; LLVM IR from ritikbanger/Hacktoberfest2022-DSA :: 10. Linked List/c lang/SinglyLinkedList (Reverse a Linked 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.node = type { i32, ptr }

@.str = external hidden unnamed_addr constant [10 x i8], align 1
@head = external dso_local global ptr, align 8

; Function Attrs: nounwind uwtable
define dso_local void @ie(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca ptr, align 8
  %4 = alloca i32, align 4
  %5 = alloca ptr, align 8
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #4
  store ptr null, ptr %3, align 8, !tbaa !9
  %6 = call noalias ptr @malloc(i64 noundef 16) #5
  store ptr %6, ptr %3, align 8, !tbaa !9
  %7 = load ptr, ptr %3, align 8, !tbaa !9
  %8 = icmp eq ptr %7, null
  br i1 %8, label %9, label %11

9:                                                ; preds = %1
  %10 = call i32 (ptr, ...) @printf(ptr noundef @.str)
  store i32 1, ptr %4, align 4
  br label %37

11:                                               ; preds = %1
  %12 = load i32, ptr %2, align 4, !tbaa !5
  %13 = load ptr, ptr %3, align 8, !tbaa !9
  %14 = getelementptr inbounds %struct.node, ptr %13, i32 0, i32 0
  store i32 %12, ptr %14, align 8, !tbaa !11
  %15 = load ptr, ptr %3, align 8, !tbaa !9
  %16 = getelementptr inbounds %struct.node, ptr %15, i32 0, i32 1
  store ptr null, ptr %16, align 8, !tbaa !13
  %17 = load ptr, ptr @head, align 8, !tbaa !9
  %18 = icmp eq ptr %17, null
  br i1 %18, label %19, label %21

19:                                               ; preds = %11
  %20 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %20, ptr @head, align 8, !tbaa !9
  br label %36

21:                                               ; preds = %11
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #4
  %22 = load ptr, ptr @head, align 8, !tbaa !9
  store ptr %22, ptr %5, align 8, !tbaa !9
  br label %23

23:                                               ; preds = %28, %21
  %24 = load ptr, ptr %5, align 8, !tbaa !9
  %25 = getelementptr inbounds %struct.node, ptr %24, i32 0, i32 1
  %26 = load ptr, ptr %25, align 8, !tbaa !13
  %27 = icmp ne ptr %26, null
  br i1 %27, label %28, label %32

28:                                               ; preds = %23
  %29 = load ptr, ptr %5, align 8, !tbaa !9
  %30 = getelementptr inbounds %struct.node, ptr %29, i32 0, i32 1
  %31 = load ptr, ptr %30, align 8, !tbaa !13
  store ptr %31, ptr %5, align 8, !tbaa !9
  br label %23, !llvm.loop !14

32:                                               ; preds = %23
  %33 = load ptr, ptr %3, align 8, !tbaa !9
  %34 = load ptr, ptr %5, align 8, !tbaa !9
  %35 = getelementptr inbounds %struct.node, ptr %34, i32 0, i32 1
  store ptr %33, ptr %35, align 8, !tbaa !13
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #4
  br label %36

36:                                               ; preds = %32, %19
  store i32 0, ptr %4, align 4
  br label %37

37:                                               ; preds = %36, %9
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #4
  %38 = load i32, ptr %4, align 4
  switch i32 %38, label %40 [
    i32 0, label %39
    i32 1, label %39
  ]

39:                                               ; preds = %37, %37
  ret void

40:                                               ; preds = %37
  unreachable
}

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: nounwind allocsize(0)
declare noalias ptr @malloc(i64 noundef) #2

declare i32 @printf(ptr noundef, ...) #3

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

attributes #0 = { 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 allocsize(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 #3 = { "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 #4 = { nounwind }
attributes #5 = { nounwind allocsize(0) }

!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/C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"any pointer", !7, i64 0}
!11 = !{!12, !6, i64 0}
!12 = !{!"node", !6, i64 0, !10, i64 8}
!13 = !{!12, !10, 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"

@.str = external hidden unnamed_addr constant [10 x i8], align 1
@head = external dso_local local_unnamed_addr global ptr, align 8

; Function Attrs: nofree nounwind uwtable
define dso_local void @ie(i32 noundef %0) local_unnamed_addr #0 {
  %2 = tail call noalias dereferenceable_or_null(16) ptr @malloc(i64 noundef 16) #3
  %3 = icmp eq ptr %2, null
  br i1 %3, label %4, label %6

4:                                                ; preds = %1
  %5 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str)
  br label %15

6:                                                ; preds = %1
  store i32 %0, ptr %2, align 8, !tbaa !5
  %7 = getelementptr inbounds i8, ptr %2, i64 8
  store ptr null, ptr %7, align 8, !tbaa !11
  %8 = load ptr, ptr @head, align 8, !tbaa !12
  %9 = icmp eq ptr %8, null
  br i1 %9, label %10, label %.preheader

10:                                               ; preds = %6
  store ptr %2, ptr @head, align 8, !tbaa !12
  br label %15

.preheader:                                       ; preds = %6, %.preheader
  %.0 = phi ptr [ %12, %.preheader ], [ %8, %6 ]
  %11 = getelementptr inbounds i8, ptr %.0, i64 8
  %12 = load ptr, ptr %11, align 8, !tbaa !11
  %.not = icmp eq ptr %12, null
  br i1 %.not, label %13, label %.preheader, !llvm.loop !13

13:                                               ; preds = %.preheader
  %14 = getelementptr inbounds i8, ptr %.0, i64 8
  store ptr %2, ptr %14, align 8, !tbaa !11
  br label %15

15:                                               ; preds = %10, %13, %4
  ret void
}

; Function Attrs: mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0) memory(inaccessiblemem: readwrite)
declare noalias noundef ptr @malloc(i64 noundef) local_unnamed_addr #1

; Function Attrs: nofree nounwind
declare noundef i32 @printf(ptr nocapture noundef readonly, ...) local_unnamed_addr #2

attributes #0 = { nofree 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 = { mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0) memory(inaccessiblemem: readwrite) "alloc-family"="malloc" "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 = { nofree nounwind "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 #3 = { nounwind allocsize(0) }

!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 = !{!"node", !7, i64 0, !10, i64 8}
!7 = !{!"int", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C/C++ TBAA"}
!10 = !{!"any pointer", !8, i64 0}
!11 = !{!6, !10, i64 8}
!12 = !{!10, !10, i64 0}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}


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