; LLVM IR from bartobri/data-structures-c :: symbol-table/array-key-index (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"

@st = external hidden global ptr, align 8
@M = external hidden global i32, align 4

; 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 i32, align 4
  %5 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  store i32 0, ptr %4, align 4, !tbaa !5
  br label %6

6:                                                ; preds = %29, %1
  %7 = load i32, ptr %4, align 4, !tbaa !5
  %8 = load i32, ptr @M, align 4, !tbaa !5
  %9 = icmp slt i32 %7, %8
  br i1 %9, label %10, label %32

10:                                               ; preds = %6
  %11 = load ptr, ptr @st, align 8, !tbaa !9
  %12 = load i32, ptr %4, align 4, !tbaa !5
  %13 = sext i32 %12 to i64
  %14 = getelementptr inbounds ptr, ptr %11, i64 %13
  %15 = load ptr, ptr %14, align 8, !tbaa !9
  %16 = icmp ne ptr %15, null
  br i1 %16, label %17, label %28

17:                                               ; preds = %10
  %18 = load i32, ptr %3, align 4, !tbaa !5
  %19 = add nsw i32 %18, -1
  store i32 %19, ptr %3, align 4, !tbaa !5
  %20 = icmp eq i32 %18, 0
  br i1 %20, label %21, label %27

21:                                               ; preds = %17
  %22 = load ptr, ptr @st, align 8, !tbaa !9
  %23 = load i32, ptr %4, align 4, !tbaa !5
  %24 = sext i32 %23 to i64
  %25 = getelementptr inbounds ptr, ptr %22, i64 %24
  %26 = load ptr, ptr %25, align 8, !tbaa !9
  store ptr %26, ptr %2, align 8
  store i32 1, ptr %5, align 4
  br label %33

27:                                               ; preds = %17
  br label %28

28:                                               ; preds = %27, %10
  br label %29

29:                                               ; preds = %28
  %30 = load i32, ptr %4, align 4, !tbaa !5
  %31 = add nsw i32 %30, 1
  store i32 %31, ptr %4, align 4, !tbaa !5
  br label %6, !llvm.loop !11

32:                                               ; preds = %6
  store i32 0, ptr %5, align 4
  br label %33

33:                                               ; preds = %32, %21
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  %34 = load i32, ptr %5, align 4
  switch i32 %34, label %37 [
    i32 0, label %35
    i32 1, label %35
  ]

35:                                               ; preds = %33, %33
  %36 = load ptr, ptr %2, align 8
  ret ptr %36

37:                                               ; preds = %33
  unreachable
}

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 = distinct !{!11, !12}
!12 = !{!"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"

@st = external hidden local_unnamed_addr global ptr, align 8
@M = external hidden local_unnamed_addr global i32, align 4

; 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 i32, ptr @M, align 4, !tbaa !5
  %3 = icmp sgt i32 %2, 0
  br i1 %3, label %.lr.ph, label %._crit_edge

.lr.ph:                                           ; preds = %1
  %4 = load ptr, ptr @st, align 8, !tbaa !9
  %wide.trip.count = zext nneg i32 %2 to i64
  br label %5

5:                                                ; preds = %.lr.ph, %11
  %indvars.iv = phi i64 [ 0, %.lr.ph ], [ %indvars.iv.next, %11 ]
  %.058 = phi i32 [ %0, %.lr.ph ], [ %.1, %11 ]
  %6 = getelementptr inbounds ptr, ptr %4, i64 %indvars.iv
  %7 = load ptr, ptr %6, align 8, !tbaa !9
  %.not = icmp eq ptr %7, null
  br i1 %.not, label %11, label %8

8:                                                ; preds = %5
  %9 = add nsw i32 %.058, -1
  %10 = icmp eq i32 %.058, 0
  br i1 %10, label %._crit_edge, label %11

11:                                               ; preds = %5, %8
  %.1 = phi i32 [ %9, %8 ], [ %.058, %5 ]
  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
  %exitcond.not = icmp eq i64 %indvars.iv.next, %wide.trip.count
  br i1 %exitcond.not, label %._crit_edge, label %5, !llvm.loop !11

._crit_edge:                                      ; preds = %8, %11, %1
  %.06 = phi ptr [ undef, %1 ], [ %7, %11 ], [ %7, %8 ]
  ret ptr %.06
}

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 = !{!"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 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}


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