; LLVM IR from mahendramahara/DSA-in-C-Programing :: LINKED-LIST (DeleteAtLastLinkedList)

; 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 }

@head = external dso_local global ptr, align 8
@.str = external hidden unnamed_addr constant [42 x i8], align 1
@.str.1 = external hidden unnamed_addr constant [20 x i8], align 1

; 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 @deleteFromEnd() #1 {
  %1 = alloca ptr, align 8
  %2 = alloca ptr, align 8
  %3 = load ptr, ptr @head, align 8, !tbaa !5
  %4 = icmp eq ptr %3, null
  br i1 %4, label %5, label %7

5:                                                ; preds = %0
  %6 = call i32 (ptr, ...) @printf(ptr noundef @.str)
  br label %32

7:                                                ; preds = %0
  %8 = load ptr, ptr @head, align 8, !tbaa !5
  %9 = getelementptr inbounds %struct.Node, ptr %8, i32 0, i32 1
  %10 = load ptr, ptr %9, align 8, !tbaa !9
  %11 = icmp eq ptr %10, null
  br i1 %11, label %12, label %15

12:                                               ; preds = %7
  %13 = load ptr, ptr @head, align 8, !tbaa !5
  call void @free(ptr noundef %13) #4
  store ptr null, ptr @head, align 8, !tbaa !5
  %14 = call i32 (ptr, ...) @printf(ptr noundef @.str.1)
  br label %32

15:                                               ; preds = %7
  call void @llvm.lifetime.start.p0(i64 8, ptr %1) #4
  %16 = load ptr, ptr @head, align 8, !tbaa !5
  store ptr %16, ptr %1, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %2) #4
  store ptr null, ptr %2, align 8, !tbaa !5
  br label %17

17:                                               ; preds = %22, %15
  %18 = load ptr, ptr %1, align 8, !tbaa !5
  %19 = getelementptr inbounds %struct.Node, ptr %18, i32 0, i32 1
  %20 = load ptr, ptr %19, align 8, !tbaa !9
  %21 = icmp ne ptr %20, null
  br i1 %21, label %22, label %27

22:                                               ; preds = %17
  %23 = load ptr, ptr %1, align 8, !tbaa !5
  store ptr %23, ptr %2, align 8, !tbaa !5
  %24 = load ptr, ptr %1, align 8, !tbaa !5
  %25 = getelementptr inbounds %struct.Node, ptr %24, i32 0, i32 1
  %26 = load ptr, ptr %25, align 8, !tbaa !9
  store ptr %26, ptr %1, align 8, !tbaa !5
  br label %17, !llvm.loop !12

27:                                               ; preds = %17
  %28 = load ptr, ptr %2, align 8, !tbaa !5
  %29 = getelementptr inbounds %struct.Node, ptr %28, i32 0, i32 1
  store ptr null, ptr %29, align 8, !tbaa !9
  %30 = load ptr, ptr %1, align 8, !tbaa !5
  call void @free(ptr noundef %30) #4
  %31 = call i32 (ptr, ...) @printf(ptr noundef @.str.1)
  call void @llvm.lifetime.end.p0(i64 8, ptr %2) #4
  call void @llvm.lifetime.end.p0(i64 8, ptr %1) #4
  br label %32

32:                                               ; preds = %27, %12, %5
  ret void
}

declare i32 @printf(ptr noundef, ...) #2

; Function Attrs: nounwind
declare void @free(ptr noundef) #3

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 = { "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 "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 }

!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"

@head = external dso_local local_unnamed_addr global ptr, align 8
@.str = external hidden unnamed_addr constant [42 x i8], align 1
@.str.1 = external hidden unnamed_addr constant [20 x i8], align 1

; Function Attrs: nounwind uwtable
define dso_local void @deleteFromEnd() local_unnamed_addr #0 {
  %1 = load ptr, ptr @head, align 8, !tbaa !5
  %2 = icmp eq ptr %1, null
  br i1 %2, label %12, label %3

3:                                                ; preds = %0
  %4 = getelementptr inbounds i8, ptr %1, i64 8
  %5 = load ptr, ptr %4, align 8, !tbaa !9
  %6 = icmp eq ptr %5, null
  br i1 %6, label %7, label %.preheader

7:                                                ; preds = %3
  tail call void @free(ptr noundef nonnull %1) #3
  store ptr null, ptr @head, align 8, !tbaa !5
  br label %12

.preheader:                                       ; preds = %3, %.preheader
  %.05 = phi ptr [ %9, %.preheader ], [ %1, %3 ]
  %.0 = phi ptr [ %.05, %.preheader ], [ null, %3 ]
  %8 = getelementptr inbounds i8, ptr %.05, i64 8
  %9 = load ptr, ptr %8, align 8, !tbaa !9
  %.not = icmp eq ptr %9, null
  br i1 %.not, label %10, label %.preheader, !llvm.loop !12

10:                                               ; preds = %.preheader
  %11 = getelementptr inbounds i8, ptr %.0, i64 8
  store ptr null, ptr %11, align 8, !tbaa !9
  tail call void @free(ptr noundef nonnull %.05) #3
  br label %12

12:                                               ; preds = %0, %10, %7
  %.str.1.sink = phi ptr [ @.str.1, %10 ], [ @.str.1, %7 ], [ @.str, %0 ]
  %13 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) %.str.1.sink)
  ret void
}

; Function Attrs: nofree nounwind
declare noundef i32 @printf(ptr nocapture noundef readonly, ...) local_unnamed_addr #1

; Function Attrs: mustprogress nounwind willreturn allockind("free") memory(argmem: readwrite, inaccessiblemem: readwrite)
declare void @free(ptr allocptr nocapture noundef) local_unnamed_addr #2

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 = { 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 #2 = { 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 #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"}


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