; LLVM IR from TheAlgorithms/C-Plus-Plus :: math/double_factorial.ll (Z26double_factorial_iterativem)

; 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 i64 @_Z26double_factorial_iterativem(i64 noundef %0) #0 {
  %2 = alloca i64, align 8
  %3 = alloca i64, align 8
  %4 = alloca i64, align 8
  store i64 %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  store i64 1, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %5 = load i64, ptr %2, align 8, !tbaa !5
  store i64 %5, ptr %4, align 8, !tbaa !5
  br label %6

6:                                                ; preds = %18, %1
  %7 = load i64, ptr %4, align 8, !tbaa !5
  %8 = icmp eq i64 %7, 0
  br i1 %8, label %12, label %9

9:                                                ; preds = %6
  %10 = load i64, ptr %4, align 8, !tbaa !5
  %11 = icmp eq i64 %10, 1
  br i1 %11, label %12, label %14

12:                                               ; preds = %9, %6
  %13 = load i64, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  ret i64 %13

14:                                               ; preds = %9
  %15 = load i64, ptr %4, align 8, !tbaa !5
  %16 = load i64, ptr %3, align 8, !tbaa !5
  %17 = mul i64 %16, %15
  store i64 %17, ptr %3, align 8, !tbaa !5
  br label %18

18:                                               ; preds = %14
  %19 = load i64, ptr %4, align 8, !tbaa !5
  %20 = sub i64 %19, 2
  store i64 %20, ptr %4, align 8, !tbaa !5
  br label %6, !llvm.loop !9
}

; 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 = !{!"long", !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 i64 @_Z26double_factorial_iterativem(i64 noundef %0) local_unnamed_addr #0 {
  %or.cond9 = icmp ult i64 %0, 2
  br i1 %or.cond9, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %1
  %2 = add i64 %0, -2
  %3 = lshr i64 %2, 1
  %4 = add nuw i64 %3, 1
  %xtraiter = and i64 %4, 7
  %5 = icmp ult i64 %2, 14
  br i1 %5, label %._crit_edge.loopexit.unr-lcssa, label %.lr.ph.preheader.new

.lr.ph.preheader.new:                             ; preds = %.lr.ph.preheader
  %unroll_iter = and i64 %4, -8
  br label %.lr.ph

._crit_edge.loopexit.unr-lcssa:                   ; preds = %.lr.ph, %.lr.ph.preheader
  %.lcssa.ph = phi i64 [ poison, %.lr.ph.preheader ], [ %22, %.lr.ph ]
  %.011.unr = phi i64 [ %0, %.lr.ph.preheader ], [ %23, %.lr.ph ]
  %.0810.unr = phi i64 [ 1, %.lr.ph.preheader ], [ %22, %.lr.ph ]
  %lcmp.mod.not = icmp eq i64 %xtraiter, 0
  br i1 %lcmp.mod.not, label %._crit_edge, label %.lr.ph.epil

.lr.ph.epil:                                      ; preds = %._crit_edge.loopexit.unr-lcssa, %.lr.ph.epil
  %.011.epil = phi i64 [ %7, %.lr.ph.epil ], [ %.011.unr, %._crit_edge.loopexit.unr-lcssa ]
  %.0810.epil = phi i64 [ %6, %.lr.ph.epil ], [ %.0810.unr, %._crit_edge.loopexit.unr-lcssa ]
  %epil.iter = phi i64 [ %epil.iter.next, %.lr.ph.epil ], [ 0, %._crit_edge.loopexit.unr-lcssa ]
  %6 = mul i64 %.011.epil, %.0810.epil
  %7 = add i64 %.011.epil, -2
  %epil.iter.next = add i64 %epil.iter, 1
  %epil.iter.cmp.not = icmp eq i64 %epil.iter.next, %xtraiter
  br i1 %epil.iter.cmp.not, label %._crit_edge, label %.lr.ph.epil, !llvm.loop !5

._crit_edge:                                      ; preds = %._crit_edge.loopexit.unr-lcssa, %.lr.ph.epil, %1
  %.08.lcssa = phi i64 [ 1, %1 ], [ %.lcssa.ph, %._crit_edge.loopexit.unr-lcssa ], [ %6, %.lr.ph.epil ]
  ret i64 %.08.lcssa

.lr.ph:                                           ; preds = %.lr.ph, %.lr.ph.preheader.new
  %.011 = phi i64 [ %0, %.lr.ph.preheader.new ], [ %23, %.lr.ph ]
  %.0810 = phi i64 [ 1, %.lr.ph.preheader.new ], [ %22, %.lr.ph ]
  %niter = phi i64 [ 0, %.lr.ph.preheader.new ], [ %niter.next.7, %.lr.ph ]
  %8 = mul i64 %.011, %.0810
  %9 = add i64 %.011, -2
  %10 = mul i64 %9, %8
  %11 = add i64 %.011, -4
  %12 = mul i64 %11, %10
  %13 = add i64 %.011, -6
  %14 = mul i64 %13, %12
  %15 = add i64 %.011, -8
  %16 = mul i64 %15, %14
  %17 = add i64 %.011, -10
  %18 = mul i64 %17, %16
  %19 = add i64 %.011, -12
  %20 = mul i64 %19, %18
  %21 = add i64 %.011, -14
  %22 = mul i64 %21, %20
  %23 = add i64 %.011, -16
  %niter.next.7 = add i64 %niter, 8
  %niter.ncmp.7 = icmp eq i64 %niter.next.7, %unroll_iter
  br i1 %niter.ncmp.7, label %._crit_edge.loopexit.unr-lcssa, label %.lr.ph, !llvm.loop !7
}

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" }

!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}
!6 = !{!"llvm.loop.unroll.disable"}
!7 = distinct !{!7, !8}
!8 = !{!"llvm.loop.mustprogress"}


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