; LLVM IR from nonstriater/Learn-Algorithms :: 9 Algorithms Job Interview/codes/5 array (factorial)

; 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 @factorial(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  store i32 0, ptr %3, align 4, !tbaa !5
  %4 = load i32, ptr %2, align 4, !tbaa !5
  %5 = icmp eq i32 %4, 0
  br i1 %5, label %13, label %6

6:                                                ; preds = %1
  %7 = load i32, ptr %2, align 4, !tbaa !5
  %8 = load i32, ptr %2, align 4, !tbaa !5
  %9 = sub nsw i32 %8, 1
  %10 = call i32 @factorial(i32 noundef %9)
  %11 = add nsw i32 %7, %10
  store i32 %11, ptr %3, align 4, !tbaa !5
  %12 = icmp ne i32 %11, 0
  br label %13

13:                                               ; preds = %6, %1
  %14 = phi i1 [ true, %1 ], [ %12, %6 ]
  %15 = zext i1 %14 to i32
  %16 = load i32, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  ret i32 %16
}

; 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 = { 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/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 i32 @factorial(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
  %3 = add i32 %0, -1
  %4 = mul i32 %3, %3
  %5 = zext i32 %3 to i33
  %6 = add i32 %0, -2
  %7 = zext i32 %6 to i33
  %8 = mul i33 %5, %7
  %9 = lshr i33 %8, 1
  %10 = trunc nuw i33 %9 to i32
  %11 = add i32 %4, %0
  %12 = sub i32 %11, %10
  br label %tailrecurse._crit_edge

tailrecurse._crit_edge:                           ; preds = %tailrecurse.preheader, %1
  %accumulator.tr.lcssa = phi i32 [ 0, %1 ], [ %12, %tailrecurse.preheader ]
  ret i32 %accumulator.tr.lcssa
}

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)"}


; Effective O3 passes: EarlyCSEPass,GVNPass,GlobalOptPass,IPSCCPPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,LCSSAPass,LoopRotatePass,LoopSimplifyPass,PostOrderFunctionAttrsPass,ReassociatePass,SCCPPass,SROAPass,SimplifyCFGPass,TailCallElimPass