; LLVM IR from HarshCasper/NeoAlgo :: C-Plus-Plus/math/double_factorial.ll (Z9Iterativei)

; 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: mustprogress nounwind uwtable
define dso_local noundef i32 @_Z9Iterativei(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = 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 1, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  %7 = load i32, ptr %3, align 4, !tbaa !5
  store i32 %7, ptr %5, align 4, !tbaa !5
  br label %8

8:                                                ; preds = %25, %1
  %9 = load i32, ptr %5, align 4, !tbaa !5
  %10 = icmp sge i32 %9, 0
  br i1 %10, label %12, label %11

11:                                               ; preds = %8
  store i32 2, ptr %6, align 4
  br label %28

12:                                               ; preds = %8
  %13 = load i32, ptr %5, align 4, !tbaa !5
  %14 = icmp eq i32 %13, 0
  br i1 %14, label %18, label %15

15:                                               ; preds = %12
  %16 = load i32, ptr %5, align 4, !tbaa !5
  %17 = icmp eq i32 %16, 1
  br i1 %17, label %18, label %20

18:                                               ; preds = %15, %12
  %19 = load i32, ptr %4, align 4, !tbaa !5
  store i32 %19, ptr %2, align 4
  store i32 1, ptr %6, align 4
  br label %28

20:                                               ; preds = %15
  %21 = load i32, ptr %5, align 4, !tbaa !5
  %22 = load i32, ptr %4, align 4, !tbaa !5
  %23 = mul nsw i32 %22, %21
  store i32 %23, ptr %4, align 4, !tbaa !5
  br label %24

24:                                               ; preds = %20
  br label %25

25:                                               ; preds = %24
  %26 = load i32, ptr %5, align 4, !tbaa !5
  %27 = sub nsw i32 %26, 2
  store i32 %27, ptr %5, align 4, !tbaa !5
  br label %8, !llvm.loop !9

28:                                               ; preds = %18, %11
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  %29 = load i32, ptr %6, align 4
  switch i32 %29, label %32 [
    i32 2, label %30
  ]

30:                                               ; preds = %28
  %31 = load i32, ptr %4, align 4, !tbaa !5
  store i32 %31, ptr %2, align 4
  store i32 1, ptr %6, align 4
  br label %32

32:                                               ; preds = %30, %28
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  %33 = load i32, ptr %2, align 4
  ret i32 %33
}

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

attributes #0 = { mustprogress 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 #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
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"}
!9 = distinct !{!9, !10}
!10 = !{!"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"

; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable
define dso_local noundef range(i32 1, -2147483648) i32 @_Z9Iterativei(i32 noundef %0) local_unnamed_addr #0 {
  %or.cond1516 = icmp slt i32 %0, 2
  br i1 %or.cond1516, label %.critedge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %1
  %2 = add nsw i32 %0, -2
  %3 = lshr i32 %2, 1
  %4 = add nuw i32 %3, 1
  %min.iters.check = icmp ult i32 %2, 14
  br i1 %min.iters.check, label %.lr.ph.preheader21, label %vector.ph

vector.ph:                                        ; preds = %.lr.ph.preheader
  %n.vec = and i32 %4, -8
  %5 = shl i32 %n.vec, 1
  %ind.end = sub i32 %0, %5
  %.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 nsw <4 x i32> %.splat, <i32 0, i32 -2, i32 -4, i32 -6>
  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 ], [ %6, %vector.body ]
  %vec.phi20 = phi <4 x i32> [ <i32 1, i32 1, i32 1, i32 1>, %vector.ph ], [ %7, %vector.body ]
  %step.add = add <4 x i32> %vec.ind, <i32 -8, i32 -8, i32 -8, i32 -8>
  %6 = mul <4 x i32> %vec.ind, %vec.phi
  %7 = mul <4 x i32> %step.add, %vec.phi20
  %index.next = add nuw i32 %index, 8
  %vec.ind.next = add <4 x i32> %vec.ind, <i32 -16, i32 -16, i32 -16, i32 -16>
  %8 = icmp eq i32 %index.next, %n.vec
  br i1 %8, label %middle.block, label %vector.body, !llvm.loop !5

middle.block:                                     ; preds = %vector.body
  %bin.rdx = mul <4 x i32> %7, %6
  %9 = tail call i32 @llvm.vector.reduce.mul.v4i32(<4 x i32> %bin.rdx)
  %cmp.n = icmp eq i32 %4, %n.vec
  br i1 %cmp.n, label %.critedge, label %.lr.ph.preheader21

.lr.ph.preheader21:                               ; preds = %middle.block, %.lr.ph.preheader
  %.01218.ph = phi i32 [ %0, %.lr.ph.preheader ], [ %ind.end, %middle.block ]
  %.01317.ph = phi i32 [ 1, %.lr.ph.preheader ], [ %9, %middle.block ]
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph.preheader21, %.lr.ph
  %.01218 = phi i32 [ %11, %.lr.ph ], [ %.01218.ph, %.lr.ph.preheader21 ]
  %.01317 = phi i32 [ %10, %.lr.ph ], [ %.01317.ph, %.lr.ph.preheader21 ]
  %10 = mul nuw nsw i32 %.01218, %.01317
  %11 = add nsw i32 %.01218, -2
  %or.cond15 = icmp ult i32 %.01218, 4
  br i1 %or.cond15, label %.critedge, label %.lr.ph, !llvm.loop !9

.critedge:                                        ; preds = %.lr.ph, %middle.block, %1
  %.013.lcssa = phi i32 [ 1, %1 ], [ %9, %middle.block ], [ %10, %.lr.ph ]
  ret i32 %.013.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, !8}
!6 = !{!"llvm.loop.mustprogress"}
!7 = !{!"llvm.loop.isvectorized", i32 1}
!8 = !{!"llvm.loop.unroll.runtime.disable"}
!9 = distinct !{!9, !6, !8, !7}


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