; LLVM IR from bhrigukansra/algorithms-in-C-Cplusplus-Java-Python-JavaScript :: Data Structures/Linked List/C++/SLList.ll (ZN6SLList16delete_from_tailEv)

; 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"

%class.SLList = type { ptr, ptr }
%class.SLLNode = 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: nobuiltin nounwind
declare void @_ZdlPvm(ptr noundef, i64 noundef) #1

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef i32 @_ZN6SLList16delete_from_tailEv(ptr noundef nonnull align 8 dereferenceable(16) %0) #2 align 2 {
  %2 = alloca ptr, align 8
  %3 = alloca i32, align 4
  %4 = alloca ptr, align 8
  store ptr %0, ptr %2, align 8, !tbaa !5
  %5 = load ptr, ptr %2, align 8
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #3
  %6 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 1
  %7 = load ptr, ptr %6, align 8, !tbaa !9
  %8 = getelementptr inbounds %class.SLLNode, ptr %7, i32 0, i32 0
  %9 = load i32, ptr %8, align 8, !tbaa !11
  store i32 %9, ptr %3, align 4, !tbaa !14
  %10 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 0
  %11 = load ptr, ptr %10, align 8, !tbaa !15
  %12 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 1
  %13 = load ptr, ptr %12, align 8, !tbaa !9
  %14 = icmp eq ptr %11, %13
  br i1 %14, label %15, label %23

15:                                               ; preds = %1
  %16 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 0
  %17 = load ptr, ptr %16, align 8, !tbaa !15
  %18 = icmp eq ptr %17, null
  br i1 %18, label %20, label %19

19:                                               ; preds = %15
  call void @_ZdlPvm(ptr noundef %17, i64 noundef 16) #4
  br label %20

20:                                               ; preds = %19, %15
  %21 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 1
  store ptr null, ptr %21, align 8, !tbaa !9
  %22 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 0
  store ptr null, ptr %22, align 8, !tbaa !15
  br label %49

23:                                               ; preds = %1
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #3
  %24 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 0
  %25 = load ptr, ptr %24, align 8, !tbaa !15
  store ptr %25, ptr %4, align 8, !tbaa !5
  br label %26

26:                                               ; preds = %34, %23
  %27 = load ptr, ptr %4, align 8, !tbaa !5
  %28 = getelementptr inbounds %class.SLLNode, ptr %27, i32 0, i32 1
  %29 = load ptr, ptr %28, align 8, !tbaa !16
  %30 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 1
  %31 = load ptr, ptr %30, align 8, !tbaa !9
  %32 = icmp ne ptr %29, %31
  br i1 %32, label %33, label %38

33:                                               ; preds = %26
  br label %34

34:                                               ; preds = %33
  %35 = load ptr, ptr %4, align 8, !tbaa !5
  %36 = getelementptr inbounds %class.SLLNode, ptr %35, i32 0, i32 1
  %37 = load ptr, ptr %36, align 8, !tbaa !16
  store ptr %37, ptr %4, align 8, !tbaa !5
  br label %26, !llvm.loop !17

38:                                               ; preds = %26
  %39 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 1
  %40 = load ptr, ptr %39, align 8, !tbaa !9
  %41 = icmp eq ptr %40, null
  br i1 %41, label %43, label %42

42:                                               ; preds = %38
  call void @_ZdlPvm(ptr noundef %40, i64 noundef 16) #4
  br label %43

43:                                               ; preds = %42, %38
  %44 = load ptr, ptr %4, align 8, !tbaa !5
  %45 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 1
  store ptr %44, ptr %45, align 8, !tbaa !9
  %46 = getelementptr inbounds %class.SLList, ptr %5, i32 0, i32 1
  %47 = load ptr, ptr %46, align 8, !tbaa !9
  %48 = getelementptr inbounds %class.SLLNode, ptr %47, i32 0, i32 1
  store ptr null, ptr %48, align 8, !tbaa !16
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #3
  br label %49

49:                                               ; preds = %43, %20
  %50 = load i32, ptr %3, align 4, !tbaa !14
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #3
  ret i32 %50
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { nobuiltin 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 #2 = { mustprogress 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 #3 = { nounwind }
attributes #4 = { builtin 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++ TBAA"}
!9 = !{!10, !6, i64 8}
!10 = !{!"_ZTS6SLList", !6, i64 0, !6, i64 8}
!11 = !{!12, !13, i64 0}
!12 = !{!"_ZTS7SLLNode", !13, i64 0, !6, i64 8}
!13 = !{!"int", !7, i64 0}
!14 = !{!13, !13, i64 0}
!15 = !{!10, !6, i64 0}
!16 = !{!12, !6, i64 8}
!17 = distinct !{!17, !18}
!18 = !{!"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: nobuiltin nounwind
declare void @_ZdlPvm(ptr noundef, i64 noundef) local_unnamed_addr #0

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef i32 @_ZN6SLList16delete_from_tailEv(ptr nocapture noundef nonnull align 8 dereferenceable(16) %0) local_unnamed_addr #1 align 2 {
  %2 = getelementptr inbounds i8, ptr %0, i64 8
  %3 = load ptr, ptr %2, align 8, !tbaa !5
  %4 = load i32, ptr %3, align 8, !tbaa !10
  %5 = load ptr, ptr %0, align 8, !tbaa !13
  %6 = icmp eq ptr %5, %3
  br i1 %6, label %7, label %.preheader

7:                                                ; preds = %1
  tail call void @_ZdlPvm(ptr noundef nonnull %5, i64 noundef 16) #3
  tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 8 dereferenceable(16) %0, i8 0, i64 16, i1 false)
  br label %12

.preheader:                                       ; preds = %1, %.preheader
  %.0 = phi ptr [ %9, %.preheader ], [ %5, %1 ]
  %8 = getelementptr inbounds i8, ptr %.0, i64 8
  %9 = load ptr, ptr %8, align 8, !tbaa !14
  %.not = icmp eq ptr %9, %3
  br i1 %.not, label %10, label %.preheader, !llvm.loop !15

10:                                               ; preds = %.preheader
  %11 = getelementptr inbounds i8, ptr %.0, i64 8
  tail call void @_ZdlPvm(ptr noundef %3, i64 noundef 16) #3
  store ptr %.0, ptr %2, align 8, !tbaa !5
  store ptr null, ptr %11, align 8, !tbaa !14
  br label %12

12:                                               ; preds = %10, %7
  ret i32 %4
}

; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: write)
declare void @llvm.memset.p0.i64(ptr nocapture writeonly, i8, i64, i1 immarg) #2

attributes #0 = { nobuiltin 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 #1 = { mustprogress 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 = { nocallback nofree nounwind willreturn memory(argmem: write) }
attributes #3 = { builtin 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, !7, i64 8}
!6 = !{!"_ZTS6SLList", !7, i64 0, !7, i64 8}
!7 = !{!"any pointer", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C++ TBAA"}
!10 = !{!11, !12, i64 0}
!11 = !{!"_ZTS7SLLNode", !12, i64 0, !7, i64 8}
!12 = !{!"int", !8, i64 0}
!13 = !{!6, !7, i64 0}
!14 = !{!11, !7, i64 8}
!15 = distinct !{!15, !16}
!16 = !{!"llvm.loop.mustprogress"}


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