; LLVM IR from ritikbanger/Hacktoberfest2022-DSA :: 10. Linked List/c lang (Implementation Of Circular 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.CLL = type { ptr }
%struct.cnode = 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: 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 i32 @countnodes(ptr %0) #1 {
  %2 = alloca %struct.CLL, align 8
  %3 = alloca i32, align 4
  %4 = alloca ptr, align 8
  %5 = getelementptr inbounds %struct.CLL, ptr %2, i32 0, i32 0
  store ptr %0, ptr %5, align 8
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  store i32 0, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %6 = getelementptr inbounds %struct.CLL, ptr %2, i32 0, i32 0
  %7 = load ptr, ptr %6, align 8, !tbaa !9
  %8 = getelementptr inbounds %struct.cnode, ptr %7, i32 0, i32 1
  %9 = load ptr, ptr %8, align 8, !tbaa !12
  store ptr %9, ptr %4, align 8, !tbaa !14
  br label %10

10:                                               ; preds = %15, %1
  %11 = load ptr, ptr %4, align 8, !tbaa !14
  %12 = getelementptr inbounds %struct.CLL, ptr %2, i32 0, i32 0
  %13 = load ptr, ptr %12, align 8, !tbaa !9
  %14 = icmp ne ptr %11, %13
  br i1 %14, label %15, label %21

15:                                               ; preds = %10
  %16 = load i32, ptr %3, align 4, !tbaa !5
  %17 = add nsw i32 %16, 1
  store i32 %17, ptr %3, align 4, !tbaa !5
  %18 = load ptr, ptr %4, align 8, !tbaa !14
  %19 = getelementptr inbounds %struct.cnode, ptr %18, i32 0, i32 1
  %20 = load ptr, ptr %19, align 8, !tbaa !12
  store ptr %20, ptr %4, align 8, !tbaa !14
  br label %10, !llvm.loop !15

21:                                               ; preds = %10
  %22 = load i32, ptr %3, align 4, !tbaa !5
  %23 = add nsw i32 %22, 1
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  ret i32 %23
}

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 }

!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, !11, i64 0}
!10 = !{!"", !11, i64 0}
!11 = !{!"any pointer", !7, i64 0}
!12 = !{!13, !11, i64 8}
!13 = !{!"cnode", !6, i64 0, !11, i64 8}
!14 = !{!11, !11, i64 0}
!15 = distinct !{!15, !16}
!16 = !{!"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: nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local range(i32 -2147483647, -2147483648) i32 @countnodes(ptr readonly %0) local_unnamed_addr #0 {
  br label %2

2:                                                ; preds = %2, %1
  %.04 = phi i32 [ 0, %1 ], [ %3, %2 ]
  %.pn = phi ptr [ %0, %1 ], [ %.0, %2 ]
  %.0.in = getelementptr inbounds i8, ptr %.pn, i64 8
  %.0 = load ptr, ptr %.0.in, align 8, !tbaa !5
  %.not = icmp eq ptr %.0, %0
  %3 = add nuw nsw i32 %.04, 1
  br i1 %.not, label %4, label %2, !llvm.loop !11

4:                                                ; preds = %2
  ret i32 %3
}

attributes #0 = { nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) 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" }

!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, !10, i64 8}
!6 = !{!"cnode", !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 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: GVNPass,GlobalOptPass,IPSCCPPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,LCSSAPass,LoopRotatePass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass