; LLVM IR from ravireddy07/cpp-book :: src/Coding-Blocks/FriendsPairing.ll (Z9friendsDPi)

; 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"

@dp = external dso_local global [100005 x i32], align 16

; Function Attrs: mustprogress uwtable
define dso_local noundef i32 @_Z9friendsDPi(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  %5 = load i32, ptr %3, align 4, !tbaa !5
  %6 = icmp eq i32 %5, 0
  br i1 %6, label %10, label %7

7:                                                ; preds = %1
  %8 = load i32, ptr %3, align 4, !tbaa !5
  %9 = icmp eq i32 %8, 1
  br i1 %9, label %10, label %11

10:                                               ; preds = %7, %1
  store i32 1, ptr %2, align 4
  br label %45

11:                                               ; preds = %7
  %12 = load i32, ptr %3, align 4, !tbaa !5
  %13 = icmp eq i32 %12, 2
  br i1 %13, label %14, label %15

14:                                               ; preds = %11
  store i32 2, ptr %2, align 4
  br label %45

15:                                               ; preds = %11
  %16 = load i32, ptr %3, align 4, !tbaa !5
  %17 = sext i32 %16 to i64
  %18 = getelementptr inbounds [100005 x i32], ptr @dp, i64 0, i64 %17
  %19 = load i32, ptr %18, align 4, !tbaa !5
  %20 = icmp ne i32 %19, 0
  br i1 %20, label %21, label %26

21:                                               ; preds = %15
  %22 = load i32, ptr %3, align 4, !tbaa !5
  %23 = sext i32 %22 to i64
  %24 = getelementptr inbounds [100005 x i32], ptr @dp, i64 0, i64 %23
  %25 = load i32, ptr %24, align 4, !tbaa !5
  store i32 %25, ptr %2, align 4
  br label %45

26:                                               ; preds = %15
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  %27 = load i32, ptr %3, align 4, !tbaa !5
  %28 = sub nsw i32 %27, 1
  %29 = call noundef i32 @_Z9friendsDPi(i32 noundef %28)
  %30 = load i32, ptr %3, align 4, !tbaa !5
  %31 = sub nsw i32 %30, 1
  %32 = load i32, ptr %3, align 4, !tbaa !5
  %33 = sub nsw i32 %32, 2
  %34 = call noundef i32 @_Z9friendsDPi(i32 noundef %33)
  %35 = mul nsw i32 %31, %34
  %36 = add nsw i32 %29, %35
  store i32 %36, ptr %4, align 4, !tbaa !5
  %37 = load i32, ptr %4, align 4, !tbaa !5
  %38 = load i32, ptr %3, align 4, !tbaa !5
  %39 = sext i32 %38 to i64
  %40 = getelementptr inbounds [100005 x i32], ptr @dp, i64 0, i64 %39
  store i32 %37, ptr %40, align 4, !tbaa !5
  %41 = load i32, ptr %3, align 4, !tbaa !5
  %42 = sext i32 %41 to i64
  %43 = getelementptr inbounds [100005 x i32], ptr @dp, i64 0, i64 %42
  %44 = load i32, ptr %43, align 4, !tbaa !5
  store i32 %44, ptr %2, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  br label %45

45:                                               ; preds = %26, %21, %14, %10
  %46 = load i32, ptr %2, align 4
  ret i32 %46
}

; 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 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"}


; 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"

@dp = external dso_local local_unnamed_addr global [100005 x i32], align 16

; Function Attrs: mustprogress nofree nosync nounwind memory(readwrite, argmem: none, inaccessiblemem: none) uwtable
define dso_local noundef i32 @_Z9friendsDPi(i32 noundef %0) local_unnamed_addr #0 {
  %or.cond = icmp ult i32 %0, 2
  br i1 %or.cond, label %common.ret15, label %2

2:                                                ; preds = %1
  %3 = icmp eq i32 %0, 2
  br i1 %3, label %common.ret15, label %4

4:                                                ; preds = %2
  %5 = sext i32 %0 to i64
  %6 = getelementptr inbounds [100005 x i32], ptr @dp, i64 0, i64 %5
  %7 = load i32, ptr %6, align 4, !tbaa !5
  %.not = icmp eq i32 %7, 0
  br i1 %.not, label %8, label %common.ret15

common.ret15:                                     ; preds = %4, %2, %1, %8
  %common.ret15.op = phi i32 [ %14, %8 ], [ 1, %1 ], [ 2, %2 ], [ %7, %4 ]
  ret i32 %common.ret15.op

8:                                                ; preds = %4
  %9 = add nsw i32 %0, -1
  %10 = tail call noundef i32 @_Z9friendsDPi(i32 noundef %9)
  %11 = add nsw i32 %0, -2
  %12 = tail call noundef i32 @_Z9friendsDPi(i32 noundef %11)
  %13 = mul nsw i32 %12, %9
  %14 = add nsw i32 %13, %10
  store i32 %14, ptr %6, align 4, !tbaa !5
  br label %common.ret15
}

attributes #0 = { mustprogress nofree 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" }

!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"}


; Effective O3 passes: EarlyCSEPass,GlobalOptPass,IPSCCPPass,InferFunctionAttrsPass,InstCombinePass,PostOrderFunctionAttrsPass,ReassociatePass,SROAPass,SimplifyCFGPass,TailCallElimPass