; LLVM IR from next-step-for-interview-prep/Coding-Ninjas-DSA-course_code_and_notes_cpp :: Milestone-1=Intro_to_C++/questions and solutions/Lec-3=Conditionals_and_loops/02-Ev_b6d7e546 (Z8nEvenSumi)

; 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 nounwind uwtable
define dso_local noundef i32 @_Z8nEvenSumi(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  store i32 0, ptr %4, align 4, !tbaa !5
  store i32 1, ptr %3, align 4, !tbaa !5
  br label %5

5:                                                ; preds = %18, %1
  %6 = load i32, ptr %3, align 4, !tbaa !5
  %7 = load i32, ptr %2, align 4, !tbaa !5
  %8 = icmp sle i32 %6, %7
  br i1 %8, label %9, label %21

9:                                                ; preds = %5
  %10 = load i32, ptr %3, align 4, !tbaa !5
  %11 = srem i32 %10, 2
  %12 = icmp eq i32 %11, 0
  br i1 %12, label %13, label %17

13:                                               ; preds = %9
  %14 = load i32, ptr %3, align 4, !tbaa !5
  %15 = load i32, ptr %4, align 4, !tbaa !5
  %16 = add nsw i32 %15, %14
  store i32 %16, ptr %4, align 4, !tbaa !5
  br label %17

17:                                               ; preds = %13, %9
  br label %18

18:                                               ; preds = %17
  %19 = load i32, ptr %3, align 4, !tbaa !5
  %20 = add nsw i32 %19, 1
  store i32 %20, ptr %3, align 4, !tbaa !5
  br label %5, !llvm.loop !9

21:                                               ; preds = %5
  %22 = load i32, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  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 nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

attributes #0 = { mustprogress 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++ 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: mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable
define dso_local noundef i32 @_Z8nEvenSumi(i32 noundef %0) local_unnamed_addr #0 {
  %.not8 = icmp slt i32 %0, 1
  br i1 %.not8, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %1
  %min.iters.check = icmp ult i32 %0, 8
  br i1 %min.iters.check, label %.lr.ph.preheader13, label %vector.ph

vector.ph:                                        ; preds = %.lr.ph.preheader
  %n.vec = and i32 %0, 2147483640
  %ind.end = or disjoint i32 %n.vec, 1
  br label %vector.body

vector.body:                                      ; preds = %vector.body, %vector.ph
  %index = phi i32 [ 0, %vector.ph ], [ %index.next, %vector.body ]
  %vec.phi = phi <4 x i32> [ zeroinitializer, %vector.ph ], [ %8, %vector.body ]
  %vec.phi11 = phi <4 x i32> [ zeroinitializer, %vector.ph ], [ %9, %vector.body ]
  %vec.ind = phi <4 x i32> [ <i32 1, i32 2, i32 3, i32 4>, %vector.ph ], [ %vec.ind.next, %vector.body ]
  %step.add = add <4 x i32> %vec.ind, <i32 4, i32 4, i32 4, i32 4>
  %2 = and <4 x i32> %vec.ind, <i32 1, i32 1, i32 1, i32 1>
  %3 = and <4 x i32> %vec.ind, <i32 1, i32 1, i32 1, i32 1>
  %4 = icmp eq <4 x i32> %2, zeroinitializer
  %5 = icmp eq <4 x i32> %3, zeroinitializer
  %6 = select <4 x i1> %4, <4 x i32> %vec.ind, <4 x i32> zeroinitializer
  %7 = select <4 x i1> %5, <4 x i32> %step.add, <4 x i32> zeroinitializer
  %8 = add <4 x i32> %6, %vec.phi
  %9 = add <4 x i32> %7, %vec.phi11
  %index.next = add nuw i32 %index, 8
  %vec.ind.next = add <4 x i32> %vec.ind, <i32 8, i32 8, i32 8, i32 8>
  %10 = icmp eq i32 %index.next, %n.vec
  br i1 %10, label %middle.block, label %vector.body, !llvm.loop !5

middle.block:                                     ; preds = %vector.body
  %bin.rdx = add <4 x i32> %9, %8
  %11 = tail call i32 @llvm.vector.reduce.add.v4i32(<4 x i32> %bin.rdx)
  %cmp.n = icmp eq i32 %n.vec, %0
  br i1 %cmp.n, label %._crit_edge, label %.lr.ph.preheader13

.lr.ph.preheader13:                               ; preds = %middle.block, %.lr.ph.preheader
  %.010.ph = phi i32 [ 0, %.lr.ph.preheader ], [ %11, %middle.block ]
  %.079.ph = phi i32 [ 1, %.lr.ph.preheader ], [ %ind.end, %middle.block ]
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph.preheader13, %.lr.ph
  %.010 = phi i32 [ %spec.select, %.lr.ph ], [ %.010.ph, %.lr.ph.preheader13 ]
  %.079 = phi i32 [ %15, %.lr.ph ], [ %.079.ph, %.lr.ph.preheader13 ]
  %12 = and i32 %.079, 1
  %13 = icmp eq i32 %12, 0
  %14 = select i1 %13, i32 %.079, i32 0
  %spec.select = add nuw nsw i32 %14, %.010
  %15 = add nuw i32 %.079, 1
  %exitcond.not = icmp eq i32 %.079, %0
  br i1 %exitcond.not, label %._crit_edge, label %.lr.ph, !llvm.loop !9

._crit_edge:                                      ; preds = %.lr.ph, %middle.block, %1
  %.0.lcssa = phi i32 [ 0, %1 ], [ %11, %middle.block ], [ %spec.select, %.lr.ph ]
  ret i32 %.0.lcssa
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i32 @llvm.vector.reduce.add.v4i32(<4 x i32>) #1

attributes #0 = { mustprogress nofree norecurse 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" }
attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }

!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, !7, !8}
!6 = !{!"llvm.loop.mustprogress"}
!7 = !{!"llvm.loop.isvectorized", i32 1}
!8 = !{!"llvm.loop.unroll.runtime.disable"}
!9 = distinct !{!9, !6, !8, !7}


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