; LLVM IR from AlgoGenesis/C :: Backtracking Algorithms/Dancing Links (DLX) (program)

; 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.Column = type { %struct.Node, i32, [20 x i8] }
%struct.Node = type { ptr, ptr, ptr, ptr, ptr }

@root = external hidden global %struct.Column, align 8

; 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 ptr @choose_column() #1 {
  %1 = alloca ptr, align 8
  %2 = alloca i32, align 4
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  call void @llvm.lifetime.start.p0(i64 8, ptr %1) #2
  store ptr null, ptr %1, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %2) #2
  store i32 1000, ptr %2, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  %5 = load ptr, ptr getelementptr inbounds (%struct.Node, ptr @root, i32 0, i32 1), align 8, !tbaa !11
  store ptr %5, ptr %3, align 8, !tbaa !5
  br label %6

6:                                                ; preds = %25, %0
  %7 = load ptr, ptr %3, align 8, !tbaa !5
  %8 = icmp ne ptr %7, @root
  br i1 %8, label %10, label %9

9:                                                ; preds = %6
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  br label %29

10:                                               ; preds = %6
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %11 = load ptr, ptr %3, align 8, !tbaa !5
  %12 = getelementptr inbounds %struct.Node, ptr %11, i32 0, i32 4
  %13 = load ptr, ptr %12, align 8, !tbaa !14
  store ptr %13, ptr %4, align 8, !tbaa !5
  %14 = load ptr, ptr %4, align 8, !tbaa !5
  %15 = getelementptr inbounds %struct.Column, ptr %14, i32 0, i32 1
  %16 = load i32, ptr %15, align 8, !tbaa !15
  %17 = load i32, ptr %2, align 4, !tbaa !9
  %18 = icmp slt i32 %16, %17
  br i1 %18, label %19, label %24

19:                                               ; preds = %10
  %20 = load ptr, ptr %4, align 8, !tbaa !5
  %21 = getelementptr inbounds %struct.Column, ptr %20, i32 0, i32 1
  %22 = load i32, ptr %21, align 8, !tbaa !15
  store i32 %22, ptr %2, align 4, !tbaa !9
  %23 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %23, ptr %1, align 8, !tbaa !5
  br label %24

24:                                               ; preds = %19, %10
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  br label %25

25:                                               ; preds = %24
  %26 = load ptr, ptr %3, align 8, !tbaa !5
  %27 = getelementptr inbounds %struct.Node, ptr %26, i32 0, i32 1
  %28 = load ptr, ptr %27, align 8, !tbaa !16
  store ptr %28, ptr %3, align 8, !tbaa !5
  br label %6, !llvm.loop !17

29:                                               ; preds = %9
  %30 = load ptr, ptr %1, align 8, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 4, ptr %2) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %1) #2
  ret ptr %30
}

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 8}
!12 = !{!"Column", !13, i64 0, !10, i64 40, !7, i64 44}
!13 = !{!"Node", !6, i64 0, !6, i64 8, !6, i64 16, !6, i64 24, !6, i64 32}
!14 = !{!13, !6, i64 32}
!15 = !{!12, !10, i64 40}
!16 = !{!13, !6, i64 8}
!17 = distinct !{!17, !18}
!18 = !{!"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"

%struct.Column = type { %struct.Node, i32, [20 x i8] }
%struct.Node = type { ptr, ptr, ptr, ptr, ptr }

@root = external hidden global %struct.Column, align 8

; Function Attrs: nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local ptr @choose_column() local_unnamed_addr #0 {
  %.0712 = load ptr, ptr getelementptr inbounds (i8, ptr @root, i64 8), align 8, !tbaa !5
  %.not13 = icmp eq ptr %.0712, @root
  br i1 %.not13, label %._crit_edge, label %.lr.ph

._crit_edge:                                      ; preds = %.lr.ph, %0
  %.0.lcssa = phi ptr [ null, %0 ], [ %spec.select11, %.lr.ph ]
  ret ptr %.0.lcssa

.lr.ph:                                           ; preds = %0, %.lr.ph
  %.0716 = phi ptr [ %.07, %.lr.ph ], [ %.0712, %0 ]
  %.015 = phi ptr [ %spec.select11, %.lr.ph ], [ null, %0 ]
  %.0814 = phi i32 [ %spec.select, %.lr.ph ], [ 1000, %0 ]
  %1 = getelementptr inbounds i8, ptr %.0716, i64 32
  %2 = load ptr, ptr %1, align 8, !tbaa !10
  %3 = getelementptr inbounds i8, ptr %2, i64 40
  %4 = load i32, ptr %3, align 8, !tbaa !11
  %5 = icmp slt i32 %4, %.0814
  %spec.select = tail call i32 @llvm.smin.i32(i32 %4, i32 %.0814)
  %spec.select11 = select i1 %5, ptr %2, ptr %.015
  %6 = getelementptr inbounds i8, ptr %.0716, i64 8
  %.07 = load ptr, ptr %6, align 8, !tbaa !5
  %.not = icmp eq ptr %.07, @root
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !14
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i32 @llvm.smin.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 8}
!6 = !{!"Node", !7, i64 0, !7, i64 8, !7, i64 16, !7, i64 24, !7, i64 32}
!7 = !{!"any pointer", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C/C++ TBAA"}
!10 = !{!6, !7, i64 32}
!11 = !{!12, !13, i64 40}
!12 = !{!"Column", !6, i64 0, !13, i64 40, !8, i64 44}
!13 = !{!"int", !8, i64 0}
!14 = distinct !{!14, !15}
!15 = !{!"llvm.loop.mustprogress"}


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