; LLVM IR from smv1999/CompetitiveProgrammingQuestionBank :: Hackerrank solutions/30 days Of Code (Day9-Recursion3)

; 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"

@factorial.fact = external hidden global i32, align 4

; Function Attrs: nounwind uwtable
define dso_local i32 @factorial(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  br label %4

4:                                                ; preds = %1
  %5 = load i32, ptr %3, align 4, !tbaa !5
  %6 = icmp ne i32 %5, 0
  br i1 %6, label %7, label %14

7:                                                ; preds = %4
  %8 = load i32, ptr @factorial.fact, align 4, !tbaa !5
  %9 = load i32, ptr %3, align 4, !tbaa !5
  %10 = mul nsw i32 %8, %9
  store i32 %10, ptr @factorial.fact, align 4, !tbaa !5
  %11 = load i32, ptr %3, align 4, !tbaa !5
  %12 = sub nsw i32 %11, 1
  %13 = call i32 @factorial(i32 noundef %12)
  store i32 %13, ptr %2, align 4
  br label %16

14:                                               ; preds = %4
  %15 = load i32, ptr @factorial.fact, align 4, !tbaa !5
  store i32 %15, ptr %2, align 4
  br label %16

16:                                               ; preds = %14, %7
  %17 = load i32, ptr %2, align 4
  ret i32 %17
}

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"

@factorial.fact = external hidden local_unnamed_addr global i32, align 4

; Function Attrs: nofree norecurse nosync nounwind memory(readwrite, argmem: none, inaccessiblemem: none) uwtable
define dso_local i32 @factorial(i32 noundef %0) local_unnamed_addr #0 {
  %factorial.fact.promoted = load i32, ptr @factorial.fact, align 4, !tbaa !5
  %.not5 = icmp eq i32 %0, 0
  br i1 %.not5, label %10, label %tailrecurse.preheader

tailrecurse.preheader:                            ; preds = %1
  %min.iters.check = icmp ult i32 %0, 8
  br i1 %min.iters.check, label %tailrecurse.preheader9, label %vector.ph

vector.ph:                                        ; preds = %tailrecurse.preheader
  %n.vec = and i32 %0, -8
  %ind.end = and i32 %0, 7
  %.splatinsert = insertelement <4 x i32> poison, i32 %0, i64 0
  %.splat = shufflevector <4 x i32> %.splatinsert, <4 x i32> poison, <4 x i32> zeroinitializer
  %induction = add <4 x i32> %.splat, <i32 0, i32 -1, i32 -2, i32 -3>
  %2 = insertelement <4 x i32> <i32 poison, i32 1, i32 1, i32 1>, i32 %factorial.fact.promoted, i64 0
  br label %vector.body

vector.body:                                      ; preds = %vector.body, %vector.ph
  %index = phi i32 [ 0, %vector.ph ], [ %index.next, %vector.body ]
  %vec.ind = phi <4 x i32> [ %induction, %vector.ph ], [ %vec.ind.next, %vector.body ]
  %vec.phi = phi <4 x i32> [ %2, %vector.ph ], [ %3, %vector.body ]
  %vec.phi8 = phi <4 x i32> [ <i32 1, i32 1, i32 1, i32 1>, %vector.ph ], [ %4, %vector.body ]
  %step.add = add <4 x i32> %vec.ind, <i32 -4, i32 -4, i32 -4, i32 -4>
  %3 = mul <4 x i32> %vec.phi, %vec.ind
  %4 = mul <4 x i32> %vec.phi8, %step.add
  %index.next = add nuw i32 %index, 8
  %vec.ind.next = add <4 x i32> %vec.ind, <i32 -8, i32 -8, i32 -8, i32 -8>
  %5 = icmp eq i32 %index.next, %n.vec
  br i1 %5, label %middle.block, label %vector.body, !llvm.loop !9

middle.block:                                     ; preds = %vector.body
  %bin.rdx = mul <4 x i32> %4, %3
  %6 = tail call i32 @llvm.vector.reduce.mul.v4i32(<4 x i32> %bin.rdx)
  %cmp.n = icmp eq i32 %n.vec, %0
  br i1 %cmp.n, label %tailrecurse._crit_edge, label %tailrecurse.preheader9

tailrecurse.preheader9:                           ; preds = %middle.block, %tailrecurse.preheader
  %.tr6.ph = phi i32 [ %0, %tailrecurse.preheader ], [ %ind.end, %middle.block ]
  %.ph = phi i32 [ %factorial.fact.promoted, %tailrecurse.preheader ], [ %6, %middle.block ]
  br label %tailrecurse

tailrecurse:                                      ; preds = %tailrecurse.preheader9, %tailrecurse
  %.tr6 = phi i32 [ %9, %tailrecurse ], [ %.tr6.ph, %tailrecurse.preheader9 ]
  %7 = phi i32 [ %8, %tailrecurse ], [ %.ph, %tailrecurse.preheader9 ]
  %8 = mul nsw i32 %7, %.tr6
  %9 = add nsw i32 %.tr6, -1
  %.not = icmp eq i32 %9, 0
  br i1 %.not, label %tailrecurse._crit_edge, label %tailrecurse, !llvm.loop !12

tailrecurse._crit_edge:                           ; preds = %tailrecurse, %middle.block
  %.lcssa = phi i32 [ %6, %middle.block ], [ %8, %tailrecurse ]
  store i32 %.lcssa, ptr @factorial.fact, align 4, !tbaa !5
  br label %10

10:                                               ; preds = %tailrecurse._crit_edge, %1
  %11 = phi i32 [ %.lcssa, %tailrecurse._crit_edge ], [ %factorial.fact.promoted, %1 ]
  ret i32 %11
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i32 @llvm.vector.reduce.mul.v4i32(<4 x i32>) #1

attributes #0 = { nofree norecurse nosync nounwind memory(readwrite, argmem: none, 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, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
!9 = distinct !{!9, !10, !11}
!10 = !{!"llvm.loop.isvectorized", i32 1}
!11 = !{!"llvm.loop.unroll.runtime.disable"}
!12 = distinct !{!12, !11, !10}


; Effective O3 passes: GVNPass,GlobalOptPass,IPSCCPPass,InferAlignmentPass,InstCombinePass,InstSimplifyPass,LCSSAPass,LICMPass,LoopLoadEliminationPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,LoopVectorizePass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass