; LLVM IR from ritikbanger/Hacktoberfest2022-DSA :: 10. Linked List/c lang (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.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: nounwind uwtable
define dso_local i32 @maximum(ptr noundef %0) #1 {
  %2 = alloca ptr, align 8
  %3 = alloca i32, align 4
  store ptr %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  %4 = load ptr, ptr %2, align 8, !tbaa !5
  %5 = getelementptr inbounds %struct.node, ptr %4, i32 0, i32 0
  %6 = load i32, ptr %5, align 8, !tbaa !9
  store i32 %6, ptr %3, align 4, !tbaa !12
  %7 = load ptr, ptr %2, align 8, !tbaa !5
  %8 = getelementptr inbounds %struct.node, ptr %7, i32 0, i32 1
  %9 = load ptr, ptr %8, align 8, !tbaa !13
  store ptr %9, ptr %2, align 8, !tbaa !5
  br label %10

10:                                               ; preds = %23, %1
  %11 = load ptr, ptr %2, align 8, !tbaa !5
  %12 = icmp ne ptr %11, null
  br i1 %12, label %13, label %27

13:                                               ; preds = %10
  %14 = load ptr, ptr %2, align 8, !tbaa !5
  %15 = getelementptr inbounds %struct.node, ptr %14, i32 0, i32 0
  %16 = load i32, ptr %15, align 8, !tbaa !9
  %17 = load i32, ptr %3, align 4, !tbaa !12
  %18 = icmp sgt i32 %16, %17
  br i1 %18, label %19, label %23

19:                                               ; preds = %13
  %20 = load ptr, ptr %2, align 8, !tbaa !5
  %21 = getelementptr inbounds %struct.node, ptr %20, i32 0, i32 0
  %22 = load i32, ptr %21, align 8, !tbaa !9
  store i32 %22, ptr %3, align 4, !tbaa !12
  br label %23

23:                                               ; preds = %19, %13
  %24 = load ptr, ptr %2, align 8, !tbaa !5
  %25 = getelementptr inbounds %struct.node, ptr %24, i32 0, i32 1
  %26 = load ptr, ptr %25, align 8, !tbaa !13
  store ptr %26, ptr %2, align 8, !tbaa !5
  br label %10, !llvm.loop !14

27:                                               ; preds = %10
  %28 = load i32, ptr %3, align 4, !tbaa !12
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  ret i32 %28
}

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

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

; Function Attrs: nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local i32 @maximum(ptr nocapture noundef readonly %0) local_unnamed_addr #0 {
  %2 = load i32, ptr %0, align 8, !tbaa !5
  %.07.in9 = getelementptr inbounds i8, ptr %0, i64 8
  %.0710 = load ptr, ptr %.07.in9, align 8, !tbaa !11
  %.not11 = icmp eq ptr %.0710, null
  br i1 %.not11, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %1, %.lr.ph
  %.0713 = phi ptr [ %.07, %.lr.ph ], [ %.0710, %1 ]
  %.012 = phi i32 [ %spec.select, %.lr.ph ], [ %2, %1 ]
  %3 = load i32, ptr %.0713, align 8, !tbaa !5
  %spec.select = tail call i32 @llvm.smax.i32(i32 %3, i32 %.012)
  %.07.in = getelementptr inbounds i8, ptr %.0713, i64 8
  %.07 = load ptr, ptr %.07.in, align 8, !tbaa !11
  %.not = icmp eq ptr %.07, null
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !12

._crit_edge:                                      ; preds = %.lr.ph, %1
  %.0.lcssa = phi i32 [ %2, %1 ], [ %spec.select, %.lr.ph ]
  ret i32 %.0.lcssa
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i32 @llvm.smax.i32(i32, i32) #1

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" }
attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }

!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 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}


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