; LLVM IR from Mohammed-Shoaib/Coding-Problems :: Codeforces/Solutions (1108D)

; 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"

; 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
define dso_local noundef i32 @_Z6changeiicRNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE(i32 noundef %0, i32 noundef %1, i8 noundef signext %2, ptr noundef nonnull align 8 dereferenceable(32) %3) #1 {
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  %7 = alloca i8, align 1
  %8 = alloca ptr, align 8
  %9 = alloca i32, align 4
  store i32 %0, ptr %5, align 4, !tbaa !5
  store i32 %1, ptr %6, align 4, !tbaa !5
  store i8 %2, ptr %7, align 1, !tbaa !9
  store ptr %3, ptr %8, align 8, !tbaa !10
  call void @llvm.lifetime.start.p0(i64 4, ptr %9) #3
  store i32 0, ptr %9, align 4, !tbaa !5
  %10 = load i32, ptr %6, align 4, !tbaa !5
  %11 = sdiv i32 %10, 2
  store i32 %11, ptr %6, align 4, !tbaa !5
  br label %12

12:                                               ; preds = %16, %4
  %13 = load i32, ptr %6, align 4, !tbaa !5
  %14 = add nsw i32 %13, -1
  store i32 %14, ptr %6, align 4, !tbaa !5
  %15 = icmp ne i32 %13, 0
  br i1 %15, label %16, label %26

16:                                               ; preds = %12
  %17 = load i8, ptr %7, align 1, !tbaa !9
  %18 = load ptr, ptr %8, align 8, !tbaa !10
  %19 = load i32, ptr %5, align 4, !tbaa !5
  %20 = sext i32 %19 to i64
  %21 = call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %18, i64 noundef %20)
  store i8 %17, ptr %21, align 1, !tbaa !9
  %22 = load i32, ptr %5, align 4, !tbaa !5
  %23 = sub nsw i32 %22, 2
  store i32 %23, ptr %5, align 4, !tbaa !5
  %24 = load i32, ptr %9, align 4, !tbaa !5
  %25 = add nsw i32 %24, 1
  store i32 %25, ptr %9, align 4, !tbaa !5
  br label %12, !llvm.loop !12

26:                                               ; preds = %12
  %27 = load i32, ptr %9, align 4, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 4, ptr %9) #3
  ret i32 %27
}

; 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

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 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 = { 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 = !{!11, !11, i64 0}
!11 = !{!"any pointer", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"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"

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef i32 @_Z6changeiicRNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE(i32 noundef %0, i32 noundef %1, i8 noundef signext %2, ptr noundef nonnull align 8 dereferenceable(32) %3) local_unnamed_addr #0 {
  %5 = sdiv i32 %1, 2
  %.off = add i32 %1, 1
  %.not9 = icmp ult i32 %.off, 3
  br i1 %.not9, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %4
  %6 = sext i32 %0 to i64
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph.preheader, %.lr.ph
  %indvars.iv = phi i64 [ %6, %.lr.ph.preheader ], [ %indvars.iv.next, %.lr.ph ]
  %.0810 = phi i32 [ %5, %.lr.ph.preheader ], [ %7, %.lr.ph ]
  %7 = add nsw i32 %.0810, -1
  %8 = tail call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %3, i64 noundef %indvars.iv)
  store i8 %2, ptr %8, align 1, !tbaa !5
  %indvars.iv.next = add nsw i64 %indvars.iv, -2
  %.not = icmp eq i32 %7, 0
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !8

._crit_edge:                                      ; preds = %.lr.ph, %4
  %.0.lcssa = phi i32 [ 0, %4 ], [ %5, %.lr.ph ]
  ret i32 %.0.lcssa
}

; 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

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" }

!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 = !{!"omnipotent char", !7, i64 0}
!7 = !{!"Simple C++ TBAA"}
!8 = distinct !{!8, !9}
!9 = !{!"llvm.loop.mustprogress"}


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