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

; 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"

@__const.fibonacci.result = external hidden unnamed_addr constant [2 x i32], align 4

; Function Attrs: nounwind uwtable
define dso_local i32 @fibonacci(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca [2 x i32], align 4
  %5 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #3
  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %4, ptr align 4 @__const.fibonacci.result, i64 8, i1 false)
  %6 = load i32, ptr %3, align 4, !tbaa !5
  %7 = icmp slt i32 %6, 2
  br i1 %7, label %8, label %13

8:                                                ; preds = %1
  %9 = load i32, ptr %3, align 4, !tbaa !5
  %10 = sext i32 %9 to i64
  %11 = getelementptr inbounds [2 x i32], ptr %4, i64 0, i64 %10
  %12 = load i32, ptr %11, align 4, !tbaa !5
  store i32 %12, ptr %2, align 4
  store i32 1, ptr %5, align 4
  br label %21

13:                                               ; preds = %1
  %14 = load i32, ptr %3, align 4, !tbaa !5
  %15 = sub nsw i32 %14, 1
  %16 = call i32 @fibonacci(i32 noundef %15)
  %17 = load i32, ptr %3, align 4, !tbaa !5
  %18 = sub nsw i32 %17, 2
  %19 = call i32 @fibonacci(i32 noundef %18)
  %20 = add nsw i32 %16, %19
  store i32 %20, ptr %2, align 4
  store i32 1, ptr %5, align 4
  br label %21

21:                                               ; preds = %13, %8
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #3
  %22 = load i32, ptr %2, align 4
  ret i32 %22
}

; 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 nounwind willreturn memory(argmem: readwrite)
declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg) #2

; 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 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
attributes #3 = { 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"

@__const.fibonacci.result = external hidden unnamed_addr constant [2 x i32], align 4

; Function Attrs: nofree nosync nounwind memory(none) uwtable
define dso_local i32 @fibonacci(i32 noundef %0) local_unnamed_addr #0 {
  %2 = icmp slt i32 %0, 2
  br i1 %2, label %tailrecurse._crit_edge, label %tailrecurse

tailrecurse._crit_edge:                           ; preds = %tailrecurse, %1
  %accumulator.tr.lcssa = phi i32 [ 0, %1 ], [ %9, %tailrecurse ]
  %.tr.lcssa = phi i32 [ %0, %1 ], [ %8, %tailrecurse ]
  %3 = sext i32 %.tr.lcssa to i64
  %4 = getelementptr inbounds [2 x i32], ptr @__const.fibonacci.result, i64 0, i64 %3
  %5 = load i32, ptr %4, align 4, !tbaa !5
  %accumulator.ret.tr = add nsw i32 %5, %accumulator.tr.lcssa
  ret i32 %accumulator.ret.tr

tailrecurse:                                      ; preds = %1, %tailrecurse
  %.tr7 = phi i32 [ %8, %tailrecurse ], [ %0, %1 ]
  %accumulator.tr6 = phi i32 [ %9, %tailrecurse ], [ 0, %1 ]
  %6 = add nsw i32 %.tr7, -1
  %7 = tail call i32 @fibonacci(i32 noundef %6)
  %8 = add nsw i32 %.tr7, -2
  %9 = add nsw i32 %7, %accumulator.tr6
  %10 = icmp ult i32 %.tr7, 4
  br i1 %10, label %tailrecurse._crit_edge, label %tailrecurse
}

attributes #0 = { nofree nosync nounwind 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 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}


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