29 = getelementptr inbounds [21 x i32], ptr @used, i64 0, i64 %28
  %30 = load i32, ptr %29, align 4, !tbaa !5
  %31 = add nsw i32 %30, 1
  store i32 %31, ptr %29, align 4, !tbaa !5
  %32 = load i32, ptr %5, align 4, !tbaa !5
  %33 = load i32, ptr %4, align 4, !tbaa !5
  %34 = load i32, ptr %3, align 4, !tbaa !5
  %35 = sext i32 %34 to i64
  %36 = getelementptr inbounds [21 x [21 x i32]], ptr @f, i64 0, i64 %35
  %37 = load i32, ptr %5, align 4, !tbaa !5
  %38 = sext i32 %37 to i64
  %39 = getelementptr inbounds [21 x i32], ptr %36, i64 0, i64 %38
  %40 = load i32, ptr %39, align 4, !tbaa !5
  %41 = add nsw i32 %33, %40
  call void @_Z3dfsii(i32 noundef %32, i32 noundef %41)
  %42 = load i32, ptr %5, align 4, !tbaa !5
  %43 = sext i32 %42 to i64
  %44 = getelementptr inbounds [21 x i32], ptr @used, i64 0, i64 %43
  %45 = load i32, ptr %44, align 4, !tbaa !5
  %46 = add nsw i32 %45, -1
  store i32 %46, ptr %44, align 4, !tbaa !5
  br label %47

47:                                               ; preds = %26, %17, %11
  br label %48

48:                                               ; preds = %47
  %49 = load i32, ptr %5, align 4, !tbaa !5
  %50 = add nsw i32 %49, 1
  store i32 %50, ptr %5, align 4, !tbaa !5
  br label %6, !llvm.loop !9

51:                                               ; preds = %10
  %52 = load i32, ptr %4, align 4, !tbaa !5
  %53 = load i32, ptr @ans, align 4, !tbaa !5
  %54 = icmp sgt i32 %52, %53
  br i1 %54, label %55, label %57

55:                                               ; preds = %51
  %56 = load i32, ptr %4, align 4, !tbaa !5
  store i32 %56, ptr @ans, align 4, !tbaa !5
  br label %57

57:                                               ; preds = %55, %51
  ret void
}

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

attributes #0 = { mustprogress 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 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #2 = { nounwind }

!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 local_unnamed_addr global i32, align 4
@f = external dso_local local_unnamed_addr global [21 x [21 x i32]], align 16
@used = external dso_local local_unnamed_addr global [21 x i32], align 16
@ans = external dso_local local_unnamed_addr global i32, align 4

; Function Attrs: mustprogress nofree nosync nounwind memory(readwrite, argmem: none, inaccessiblemem: none) uwtable
define dso_local void @_Z3dfsii(i32 noundef %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = load i32, ptr @n, align 4, !tbaa !5
  %.not16 = icmp slt i32 %3, 1
  br i1 %.not16, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %2
  %4 = sext i32 %0 to i64
  br label %7

._crit_edge:                                      ; preds = %21, %2
  %5 = load i32, ptr @ans, align 4, !tbaa !5
  %6 = icmp slt i32 %5, %1
  br i1 %6, label %24, label %25

7:                                                ; preds = %.lr.ph, %21
  %8 = phi i32 [ %3, %.lr.ph ], [ %22, %21 ]
  %indvars.iv = phi i64 [ 1, %.lr.ph ], [ %indvars.iv.next, %21 ]
  %9 = getelementptr inbounds [21 x i32], ptr @used, i64 0, i64 %indvars.iv
  %10 = load i32, ptr %9, align 4, !tbaa !5
  %11 = icmp slt i32 %10, 2
  br i1 %11, label %12, label %21

12:                                               ; preds = %7
  %13 = getelementptr inbounds [21 x [21 x i32]], ptr @f, i64 0, i64 %4, i64 %indvars.iv
  %14 = load i32, ptr %13, align 4, !tbaa !5
  %.not15 = icmp eq i32 %14, 0
  br i1 %.not15, label %21, label %15

15:                                               ; preds = %12
  %16 = add nsw i32 %10, 1
  store i32 %16, ptr %9, align 4, !tbaa !5
  %17 = add nsw i32 %14, %1
  %18 = trunc nuw nsw i64 %indvars.iv to i32
  tail call void @_Z3dfsii(i32 noundef %18, i32 noundef %17)
  %19 = load i32, ptr %9, align 4, !tbaa !5
  %20 = add nsw i32 %19, -1
  store i32 %20, ptr %9, align 4, !tbaa !5
  %.pre = load i32, ptr @n, align 4, !tbaa !5
  br label %21

21:                                               ; preds = %7, %12, %15
  %22 = phi i32 [ %8, %7 ], [ %8, %12 ], [ %.pre, %15 ]
  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
  %23 = sext i32 %22 to i64
  %.not.not = icmp slt i64 %indvars.iv, %23
  br i1 %.not.not, label %7, label %._crit_edge, !llvm.loop !9

24:                                               ; preds = %._crit_edge
  store i32 %1, ptr @ans, align 4, !tbaa !5
  br label %25

25:                                               ; preds = %24, %._crit_edge
  ret void
}

attributes #0 = { mustprogress nofree nosync nounwind memory(readwrite, argmem: none, inaccessiblemem: none) 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" }

!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,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LICMPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass