; LLVM IR from AllenDowney/ExercisesInC :: exercises/ex13 (list_errors)

; 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 }

; 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 void @reverse(ptr noundef %0) #1 {
  %2 = alloca ptr, align 8
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  %6 = alloca i32, align 4
  store ptr %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  %7 = load ptr, ptr %2, align 8, !tbaa !5
  %8 = load ptr, ptr %7, align 8, !tbaa !5
  store ptr %8, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  %9 = load ptr, ptr %3, align 8, !tbaa !5
  %10 = icmp eq ptr %9, null
  br i1 %10, label %16, label %11

11:                                               ; preds = %1
  %12 = load ptr, ptr %3, align 8, !tbaa !5
  %13 = getelementptr inbounds %struct.node, ptr %12, i32 0, i32 1
  %14 = load ptr, ptr %13, align 8, !tbaa !9
  %15 = icmp eq ptr %14, null
  br i1 %15, label %16, label %17

16:                                               ; preds = %11, %1
  store i32 1, ptr %6, align 4
  br label %38

17:                                               ; preds = %11
  %18 = load ptr, ptr %3, align 8, !tbaa !5
  %19 = getelementptr inbounds %struct.node, ptr %18, i32 0, i32 1
  %20 = load ptr, ptr %19, align 8, !tbaa !9
  store ptr %20, ptr %4, align 8, !tbaa !5
  %21 = load ptr, ptr %3, align 8, !tbaa !5
  %22 = getelementptr inbounds %struct.node, ptr %21, i32 0, i32 1
  store ptr null, ptr %22, align 8, !tbaa !9
  br label %23

23:                                               ; preds = %26, %17
  %24 = load ptr, ptr %4, align 8, !tbaa !5
  %25 = icmp ne ptr %24, null
  br i1 %25, label %26, label %35

26:                                               ; preds = %23
  %27 = load ptr, ptr %4, align 8, !tbaa !5
  %28 = getelementptr inbounds %struct.node, ptr %27, i32 0, i32 1
  %29 = load ptr, ptr %28, align 8, !tbaa !9
  store ptr %29, ptr %5, align 8, !tbaa !5
  %30 = load ptr, ptr %3, align 8, !tbaa !5
  %31 = load ptr, ptr %4, align 8, !tbaa !5
  %32 = getelementptr inbounds %struct.node, ptr %31, i32 0, i32 1
  store ptr %30, ptr %32, align 8, !tbaa !9
  %33 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %33, ptr %3, align 8, !tbaa !5
  %34 = load ptr, ptr %5, align 8, !tbaa !5
  store ptr %34, ptr %4, align 8, !tbaa !5
  br label %23, !llvm.loop !12

35:                                               ; preds = %23
  %36 = load ptr, ptr %3, align 8, !tbaa !5
  %37 = load ptr, ptr %2, align 8, !tbaa !5
  store ptr %36, ptr %37, align 8, !tbaa !5
  store i32 0, ptr %6, align 4
  br label %38

38:                                               ; preds = %35, %16
  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
  %39 = load i32, ptr %6, align 4
  switch i32 %39, label %41 [
    i32 0, label %40
    i32 1, label %40
  ]

40:                                               ; preds = %38, %38
  ret void

41:                                               ; preds = %38
  unreachable
}

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}
!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 void @reverse(ptr nocapture noundef %0) local_unnamed_addr #0 {
  %2 = load ptr, ptr %0, align 8, !tbaa !5
  %3 = icmp eq ptr %2, null
  br i1 %3, label %13, label %4

4:                                                ; preds = %1
  %5 = getelementptr inbounds i8, ptr %2, i64 8
  %6 = load ptr, ptr %5, align 8, !tbaa !9
  %7 = icmp eq ptr %6, null
  br i1 %7, label %13, label %8

8:                                                ; preds = %4
  store ptr null, ptr %5, align 8, !tbaa !9
  br label %9

9:                                                ; preds = %8, %9
  %.017 = phi ptr [ %2, %8 ], [ %.01316, %9 ]
  %.01316 = phi ptr [ %6, %8 ], [ %11, %9 ]
  %10 = getelementptr inbounds i8, ptr %.01316, i64 8
  %11 = load ptr, ptr %10, align 8, !tbaa !9
  store ptr %.017, ptr %10, align 8, !tbaa !9
  %.not = icmp eq ptr %11, null
  br i1 %.not, label %12, label %9, !llvm.loop !12

12:                                               ; preds = %9
  store ptr %.01316, ptr %0, align 8, !tbaa !5
  br label %13

13:                                               ; preds = %1, %4, %12
  ret void
}

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, !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}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}


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