; LLVM IR from sbshah97/DS-Algo-Handbook :: Data-Structures/Linked_List/Doubly_Linked_List (doubly)

; 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, i32, ptr, ptr }

@last = external dso_local global ptr, align 8
@.str = external hidden unnamed_addr constant [4 x i8], align 1
@.str.1 = external hidden unnamed_addr constant [9 x i8], align 1
@.str.2 = external hidden unnamed_addr constant [3 x i8], align 1
@.str.3 = external hidden unnamed_addr constant [2 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

declare i32 @printf(ptr noundef, ...) #1

; Function Attrs: nounwind uwtable
define dso_local void @displayBackward() #2 {
  %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
  store ptr %2, ptr %1, align 8, !tbaa !5
  %3 = call i32 (ptr, ...) @printf(ptr noundef @.str)
  br label %4

4:                                                ; preds = %7, %0
  %5 = load ptr, ptr %1, align 8, !tbaa !5
  %6 = icmp ne ptr %5, null
  br i1 %6, label %7, label %19

7:                                                ; preds = %4
  %8 = load ptr, ptr %1, align 8, !tbaa !5
  %9 = getelementptr inbounds %struct.node, ptr %8, i32 0, i32 1
  %10 = load i32, ptr %9, align 4, !tbaa !9
  %11 = load ptr, ptr %1, align 8, !tbaa !5
  %12 = getelementptr inbounds %struct.node, ptr %11, i32 0, i32 0
  %13 = load i32, ptr %12, align 8, !tbaa !12
  %14 = call i32 (ptr, ...) @printf(ptr noundef @.str.1, i32 noundef %10, i32 noundef %13)
  %15 = load ptr, ptr %1, align 8, !tbaa !5
  %16 = getelementptr inbounds %struct.node, ptr %15, i32 0, i32 3
  %17 = load ptr, ptr %16, align 8, !tbaa !13
  store ptr %17, ptr %1, align 8, !tbaa !5
  %18 = call i32 (ptr, ...) @printf(ptr noundef @.str.3)
  br label %4, !llvm.loop !14

19:                                               ; preds = %4
  %20 = call i32 (ptr, ...) @printf(ptr noundef @.str.2)
  call void @llvm.lifetime.end.p0(i64 8, ptr %1) #3
  ret void
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { "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 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 }

!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, !11, i64 4}
!10 = !{!"node", !11, i64 0, !11, i64 4, !6, i64 8, !6, i64 16}
!11 = !{!"int", !7, i64 0}
!12 = !{!10, !11, i64 0}
!13 = !{!10, !6, i64 16}
!14 = distinct !{!14, !15}
!15 = !{!"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 [4 x i8], align 1
@.str.1 = external hidden unnamed_addr constant [9 x i8], align 1
@.str.2 = external hidden unnamed_addr constant [3 x i8], align 1
@.str.3 = external hidden unnamed_addr constant [2 x i8], align 1

; Function Attrs: nofree nounwind
declare noundef i32 @printf(ptr nocapture noundef readonly, ...) local_unnamed_addr #0

; Function Attrs: nofree nounwind uwtable
define dso_local void @displayBackward() local_unnamed_addr #1 {
  %1 = load ptr, ptr @last, align 8, !tbaa !5
  %2 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str)
  %.not4 = icmp eq ptr %1, null
  br i1 %.not4, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %0, %.lr.ph
  %.05 = phi ptr [ %8, %.lr.ph ], [ %1, %0 ]
  %3 = getelementptr inbounds i8, ptr %.05, i64 4
  %4 = load i32, ptr %3, align 4, !tbaa !9
  %5 = load i32, ptr %.05, align 8, !tbaa !12
  %6 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str.1, i32 noundef %4, i32 noundef %5)
  %7 = getelementptr inbounds i8, ptr %.05, i64 16
  %8 = load ptr, ptr %7, align 8, !tbaa !13
  %9 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str.3)
  %.not = icmp eq ptr %8, null
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !14

._crit_edge:                                      ; preds = %.lr.ph, %0
  %10 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str.2)
  ret void
}

attributes #0 = { 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 #1 = { 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" }

!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, !11, i64 4}
!10 = !{!"node", !11, i64 0, !11, i64 4, !6, i64 8, !6, i64 16}
!11 = !{!"int", !7, i64 0}
!12 = !{!10, !11, i64 0}
!13 = !{!10, !6, i64 16}
!14 = distinct !{!14, !15}
!15 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: EarlyCSEPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass