; LLVM IR from tangjz/acm-icpc :: usaco/Training/Chapter 1 Getting started/dualpal.ll (Z5checkv)

; 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"

@num = external dso_local global [36 x i32], align 16
@len = external dso_local global i32, align 4

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef zeroext i1 @_Z5checkv() #0 {
  %1 = alloca i1, align 1
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  call void @llvm.lifetime.start.p0(i64 4, ptr %2) #2
  store i32 0, ptr %2, align 4, !tbaa !5
  br label %4

4:                                                ; preds = %25, %0
  %5 = load i32, ptr %2, align 4, !tbaa !5
  %6 = load i32, ptr @len, align 4, !tbaa !5
  %7 = ashr i32 %6, 1
  %8 = icmp sle i32 %5, %7
  br i1 %8, label %10, label %9

9:                                                ; preds = %4
  store i32 2, ptr %3, align 4
  br label %28

10:                                               ; preds = %4
  %11 = load i32, ptr %2, align 4, !tbaa !5
  %12 = sext i32 %11 to i64
  %13 = getelementptr inbounds [36 x i32], ptr @num, i64 0, i64 %12
  %14 = load i32, ptr %13, align 4, !tbaa !5
  %15 = load i32, ptr @len, align 4, !tbaa !5
  %16 = sub nsw i32 %15, 1
  %17 = load i32, ptr %2, align 4, !tbaa !5
  %18 = sub nsw i32 %16, %17
  %19 = sext i32 %18 to i64
  %20 = getelementptr inbounds [36 x i32], ptr @num, i64 0, i64 %19
  %21 = load i32, ptr %20, align 4, !tbaa !5
  %22 = icmp ne i32 %14, %21
  br i1 %22, label %23, label %24

23:                                               ; preds = %10
  store i1 false, ptr %1, align 1
  store i32 1, ptr %3, align 4
  br label %28

24:                                               ; preds = %10
  br label %25

25:                                               ; preds = %24
  %26 = load i32, ptr %2, align 4, !tbaa !5
  %27 = add nsw i32 %26, 1
  store i32 %27, ptr %2, align 4, !tbaa !5
  br label %4, !llvm.loop !9

28:                                               ; preds = %23, %9
  call void @llvm.lifetime.end.p0(i64 4, ptr %2) #2
  %29 = load i32, ptr %3, align 4
  switch i32 %29, label %33 [
    i32 2, label %30
    i32 1, label %31
  ]

30:                                               ; preds = %28
  store i1 true, ptr %1, align 1
  br label %31

31:                                               ; preds = %30, %28
  %32 = load i1, ptr %1, align 1
  ret i1 %32

33:                                               ; preds = %28
  unreachable
}

; 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"

@num = external dso_local local_unnamed_addr global [36 x i32], align 16
@len = external dso_local local_unnamed_addr global i32, align 4

; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(read, argmem: none, inaccessiblemem: none) uwtable
define dso_local noundef zeroext i1 @_Z5checkv() local_unnamed_addr #0 {
  %1 = load i32, ptr @len, align 4, !tbaa !5
  %2 = ashr i32 %1, 1
  %.not8 = icmp slt i32 %2, 0
  br i1 %.not8, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %0
  %3 = zext nneg i32 %2 to i64
  %4 = add nuw nsw i32 %2, 1
  %wide.trip.count = zext nneg i32 %4 to i64
  %5 = load i32, ptr @num, align 16, !tbaa !5
  %6 = add i32 %1, -1
  %7 = sext i32 %6 to i64
  %8 = getelementptr inbounds [36 x i32], ptr @num, i64 0, i64 %7
  %9 = load i32, ptr %8, align 4, !tbaa !5
  %.not713 = icmp eq i32 %5, %9
  br i1 %.not713, label %.lr.ph15, label %._crit_edge

.lr.ph15:                                         ; preds = %.lr.ph.preheader, %.lr.ph
  %indvars.iv14 = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %.lr.ph.preheader ]
  %indvars.iv.next = add nuw nsw i64 %indvars.iv14, 1
  %exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
  br i1 %exitcond, label %._crit_edge.loopexit, label %.lr.ph, !llvm.loop !9

.lr.ph:                                           ; preds = %.lr.ph15
  %10 = getelementptr inbounds [36 x i32], ptr @num, i64 0, i64 %indvars.iv.next
  %11 = load i32, ptr %10, align 4, !tbaa !5
  %12 = trunc i64 %indvars.iv.next to i32
  %13 = xor i32 %12, -1
  %14 = add i32 %1, %13
  %15 = sext i32 %14 to i64
  %16 = getelementptr inbounds [36 x i32], ptr @num, i64 0, i64 %15
  %17 = load i32, ptr %16, align 4, !tbaa !5
  %.not7 = icmp eq i32 %11, %17
  br i1 %.not7, label %.lr.ph15, label %._crit_edge.loopexit, !llvm.loop !9

._crit_edge.loopexit:                             ; preds = %.lr.ph15, %.lr.ph
  %.not.le = icmp uge i64 %indvars.iv14, %3
  br label %._crit_edge

._crit_edge:                                      ; preds = %._crit_edge.loopexit, %.lr.ph.preheader, %0
  %.not.lcssa = phi i1 [ true, %0 ], [ false, %.lr.ph.preheader ], [ %.not.le, %._crit_edge.loopexit ]
  ret i1 %.not.lcssa
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(read, 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: CorrelatedValuePropagationPass,EarlyCSEPass,GVNPass,GlobalOptPass,IPSCCPPass,IndVarSimplifyPass,InferAlignmentPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LICMPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass