; LLVM IR from ritikbanger/Hacktoberfest2022-DSA :: 10. Linked List/c lang/CircularLinkedList (Deleting)

; 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 }

@start = external dso_local global ptr, align 8

; 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 @deleteBeg() #1 {
  %1 = alloca ptr, align 8
  %2 = alloca ptr, align 8
  call void @llvm.lifetime.start.p0(i64 8, ptr %1) #3
  call void @llvm.lifetime.start.p0(i64 8, ptr %2) #3
  %3 = load ptr, ptr @start, align 8, !tbaa !5
  store ptr %3, ptr %1, align 8, !tbaa !5
  %4 = load ptr, ptr @start, align 8, !tbaa !5
  store ptr %4, ptr %2, align 8, !tbaa !5
  br label %5

5:                                                ; preds = %11, %0
  %6 = load ptr, ptr %1, align 8, !tbaa !5
  %7 = getelementptr inbounds %struct.node, ptr %6, i32 0, i32 1
  %8 = load ptr, ptr %7, align 8, !tbaa !9
  %9 = load ptr, ptr @start, align 8, !tbaa !5
  %10 = icmp ne ptr %8, %9
  br i1 %10, label %11, label %15

11:                                               ; preds = %5
  %12 = load ptr, ptr %1, align 8, !tbaa !5
  %13 = getelementptr inbounds %struct.node, ptr %12, i32 0, i32 1
  %14 = load ptr, ptr %13, align 8, !tbaa !9
  store ptr %14, ptr %1, align 8, !tbaa !5
  br label %5, !llvm.loop !12

15:                                               ; preds = %5
  %16 = load ptr, ptr %2, align 8, !tbaa !5
  %17 = getelementptr inbounds %struct.node, ptr %16, i32 0, i32 1
  %18 = load ptr, ptr %17, align 8, !tbaa !9
  store ptr %18, ptr @start, align 8, !tbaa !5
  %19 = load ptr, ptr @start, align 8, !tbaa !5
  %20 = load ptr, ptr %1, align 8, !tbaa !5
  %21 = getelementptr inbounds %struct.node, ptr %20, i32 0, i32 1
  store ptr %19, ptr %21, align 8, !tbaa !9
  %22 = load ptr, ptr %2, align 8, !tbaa !5
  call void @free(ptr noundef %22) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %2) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %1) #3
  ret void
}

; Function Attrs: nounwind
declare void @free(ptr noundef) #2

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 "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 }

!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"

@start = external dso_local local_unnamed_addr global ptr, align 8

; Function Attrs: nounwind uwtable
define dso_local void @deleteBeg() local_unnamed_addr #0 {
  %1 = load ptr, ptr @start, align 8, !tbaa !5
  br label %2

2:                                                ; preds = %2, %0
  %.0 = phi ptr [ %1, %0 ], [ %4, %2 ]
  %3 = getelementptr inbounds i8, ptr %.0, i64 8
  %4 = load ptr, ptr %3, align 8, !tbaa !9
  %.not = icmp eq ptr %4, %1
  br i1 %.not, label %5, label %2, !llvm.loop !12

5:                                                ; preds = %2
  %6 = getelementptr inbounds i8, ptr %.0, i64 8
  %7 = getelementptr inbounds i8, ptr %1, i64 8
  %8 = load ptr, ptr %7, align 8, !tbaa !9
  store ptr %8, ptr @start, align 8, !tbaa !5
  store ptr %8, ptr %6, align 8, !tbaa !9
  tail call void @free(ptr noundef %1) #2
  ret void
}

; Function Attrs: mustprogress nounwind willreturn allockind("free") memory(argmem: readwrite, inaccessiblemem: readwrite)
declare void @free(ptr allocptr nocapture noundef) local_unnamed_addr #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 = { mustprogress nounwind willreturn allockind("free") memory(argmem: readwrite, 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 = { 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"}


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