; LLVM IR from Hunterdii/GeeksforGeeks-POTD :: October 2024 GFG SOLUTION/October-01.ll (Z7reversePP4Node)

; 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 }

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef ptr @_Z7reversePP4Node(ptr noundef %0) #1 {
  %2 = alloca ptr, align 8
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  store ptr %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  store ptr null, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %6 = load ptr, ptr %2, align 8, !tbaa !5
  %7 = load ptr, ptr %6, align 8, !tbaa !5
  store ptr %7, ptr %4, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  br label %8

8:                                                ; preds = %11, %1
  %9 = load ptr, ptr %4, align 8, !tbaa !5
  %10 = icmp ne ptr %9, null
  br i1 %10, label %11, label %20

11:                                               ; preds = %8
  %12 = load ptr, ptr %4, align 8, !tbaa !5
  %13 = getelementptr inbounds %struct.Node, ptr %12, i32 0, i32 1
  %14 = load ptr, ptr %13, align 8, !tbaa !9
  store ptr %14, ptr %5, align 8, !tbaa !5
  %15 = load ptr, ptr %3, align 8, !tbaa !5
  %16 = load ptr, ptr %4, align 8, !tbaa !5
  %17 = getelementptr inbounds %struct.Node, ptr %16, i32 0, i32 1
  store ptr %15, ptr %17, align 8, !tbaa !9
  %18 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %18, ptr %3, align 8, !tbaa !5
  %19 = load ptr, ptr %5, align 8, !tbaa !5
  store ptr %19, ptr %4, align 8, !tbaa !5
  br label %8, !llvm.loop !12

20:                                               ; preds = %8
  %21 = load ptr, ptr %3, align 8, !tbaa !5
  %22 = load ptr, ptr %2, align 8, !tbaa !5
  store ptr %21, ptr %22, align 8, !tbaa !5
  unreachable
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { mustprogress 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++ TBAA"}
!9 = !{!10, !6, i64 8}
!10 = !{!"_ZTS4Node", !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"

; Function Attrs: mustprogress nofree norecurse noreturn nosync nounwind memory(readwrite, inaccessiblemem: write) uwtable
define dso_local noalias noundef nonnull ptr @_Z7reversePP4Node(ptr nocapture noundef readonly %0) local_unnamed_addr #0 {
  %2 = load ptr, ptr %0, align 8, !tbaa !5
  br label %3

3:                                                ; preds = %3, %1
  %.07 = phi ptr [ %2, %1 ], [ %6, %3 ]
  %.0 = phi ptr [ null, %1 ], [ %.07, %3 ]
  %4 = icmp ne ptr %.07, null
  tail call void @llvm.assume(i1 %4)
  %5 = getelementptr inbounds i8, ptr %.07, i64 8
  %6 = load ptr, ptr %5, align 8, !tbaa !9
  store ptr %.0, ptr %5, align 8, !tbaa !9
  br label %3, !llvm.loop !12
}

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: write)
declare void @llvm.assume(i1 noundef) #1

attributes #0 = { mustprogress nofree norecurse noreturn nosync nounwind memory(readwrite, inaccessiblemem: 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 = { nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: write) }

!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++ TBAA"}
!9 = !{!10, !6, i64 8}
!10 = !{!"_ZTS4Node", !11, i64 0, !6, i64 8}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}


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