; LLVM IR from ahampriyanshu/algo-ds-101 :: Algorithms/String/Palindrome (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: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0

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

8:                                                ; preds = %30, %1
  %9 = load i32, ptr %3, align 4, !tbaa !9
  %10 = load i32, ptr %4, align 4, !tbaa !9
  %11 = icmp slt i32 %9, %10
  br i1 %11, label %12, label %28

12:                                               ; preds = %8
  %13 = load ptr, ptr %2, align 8, !tbaa !5
  %14 = load i32, ptr %3, align 4, !tbaa !9
  %15 = add nsw i32 %14, 1
  store i32 %15, ptr %3, align 4, !tbaa !9
  %16 = sext i32 %15 to i64
  %17 = getelementptr inbounds i8, ptr %13, i64 %16
  %18 = load i8, ptr %17, align 1, !tbaa !11
  %19 = sext i8 %18 to i32
  %20 = load ptr, ptr %2, align 8, !tbaa !5
  %21 = load i32, ptr %4, align 4, !tbaa !9
  %22 = add nsw i32 %21, -1
  store i32 %22, ptr %4, align 4, !tbaa !9
  %23 = sext i32 %22 to i64
  %24 = getelementptr inbounds i8, ptr %20, i64 %23
  %25 = load i8, ptr %24, align 1, !tbaa !11
  %26 = sext i8 %25 to i32
  %27 = icmp eq i32 %19, %26
  br label %28

28:                                               ; preds = %12, %8
  %29 = phi i1 [ false, %8 ], [ %27, %12 ]
  br i1 %29, label %30, label %31

30:                                               ; preds = %28
  br label %8, !llvm.loop !12

31:                                               ; preds = %28
  %32 = load i32, ptr %4, align 4, !tbaa !9
  %33 = load i32, ptr %3, align 4, !tbaa !9
  %34 = icmp sle i32 %32, %33
  %35 = zext i1 %34 to i32
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #3
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #3
  ret i32 %35
}

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

; Function Attrs: nounwind willreturn memory(read)
declare i64 @strlen(ptr noundef) #2

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 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 0, 2) i32 @is_palindrome(ptr nocapture noundef readonly %0) local_unnamed_addr #0 {
  %2 = tail call i64 @strlen(ptr noundef nonnull dereferenceable(1) %0) #2
  %sext = shl i64 %2, 32
  %3 = ashr exact i64 %sext, 32
  br label %4

4:                                                ; preds = %6, %1
  %indvars.iv10 = phi i64 [ %indvars.iv.next11, %6 ], [ %3, %1 ]
  %indvars.iv = phi i64 [ %indvars.iv.next, %6 ], [ -1, %1 ]
  %5 = icmp slt i64 %indvars.iv, %indvars.iv10
  br i1 %5, label %6, label %.critedge

6:                                                ; preds = %4
  %indvars.iv.next = add nsw i64 %indvars.iv, 1
  %7 = getelementptr inbounds i8, ptr %0, i64 %indvars.iv.next
  %8 = load i8, ptr %7, align 1, !tbaa !5
  %indvars.iv.next11 = add nsw i64 %indvars.iv10, -1
  %9 = getelementptr inbounds i8, ptr %0, i64 %indvars.iv.next11
  %10 = load i8, ptr %9, align 1, !tbaa !5
  %11 = icmp eq i8 %8, %10
  br i1 %11, label %4, label %.critedge, !llvm.loop !8

.critedge:                                        ; preds = %4, %6
  %.19.in = phi i64 [ %indvars.iv.next, %6 ], [ %indvars.iv, %4 ]
  %.1.in = phi i64 [ %indvars.iv.next11, %6 ], [ %indvars.iv10, %4 ]
  %.1 = trunc i64 %.1.in to i32
  %.19 = trunc i64 %.19.in to i32
  %12 = icmp sle i32 %.1, %.19
  %13 = zext i1 %12 to i32
  ret i32 %13
}

; 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 = !{!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: GlobalOptPass,IPSCCPPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass