; LLVM IR from namantam1/x86-assembly :: leetcode (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"

; Function Attrs: nounwind uwtable
define dso_local i32 @fib_C(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  %7 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  %8 = load i32, ptr %3, align 4, !tbaa !5
  %9 = icmp eq i32 %8, 0
  br i1 %9, label %10, label %11

10:                                               ; preds = %1
  store i32 0, ptr %2, align 4
  br label %26

11:                                               ; preds = %1
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  store i32 0, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  store i32 1, ptr %5, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #2
  store i32 2, ptr %6, align 4, !tbaa !5
  br label %12

12:                                               ; preds = %16, %11
  %13 = load i32, ptr %6, align 4, !tbaa !5
  %14 = load i32, ptr %3, align 4, !tbaa !5
  %15 = icmp sle i32 %13, %14
  br i1 %15, label %16, label %24

16:                                               ; preds = %12
  call void @llvm.lifetime.start.p0(i64 4, ptr %7) #2
  %17 = load i32, ptr %5, align 4, !tbaa !5
  %18 = load i32, ptr %4, align 4, !tbaa !5
  %19 = add nsw i32 %17, %18
  store i32 %19, ptr %7, align 4, !tbaa !5
  %20 = load i32, ptr %5, align 4, !tbaa !5
  store i32 %20, ptr %4, align 4, !tbaa !5
  %21 = load i32, ptr %7, align 4, !tbaa !5
  store i32 %21, ptr %5, align 4, !tbaa !5
  %22 = load i32, ptr %6, align 4, !tbaa !5
  %23 = add nsw i32 %22, 1
  store i32 %23, ptr %6, align 4, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 4, ptr %7) #2
  br label %12, !llvm.loop !9

24:                                               ; preds = %12
  %25 = load i32, ptr %5, align 4, !tbaa !5
  store i32 %25, ptr %2, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  br label %26

26:                                               ; preds = %24, %10
  %27 = load i32, ptr %2, align 4
  ret i32 %27
}

; 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"}
!9 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}


; 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 norecurse nosync nounwind memory(none) uwtable
define dso_local i32 @fib_C(i32 noundef %0) local_unnamed_addr #0 {
  %2 = icmp eq i32 %0, 0
  br i1 %2, label %.loopexit, label %.preheader

.preheader:                                       ; preds = %1
  %.not14 = icmp slt i32 %0, 2
  br i1 %.not14, label %.loopexit, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %.preheader
  %3 = add nsw i32 %0, -1
  %4 = add nsw i32 %0, -2
  %xtraiter = and i32 %3, 7
  %5 = icmp ult i32 %4, 7
  br i1 %5, label %.loopexit.loopexit.unr-lcssa, label %.lr.ph.preheader.new

.lr.ph.preheader.new:                             ; preds = %.lr.ph.preheader
  %unroll_iter = and i32 %3, -8
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph, %.lr.ph.preheader.new
  %.01116 = phi i32 [ 1, %.lr.ph.preheader.new ], [ %13, %.lr.ph ]
  %.01215 = phi i32 [ 0, %.lr.ph.preheader.new ], [ %12, %.lr.ph ]
  %niter = phi i32 [ 0, %.lr.ph.preheader.new ], [ %niter.next.7, %.lr.ph ]
  %6 = add nsw i32 %.01116, %.01215
  %7 = add nsw i32 %6, %.01116
  %8 = add nsw i32 %7, %6
  %9 = add nsw i32 %8, %7
  %10 = add nsw i32 %9, %8
  %11 = add nsw i32 %10, %9
  %12 = add nsw i32 %11, %10
  %13 = add nsw i32 %12, %11
  %niter.next.7 = add i32 %niter, 8
  %niter.ncmp.7 = icmp eq i32 %niter.next.7, %unroll_iter
  br i1 %niter.ncmp.7, label %.loopexit.loopexit.unr-lcssa, label %.lr.ph, !llvm.loop !5

.loopexit.loopexit.unr-lcssa:                     ; preds = %.lr.ph, %.lr.ph.preheader
  %.lcssa.ph = phi i32 [ poison, %.lr.ph.preheader ], [ %13, %.lr.ph ]
  %.01116.unr = phi i32 [ 1, %.lr.ph.preheader ], [ %13, %.lr.ph ]
  %.01215.unr = phi i32 [ 0, %.lr.ph.preheader ], [ %12, %.lr.ph ]
  %lcmp.mod.not = icmp eq i32 %xtraiter, 0
  br i1 %lcmp.mod.not, label %.loopexit, label %.lr.ph.epil

.lr.ph.epil:                                      ; preds = %.loopexit.loopexit.unr-lcssa, %.lr.ph.epil
  %.01116.epil = phi i32 [ %14, %.lr.ph.epil ], [ %.01116.unr, %.loopexit.loopexit.unr-lcssa ]
  %.01215.epil = phi i32 [ %.01116.epil, %.lr.ph.epil ], [ %.01215.unr, %.loopexit.loopexit.unr-lcssa ]
  %epil.iter = phi i32 [ %epil.iter.next, %.lr.ph.epil ], [ 0, %.loopexit.loopexit.unr-lcssa ]
  %14 = add nsw i32 %.01116.epil, %.01215.epil
  %epil.iter.next = add i32 %epil.iter, 1
  %epil.iter.cmp.not = icmp eq i32 %epil.iter.next, %xtraiter
  br i1 %epil.iter.cmp.not, label %.loopexit, label %.lr.ph.epil, !llvm.loop !7

.loopexit:                                        ; preds = %.loopexit.loopexit.unr-lcssa, %.lr.ph.epil, %.preheader, %1
  %.0 = phi i32 [ 0, %1 ], [ 1, %.preheader ], [ %.lcssa.ph, %.loopexit.loopexit.unr-lcssa ], [ %14, %.lr.ph.epil ]
  ret i32 %.0
}

attributes #0 = { nofree norecurse 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 = distinct !{!5, !6}
!6 = !{!"llvm.loop.mustprogress"}
!7 = distinct !{!7, !8}
!8 = !{!"llvm.loop.unroll.disable"}


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