; LLVM IR from nonstriater/Learn-Algorithms :: 9 Algorithms Job Interview/codes/1 string (revert_by_word)

; 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
declare dso_local void @_reverse(ptr noundef, ptr noundef) #0

; 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

; Function Attrs: nounwind uwtable
declare dso_local ptr @_revert_by_word(ptr noundef) #0

; Function Attrs: nounwind uwtable
define dso_local ptr @revert_by_word(ptr noundef %0) #0 {
  %2 = alloca ptr, align 8
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  %6 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %7 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %7, ptr %4, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  %8 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %8, ptr %5, align 8, !tbaa !5
  %9 = load ptr, ptr %3, align 8, !tbaa !5
  %10 = icmp eq ptr %9, null
  br i1 %10, label %11, label %12

11:                                               ; preds = %1
  store ptr null, ptr %2, align 8
  store i32 1, ptr %6, align 4
  br label %29

12:                                               ; preds = %1
  br label %13

13:                                               ; preds = %18, %12
  %14 = load ptr, ptr %4, align 8, !tbaa !5
  %15 = load i8, ptr %14, align 1, !tbaa !9
  %16 = sext i8 %15 to i32
  %17 = icmp ne i32 %16, 0
  br i1 %17, label %18, label %21

18:                                               ; preds = %13
  %19 = load ptr, ptr %4, align 8, !tbaa !5
  %20 = getelementptr inbounds i8, ptr %19, i32 1
  store ptr %20, ptr %4, align 8, !tbaa !5
  br label %13, !llvm.loop !10

21:                                               ; preds = %13
  %22 = load ptr, ptr %4, align 8, !tbaa !5
  %23 = getelementptr inbounds i8, ptr %22, i32 -1
  store ptr %23, ptr %4, align 8, !tbaa !5
  %24 = load ptr, ptr %5, align 8, !tbaa !5
  %25 = load ptr, ptr %4, align 8, !tbaa !5
  call void @_reverse(ptr noundef %24, ptr noundef %25)
  %26 = load ptr, ptr %3, align 8, !tbaa !5
  %27 = call ptr @_revert_by_word(ptr noundef %26)
  %28 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %28, ptr %2, align 8
  store i32 1, ptr %6, align 4
  br label %29

29:                                               ; preds = %21, %11
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  %30 = load ptr, ptr %2, align 8
  ret ptr %30
}

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 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
!9 = !{!7, !7, i64 0}
!10 = distinct !{!10, !11}
!11 = !{!"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: nounwind uwtable
declare dso_local void @_reverse(ptr noundef, ptr noundef) local_unnamed_addr #0

; Function Attrs: nounwind uwtable
declare dso_local ptr @_revert_by_word(ptr noundef) local_unnamed_addr #0

; Function Attrs: nounwind uwtable
define dso_local noundef ptr @revert_by_word(ptr noundef returned %0) local_unnamed_addr #0 {
  %2 = icmp eq ptr %0, null
  br i1 %2, label %8, label %.preheader

.preheader:                                       ; preds = %1, %.preheader
  %.011 = phi ptr [ %4, %.preheader ], [ %0, %1 ]
  %3 = load i8, ptr %.011, align 1, !tbaa !5
  %.not = icmp eq i8 %3, 0
  %4 = getelementptr inbounds i8, ptr %.011, i64 1
  br i1 %.not, label %5, label %.preheader, !llvm.loop !8

5:                                                ; preds = %.preheader
  %6 = getelementptr inbounds i8, ptr %.011, i64 -1
  tail call void @_reverse(ptr noundef nonnull %0, ptr noundef nonnull %6)
  %7 = tail call ptr @_revert_by_word(ptr noundef nonnull %0)
  br label %8

8:                                                ; preds = %1, %5
  ret ptr %0
}

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 = !{!"omnipotent char", !7, i64 0}
!7 = !{!"Simple C/C++ TBAA"}
!8 = distinct !{!8, !9}
!9 = !{!"llvm.loop.mustprogress"}


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