; LLVM IR from next-step-for-interview-prep/Coding-Ninjas-DSA-course_code_and_notes_cpp :: Milestone-2=Intro_to_C++/questions and solutions/Lec-8=Arrays (swap_alternate)

; 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 void @_Z13swapAlternatePii(ptr noundef %0, i32 noundef %1) #0 {
  %3 = alloca ptr, align 8
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  store i32 %1, ptr %4, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  store i32 0, ptr %5, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #2
  store i32 0, ptr %6, align 4, !tbaa !9
  br label %7

7:                                                ; preds = %35, %2
  %8 = load i32, ptr %6, align 4, !tbaa !9
  %9 = load i32, ptr %4, align 4, !tbaa !9
  %10 = sub nsw i32 %9, 1
  %11 = icmp slt i32 %8, %10
  br i1 %11, label %13, label %12

12:                                               ; preds = %7
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #2
  br label %38

13:                                               ; preds = %7
  %14 = load ptr, ptr %3, align 8, !tbaa !5
  %15 = load i32, ptr %6, align 4, !tbaa !9
  %16 = add nsw i32 %15, 1
  %17 = sext i32 %16 to i64
  %18 = getelementptr inbounds i32, ptr %14, i64 %17
  %19 = load i32, ptr %18, align 4, !tbaa !9
  store i32 %19, ptr %5, align 4, !tbaa !9
  %20 = load ptr, ptr %3, align 8, !tbaa !5
  %21 = load i32, ptr %6, align 4, !tbaa !9
  %22 = sext i32 %21 to i64
  %23 = getelementptr inbounds i32, ptr %20, i64 %22
  %24 = load i32, ptr %23, align 4, !tbaa !9
  %25 = load ptr, ptr %3, align 8, !tbaa !5
  %26 = load i32, ptr %6, align 4, !tbaa !9
  %27 = add nsw i32 %26, 1
  %28 = sext i32 %27 to i64
  %29 = getelementptr inbounds i32, ptr %25, i64 %28
  store i32 %24, ptr %29, align 4, !tbaa !9
  %30 = load i32, ptr %5, align 4, !tbaa !9
  %31 = load ptr, ptr %3, align 8, !tbaa !5
  %32 = load i32, ptr %6, align 4, !tbaa !9
  %33 = sext i32 %32 to i64
  %34 = getelementptr inbounds i32, ptr %31, i64 %33
  store i32 %30, ptr %34, align 4, !tbaa !9
  br label %35

35:                                               ; preds = %13
  %36 = load i32, ptr %6, align 4, !tbaa !9
  %37 = add nsw i32 %36, 2
  store i32 %37, ptr %6, align 4, !tbaa !9
  br label %7, !llvm.loop !11

38:                                               ; preds = %12
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  ret void
}

; 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 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"int", !7, i64 0}
!11 = distinct !{!11, !12}
!12 = !{!"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 memory(argmem: readwrite) uwtable
define dso_local void @_Z13swapAlternatePii(ptr nocapture noundef %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = icmp sgt i32 %1, 1
  br i1 %3, label %.lr.ph.preheader, label %._crit_edge

.lr.ph.preheader:                                 ; preds = %2
  %4 = add nsw i32 %1, -1
  %5 = zext nneg i32 %4 to i64
  %umax = tail call i64 @llvm.umax.i64(i64 %5, i64 2)
  %6 = add nsw i64 %umax, -1
  %7 = lshr i64 %6, 1
  %8 = add nuw nsw i64 %7, 1
  %min.iters.check = icmp ult i32 %1, 8
  br i1 %min.iters.check, label %.lr.ph.preheader18, label %vector.ph

.lr.ph.preheader18:                               ; preds = %middle.block, %.lr.ph.preheader
  %indvars.iv.ph = phi i64 [ 0, %.lr.ph.preheader ], [ %ind.end, %middle.block ]
  br label %.lr.ph

vector.ph:                                        ; preds = %.lr.ph.preheader
  %n.vec = and i64 %8, 9223372036854775804
  %ind.end = shl nuw i64 %n.vec, 1
  %invariant.gep = getelementptr i8, ptr %0, i64 -4
  %invariant.gep19 = getelementptr i8, ptr %0, i64 -4
  br label %vector.body

vector.body:                                      ; preds = %vector.body, %vector.ph
  %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
  %offset.idx = shl i64 %index, 1
  %9 = or disjoint i64 %offset.idx, 4
  %10 = or disjoint i64 %offset.idx, 1
  %11 = or disjoint i64 %offset.idx, 5
  %gep = getelementptr i32, ptr %invariant.gep, i64 %10
  %gep20 = getelementptr i32, ptr %invariant.gep19, i64 %11
  %wide.vec = load <4 x i32>, ptr %gep, align 4, !tbaa !5
  %wide.vec13 = load <4 x i32>, ptr %gep20, align 4, !tbaa !5
  %12 = getelementptr inbounds i32, ptr %0, i64 %offset.idx
  %13 = getelementptr inbounds i32, ptr %0, i64 %9
  %interleaved.vec = shufflevector <4 x i32> %wide.vec, <4 x i32> poison, <4 x i32> <i32 1, i32 0, i32 3, i32 2>
  store <4 x i32> %interleaved.vec, ptr %12, align 4, !tbaa !5
  %interleaved.vec17 = shufflevector <4 x i32> %wide.vec13, <4 x i32> poison, <4 x i32> <i32 1, i32 0, i32 3, i32 2>
  store <4 x i32> %interleaved.vec17, ptr %13, align 4, !tbaa !5
  %index.next = add nuw i64 %index, 4
  %14 = icmp eq i64 %index.next, %n.vec
  br i1 %14, label %middle.block, label %vector.body, !llvm.loop !9

middle.block:                                     ; preds = %vector.body
  %cmp.n = icmp eq i64 %8, %n.vec
  br i1 %cmp.n, label %._crit_edge, label %.lr.ph.preheader18

._crit_edge:                                      ; preds = %.lr.ph, %middle.block, %2
  ret void

.lr.ph:                                           ; preds = %.lr.ph.preheader18, %.lr.ph
  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ %indvars.iv.ph, %.lr.ph.preheader18 ]
  %15 = getelementptr inbounds i32, ptr %0, i64 %indvars.iv
  %16 = load <2 x i32>, ptr %15, align 4, !tbaa !5
  %17 = shufflevector <2 x i32> %16, <2 x i32> poison, <2 x i32> <i32 1, i32 0>
  store <2 x i32> %17, ptr %15, align 4, !tbaa !5
  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 2
  %18 = icmp ult i64 %indvars.iv.next, %5
  br i1 %18, label %.lr.ph, label %._crit_edge, !llvm.loop !13
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i64 @llvm.umax.i64(i64, i64) #1

attributes #0 = { mustprogress nofree norecurse nosync nounwind memory(argmem: readwrite) 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 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = distinct !{!9, !10, !11, !12}
!10 = !{!"llvm.loop.mustprogress"}
!11 = !{!"llvm.loop.isvectorized", i32 1}
!12 = !{!"llvm.loop.unroll.runtime.disable"}
!13 = distinct !{!13, !10, !12, !11}


; Effective O3 passes: CorrelatedValuePropagationPass,EarlyCSEPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LICMPass,LoopLoadEliminationPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,LoopVectorizePass,PostOrderFunctionAttrsPass,SLPVectorizerPass,SROAPass,SimplifyCFGPass,TailCallElimPass,VectorCombinePass