; LLVM IR from sgtlaugh/algovault :: code_library/misc (gray_codes)

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

4:                                                ; preds = %11, %1
  %5 = load i64, ptr %2, align 8, !tbaa !5
  %6 = icmp ne i64 %5, 0
  br i1 %6, label %7, label %14

7:                                                ; preds = %4
  %8 = load i64, ptr %2, align 8, !tbaa !5
  %9 = load i64, ptr %3, align 8, !tbaa !5
  %10 = xor i64 %9, %8
  store i64 %10, ptr %3, align 8, !tbaa !5
  br label %11

11:                                               ; preds = %7
  %12 = load i64, ptr %2, align 8, !tbaa !5
  %13 = lshr i64 %12, 1
  store i64 %13, ptr %2, align 8, !tbaa !5
  br label %4, !llvm.loop !9

14:                                               ; preds = %4
  %15 = load i64, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  ret i64 %15
}

; 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 = !{!"long long", !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 i64 @inverse_gray_code(i64 noundef %0) local_unnamed_addr #0 {
  %.not6 = icmp eq i64 %0, 0
  br i1 %.not6, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %1, %.lr.ph
  %.08 = phi i64 [ %2, %.lr.ph ], [ 0, %1 ]
  %.057 = phi i64 [ %3, %.lr.ph ], [ %0, %1 ]
  %2 = xor i64 %.08, %.057
  %3 = lshr i64 %.057, 1
  %.not = icmp ult i64 %.057, 2
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !5

._crit_edge:                                      ; preds = %.lr.ph, %1
  %.0.lcssa = phi i64 [ 0, %1 ], [ %2, %.lr.ph ]
  ret i64 %.0.lcssa
}

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"}


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