; LLVM IR from next-step-for-interview-prep/Coding-Ninjas-DSA-course_code_and_notes_cpp :: Milestone-3=DSA/lecture-notes/lecture-3=Recursion-1/code.ll (Z9factoriali)

; 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: 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: mustprogress uwtable
define dso_local noundef i32 @_Z9factoriali(i32 noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  %6 = load i32, ptr %3, align 4, !tbaa !5
  %7 = icmp eq i32 %6, 0
  br i1 %7, label %8, label %9

8:                                                ; preds = %1
  store i32 1, ptr %2, align 4
  br label %17

9:                                                ; preds = %1
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  %10 = load i32, ptr %3, align 4, !tbaa !5
  %11 = sub nsw i32 %10, 1
  %12 = call noundef i32 @_Z9factoriali(i32 noundef %11)
  store i32 %12, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  %13 = load i32, ptr %3, align 4, !tbaa !5
  %14 = load i32, ptr %4, align 4, !tbaa !5
  %15 = mul nsw i32 %13, %14
  store i32 %15, ptr %5, align 4, !tbaa !5
  %16 = load i32, ptr %5, align 4, !tbaa !5
  store i32 %16, ptr %2, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  br label %17

17:                                               ; preds = %9, %8
  %18 = load i32, ptr %2, align 4
  ret i32 %18
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { mustprogress 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++ 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: mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable
define dso_local noundef i32 @_Z9factoriali(i32 noundef %0) local_unnamed_addr #0 {
  %2 = icmp eq i32 %0, 0
  br i1 %2, label %tailrecurse._crit_edge, label %tailrecurse.preheader

tailrecurse.preheader:                            ; preds = %1
  %min.iters.check = icmp ult i32 %0, 8
  br i1 %min.iters.check, label %tailrecurse.preheader11, 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>
  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> [ <i32 1, i32 1, i32 1, i32 1>, %vector.ph ], [ %3, %vector.body ]
  %vec.phi10 = 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.ind, %vec.phi
  %4 = mul <4 x i32> %step.add, %vec.phi10
  %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 !5

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.preheader11

tailrecurse.preheader11:                          ; preds = %middle.block, %tailrecurse.preheader
  %.tr8.ph = phi i32 [ %0, %tailrecurse.preheader ], [ %ind.end, %middle.block ]
  %accumulator.tr7.ph = phi i32 [ 1, %tailrecurse.preheader ], [ %6, %middle.block ]
  br label %tailrecurse

tailrecurse:                                      ; preds = %tailrecurse.preheader11, %tailrecurse
  %.tr8 = phi i32 [ %7, %tailrecurse ], [ %.tr8.ph, %tailrecurse.preheader11 ]
  %accumulator.tr7 = phi i32 [ %8, %tailrecurse ], [ %accumulator.tr7.ph, %tailrecurse.preheader11 ]
  %7 = add nsw i32 %.tr8, -1
  %8 = mul nsw i32 %.tr8, %accumulator.tr7
  %9 = icmp eq i32 %7, 0
  br i1 %9, label %tailrecurse._crit_edge, label %tailrecurse, !llvm.loop !8

tailrecurse._crit_edge:                           ; preds = %tailrecurse, %middle.block, %1
  %accumulator.tr.lcssa = phi i32 [ 1, %1 ], [ %6, %middle.block ], [ %8, %tailrecurse ]
  ret i32 %accumulator.tr.lcssa
}

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

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn 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" }
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 = distinct !{!5, !6, !7}
!6 = !{!"llvm.loop.isvectorized", i32 1}
!7 = !{!"llvm.loop.unroll.runtime.disable"}
!8 = distinct !{!8, !7, !6}


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