; LLVM IR from wichue/nethello :: src/event/SelectWrap.ll (ZN3chw5FdSet6fdZeroEv)

; 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"

%"class.chw::FdSet" = type { ptr }
%struct.fd_set = type { [16 x i64] }

; Function Attrs: mustprogress nounwind uwtable
define dso_local void @_ZN3chw5FdSet6fdZeroEv(ptr noundef nonnull align 8 dereferenceable(8) %0) #0 align 2 {
  %2 = alloca ptr, align 8
  %3 = alloca i32, align 4
  %4 = alloca ptr, align 8
  store ptr %0, ptr %2, align 8, !tbaa !5
  %5 = load ptr, ptr %2, align 8
  br label %6

6:                                                ; preds = %1
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %7 = getelementptr inbounds %"class.chw::FdSet", ptr %5, i32 0, i32 0
  %8 = load ptr, ptr %7, align 8, !tbaa !9
  store ptr %8, ptr %4, align 8, !tbaa !5
  store i32 0, ptr %3, align 4, !tbaa !11
  br label %9

9:                                                ; preds = %19, %6
  %10 = load i32, ptr %3, align 4, !tbaa !11
  %11 = zext i32 %10 to i64
  %12 = icmp ult i64 %11, 16
  br i1 %12, label %13, label %22

13:                                               ; preds = %9
  %14 = load ptr, ptr %4, align 8, !tbaa !5
  %15 = getelementptr inbounds %struct.fd_set, ptr %14, i32 0, i32 0
  %16 = load i32, ptr %3, align 4, !tbaa !11
  %17 = zext i32 %16 to i64
  %18 = getelementptr inbounds [16 x i64], ptr %15, i64 0, i64 %17
  store i64 0, ptr %18, align 8, !tbaa !13
  br label %19

19:                                               ; preds = %13
  %20 = load i32, ptr %3, align 4, !tbaa !11
  %21 = add i32 %20, 1
  store i32 %21, ptr %3, align 4, !tbaa !11
  br label %9, !llvm.loop !15

22:                                               ; preds = %9
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  br label %23

23:                                               ; preds = %22
  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, !6, i64 0}
!10 = !{!"_ZTSN3chw5FdSetE", !6, i64 0}
!11 = !{!12, !12, i64 0}
!12 = !{!"int", !7, i64 0}
!13 = !{!14, !14, i64 0}
!14 = !{!"long", !7, i64 0}
!15 = distinct !{!15, !16}
!16 = !{!"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(write, argmem: readwrite, inaccessiblemem: none) uwtable
define dso_local void @_ZN3chw5FdSet6fdZeroEv(ptr nocapture noundef nonnull readonly align 8 dereferenceable(8) %0) local_unnamed_addr #0 align 2 {
  %2 = load ptr, ptr %0, align 8, !tbaa !5
  tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 8 dereferenceable(128) %2, i8 0, i64 128, i1 false), !tbaa !10
  ret void
}

; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: write)
declare void @llvm.memset.p0.i64(ptr nocapture writeonly, i8, i64, i1 immarg) #1

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(write, argmem: readwrite, inaccessiblemem: 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 nounwind willreturn memory(argmem: write) }

!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, !7, i64 0}
!6 = !{!"_ZTSN3chw5FdSetE", !7, i64 0}
!7 = !{!"any pointer", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C++ TBAA"}
!10 = !{!11, !11, i64 0}
!11 = !{!"long", !8, i64 0}


; Effective O3 passes: CorrelatedValuePropagationPass,EarlyCSEPass,GVNPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,LoopIdiomRecognizePass,LoopRotatePass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass