; LLVM IR from tangjz/acm-icpc :: codeforces/gym/101201F.ll (Z4dfs2i)

; 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"

%struct.Edge = type { i32, i32 }

@tot = external dso_local global i32, align 4
@rev = external dso_local global [2001 x i32], align 16
@scc = external dso_local global [2001 x i32], align 16
@e = external dso_local global [4000003 x %struct.Edge], align 16

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: mustprogress uwtable
define dso_local void @_Z4dfs2i(i32 noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  store i32 %0, ptr %2, align 4, !tbaa !5
  %4 = load i32, ptr @tot, align 4, !tbaa !5
  %5 = load i32, ptr %2, align 4, !tbaa !5
  %6 = sext i32 %5 to i64
  %7 = getelementptr inbounds [2001 x i32], ptr @scc, i64 0, i64 %6
  store i32 %4, ptr %7, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  %8 = load i32, ptr %2, align 4, !tbaa !5
  %9 = sext i32 %8 to i64
  %10 = getelementptr inbounds [2001 x i32], ptr @rev, i64 0, i64 %9
  %11 = load i32, ptr %10, align 4, !tbaa !5
  store i32 %11, ptr %3, align 4, !tbaa !5
  br label %12

12:                                               ; preds = %33, %1
  %13 = load i32, ptr %3, align 4, !tbaa !5
  %14 = icmp ne i32 %13, -1
  br i1 %14, label %16, label %15

15:                                               ; preds = %12
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  br label %39

16:                                               ; preds = %12
  %17 = load i32, ptr %3, align 4, !tbaa !5
  %18 = sext i32 %17 to i64
  %19 = getelementptr inbounds [4000003 x %struct.Edge], ptr @e, i64 0, i64 %18
  %20 = getelementptr inbounds %struct.Edge, ptr %19, i32 0, i32 1
  %21 = load i32, ptr %20, align 4, !tbaa !9
  %22 = sext i32 %21 to i64
  %23 = getelementptr inbounds [2001 x i32], ptr @scc, i64 0, i64 %22
  %24 = load i32, ptr %23, align 4, !tbaa !5
  %25 = icmp eq i32 %24, -1
  br i1 %25, label %26, label %32

26:                                               ; preds = %16
  %27 = load i32, ptr %3, align 4, !tbaa !5
  %28 = sext i32 %27 to i64
  %29 = getelementptr inbounds [4000003 x %struct.Edge], ptr @e, i64 0, i64 %28
  %30 = getelementptr inbounds %struct.Edge, ptr %29, i32 0, i32 1
  %31 = load i32, ptr %30, align 4, !tbaa !9
  call void @_Z4dfs2i(i32 noundef %31)
  br label %32

32:                                               ; preds = %26, %16
  br label %33

33:                                               ; preds = %32
  %34 = load i32, ptr %3, align 4, !tbaa !5
  %35 = sext i32 %34 to i64
  %36 = getelementptr inbounds [4000003 x %struct.Edge], ptr @e, i64 0, i64 %35
  %37 = getelementptr inbounds %struct.Edge, ptr %36, i32 0, i32 0
  %38 = load i32, ptr %37, align 8, !tbaa !11
  store i32 %38, ptr %3, align 4, !tbaa !5
  br label %12, !llvm.loop !12

39:                                               ; preds = %15
  ret void
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { 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 #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 = !{!10, !6, i64 4}
!10 = !{!"_ZTS4Edge", !6, i64 0, !6, i64 4}
!11 = !{!10, !6, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"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"

%struct.Edge = type { i32, i32 }

@tot = external dso_local local_unnamed_addr global i32, align 4
@rev = external dso_local local_unnamed_addr global [2001 x i32], align 16
@scc = external dso_local local_unnamed_addr global [2001 x i32], align 16
@e = external dso_local local_unnamed_addr global [4000003 x %struct.Edge], align 16

; Function Attrs: mustprogress nofree nosync nounwind memory(readwrite, argmem: none, inaccessiblemem: none) uwtable
define dso_local void @_Z4dfs2i(i32 noundef %0) local_unnamed_addr #0 {
  %2 = load i32, ptr @tot, align 4, !tbaa !5
  %3 = sext i32 %0 to i64
  %4 = getelementptr inbounds [2001 x i32], ptr @scc, i64 0, i64 %3
  store i32 %2, ptr %4, align 4, !tbaa !5
  %5 = getelementptr inbounds [2001 x i32], ptr @rev, i64 0, i64 %3
  %.06 = load i32, ptr %5, align 4, !tbaa !5
  %.not7 = icmp eq i32 %.06, -1
  br i1 %.not7, label %._crit_edge, label %.lr.ph

._crit_edge:                                      ; preds = %15, %1
  ret void

.lr.ph:                                           ; preds = %1, %15
  %.08 = phi i32 [ %.0, %15 ], [ %.06, %1 ]
  %6 = sext i32 %.08 to i64
  %7 = getelementptr inbounds [4000003 x %struct.Edge], ptr @e, i64 0, i64 %6
  %8 = getelementptr inbounds i8, ptr %7, i64 4
  %9 = load i32, ptr %8, align 4, !tbaa !9
  %10 = sext i32 %9 to i64
  %11 = getelementptr inbounds [2001 x i32], ptr @scc, i64 0, i64 %10
  %12 = load i32, ptr %11, align 4, !tbaa !5
  %13 = icmp eq i32 %12, -1
  br i1 %13, label %14, label %15

14:                                               ; preds = %.lr.ph
  tail call void @_Z4dfs2i(i32 noundef %9)
  br label %15

15:                                               ; preds = %.lr.ph, %14
  %.0 = load i32, ptr %7, align 8, !tbaa !5
  %.not = icmp eq i32 %.0, -1
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !11
}

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 = !{!10, !6, i64 4}
!10 = !{!"_ZTS4Edge", !6, i64 0, !6, i64 4}
!11 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}


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