; LLVM IR from sbshah97/DS-Algo-Handbook :: labs/lab2/Fibonacci (fibonacci_recursion)

; 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 @fibo(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  %4 = load i32, ptr %3, align 4, !tbaa !5
  %5 = icmp sle i32 %4, 1
  br i1 %5, label %6, label %7

6:                                                ; preds = %1
  store i32 1, ptr %2, align 4
  br label %15

7:                                                ; preds = %1
  %8 = load i32, ptr %3, align 4, !tbaa !5
  %9 = sub nsw i32 %8, 1
  %10 = call i32 @fibo(i32 noundef %9)
  %11 = load i32, ptr %3, align 4, !tbaa !5
  %12 = sub nsw i32 %11, 2
  %13 = call i32 @fibo(i32 noundef %12)
  %14 = add nsw i32 %10, %13
  store i32 %14, ptr %2, align 4
  br label %15

15:                                               ; preds = %7, %6
  %16 = load i32, ptr %2, align 4
  ret i32 %16
}

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" }

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

tailrecurse:                                      ; preds = %1, %tailrecurse
  %.tr6 = phi i32 [ %5, %tailrecurse ], [ %0, %1 ]
  %accumulator.tr5 = phi i32 [ %6, %tailrecurse ], [ 0, %1 ]
  %3 = add nsw i32 %.tr6, -1
  %4 = tail call i32 @fibo(i32 noundef %3)
  %5 = add nsw i32 %.tr6, -2
  %6 = add nsw i32 %4, %accumulator.tr5
  %7 = icmp ult i32 %.tr6, 4
  br i1 %7, label %tailrecurse._crit_edge.loopexit, label %tailrecurse

tailrecurse._crit_edge.loopexit:                  ; preds = %tailrecurse
  %8 = add nsw i32 %6, 1
  br label %tailrecurse._crit_edge

tailrecurse._crit_edge:                           ; preds = %tailrecurse._crit_edge.loopexit, %1
  %accumulator.tr.lcssa = phi i32 [ 1, %1 ], [ %8, %tailrecurse._crit_edge.loopexit ]
  ret i32 %accumulator.tr.lcssa
}

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)"}


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