; LLVM IR from ahampriyanshu/algo-ds-101 :: Algorithms/Sorting/Merge_Sort_on_Doubly_Linked_List (Mergesort_doubly)

; 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"

%struct.Node = type { i32, ptr, ptr }

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

; Function Attrs: nounwind uwtable
define dso_local ptr @split(ptr noundef %0) #1 {
  %2 = alloca ptr, align 8
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  store ptr %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  %6 = load ptr, ptr %2, align 8, !tbaa !5
  store ptr %6, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %7 = load ptr, ptr %2, align 8, !tbaa !5
  store ptr %7, ptr %4, align 8, !tbaa !5
  br label %8

8:                                                ; preds = %22, %1
  %9 = load ptr, ptr %3, align 8, !tbaa !5
  %10 = getelementptr inbounds %struct.Node, ptr %9, i32 0, i32 1
  %11 = load ptr, ptr %10, align 8, !tbaa !9
  %12 = icmp ne ptr %11, null
  br i1 %12, label %13, label %20

13:                                               ; preds = %8
  %14 = load ptr, ptr %3, align 8, !tbaa !5
  %15 = getelementptr inbounds %struct.Node, ptr %14, i32 0, i32 1
  %16 = load ptr, ptr %15, align 8, !tbaa !9
  %17 = getelementptr inbounds %struct.Node, ptr %16, i32 0, i32 1
  %18 = load ptr, ptr %17, align 8, !tbaa !9
  %19 = icmp ne ptr %18, null
  br label %20

20:                                               ; preds = %13, %8
  %21 = phi i1 [ false, %8 ], [ %19, %13 ]
  br i1 %21, label %22, label %31

22:                                               ; preds = %20
  %23 = load ptr, ptr %3, align 8, !tbaa !5
  %24 = getelementptr inbounds %struct.Node, ptr %23, i32 0, i32 1
  %25 = load ptr, ptr %24, align 8, !tbaa !9
  %26 = getelementptr inbounds %struct.Node, ptr %25, i32 0, i32 1
  %27 = load ptr, ptr %26, align 8, !tbaa !9
  store ptr %27, ptr %3, align 8, !tbaa !5
  %28 = load ptr, ptr %4, align 8, !tbaa !5
  %29 = getelementptr inbounds %struct.Node, ptr %28, i32 0, i32 1
  %30 = load ptr, ptr %29, align 8, !tbaa !9
  store ptr %30, ptr %4, align 8, !tbaa !5
  br label %8, !llvm.loop !12

31:                                               ; preds = %20
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  %32 = load ptr, ptr %4, align 8, !tbaa !5
  %33 = getelementptr inbounds %struct.Node, ptr %32, i32 0, i32 1
  %34 = load ptr, ptr %33, align 8, !tbaa !9
  store ptr %34, ptr %5, align 8, !tbaa !5
  %35 = load ptr, ptr %4, align 8, !tbaa !5
  %36 = getelementptr inbounds %struct.Node, ptr %35, i32 0, i32 1
  store ptr null, ptr %36, align 8, !tbaa !9
  %37 = load ptr, ptr %5, align 8, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  ret ptr %37
}

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

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { 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 #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 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
!9 = !{!10, !6, i64 8}
!10 = !{!"Node", !11, i64 0, !6, i64 8, !6, i64 16}
!11 = !{!"int", !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: nofree norecurse nosync nounwind memory(readwrite, inaccessiblemem: none) uwtable
define dso_local ptr @split(ptr nocapture noundef %0) local_unnamed_addr #0 {
  %2 = getelementptr inbounds i8, ptr %0, i64 8
  %3 = load ptr, ptr %2, align 8, !tbaa !5
  %.not13 = icmp eq ptr %3, null
  br i1 %.not13, label %.critedge, label %.lr.ph

.lr.ph:                                           ; preds = %1, %7
  %4 = phi ptr [ %11, %7 ], [ %3, %1 ]
  %.0914 = phi ptr [ %9, %7 ], [ %0, %1 ]
  %5 = getelementptr inbounds i8, ptr %4, i64 8
  %6 = load ptr, ptr %5, align 8, !tbaa !5
  %.not12 = icmp eq ptr %6, null
  br i1 %.not12, label %.critedge.loopexit, label %7

7:                                                ; preds = %.lr.ph
  %8 = getelementptr inbounds i8, ptr %.0914, i64 8
  %9 = load ptr, ptr %8, align 8, !tbaa !5
  %10 = getelementptr inbounds i8, ptr %6, i64 8
  %11 = load ptr, ptr %10, align 8, !tbaa !5
  %.not = icmp eq ptr %11, null
  br i1 %.not, label %.critedge.loopexit, label %.lr.ph, !llvm.loop !11

.critedge.loopexit:                               ; preds = %7, %.lr.ph
  %.09.lcssa.ph = phi ptr [ %.0914, %.lr.ph ], [ %9, %7 ]
  %.phi.trans.insert = getelementptr inbounds i8, ptr %.09.lcssa.ph, i64 8
  %.pre = load ptr, ptr %.phi.trans.insert, align 8, !tbaa !5
  br label %.critedge

.critedge:                                        ; preds = %.critedge.loopexit, %1
  %12 = phi ptr [ null, %1 ], [ %.pre, %.critedge.loopexit ]
  %.09.lcssa = phi ptr [ %0, %1 ], [ %.09.lcssa.ph, %.critedge.loopexit ]
  %13 = getelementptr inbounds i8, ptr %.09.lcssa, i64 8
  store ptr null, ptr %13, align 8, !tbaa !5
  ret ptr %12
}

attributes #0 = { nofree norecurse nosync nounwind memory(readwrite, 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, !10, i64 8}
!6 = !{!"Node", !7, i64 0, !10, i64 8, !10, i64 16}
!7 = !{!"int", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C/C++ TBAA"}
!10 = !{!"any pointer", !8, i64 0}
!11 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}


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