; LLVM IR from upupming/algorithm :: kick-start/2021/RoundA/A. K-Goodness String.ll (Z5solvev)

; 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::__cxx11::basic_string" = type { %"struct.std::__cxx11::basic_string<char>::_Alloc_hider", i64, %union.anon }
%"struct.std::__cxx11::basic_string<char>::_Alloc_hider" = type { ptr }
%union.anon = type { i64, [8 x i8] }

@n = external dso_local global i32, align 4
@k = external dso_local global i32, align 4
@_Z1sB5cxx11 = external dso_local global %"class.std::__cxx11::basic_string", align 8

; Function Attrs: mustprogress uwtable
define dso_local noundef i32 @_Z5solvev() #0 {
  %1 = alloca i32, align 4
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  call void @llvm.lifetime.start.p0(i64 4, ptr %1) #4
  store i32 0, ptr %1, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %2) #4
  store i32 0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #4
  %4 = load i32, ptr @n, align 4, !tbaa !5
  %5 = sub nsw i32 %4, 1
  store i32 %5, ptr %3, align 4, !tbaa !5
  br label %6

6:                                                ; preds = %27, %0
  %7 = load i32, ptr %2, align 4, !tbaa !5
  %8 = load i32, ptr %3, 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 %3) #4
  call void @llvm.lifetime.end.p0(i64 4, ptr %2) #4
  br label %32

11:                                               ; preds = %6
  %12 = load i32, ptr %2, align 4, !tbaa !5
  %13 = sext i32 %12 to i64
  %14 = call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) @_Z1sB5cxx11, i64 noundef %13)
  %15 = load i8, ptr %14, align 1, !tbaa !9
  %16 = sext i8 %15 to i32
  %17 = load i32, ptr %3, align 4, !tbaa !5
  %18 = sext i32 %17 to i64
  %19 = call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) @_Z1sB5cxx11, i64 noundef %18)
  %20 = load i8, ptr %19, align 1, !tbaa !9
  %21 = sext i8 %20 to i32
  %22 = icmp ne i32 %16, %21
  br i1 %22, label %23, label %26

23:                                               ; preds = %11
  %24 = load i32, ptr %1, align 4, !tbaa !5
  %25 = add nsw i32 %24, 1
  store i32 %25, ptr %1, align 4, !tbaa !5
  br label %26

26:                                               ; preds = %23, %11
  br label %27

27:                                               ; preds = %26
  %28 = load i32, ptr %2, align 4, !tbaa !5
  %29 = add nsw i32 %28, 1
  store i32 %29, ptr %2, align 4, !tbaa !5
  %30 = load i32, ptr %3, align 4, !tbaa !5
  %31 = add nsw i32 %30, -1
  store i32 %31, ptr %3, align 4, !tbaa !5
  br label %6, !llvm.loop !10

32:                                               ; preds = %10
  %33 = load i32, ptr @k, align 4, !tbaa !5
  %34 = load i32, ptr %1, align 4, !tbaa !5
  %35 = sub nsw i32 %33, %34
  %36 = call i32 @llvm.abs.i32(i32 %35, i1 true)
  call void @llvm.lifetime.end.p0(i64 4, ptr %1) #4
  ret i32 %36
}

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

; Function Attrs: mustprogress nounwind uwtable
declare noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32), i64 noundef) #2 align 2

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

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i32 @llvm.abs.i32(i32, i1 immarg) #3

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 = { 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 #3 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
attributes #4 = { 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 = !{!7, !7, i64 0}
!10 = distinct !{!10, !11}
!11 = !{!"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::__cxx11::basic_string" = type { %"struct.std::__cxx11::basic_string<char>::_Alloc_hider", i64, %union.anon }
%"struct.std::__cxx11::basic_string<char>::_Alloc_hider" = type { ptr }
%union.anon = type { i64, [8 x i8] }

@n = external dso_local local_unnamed_addr global i32, align 4
@k = external dso_local local_unnamed_addr global i32, align 4
@_Z1sB5cxx11 = external dso_local global %"class.std::__cxx11::basic_string", align 8

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef range(i32 0, -2147483648) i32 @_Z5solvev() local_unnamed_addr #0 {
  %1 = load i32, ptr @n, align 4, !tbaa !5
  %.not.not10 = icmp sgt i32 %1, 0
  br i1 %.not.not10, label %.lr.ph.preheader, label %._crit_edge

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

._crit_edge:                                      ; preds = %.lr.ph, %0
  %.09.lcssa = phi i32 [ 0, %0 ], [ %spec.select, %.lr.ph ]
  %3 = load i32, ptr @k, align 4, !tbaa !5
  %4 = sub nsw i32 %3, %.09.lcssa
  %5 = tail call i32 @llvm.abs.i32(i32 %4, i1 true)
  ret i32 %5

.lr.ph:                                           ; preds = %.lr.ph.preheader, %.lr.ph
  %indvars.iv14 = phi i64 [ 0, %.lr.ph.preheader ], [ %indvars.iv.next15, %.lr.ph ]
  %indvars.iv = phi i64 [ %2, %.lr.ph.preheader ], [ %indvars.iv.next, %.lr.ph ]
  %.0911 = phi i32 [ 0, %.lr.ph.preheader ], [ %spec.select, %.lr.ph ]
  %indvars.iv.next = add nsw i64 %indvars.iv, -1
  %6 = tail call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) @_Z1sB5cxx11, i64 noundef %indvars.iv14)
  %7 = load i8, ptr %6, align 1, !tbaa !9
  %8 = tail call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) @_Z1sB5cxx11, i64 noundef %indvars.iv.next)
  %9 = load i8, ptr %8, align 1, !tbaa !9
  %.not = icmp ne i8 %7, %9
  %10 = zext i1 %.not to i32
  %spec.select = add nuw nsw i32 %.0911, %10
  %indvars.iv.next15 = add nuw nsw i64 %indvars.iv14, 1
  %.not.not = icmp slt i64 %indvars.iv.next15, %indvars.iv.next
  br i1 %.not.not, label %.lr.ph, label %._crit_edge, !llvm.loop !10
}

; Function Attrs: mustprogress nounwind uwtable
declare noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32), i64 noundef) local_unnamed_addr #0 align 2

; Function Attrs: mustprogress nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i32 @llvm.abs.i32(i32, i1 immarg) #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 = { mustprogress nocallback nofree nosync nounwind speculatable willreturn memory(none) }

!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 = !{!7, !7, i64 0}
!10 = distinct !{!10, !11}
!11 = !{!"llvm.loop.mustprogress"}


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