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

; 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: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: nounwind uwtable
define dso_local ptr @strcpy(ptr noundef %0, ptr noundef %1) #1 {
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  store ptr %0, ptr %3, align 8, !tbaa !5
  store ptr %1, ptr %4, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  %6 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %6, ptr %5, align 8, !tbaa !5
  br label %7

7:                                                ; preds = %11, %2
  %8 = load ptr, ptr %3, align 8, !tbaa !5
  %9 = load i8, ptr %8, align 1, !tbaa !9
  %10 = icmp ne i8 %9, 0
  br i1 %10, label %11, label %17

11:                                               ; preds = %7
  %12 = load ptr, ptr %3, align 8, !tbaa !5
  %13 = getelementptr inbounds i8, ptr %12, i32 1
  store ptr %13, ptr %3, align 8, !tbaa !5
  %14 = load i8, ptr %12, align 1, !tbaa !9
  %15 = load ptr, ptr %4, align 8, !tbaa !5
  %16 = getelementptr inbounds i8, ptr %15, i32 1
  store ptr %16, ptr %4, align 8, !tbaa !5
  store i8 %14, ptr %15, align 1, !tbaa !9
  br label %7, !llvm.loop !10

17:                                               ; preds = %7
  %18 = load ptr, ptr %4, align 8, !tbaa !5
  store i8 0, ptr %18, align 1, !tbaa !9
  %19 = load ptr, ptr %5, align 8, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #2
  ret ptr %19
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { 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 #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: nofree norecurse nosync nounwind memory(readwrite, inaccessiblemem: none) uwtable
define dso_local noundef ptr @strcpy(ptr nocapture noundef readonly %0, ptr noundef returned writeonly %1) local_unnamed_addr #0 {
  %3 = load i8, ptr %0, align 1, !tbaa !5
  %.not8 = icmp eq i8 %3, 0
  br i1 %.not8, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %2, %.lr.ph
  %4 = phi i8 [ %7, %.lr.ph ], [ %3, %2 ]
  %.010 = phi ptr [ %5, %.lr.ph ], [ %0, %2 ]
  %.069 = phi ptr [ %6, %.lr.ph ], [ %1, %2 ]
  %5 = getelementptr inbounds i8, ptr %.010, i64 1
  %6 = getelementptr inbounds i8, ptr %.069, i64 1
  store i8 %4, ptr %.069, align 1, !tbaa !5
  %7 = load i8, ptr %5, align 1, !tbaa !5
  %.not = icmp eq i8 %7, 0
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !8

._crit_edge:                                      ; preds = %.lr.ph, %2
  %.06.lcssa = phi ptr [ %1, %2 ], [ %6, %.lr.ph ]
  store i8 0, ptr %.06.lcssa, align 1, !tbaa !5
  ret ptr %1
}

attributes #0 = { nofree norecurse nosync nounwind memory(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" }

!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: EarlyCSEPass,GVNPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass