; LLVM IR from HarshCasper/NeoAlgo :: C/operating_system (Round_Robin_Scheduling)

; 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 }

@front = external dso_local global ptr, align 8
@rear = external dso_local global ptr, align 8

; Function Attrs: nounwind uwtable
define dso_local void @push(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca ptr, align 8
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #3
  %4 = call noalias ptr @malloc(i64 noundef 16) #4
  store ptr %4, ptr %3, align 8, !tbaa !9
  %5 = load i32, ptr %2, align 4, !tbaa !5
  %6 = load ptr, ptr %3, align 8, !tbaa !9
  %7 = getelementptr inbounds %struct.node, ptr %6, i32 0, i32 0
  store i32 %5, ptr %7, align 8, !tbaa !11
  %8 = load ptr, ptr %3, align 8, !tbaa !9
  %9 = getelementptr inbounds %struct.node, ptr %8, i32 0, i32 1
  store ptr null, ptr %9, align 8, !tbaa !13
  %10 = load ptr, ptr @front, align 8, !tbaa !9
  %11 = icmp eq ptr %10, null
  br i1 %11, label %12, label %17

12:                                               ; preds = %1
  %13 = load ptr, ptr @rear, align 8, !tbaa !9
  %14 = icmp eq ptr %13, null
  br i1 %14, label %15, label %17

15:                                               ; preds = %12
  %16 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %16, ptr @rear, align 8, !tbaa !9
  store ptr %16, ptr @front, align 8, !tbaa !9
  br label %22

17:                                               ; preds = %12, %1
  %18 = load ptr, ptr %3, align 8, !tbaa !9
  %19 = load ptr, ptr @rear, align 8, !tbaa !9
  %20 = getelementptr inbounds %struct.node, ptr %19, i32 0, i32 1
  store ptr %18, ptr %20, align 8, !tbaa !13
  %21 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %21, ptr @rear, align 8, !tbaa !9
  br label %22

22:                                               ; preds = %17, %15
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #3
  ret void
}

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: nounwind allocsize(0)
declare noalias ptr @malloc(i64 noundef) #2

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

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 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #2 = { nounwind allocsize(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 }
attributes #4 = { nounwind allocsize(0) }

!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, !10, i64 0}
!10 = !{!"any pointer", !7, i64 0}
!11 = !{!12, !6, i64 0}
!12 = !{!"node", !6, i64 0, !10, i64 8}
!13 = !{!12, !10, i64 8}


; 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"

@front = external dso_local local_unnamed_addr global ptr, align 8
@rear = external dso_local local_unnamed_addr global ptr, align 8

; Function Attrs: mustprogress nofree nounwind willreturn memory(readwrite, argmem: write) uwtable
define dso_local void @push(i32 noundef %0) local_unnamed_addr #0 {
  %2 = tail call noalias dereferenceable_or_null(16) ptr @malloc(i64 noundef 16) #2
  store i32 %0, ptr %2, align 8, !tbaa !5
  %3 = getelementptr inbounds i8, ptr %2, i64 8
  store ptr null, ptr %3, align 8, !tbaa !11
  %4 = load ptr, ptr @front, align 8, !tbaa !12
  %5 = icmp eq ptr %4, null
  %6 = load ptr, ptr @rear, align 8
  %7 = icmp eq ptr %6, null
  %or.cond = select i1 %5, i1 %7, i1 false
  %8 = getelementptr inbounds i8, ptr %6, i64 8
  %.sink = select i1 %or.cond, ptr @front, ptr %8
  store ptr %2, ptr %.sink, align 8, !tbaa !12
  store ptr %2, ptr @rear, align 8
  ret void
}

; Function Attrs: mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0) memory(inaccessiblemem: readwrite)
declare noalias noundef ptr @malloc(i64 noundef) local_unnamed_addr #1

attributes #0 = { mustprogress nofree nounwind willreturn memory(readwrite, argmem: write) 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 = { mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0) memory(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 #2 = { nounwind allocsize(0) }

!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, !7, i64 0}
!6 = !{!"node", !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 = !{!6, !10, i64 8}
!12 = !{!10, !10, i64 0}


; Effective O3 passes: EarlyCSEPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,MergedLoadStoreMotionPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass