; LLVM IR from hutusi/rethink-c :: src (list)

; 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._List = type { ptr, ptr, i32 }
%struct._ListNode = type { ptr, 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 @list_nth_node(ptr noundef %0, i32 noundef %1) #1 {
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca i32, align 4
  %6 = alloca ptr, align 8
  %7 = alloca i32, align 4
  %8 = alloca i32, align 4
  store ptr %0, ptr %4, align 8, !tbaa !5
  store i32 %1, ptr %5, align 4, !tbaa !9
  %9 = load ptr, ptr %4, align 8, !tbaa !5
  %10 = icmp eq ptr %9, null
  br i1 %10, label %11, label %12

11:                                               ; preds = %2
  store ptr null, ptr %3, align 8
  br label %38

12:                                               ; preds = %2
  call void @llvm.lifetime.start.p0(i64 8, ptr %6) #2
  %13 = load ptr, ptr %4, align 8, !tbaa !5
  %14 = getelementptr inbounds %struct._List, ptr %13, i32 0, i32 0
  %15 = load ptr, ptr %14, align 8, !tbaa !11
  store ptr %15, ptr %6, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %7) #2
  store i32 0, ptr %7, align 4, !tbaa !9
  br label %16

16:                                               ; preds = %30, %12
  %17 = load i32, ptr %7, align 4, !tbaa !9
  %18 = load i32, ptr %5, align 4, !tbaa !9
  %19 = icmp ult i32 %17, %18
  br i1 %19, label %21, label %20

20:                                               ; preds = %16
  store i32 2, ptr %8, align 4
  br label %33

21:                                               ; preds = %16
  %22 = load ptr, ptr %6, align 8, !tbaa !5
  %23 = icmp eq ptr %22, null
  br i1 %23, label %24, label %25

24:                                               ; preds = %21
  store ptr null, ptr %3, align 8
  store i32 1, ptr %8, align 4
  br label %33

25:                                               ; preds = %21
  %26 = load ptr, ptr %6, align 8, !tbaa !5
  %27 = getelementptr inbounds %struct._ListNode, ptr %26, i32 0, i32 2
  %28 = load ptr, ptr %27, align 8, !tbaa !13
  store ptr %28, ptr %6, align 8, !tbaa !5
  br label %29

29:                                               ; preds = %25
  br label %30

30:                                               ; preds = %29
  %31 = load i32, ptr %7, align 4, !tbaa !9
  %32 = add i32 %31, 1
  store i32 %32, ptr %7, align 4, !tbaa !9
  br label %16, !llvm.loop !15

33:                                               ; preds = %24, %20
  call void @llvm.lifetime.end.p0(i64 4, ptr %7) #2
  %34 = load i32, ptr %8, align 4
  switch i32 %34, label %37 [
    i32 2, label %35
  ]

35:                                               ; preds = %33
  %36 = load ptr, ptr %6, align 8, !tbaa !5
  store ptr %36, ptr %3, align 8
  store i32 1, ptr %8, align 4
  br label %37

37:                                               ; preds = %35, %33
  call void @llvm.lifetime.end.p0(i64 8, ptr %6) #2
  br label %38

38:                                               ; preds = %37, %11
  %39 = load ptr, ptr %3, align 8
  ret ptr %39
}

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, !10, i64 0}
!10 = !{!"int", !7, i64 0}
!11 = !{!12, !6, i64 0}
!12 = !{!"_List", !6, i64 0, !6, i64 8, !10, i64 16}
!13 = !{!14, !6, i64 16}
!14 = !{!"_ListNode", !6, i64 0, !6, i64 8, !6, i64 16}
!15 = distinct !{!15, !16}
!16 = !{!"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 @list_nth_node(ptr noundef readonly %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = icmp eq ptr %0, null
  br i1 %3, label %8, label %.preheader

.preheader:                                       ; preds = %2
  %.01013 = load ptr, ptr %0, align 8, !tbaa !5
  %.not14 = icmp eq i32 %1, 0
  %4 = icmp eq ptr %.01013, null
  %or.cond15 = select i1 %.not14, i1 true, i1 %4
  br i1 %or.cond15, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %.preheader, %.lr.ph
  %.01017 = phi ptr [ %.010, %.lr.ph ], [ %.01013, %.preheader ]
  %.0916 = phi i32 [ %6, %.lr.ph ], [ 0, %.preheader ]
  %5 = getelementptr inbounds i8, ptr %.01017, i64 16
  %6 = add nuw i32 %.0916, 1
  %.010 = load ptr, ptr %5, align 8, !tbaa !5
  %.not = icmp uge i32 %6, %1
  %7 = icmp eq ptr %.010, null
  %or.cond = select i1 %.not, i1 true, i1 %7
  br i1 %or.cond, label %._crit_edge, label %.lr.ph, !llvm.loop !9

._crit_edge:                                      ; preds = %.lr.ph, %.preheader
  %.010.lcssa = phi ptr [ %.01013, %.preheader ], [ %.010, %.lr.ph ]
  %.not.lcssa = phi i1 [ %.not14, %.preheader ], [ %.not, %.lr.ph ]
  %spec.select = select i1 %.not.lcssa, ptr %.010.lcssa, ptr null
  br label %8

8:                                                ; preds = %2, %._crit_edge
  %.2 = phi ptr [ %spec.select, %._crit_edge ], [ null, %2 ]
  ret ptr %.2
}

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, !6, i64 0}
!6 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
!9 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}


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