; LLVM IR from bqi343/cp-notebook :: Contests/USACO Solutions/2016-17/Dec 2016/Silver/16 Dec S1.ll (Z2b1i)

; 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"

%"class.std::vector" = type { %"struct.std::_Vector_base" }
%"struct.std::_Vector_base" = type { %"struct.std::_Vector_base<int, std::allocator<int>>::_Vector_impl" }
%"struct.std::_Vector_base<int, std::allocator<int>>::_Vector_impl" = type { %"struct.std::_Vector_base<int, std::allocator<int>>::_Vector_impl_data" }
%"struct.std::_Vector_base<int, std::allocator<int>>::_Vector_impl_data" = type { ptr, ptr, ptr }

@haybales = external dso_local global %"class.std::vector", align 8
@N = external dso_local global i32, align 4

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef i32 @_Z2b1i(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  %7 = load i32, ptr @N, align 4, !tbaa !5
  %8 = sub nsw i32 %7, 1
  %9 = sext i32 %8 to i64
  %10 = call noundef nonnull align 4 dereferenceable(4) ptr @_ZNSt6vectorIiSaIiEEixEm(ptr noundef nonnull align 8 dereferenceable(24) @haybales, i64 noundef %9) #2
  %11 = load i32, ptr %10, align 4, !tbaa !5
  %12 = load i32, ptr %3, align 4, !tbaa !5
  %13 = icmp slt i32 %11, %12
  br i1 %13, label %14, label %16

14:                                               ; preds = %1
  %15 = load i32, ptr @N, align 4, !tbaa !5
  store i32 %15, ptr %2, align 4
  br label %42

16:                                               ; preds = %1
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  store i32 0, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  %17 = load i32, ptr @N, align 4, !tbaa !5
  %18 = sub nsw i32 %17, 1
  store i32 %18, ptr %5, align 4, !tbaa !5
  br label %19

19:                                               ; preds = %39, %16
  %20 = load i32, ptr %4, align 4, !tbaa !5
  %21 = load i32, ptr %5, align 4, !tbaa !5
  %22 = icmp slt i32 %20, %21
  br i1 %22, label %23, label %40

23:                                               ; preds = %19
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #2
  %24 = load i32, ptr %4, align 4, !tbaa !5
  %25 = load i32, ptr %5, align 4, !tbaa !5
  %26 = add nsw i32 %24, %25
  %27 = sdiv i32 %26, 2
  store i32 %27, ptr %6, align 4, !tbaa !5
  %28 = load i32, ptr %6, align 4, !tbaa !5
  %29 = sext i32 %28 to i64
  %30 = call noundef nonnull align 4 dereferenceable(4) ptr @_ZNSt6vectorIiSaIiEEixEm(ptr noundef nonnull align 8 dereferenceable(24) @haybales, i64 noundef %29) #2
  %31 = load i32, ptr %30, align 4, !tbaa !5
  %32 = load i32, ptr %3, align 4, !tbaa !5
  %33 = icmp slt i32 %31, %32
  br i1 %33, label %34, label %37

34:                                               ; preds = %23
  %35 = load i32, ptr %6, align 4, !tbaa !5
  %36 = add nsw i32 %35, 1
  store i32 %36, ptr %4, align 4, !tbaa !5
  br label %39

37:                                               ; preds = %23
  %38 = load i32, ptr %6, align 4, !tbaa !5
  store i32 %38, ptr %5, align 4, !tbaa !5
  br label %39

39:                                               ; preds = %37, %34
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #2
  br label %19, !llvm.loop !9

40:                                               ; preds = %19
  %41 = load i32, ptr %4, align 4, !tbaa !5
  store i32 %41, ptr %2, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  br label %42

42:                                               ; preds = %40, %14
  %43 = load i32, ptr %2, align 4
  ret i32 %43
}

; Function Attrs: mustprogress nounwind uwtable
declare dso_local noundef nonnull align 4 dereferenceable(4) ptr @_ZNSt6vectorIiSaIiEEixEm(ptr noundef nonnull align 8 dereferenceable(24), i64 noundef) #0 align 2

; 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 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 = { 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"

%"class.std::vector" = type { %"struct.std::_Vector_base" }
%"struct.std::_Vector_base" = type { %"struct.std::_Vector_base<int, std::allocator<int>>::_Vector_impl" }
%"struct.std::_Vector_base<int, std::allocator<int>>::_Vector_impl" = type { %"struct.std::_Vector_base<int, std::allocator<int>>::_Vector_impl_data" }
%"struct.std::_Vector_base<int, std::allocator<int>>::_Vector_impl_data" = type { ptr, ptr, ptr }

@haybales = external dso_local global %"class.std::vector", align 8
@N = external dso_local local_unnamed_addr global i32, align 4

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef i32 @_Z2b1i(i32 noundef %0) local_unnamed_addr #0 {
  %2 = load i32, ptr @N, align 4, !tbaa !5
  %3 = add nsw i32 %2, -1
  %4 = sext i32 %3 to i64
  %5 = tail call noundef nonnull align 4 dereferenceable(4) ptr @_ZNSt6vectorIiSaIiEEixEm(ptr noundef nonnull align 8 dereferenceable(24) @haybales, i64 noundef %4) #1
  %6 = load i32, ptr %5, align 4, !tbaa !5
  %7 = icmp slt i32 %6, %0
  %8 = load i32, ptr @N, align 4, !tbaa !5
  br i1 %7, label %.loopexit, label %9

9:                                                ; preds = %1
  %10 = icmp sgt i32 %8, 1
  br i1 %10, label %.lr.ph.preheader, label %.loopexit

.lr.ph.preheader:                                 ; preds = %9
  %11 = add nsw i32 %8, -1
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph.preheader, %.lr.ph
  %.01116 = phi i32 [ %.1, %.lr.ph ], [ %11, %.lr.ph.preheader ]
  %.01215 = phi i32 [ %.113, %.lr.ph ], [ 0, %.lr.ph.preheader ]
  %12 = add nuw nsw i32 %.01116, %.01215
  %13 = lshr i32 %12, 1
  %14 = zext nneg i32 %13 to i64
  %15 = tail call noundef nonnull align 4 dereferenceable(4) ptr @_ZNSt6vectorIiSaIiEEixEm(ptr noundef nonnull align 8 dereferenceable(24) @haybales, i64 noundef %14) #1
  %16 = load i32, ptr %15, align 4, !tbaa !5
  %17 = icmp slt i32 %16, %0
  %18 = add nuw nsw i32 %13, 1
  %.113 = select i1 %17, i32 %18, i32 %.01215
  %.1 = select i1 %17, i32 %.01116, i32 %13
  %19 = icmp slt i32 %.113, %.1
  br i1 %19, label %.lr.ph, label %.loopexit, !llvm.loop !9

.loopexit:                                        ; preds = %.lr.ph, %1, %9
  %.0 = phi i32 [ 0, %9 ], [ %8, %1 ], [ %.113, %.lr.ph ]
  ret i32 %.0
}

; Function Attrs: mustprogress nounwind uwtable
declare dso_local noundef nonnull align 4 dereferenceable(4) ptr @_ZNSt6vectorIiSaIiEEixEm(ptr noundef nonnull align 8 dereferenceable(24), i64 noundef) local_unnamed_addr #0 align 2

attributes #0 = { mustprogress 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 = { 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"}


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