; LLVM IR from ImChong/Practice_LeetCode_C :: F02_Programming_Topics/F03_Software_Design_Pattern/01_Creational_Pattern (getSingleton)

; 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"

%struct._singleton = type { i32 }

@g_instance = external hidden global ptr, align 8

; Function Attrs: nounwind uwtable
define dso_local ptr @getSingleton() #0 {
  %1 = load ptr, ptr @g_instance, align 8, !tbaa !5
  %2 = icmp eq ptr %1, null
  br i1 %2, label %3, label %7

3:                                                ; preds = %0
  %4 = call noalias ptr @malloc(i64 noundef 4) #2
  store ptr %4, ptr @g_instance, align 8, !tbaa !5
  %5 = load ptr, ptr @g_instance, align 8, !tbaa !5
  %6 = getelementptr inbounds %struct._singleton, ptr %5, i32 0, i32 0
  store i32 0, ptr %6, align 4, !tbaa !9
  br label %7

7:                                                ; preds = %3, %0
  %8 = load ptr, ptr @g_instance, align 8, !tbaa !5
  ret ptr %8
}

; Function Attrs: nounwind allocsize(0)
declare noalias ptr @malloc(i64 noundef) #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 = { nounwind allocsize(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 #2 = { nounwind allocsize(0) }

!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 = !{!10, !11, i64 0}
!10 = !{!"_singleton", !11, i64 0}
!11 = !{!"int", !7, i64 0}


; 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"

@g_instance = external hidden local_unnamed_addr global ptr, align 8

; Function Attrs: mustprogress nofree nounwind willreturn memory(readwrite, argmem: none) uwtable
define dso_local ptr @getSingleton() local_unnamed_addr #0 {
  %1 = load ptr, ptr @g_instance, align 8, !tbaa !5
  %2 = icmp eq ptr %1, null
  br i1 %2, label %3, label %5

3:                                                ; preds = %0
  %4 = tail call noalias dereferenceable_or_null(4) ptr @malloc(i64 noundef 4) #2
  store ptr %4, ptr @g_instance, align 8, !tbaa !5
  store i32 0, ptr %4, align 4, !tbaa !9
  br label %5

5:                                                ; preds = %3, %0
  %6 = phi ptr [ %4, %3 ], [ %1, %0 ]
  ret ptr %6
}

; Function Attrs: mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0) memory(inaccessiblemem: readwrite)
declare noalias noundef ptr @malloc(i64 noundef) local_unnamed_addr #1

attributes #0 = { mustprogress nofree nounwind willreturn memory(readwrite, argmem: 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 = { mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0) memory(inaccessiblemem: readwrite) "alloc-family"="malloc" "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 #2 = { nounwind allocsize(0) }

!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 = !{!10, !11, i64 0}
!10 = !{!"_singleton", !11, i64 0}
!11 = !{!"int", !7, i64 0}


; Effective O3 passes: EarlyCSEPass,GVNPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,PostOrderFunctionAttrsPass,TailCallElimPass