; LLVM IR from bartobri/data-structures-c :: arrays/stack-based-quicksort (stack)

; 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.STACKnode = type { i32, ptr }

@head = external hidden global ptr, 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 i32 @STACKcount() #1 {
  %1 = alloca i32, align 4
  %2 = alloca ptr, align 8
  call void @llvm.lifetime.start.p0(i64 4, ptr %1) #2
  call void @llvm.lifetime.start.p0(i64 8, ptr %2) #2
  store i32 0, ptr %1, align 4, !tbaa !5
  %3 = load ptr, ptr @head, align 8, !tbaa !9
  store ptr %3, ptr %2, align 8, !tbaa !9
  br label %4

4:                                                ; preds = %8, %0
  %5 = load ptr, ptr %2, align 8, !tbaa !9
  %6 = icmp ne ptr %5, null
  br i1 %6, label %7, label %14

7:                                                ; preds = %4
  br label %8

8:                                                ; preds = %7
  %9 = load ptr, ptr %2, align 8, !tbaa !9
  %10 = getelementptr inbounds %struct.STACKnode, ptr %9, i32 0, i32 1
  %11 = load ptr, ptr %10, align 8, !tbaa !11
  store ptr %11, ptr %2, align 8, !tbaa !9
  %12 = load i32, ptr %1, align 4, !tbaa !5
  %13 = add nsw i32 %12, 1
  store i32 %13, ptr %1, align 4, !tbaa !5
  br label %4, !llvm.loop !13

14:                                               ; preds = %4
  %15 = load i32, ptr %1, align 4, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 8, ptr %2) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %1) #2
  ret i32 %15
}

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 = !{!"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, !10, i64 8}
!12 = !{!"STACKnode", !6, i64 0, !10, i64 8}
!13 = distinct !{!13, !14}
!14 = !{!"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"

@head = external hidden local_unnamed_addr global ptr, align 8

; Function Attrs: nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local i32 @STACKcount() local_unnamed_addr #0 {
  %.04 = load ptr, ptr @head, align 8, !tbaa !5
  %.not5 = icmp eq ptr %.04, null
  br i1 %.not5, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %0, %.lr.ph
  %.07 = phi ptr [ %.0, %.lr.ph ], [ %.04, %0 ]
  %.036 = phi i32 [ %2, %.lr.ph ], [ 0, %0 ]
  %1 = getelementptr inbounds i8, ptr %.07, i64 8
  %2 = add nuw nsw i32 %.036, 1
  %.0 = load ptr, ptr %1, align 8, !tbaa !5
  %.not = icmp eq ptr %.0, null
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !9

._crit_edge:                                      ; preds = %.lr.ph, %0
  %.03.lcssa = phi i32 [ 0, %0 ], [ %2, %.lr.ph ]
  ret i32 %.03.lcssa
}

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" }

!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 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}


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