; LLVM IR from div-bargali/Data-Structures-and-Algorithms :: C/Data-Structures/LinkedList (CircularDoublyLinkedList)

; 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.list = type { double, ptr, 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 @length(ptr noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  %6 = load ptr, ptr %3, align 8, !tbaa !5
  %7 = icmp eq ptr %6, null
  br i1 %7, label %8, label %9

8:                                                ; preds = %1
  store i32 0, ptr %2, align 4
  br label %25

9:                                                ; preds = %1
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %10 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %10, ptr %4, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  store i32 1, ptr %5, align 4, !tbaa !9
  br label %11

11:                                               ; preds = %17, %9
  %12 = load ptr, ptr %4, align 8, !tbaa !5
  %13 = load ptr, ptr %3, align 8, !tbaa !5
  %14 = getelementptr inbounds %struct.list, ptr %13, i32 0, i32 2
  %15 = load ptr, ptr %14, align 8, !tbaa !11
  %16 = icmp ne ptr %12, %15
  br i1 %16, label %17, label %23

17:                                               ; preds = %11
  %18 = load i32, ptr %5, align 4, !tbaa !9
  %19 = add nsw i32 %18, 1
  store i32 %19, ptr %5, align 4, !tbaa !9
  %20 = load ptr, ptr %4, align 8, !tbaa !5
  %21 = getelementptr inbounds %struct.list, ptr %20, i32 0, i32 1
  %22 = load ptr, ptr %21, align 8, !tbaa !14
  store ptr %22, ptr %4, align 8, !tbaa !5
  br label %11, !llvm.loop !15

23:                                               ; preds = %11
  %24 = load i32, ptr %5, align 4, !tbaa !9
  store i32 %24, ptr %2, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  br label %25

25:                                               ; preds = %23, %8
  %26 = load i32, ptr %2, align 4
  ret i32 %26
}

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 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"int", !7, i64 0}
!11 = !{!12, !6, i64 16}
!12 = !{!"list", !13, i64 0, !6, i64 8, !6, i64 16}
!13 = !{!"double", !7, i64 0}
!14 = !{!12, !6, i64 8}
!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 i32 @length(ptr noundef readonly %0) local_unnamed_addr #0 {
  %2 = icmp eq ptr %0, null
  br i1 %2, label %.loopexit, label %.preheader

.preheader:                                       ; preds = %1
  %3 = getelementptr inbounds i8, ptr %0, i64 16
  %4 = load ptr, ptr %3, align 8, !tbaa !5
  %.not10 = icmp eq ptr %4, %0
  br i1 %.not10, label %.loopexit, label %.lr.ph

.lr.ph:                                           ; preds = %.preheader, %.lr.ph
  %.012 = phi i32 [ %5, %.lr.ph ], [ 1, %.preheader ]
  %.0711 = phi ptr [ %7, %.lr.ph ], [ %0, %.preheader ]
  %5 = add nuw nsw i32 %.012, 1
  %6 = getelementptr inbounds i8, ptr %.0711, i64 8
  %7 = load ptr, ptr %6, align 8, !tbaa !11
  %.not = icmp eq ptr %7, %4
  br i1 %.not, label %.loopexit, label %.lr.ph, !llvm.loop !12

.loopexit:                                        ; preds = %.lr.ph, %.preheader, %1
  %.08 = phi i32 [ 0, %1 ], [ 1, %.preheader ], [ %5, %.lr.ph ]
  ret i32 %.08
}

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 16}
!6 = !{!"list", !7, i64 0, !10, i64 8, !10, i64 16}
!7 = !{!"double", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C/C++ TBAA"}
!10 = !{!"any pointer", !8, i64 0}
!11 = !{!6, !10, i64 8}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: GVNPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LICMPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass