; LLVM IR from upupming/algorithm :: acwing/算法竞赛进阶指南/0x02-递推与递归/94. 递归实现排列型枚举 (main)

; 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::set" = type { %"class.std::_Rb_tree" }
%"class.std::_Rb_tree" = type { %"struct.std::_Rb_tree<int, int, std::_Identity<int>, std::less<int>>::_Rb_tree_impl" }
%"struct.std::_Rb_tree<int, int, std::_Identity<int>, std::less<int>>::_Rb_tree_impl" = type { [8 x i8], %"struct.std::_Rb_tree_header" }
%"struct.std::_Rb_tree_header" = type { %"struct.std::_Rb_tree_node_base", i64 }
%"struct.std::_Rb_tree_node_base" = type { i32, ptr, ptr, ptr }
%"class.std::basic_istream" = type { ptr, i64, %"class.std::basic_ios" }
%"class.std::basic_ios" = type { %"class.std::ios_base", ptr, i8, i8, ptr, ptr, ptr, ptr }
%"class.std::ios_base" = type { ptr, i64, i64, i32, i32, i32, ptr, %"struct.std::ios_base::_Words", [8 x %"struct.std::ios_base::_Words"], i32, ptr, %"class.std::locale" }
%"struct.std::ios_base::_Words" = type { ptr, i64 }
%"class.std::locale" = type { ptr }
%"struct.std::pair" = type <{ %"struct.std::_Rb_tree_const_iterator", i8, [7 x i8] }>
%"struct.std::_Rb_tree_const_iterator" = type { ptr }

@n = external dso_local global i32, align 4
@s = external dso_local global %"class.std::set", align 8
@_ZSt3cin = external global %"class.std::basic_istream", align 8

; 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 @_Z3dfsv() #1

; Function Attrs: mustprogress uwtable
declare dso_local { ptr, i8 } @_ZNSt3setIiSt4lessIiESaIiEE6insertERKi(ptr noundef nonnull align 8 dereferenceable(48), ptr noundef nonnull align 4 dereferenceable(4)) #1 align 2

; Function Attrs: mustprogress norecurse uwtable
define dso_local noundef i32 @main() #2 {
  %1 = alloca i32, align 4
  %2 = alloca i32, align 4
  %3 = alloca %"struct.std::pair", align 8
  store i32 0, ptr %1, align 4
  %4 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) @n)
  call void @llvm.lifetime.start.p0(i64 4, ptr %2) #4
  store i32 1, ptr %2, align 4, !tbaa !5
  br label %5

5:                                                ; preds = %16, %0
  %6 = load i32, ptr %2, align 4, !tbaa !5
  %7 = load i32, ptr @n, align 4, !tbaa !5
  %8 = icmp sle i32 %6, %7
  br i1 %8, label %10, label %9

9:                                                ; preds = %5
  call void @llvm.lifetime.end.p0(i64 4, ptr %2) #4
  br label %19

10:                                               ; preds = %5
  %11 = call { ptr, i8 } @_ZNSt3setIiSt4lessIiESaIiEE6insertERKi(ptr noundef nonnull align 8 dereferenceable(48) @s, ptr noundef nonnull align 4 dereferenceable(4) %2)
  %12 = getelementptr inbounds { ptr, i8 }, ptr %3, i32 0, i32 0
  %13 = extractvalue { ptr, i8 } %11, 0
  store ptr %13, ptr %12, align 8
  %14 = getelementptr inbounds { ptr, i8 }, ptr %3, i32 0, i32 1
  %15 = extractvalue { ptr, i8 } %11, 1
  store i8 %15, ptr %14, align 8
  br label %16

16:                                               ; preds = %10
  %17 = load i32, ptr %2, align 4, !tbaa !5
  %18 = add nsw i32 %17, 1
  store i32 %18, ptr %2, align 4, !tbaa !5
  br label %5, !llvm.loop !9

19:                                               ; preds = %9
  call void @_Z3dfsv()
  ret i32 0
}

declare noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16), ptr noundef nonnull align 4 dereferenceable(4)) #3

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 = { mustprogress norecurse 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 = { "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 #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 = 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::set" = type { %"class.std::_Rb_tree" }
%"class.std::_Rb_tree" = type { %"struct.std::_Rb_tree<int, int, std::_Identity<int>, std::less<int>>::_Rb_tree_impl" }
%"struct.std::_Rb_tree<int, int, std::_Identity<int>, std::less<int>>::_Rb_tree_impl" = type { [8 x i8], %"struct.std::_Rb_tree_header" }
%"struct.std::_Rb_tree_header" = type { %"struct.std::_Rb_tree_node_base", i64 }
%"struct.std::_Rb_tree_node_base" = type { i32, ptr, ptr, ptr }
%"class.std::basic_istream" = type { ptr, i64, %"class.std::basic_ios" }
%"class.std::basic_ios" = type { %"class.std::ios_base", ptr, i8, i8, ptr, ptr, ptr, ptr }
%"class.std::ios_base" = type { ptr, i64, i64, i32, i32, i32, ptr, %"struct.std::ios_base::_Words", [8 x %"struct.std::ios_base::_Words"], i32, ptr, %"class.std::locale" }
%"struct.std::ios_base::_Words" = type { ptr, i64 }
%"class.std::locale" = type { ptr }

@n = external dso_local global i32, align 4
@s = external dso_local global %"class.std::set", align 8
@_ZSt3cin = external global %"class.std::basic_istream", align 8

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

; Function Attrs: mustprogress 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 @_Z3dfsv() local_unnamed_addr #1

; Function Attrs: mustprogress uwtable
declare dso_local { ptr, i8 } @_ZNSt3setIiSt4lessIiESaIiEE6insertERKi(ptr noundef nonnull align 8 dereferenceable(48), ptr noundef nonnull align 4 dereferenceable(4)) local_unnamed_addr #1 align 2

; Function Attrs: mustprogress norecurse uwtable
define dso_local noundef i32 @main() local_unnamed_addr #2 {
  %1 = alloca i32, align 4
  %2 = tail call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) @n)
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %1) #4
  store i32 1, ptr %1, align 4, !tbaa !5
  %3 = load i32, ptr @n, align 4, !tbaa !5
  %.not1 = icmp slt i32 %3, 1
  br i1 %.not1, label %._crit_edge, label %.lr.ph

._crit_edge:                                      ; preds = %.lr.ph, %0
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %1) #4
  call void @_Z3dfsv()
  ret i32 0

.lr.ph:                                           ; preds = %0, %.lr.ph
  %4 = call { ptr, i8 } @_ZNSt3setIiSt4lessIiESaIiEE6insertERKi(ptr noundef nonnull align 8 dereferenceable(48) @s, ptr noundef nonnull align 4 dereferenceable(4) %1)
  %5 = load i32, ptr %1, align 4, !tbaa !5
  %6 = add nsw i32 %5, 1
  store i32 %6, ptr %1, align 4, !tbaa !5
  %7 = load i32, ptr @n, align 4, !tbaa !5
  %.not.not = icmp slt i32 %5, %7
  br i1 %.not.not, label %.lr.ph, label %._crit_edge, !llvm.loop !9
}

declare noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16), ptr noundef nonnull align 4 dereferenceable(4)) local_unnamed_addr #3

attributes #0 = { mustprogress 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 = { mustprogress norecurse 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 = { "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 #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 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}


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