; LLVM IR from lekkas/c-algorithms :: n_choose_k (C)

; 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"

; Function Attrs: nounwind uwtable
define dso_local i32 @C(i32 noundef %0, i32 noundef %1) #0 {
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  store i32 %0, ptr %4, align 4, !tbaa !5
  store i32 %1, ptr %5, align 4, !tbaa !5
  %6 = load i32, ptr %5, align 4, !tbaa !5
  %7 = load i32, ptr %4, align 4, !tbaa !5
  %8 = icmp sgt i32 %6, %7
  br i1 %8, label %9, label %10

9:                                                ; preds = %2
  store i32 -1, ptr %3, align 4
  br label %29

10:                                               ; preds = %2
  %11 = load i32, ptr %4, align 4, !tbaa !5
  %12 = load i32, ptr %5, align 4, !tbaa !5
  %13 = icmp eq i32 %11, %12
  br i1 %13, label %17, label %14

14:                                               ; preds = %10
  %15 = load i32, ptr %5, align 4, !tbaa !5
  %16 = icmp eq i32 %15, 0
  br i1 %16, label %17, label %18

17:                                               ; preds = %14, %10
  store i32 1, ptr %3, align 4
  br label %29

18:                                               ; preds = %14
  %19 = load i32, ptr %4, align 4, !tbaa !5
  %20 = sub nsw i32 %19, 1
  %21 = load i32, ptr %5, align 4, !tbaa !5
  %22 = sub nsw i32 %21, 1
  %23 = call i32 @C(i32 noundef %20, i32 noundef %22)
  %24 = load i32, ptr %4, align 4, !tbaa !5
  %25 = sub nsw i32 %24, 1
  %26 = load i32, ptr %5, align 4, !tbaa !5
  %27 = call i32 @C(i32 noundef %25, i32 noundef %26)
  %28 = add nsw i32 %23, %27
  store i32 %28, ptr %3, align 4
  br label %29

29:                                               ; preds = %18, %17, %9
  %30 = load i32, ptr %3, align 4
  ret i32 %30
}

attributes #0 = { 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" }

!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"}


; 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 nosync nounwind memory(none) uwtable
define dso_local i32 @C(i32 noundef %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = icmp sgt i32 %1, %0
  br i1 %3, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %2
  %4 = icmp eq i32 %1, 0
  %5 = add nsw i32 %1, -1
  %6 = icmp eq i32 %0, %1
  %or.cond = or i1 %4, %6
  br i1 %or.cond, label %._crit_edge, label %tailrecurse

tailrecurse:                                      ; preds = %.lr.ph, %tailrecurse
  %accumulator.tr1421 = phi i32 [ %9, %tailrecurse ], [ 0, %.lr.ph ]
  %.tr1520 = phi i32 [ %7, %tailrecurse ], [ %0, %.lr.ph ]
  %7 = add nsw i32 %.tr1520, -1
  %8 = tail call i32 @C(i32 noundef %7, i32 noundef %5)
  %9 = add nsw i32 %8, %accumulator.tr1421
  %10 = icmp eq i32 %7, %1
  br i1 %10, label %._crit_edge, label %tailrecurse

._crit_edge:                                      ; preds = %tailrecurse, %.lr.ph, %2
  %accumulator.tr.lcssa = phi i32 [ 0, %2 ], [ 0, %.lr.ph ], [ %9, %tailrecurse ]
  %.0 = phi i32 [ -1, %2 ], [ 1, %.lr.ph ], [ 1, %tailrecurse ]
  %accumulator.ret.tr = add nsw i32 %.0, %accumulator.tr.lcssa
  ret i32 %accumulator.ret.tr
}

attributes #0 = { nofree nosync nounwind memory(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)"}


; Effective O3 passes: EarlyCSEPass,GVNPass,GlobalOptPass,IPSCCPPass,IndVarSimplifyPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LICMPass,LoopInstSimplifyPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,ReassociatePass,SCCPPass,SROAPass,SimplifyCFGPass,TailCallElimPass