; LLVM IR from ayush-tulsyan/ACM-ICPC-Handbook :: code/DFS.ll (Z7callDFSi)

; 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"

@ComNum = external dso_local global [101000 x i32], align 16
@visited = external dso_local global [101000 x i8], 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
declare dso_local void @_Z3DFSi(i32 noundef) #1

; Function Attrs: mustprogress uwtable
define dso_local void @_Z7callDFSi(i32 noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i64, align 8
  %5 = alloca i64, align 8
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.memset.p0.i64(ptr align 16 @visited, i8 0, i64 101000, i1 false)
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #3
  store i32 0, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #3
  store i64 1, ptr %4, align 8, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #3
  %6 = load i32, ptr %2, align 4, !tbaa !5
  %7 = sext i32 %6 to i64
  store i64 %7, ptr %5, align 8, !tbaa !9
  br label %8

8:                                                ; preds = %26, %1
  %9 = load i64, ptr %4, align 8, !tbaa !9
  %10 = load i64, ptr %5, align 8, !tbaa !9
  %11 = icmp sle i64 %9, %10
  br i1 %11, label %13, label %12

12:                                               ; preds = %8
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #3
  br label %29

13:                                               ; preds = %8
  %14 = load i64, ptr %4, align 8, !tbaa !9
  %15 = getelementptr inbounds [101000 x i8], ptr @visited, i64 0, i64 %14
  %16 = load i8, ptr %15, align 1, !tbaa !11, !range !13, !noundef !14
  %17 = trunc i8 %16 to i1
  br i1 %17, label %25, label %18

18:                                               ; preds = %13
  %19 = load i32, ptr %3, align 4, !tbaa !5
  %20 = add nsw i32 %19, 1
  store i32 %20, ptr %3, align 4, !tbaa !5
  %21 = load i64, ptr %4, align 8, !tbaa !9
  %22 = getelementptr inbounds [101000 x i32], ptr @ComNum, i64 0, i64 %21
  store i32 %20, ptr %22, align 4, !tbaa !5
  %23 = load i64, ptr %4, align 8, !tbaa !9
  %24 = trunc i64 %23 to i32
  call void @_Z3DFSi(i32 noundef %24)
  br label %25

25:                                               ; preds = %18, %13
  br label %26

26:                                               ; preds = %25
  %27 = load i64, ptr %4, align 8, !tbaa !9
  %28 = add nsw i64 %27, 1
  store i64 %28, ptr %4, align 8, !tbaa !9
  br label %8, !llvm.loop !15

29:                                               ; preds = %12
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #3
  ret void
}

; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: write)
declare void @llvm.memset.p0.i64(ptr nocapture writeonly, i8, i64, i1 immarg) #2

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 = { nocallback nofree nounwind willreturn memory(argmem: write) }
attributes #3 = { 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, !10, i64 0}
!10 = !{!"long long", !7, i64 0}
!11 = !{!12, !12, i64 0}
!12 = !{!"bool", !7, i64 0}
!13 = !{i8 0, i8 2}
!14 = !{}
!15 = distinct !{!15, !16}
!16 = !{!"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"

@ComNum = external dso_local local_unnamed_addr global [101000 x i32], align 16
@visited = external dso_local local_unnamed_addr global [101000 x i8], align 16

; Function Attrs: mustprogress uwtable
declare dso_local void @_Z3DFSi(i32 noundef) local_unnamed_addr #0

; Function Attrs: mustprogress uwtable
define dso_local void @_Z7callDFSi(i32 noundef %0) local_unnamed_addr #0 {
  tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 16 dereferenceable(101000) @visited, i8 0, i64 101000, i1 false)
  %.not9 = icmp slt i32 %0, 1
  br i1 %.not9, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %1
  %2 = zext nneg i32 %0 to i64
  br label %.lr.ph

._crit_edge:                                      ; preds = %10, %1
  ret void

.lr.ph:                                           ; preds = %.lr.ph.preheader, %10
  %.011 = phi i32 [ %.1, %10 ], [ 0, %.lr.ph.preheader ]
  %.0810 = phi i64 [ %11, %10 ], [ 1, %.lr.ph.preheader ]
  %3 = getelementptr inbounds [101000 x i8], ptr @visited, i64 0, i64 %.0810
  %4 = load i8, ptr %3, align 1, !tbaa !5, !range !9, !noundef !10
  %5 = trunc nuw i8 %4 to i1
  br i1 %5, label %10, label %6

6:                                                ; preds = %.lr.ph
  %7 = add nsw i32 %.011, 1
  %8 = getelementptr inbounds [101000 x i32], ptr @ComNum, i64 0, i64 %.0810
  store i32 %7, ptr %8, align 4, !tbaa !11
  %9 = trunc i64 %.0810 to i32
  tail call void @_Z3DFSi(i32 noundef %9)
  br label %10

10:                                               ; preds = %.lr.ph, %6
  %.1 = phi i32 [ %.011, %.lr.ph ], [ %7, %6 ]
  %11 = add nuw nsw i64 %.0810, 1
  %exitcond.not = icmp eq i64 %.0810, %2
  br i1 %exitcond.not, label %._crit_edge, label %.lr.ph, !llvm.loop !13
}

; Function Attrs: mustprogress nocallback nofree nounwind willreturn memory(argmem: write)
declare void @llvm.memset.p0.i64(ptr nocapture writeonly, i8, i64, i1 immarg) #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 = { mustprogress nocallback nofree nounwind willreturn memory(argmem: write) }

!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 = !{!"bool", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = !{i8 0, i8 2}
!10 = !{}
!11 = !{!12, !12, i64 0}
!12 = !{!"int", !7, i64 0}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: GlobalOptPass,IPSCCPPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,SROAPass,SimplifyCFGPass,TailCallElimPass