; LLVM IR from tangjz/acm-icpc :: luogu/1028.ll (Z3dfsi)

; 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"

@ans = external dso_local global i32, align 4

; Function Attrs: mustprogress uwtable
define dso_local void @_Z3dfsi(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  store i32 %0, ptr %2, align 4, !tbaa !5
  %4 = load i32, ptr %2, align 4, !tbaa !5
  %5 = icmp eq i32 %4, 1
  br i1 %5, label %6, label %7

6:                                                ; preds = %1
  br label %23

7:                                                ; preds = %1
  %8 = load i32, ptr %2, align 4, !tbaa !5
  %9 = ashr i32 %8, 1
  %10 = load i32, ptr @ans, align 4, !tbaa !5
  %11 = add nsw i32 %10, %9
  store i32 %11, ptr @ans, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  store i32 2, ptr %3, align 4, !tbaa !5
  br label %12

12:                                               ; preds = %20, %7
  %13 = load i32, ptr %3, align 4, !tbaa !5
  %14 = load i32, ptr %2, align 4, !tbaa !5
  %15 = ashr i32 %14, 1
  %16 = icmp sle i32 %13, %15
  br i1 %16, label %18, label %17

17:                                               ; preds = %12
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  br label %23

18:                                               ; preds = %12
  %19 = load i32, ptr %3, align 4, !tbaa !5
  call void @_Z3dfsi(i32 noundef %19)
  br label %20

20:                                               ; preds = %18
  %21 = load i32, ptr %3, align 4, !tbaa !5
  %22 = add nsw i32 %21, 1
  store i32 %22, ptr %3, align 4, !tbaa !5
  br label %12, !llvm.loop !9

23:                                               ; preds = %17, %6
  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"

@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 @_Z3dfsi(i32 noundef %0) local_unnamed_addr #0 {
  %2 = icmp eq i32 %0, 1
  br i1 %2, label %.loopexit, label %3

3:                                                ; preds = %1
  %4 = ashr i32 %0, 1
  %5 = load i32, ptr @ans, align 4, !tbaa !5
  %6 = add nsw i32 %5, %4
  store i32 %6, ptr @ans, align 4, !tbaa !5
  %.not7 = icmp slt i32 %4, 2
  br i1 %.not7, label %.loopexit, label %.lr.ph

.lr.ph:                                           ; preds = %3, %.lr.ph
  %.08 = phi i32 [ %7, %.lr.ph ], [ 2, %3 ]
  tail call void @_Z3dfsi(i32 noundef %.08)
  %7 = add nuw nsw i32 %.08, 1
  %exitcond.not = icmp eq i32 %.08, %4
  br i1 %exitcond.not, label %.loopexit, label %.lr.ph, !llvm.loop !9

.loopexit:                                        ; preds = %.lr.ph, %3, %1
  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,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass