; LLVM IR from bartobri/data-structures-c :: symbol-table/linked-list-ordered (st)

; 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.STnode = type { ptr, ptr }

@z = external hidden global ptr, align 8
@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 ptr @STselect(i32 noundef %0) #1 {
  %2 = alloca ptr, align 8
  %3 = alloca i32, align 4
  %4 = alloca ptr, align 8
  %5 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %6 = load ptr, ptr @head, align 8, !tbaa !9
  store ptr %6, ptr %4, align 8, !tbaa !9
  br label %7

7:                                                ; preds = %20, %1
  %8 = load ptr, ptr %4, align 8, !tbaa !9
  %9 = load ptr, ptr @z, align 8, !tbaa !9
  %10 = icmp ne ptr %8, %9
  br i1 %10, label %11, label %24

11:                                               ; preds = %7
  %12 = load i32, ptr %3, align 4, !tbaa !5
  %13 = add nsw i32 %12, -1
  store i32 %13, ptr %3, align 4, !tbaa !5
  %14 = icmp eq i32 %13, 0
  br i1 %14, label %15, label %19

15:                                               ; preds = %11
  %16 = load ptr, ptr %4, align 8, !tbaa !9
  %17 = getelementptr inbounds %struct.STnode, ptr %16, i32 0, i32 0
  %18 = load ptr, ptr %17, align 8, !tbaa !11
  store ptr %18, ptr %2, align 8
  store i32 1, ptr %5, align 4
  br label %25

19:                                               ; preds = %11
  br label %20

20:                                               ; preds = %19
  %21 = load ptr, ptr %4, align 8, !tbaa !9
  %22 = getelementptr inbounds %struct.STnode, ptr %21, i32 0, i32 1
  %23 = load ptr, ptr %22, align 8, !tbaa !13
  store ptr %23, ptr %4, align 8, !tbaa !9
  br label %7, !llvm.loop !14

24:                                               ; preds = %7
  store ptr null, ptr %2, align 8
  store i32 1, ptr %5, align 4
  br label %25

25:                                               ; preds = %24, %15
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  %26 = load ptr, ptr %2, align 8
  ret ptr %26
}

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 0}
!12 = !{!"STnode", !10, i64 0, !10, i64 8}
!13 = !{!12, !10, 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"

@z = external hidden local_unnamed_addr global ptr, align 8
@head = external hidden local_unnamed_addr global ptr, align 8

; Function Attrs: nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local ptr @STselect(i32 noundef %0) local_unnamed_addr #0 {
  %2 = load ptr, ptr @z, align 8, !tbaa !5
  %.08 = load ptr, ptr @head, align 8, !tbaa !5
  %.not9 = icmp eq ptr %.08, %2
  br i1 %.not9, label %.loopexit, label %.lr.ph

.lr.ph:                                           ; preds = %1, %7
  %.011 = phi ptr [ %.0, %7 ], [ %.08, %1 ]
  %.0410 = phi i32 [ %3, %7 ], [ %0, %1 ]
  %3 = add nsw i32 %.0410, -1
  %4 = icmp eq i32 %3, 0
  br i1 %4, label %5, label %7

5:                                                ; preds = %.lr.ph
  %6 = load ptr, ptr %.011, align 8, !tbaa !9
  br label %.loopexit

7:                                                ; preds = %.lr.ph
  %8 = getelementptr inbounds i8, ptr %.011, i64 8
  %.0 = load ptr, ptr %8, align 8, !tbaa !5
  %.not = icmp eq ptr %.0, %2
  br i1 %.not, label %.loopexit, label %.lr.ph, !llvm.loop !11

.loopexit:                                        ; preds = %7, %1, %5
  %.05 = phi ptr [ %6, %5 ], [ null, %1 ], [ null, %7 ]
  ret ptr %.05
}

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 = !{!10, !6, i64 0}
!10 = !{!"STnode", !6, i64 0, !6, i64 8}
!11 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}


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