; LLVM IR from drken1215/book_algorithm_solution :: codes/chap04/code_4_5.ll (Z4fiboi)

; 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 uwtable
define dso_local noundef i32 @_Z4fiboi(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 eq i32 %4, 0
  br i1 %5, label %6, label %7

6:                                                ; preds = %1
  store i32 0, ptr %2, align 4
  br label %20

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
  store i32 1, ptr %2, align 4
  br label %20

11:                                               ; preds = %7
  br label %12

12:                                               ; preds = %11
  %13 = load i32, ptr %3, align 4, !tbaa !5
  %14 = sub nsw i32 %13, 1
  %15 = call noundef i32 @_Z4fiboi(i32 noundef %14)
  %16 = load i32, ptr %3, align 4, !tbaa !5
  %17 = sub nsw i32 %16, 2
  %18 = call noundef i32 @_Z4fiboi(i32 noundef %17)
  %19 = add nsw i32 %15, %18
  store i32 %19, ptr %2, align 4
  br label %20

20:                                               ; preds = %12, %10, %6
  %21 = load i32, ptr %2, align 4
  ret i32 %21
}

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" }

!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"

; Function Attrs: mustprogress nofree nosync nounwind willreturn memory(none) uwtable
define dso_local noundef i32 @_Z4fiboi(i32 noundef %0) local_unnamed_addr #0 {
  %switch13 = icmp ult i32 %0, 2
  br i1 %switch13, label %.loopexit, label %tailrecurse

tailrecurse:                                      ; preds = %1, %tailrecurse
  %.tr15 = phi i32 [ %4, %tailrecurse ], [ %0, %1 ]
  %accumulator.tr14 = phi i32 [ %5, %tailrecurse ], [ 0, %1 ]
  %2 = add nsw i32 %.tr15, -1
  %3 = tail call noundef i32 @_Z4fiboi(i32 noundef %2)
  %4 = add nsw i32 %.tr15, -2
  %5 = add nsw i32 %3, %accumulator.tr14
  %switch = icmp ult i32 %4, 2
  br i1 %switch, label %.loopexit, label %tailrecurse

.loopexit:                                        ; preds = %tailrecurse, %1
  %accumulator.tr.lcssa = phi i32 [ 0, %1 ], [ %5, %tailrecurse ]
  %.tr.lcssa = phi i32 [ %0, %1 ], [ %4, %tailrecurse ]
  %accumulator.ret.tr = add nsw i32 %.tr.lcssa, %accumulator.tr.lcssa
  ret i32 %accumulator.ret.tr
}

attributes #0 = { mustprogress nofree 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: GVNPass,GlobalOptPass,IPSCCPPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass