; LLVM IR from lekkas/c-algorithms :: src/algos (SingleList)

; 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.SingleList = type { ptr, %struct.DataOps }
%struct.DataOps = type { ptr, ptr }
%struct.SingleListNode = type { 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: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: nounwind uwtable
define dso_local ptr @findMiddle(ptr noundef %0) #1 {
  %2 = alloca ptr, align 8
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  store ptr %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %5 = load ptr, ptr %2, align 8, !tbaa !5
  %6 = getelementptr inbounds %struct.SingleList, ptr %5, i32 0, i32 0
  %7 = load ptr, ptr %6, align 8, !tbaa !9
  store ptr %7, ptr %3, align 8, !tbaa !5
  %8 = load ptr, ptr %2, align 8, !tbaa !5
  %9 = getelementptr inbounds %struct.SingleList, ptr %8, i32 0, i32 0
  %10 = load ptr, ptr %9, align 8, !tbaa !9
  store ptr %10, ptr %4, align 8, !tbaa !5
  br label %11

11:                                               ; preds = %28, %1
  %12 = load ptr, ptr %3, align 8, !tbaa !5
  %13 = icmp ne ptr %12, null
  br i1 %13, label %14, label %26

14:                                               ; preds = %11
  %15 = load ptr, ptr %3, align 8, !tbaa !5
  %16 = getelementptr inbounds %struct.SingleListNode, ptr %15, i32 0, i32 1
  %17 = load ptr, ptr %16, align 8, !tbaa !12
  %18 = icmp ne ptr %17, null
  br i1 %18, label %19, label %26

19:                                               ; preds = %14
  %20 = load ptr, ptr %3, align 8, !tbaa !5
  %21 = getelementptr inbounds %struct.SingleListNode, ptr %20, i32 0, i32 1
  %22 = load ptr, ptr %21, align 8, !tbaa !12
  %23 = getelementptr inbounds %struct.SingleListNode, ptr %22, i32 0, i32 1
  %24 = load ptr, ptr %23, align 8, !tbaa !12
  %25 = icmp ne ptr %24, null
  br label %26

26:                                               ; preds = %19, %14, %11
  %27 = phi i1 [ false, %14 ], [ false, %11 ], [ %25, %19 ]
  br i1 %27, label %28, label %37

28:                                               ; preds = %26
  %29 = load ptr, ptr %4, align 8, !tbaa !5
  %30 = getelementptr inbounds %struct.SingleListNode, ptr %29, i32 0, i32 1
  %31 = load ptr, ptr %30, align 8, !tbaa !12
  store ptr %31, ptr %4, align 8, !tbaa !5
  %32 = load ptr, ptr %3, align 8, !tbaa !5
  %33 = getelementptr inbounds %struct.SingleListNode, ptr %32, i32 0, i32 1
  %34 = load ptr, ptr %33, align 8, !tbaa !12
  %35 = getelementptr inbounds %struct.SingleListNode, ptr %34, i32 0, i32 1
  %36 = load ptr, ptr %35, align 8, !tbaa !12
  store ptr %36, ptr %3, align 8, !tbaa !5
  br label %11, !llvm.loop !14

37:                                               ; preds = %26
  %38 = load ptr, ptr %4, align 8, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  ret ptr %38
}

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 0}
!10 = !{!"SingleList", !6, i64 0, !11, i64 8}
!11 = !{!"DataOps", !6, i64 0, !6, i64 8}
!12 = !{!13, !6, i64 8}
!13 = !{!"SingleListNode", !6, i64 0, !6, i64 8}
!14 = distinct !{!14, !15}
!15 = !{!"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(read, inaccessiblemem: none) uwtable
define dso_local ptr @findMiddle(ptr nocapture noundef readonly %0) local_unnamed_addr #0 {
  %2 = load ptr, ptr %0, align 8, !tbaa !5
  %.not13 = icmp eq ptr %2, null
  br i1 %.not13, label %.critedge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %1
  %3 = getelementptr inbounds i8, ptr %2, i64 8
  %4 = load ptr, ptr %3, align 8, !tbaa !11
  %.not1120 = icmp eq ptr %4, null
  br i1 %.not1120, label %.critedge, label %.lr.ph22

.lr.ph22:                                         ; preds = %.lr.ph.preheader, %.lr.ph
  %5 = phi ptr [ %11, %.lr.ph ], [ %4, %.lr.ph.preheader ]
  %.01521 = phi ptr [ %9, %.lr.ph ], [ %2, %.lr.ph.preheader ]
  %6 = getelementptr inbounds i8, ptr %5, i64 8
  %7 = load ptr, ptr %6, align 8, !tbaa !11
  %.not12 = icmp eq ptr %7, null
  br i1 %.not12, label %.critedge, label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph22
  %8 = getelementptr inbounds i8, ptr %.01521, i64 8
  %9 = load ptr, ptr %8, align 8, !tbaa !11
  %10 = getelementptr inbounds i8, ptr %7, i64 8
  %11 = load ptr, ptr %10, align 8, !tbaa !11
  %.not11 = icmp eq ptr %11, null
  br i1 %.not11, label %.critedge, label %.lr.ph22

.critedge:                                        ; preds = %.lr.ph, %.lr.ph22, %.lr.ph.preheader, %1
  %.0.lcssa = phi ptr [ null, %1 ], [ %2, %.lr.ph.preheader ], [ %.01521, %.lr.ph22 ], [ %9, %.lr.ph ]
  ret ptr %.0.lcssa
}

attributes #0 = { nofree norecurse nosync nounwind memory(read, 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, !7, i64 0}
!6 = !{!"SingleList", !7, i64 0, !10, i64 8}
!7 = !{!"any pointer", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C/C++ TBAA"}
!10 = !{!"DataOps", !7, i64 0, !7, i64 8}
!11 = !{!12, !7, i64 8}
!12 = !{!"SingleListNode", !7, i64 0, !7, i64 8}


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