; LLVM IR from abeaumont/competitive-programming :: uva/00100.ll (Z7collatzi)

; 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: mustprogress nounwind uwtable
define dso_local noundef i32 @_Z7collatzi(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  store i32 1, ptr %3, align 4, !tbaa !5
  br label %4

4:                                                ; preds = %18, %1
  %5 = load i32, ptr %2, align 4, !tbaa !5
  %6 = icmp sgt i32 %5, 1
  br i1 %6, label %7, label %21

7:                                                ; preds = %4
  %8 = load i32, ptr %2, align 4, !tbaa !5
  %9 = srem i32 %8, 2
  %10 = icmp ne i32 %9, 0
  br i1 %10, label %11, label %15

11:                                               ; preds = %7
  %12 = load i32, ptr %2, align 4, !tbaa !5
  %13 = mul nsw i32 %12, 3
  %14 = add nsw i32 %13, 1
  store i32 %14, ptr %2, align 4, !tbaa !5
  br label %18

15:                                               ; preds = %7
  %16 = load i32, ptr %2, align 4, !tbaa !5
  %17 = ashr i32 %16, 1
  store i32 %17, ptr %2, align 4, !tbaa !5
  br label %18

18:                                               ; preds = %15, %11
  %19 = load i32, ptr %3, align 4, !tbaa !5
  %20 = add nsw i32 %19, 1
  store i32 %20, ptr %3, align 4, !tbaa !5
  br label %4, !llvm.loop !9

21:                                               ; preds = %4
  %22 = load i32, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  ret i32 %22
}

; 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"

; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable
define dso_local noundef i32 @_Z7collatzi(i32 noundef %0) local_unnamed_addr #0 {
  %2 = icmp sgt i32 %0, 1
  br i1 %2, label %select.unfold, label %select.unfold._crit_edge

select.unfold:                                    ; preds = %1, %select.unfold
  %.08 = phi i32 [ %7, %select.unfold ], [ 1, %1 ]
  %.067 = phi i32 [ %spec.select, %select.unfold ], [ %0, %1 ]
  %3 = and i32 %.067, 1
  %.not = icmp eq i32 %3, 0
  %4 = mul nuw nsw i32 %.067, 3
  %5 = add nuw nsw i32 %4, 1
  %6 = lshr exact i32 %.067, 1
  %7 = add nuw nsw i32 %.08, 1
  %spec.select = select i1 %.not, i32 %6, i32 %5
  %8 = icmp ugt i32 %spec.select, 1
  br i1 %8, label %select.unfold, label %select.unfold._crit_edge

select.unfold._crit_edge:                         ; preds = %select.unfold, %1
  %.0.lcssa = phi i32 [ 1, %1 ], [ %7, %select.unfold ]
  ret i32 %.0.lcssa
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(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)"}


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