; LLVM IR from chirag-singhal/Coding-Interview-101 :: Miscellaneous/Labs/Lab6 (merge_sort)

; 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.student = type { [20 x i8], float }

@.str = external hidden unnamed_addr constant [11 x i8], align 1

; Function Attrs: nounwind uwtable
define dso_local void @readData(ptr noundef %0, ptr noundef %1, i32 noundef %2) #0 {
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  %6 = alloca i32, align 4
  %7 = alloca i32, align 4
  store ptr %0, ptr %4, align 8, !tbaa !5
  store ptr %1, ptr %5, align 8, !tbaa !5
  store i32 %2, ptr %6, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %7) #3
  store i32 0, ptr %7, align 4, !tbaa !9
  br label %8

8:                                                ; preds = %27, %3
  %9 = load i32, ptr %7, align 4, !tbaa !9
  %10 = load i32, ptr %6, align 4, !tbaa !9
  %11 = icmp slt i32 %9, %10
  br i1 %11, label %13, label %12

12:                                               ; preds = %8
  call void @llvm.lifetime.end.p0(i64 4, ptr %7) #3
  br label %30

13:                                               ; preds = %8
  %14 = load ptr, ptr %4, align 8, !tbaa !5
  %15 = load ptr, ptr %5, align 8, !tbaa !5
  %16 = load i32, ptr %7, align 4, !tbaa !9
  %17 = sext i32 %16 to i64
  %18 = getelementptr inbounds %struct.student, ptr %15, i64 %17
  %19 = getelementptr inbounds %struct.student, ptr %18, i32 0, i32 0
  %20 = getelementptr inbounds [20 x i8], ptr %19, i64 0, i64 0
  %21 = load ptr, ptr %5, align 8, !tbaa !5
  %22 = load i32, ptr %7, align 4, !tbaa !9
  %23 = sext i32 %22 to i64
  %24 = getelementptr inbounds %struct.student, ptr %21, i64 %23
  %25 = getelementptr inbounds %struct.student, ptr %24, i32 0, i32 1
  %26 = call i32 (ptr, ptr, ...) @__isoc99_fscanf(ptr noundef %14, ptr noundef @.str, ptr noundef %20, ptr noundef %25)
  br label %27

27:                                               ; preds = %13
  %28 = load i32, ptr %7, align 4, !tbaa !9
  %29 = add nsw i32 %28, 1
  store i32 %29, ptr %7, align 4, !tbaa !9
  br label %8, !llvm.loop !11

30:                                               ; preds = %12
  ret void
}

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

declare i32 @__isoc99_fscanf(ptr noundef, ptr noundef, ...) #2

; 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 = { "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 #3 = { 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 = !{!10, !10, i64 0}
!10 = !{!"int", !7, i64 0}
!11 = distinct !{!11, !12}
!12 = !{!"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"

%struct.student = type { [20 x i8], float }

@.str = external hidden unnamed_addr constant [11 x i8], align 1

; Function Attrs: nounwind uwtable
define dso_local void @readData(ptr noundef %0, ptr noundef %1, i32 noundef %2) local_unnamed_addr #0 {
  %4 = icmp sgt i32 %2, 0
  br i1 %4, label %.lr.ph.preheader, label %._crit_edge

.lr.ph.preheader:                                 ; preds = %3
  %wide.trip.count = zext nneg i32 %2 to i64
  br label %.lr.ph

._crit_edge:                                      ; preds = %.lr.ph, %3
  ret void

.lr.ph:                                           ; preds = %.lr.ph.preheader, %.lr.ph
  %indvars.iv = phi i64 [ 0, %.lr.ph.preheader ], [ %indvars.iv.next, %.lr.ph ]
  %5 = getelementptr inbounds %struct.student, ptr %1, i64 %indvars.iv
  %6 = getelementptr inbounds i8, ptr %5, i64 20
  %7 = tail call i32 (ptr, ptr, ...) @__isoc99_fscanf(ptr noundef %0, ptr noundef nonnull @.str, ptr noundef %5, ptr noundef nonnull %6) #2
  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
  %exitcond.not = icmp eq i64 %indvars.iv.next, %wide.trip.count
  br i1 %exitcond.not, label %._crit_edge, label %.lr.ph, !llvm.loop !5
}

declare i32 @__isoc99_fscanf(ptr noundef, ptr noundef, ...) local_unnamed_addr #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 = { "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 = distinct !{!5, !6}
!6 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: EarlyCSEPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,SROAPass,SimplifyCFGPass,TailCallElimPass