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

; 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 }

@last = external dso_local global ptr, align 8
@.str = external hidden unnamed_addr constant [17 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 @deletelast() #1 {
  %1 = alloca ptr, align 8
  call void @llvm.lifetime.start.p0(i64 8, ptr %1) #3
  %2 = load ptr, ptr @last, align 8, !tbaa !5
  %3 = icmp eq ptr %2, null
  br i1 %3, label %4, label %6

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

6:                                                ; preds = %4, %0
  %7 = load ptr, ptr @last, align 8, !tbaa !5
  %8 = getelementptr inbounds %struct.node, ptr %7, i32 0, i32 1
  %9 = load ptr, ptr %8, align 8, !tbaa !9
  store ptr %9, ptr %1, align 8, !tbaa !5
  br label %10

10:                                               ; preds = %16, %6
  %11 = load ptr, ptr %1, align 8, !tbaa !5
  %12 = getelementptr inbounds %struct.node, ptr %11, i32 0, i32 1
  %13 = load ptr, ptr %12, align 8, !tbaa !9
  %14 = load ptr, ptr @last, align 8, !tbaa !5
  %15 = icmp ne ptr %13, %14
  br i1 %15, label %16, label %20

16:                                               ; preds = %10
  %17 = load ptr, ptr %1, align 8, !tbaa !5
  %18 = getelementptr inbounds %struct.node, ptr %17, i32 0, i32 1
  %19 = load ptr, ptr %18, align 8, !tbaa !9
  store ptr %19, ptr %1, align 8, !tbaa !5
  br label %10, !llvm.loop !12

20:                                               ; preds = %10
  %21 = load ptr, ptr @last, align 8, !tbaa !5
  %22 = getelementptr inbounds %struct.node, ptr %21, i32 0, i32 1
  %23 = load ptr, ptr %22, align 8, !tbaa !9
  %24 = load ptr, ptr %1, align 8, !tbaa !5
  %25 = getelementptr inbounds %struct.node, ptr %24, i32 0, i32 1
  store ptr %23, ptr %25, align 8, !tbaa !9
  %26 = load ptr, ptr %1, align 8, !tbaa !5
  store ptr %26, ptr @last, align 8, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 8, ptr %1) #3
  ret void
}

declare i32 @printf(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 = { "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"

@last = external dso_local local_unnamed_addr global ptr, align 8
@.str = external hidden unnamed_addr constant [17 x i8], align 1

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

3:                                                ; preds = %0
  %4 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str)
  %.pre = load ptr, ptr @last, align 8, !tbaa !5
  br label %5

5:                                                ; preds = %3, %0
  %6 = phi ptr [ %.pre, %3 ], [ %1, %0 ]
  %7 = getelementptr inbounds i8, ptr %6, i64 8
  %8 = load ptr, ptr %7, align 8, !tbaa !9
  br label %9

9:                                                ; preds = %9, %5
  %.0 = phi ptr [ %8, %5 ], [ %11, %9 ]
  %10 = getelementptr inbounds i8, ptr %.0, i64 8
  %11 = load ptr, ptr %10, align 8, !tbaa !9
  %.not = icmp eq ptr %11, %6
  br i1 %.not, label %12, label %9, !llvm.loop !12

12:                                               ; preds = %9
  %13 = getelementptr inbounds i8, ptr %.0, i64 8
  store ptr %8, ptr %13, align 8, !tbaa !9
  store ptr %.0, ptr @last, align 8, !tbaa !5
  ret void
}

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

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 = { 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" }

!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,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass