; LLVM IR from HarshCasper/NeoAlgo :: C/math (Palindrome)

; 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 i32 @check_palindrome(ptr noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca ptr, align 8
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #3
  store i32 0, ptr %4, align 4, !tbaa !9
  br label %6

6:                                                ; preds = %35, %1
  %7 = load i32, ptr %4, align 4, !tbaa !9
  %8 = sext i32 %7 to i64
  %9 = load ptr, ptr %3, align 8, !tbaa !5
  %10 = call i64 @strlen(ptr noundef %9) #4
  %11 = sub i64 %10, 1
  %12 = udiv i64 %11, 2
  %13 = icmp ult i64 %8, %12
  br i1 %13, label %15, label %14

14:                                               ; preds = %6
  store i32 2, ptr %5, align 4
  br label %38

15:                                               ; preds = %6
  %16 = load ptr, ptr %3, align 8, !tbaa !5
  %17 = load i32, ptr %4, align 4, !tbaa !9
  %18 = sext i32 %17 to i64
  %19 = getelementptr inbounds i8, ptr %16, i64 %18
  %20 = load i8, ptr %19, align 1, !tbaa !11
  %21 = sext i8 %20 to i32
  %22 = load ptr, ptr %3, align 8, !tbaa !5
  %23 = load ptr, ptr %3, align 8, !tbaa !5
  %24 = call i64 @strlen(ptr noundef %23) #4
  %25 = sub i64 %24, 2
  %26 = load i32, ptr %4, align 4, !tbaa !9
  %27 = sext i32 %26 to i64
  %28 = sub i64 %25, %27
  %29 = getelementptr inbounds i8, ptr %22, i64 %28
  %30 = load i8, ptr %29, align 1, !tbaa !11
  %31 = sext i8 %30 to i32
  %32 = icmp ne i32 %21, %31
  br i1 %32, label %33, label %34

33:                                               ; preds = %15
  store i32 -1, ptr %2, align 4
  store i32 1, ptr %5, align 4
  br label %38

34:                                               ; preds = %15
  br label %35

35:                                               ; preds = %34
  %36 = load i32, ptr %4, align 4, !tbaa !9
  %37 = add nsw i32 %36, 1
  store i32 %37, ptr %4, align 4, !tbaa !9
  br label %6, !llvm.loop !12

38:                                               ; preds = %33, %14
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #3
  %39 = load i32, ptr %5, align 4
  switch i32 %39, label %43 [
    i32 2, label %40
    i32 1, label %41
  ]

40:                                               ; preds = %38
  store i32 1, ptr %2, align 4
  br label %41

41:                                               ; preds = %40, %38
  %42 = load i32, ptr %2, align 4
  ret i32 %42

43:                                               ; preds = %38
  unreachable
}

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

; Function Attrs: nounwind willreturn memory(read)
declare i64 @strlen(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 = { nounwind willreturn memory(read) "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 }
attributes #4 = { nounwind willreturn memory(read) }

!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 = !{!7, !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"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 nounwind memory(argmem: read) uwtable
define dso_local range(i32 -1, 2) i32 @check_palindrome(ptr nocapture noundef readonly %0) local_unnamed_addr #0 {
  %2 = tail call i64 @strlen(ptr noundef nonnull dereferenceable(1) %0) #2
  %3 = add i64 %2, -1
  %.not1213.not = icmp ult i64 %3, 2
  br i1 %.not1213.not, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %1
  %4 = lshr i64 %3, 1
  %5 = add i64 %2, -2
  br label %7

6:                                                ; preds = %7
  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
  %exitcond.not = icmp eq i64 %indvars.iv.next, %4
  br i1 %exitcond.not, label %._crit_edge, label %7, !llvm.loop !5

7:                                                ; preds = %.lr.ph, %6
  %indvars.iv = phi i64 [ 0, %.lr.ph ], [ %indvars.iv.next, %6 ]
  %8 = getelementptr inbounds i8, ptr %0, i64 %indvars.iv
  %9 = load i8, ptr %8, align 1, !tbaa !7
  %10 = sub i64 %5, %indvars.iv
  %11 = getelementptr inbounds i8, ptr %0, i64 %10
  %12 = load i8, ptr %11, align 1, !tbaa !7
  %.not = icmp eq i8 %9, %12
  br i1 %.not, label %6, label %._crit_edge

._crit_edge:                                      ; preds = %6, %7, %1
  %spec.select = phi i32 [ 1, %1 ], [ -1, %7 ], [ 1, %6 ]
  ret i32 %spec.select
}

; Function Attrs: mustprogress nofree nounwind willreturn memory(argmem: read)
declare i64 @strlen(ptr nocapture noundef) local_unnamed_addr #1

attributes #0 = { nofree nounwind memory(argmem: read) 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 memory(argmem: read) "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 willreturn memory(read) }

!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"}
!7 = !{!8, !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C/C++ TBAA"}


; Effective O3 passes: CorrelatedValuePropagationPass,EarlyCSEPass,GlobalOptPass,IPSCCPPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LICMPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,ReassociatePass,SROAPass,SimplifyCFGPass,TailCallElimPass