; LLVM IR from xirc/cp-algorithm :: atcoder/abc159/b.ll/Z13is_palindromeNSt7 (cxx1112basic_stringIcSt11char_traitsIcESaIcEEE)

; 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: mustprogress uwtable
define dso_local noundef zeroext i1 @_Z13is_palindromeNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE(ptr noundef %0) #0 {
  %2 = alloca i1, align 1
  %3 = alloca ptr, align 8
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #3
  %7 = call noundef i64 @_ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE4sizeEv(ptr noundef nonnull align 8 dereferenceable(32) %0) #3
  %8 = trunc i64 %7 to i32
  store i32 %8, ptr %4, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #3
  store i32 0, ptr %5, align 4, !tbaa !9
  br label %9

9:                                                ; preds = %32, %1
  %10 = load i32, ptr %5, align 4, !tbaa !9
  %11 = load i32, ptr %4, align 4, !tbaa !9
  %12 = sdiv i32 %11, 2
  %13 = icmp slt i32 %10, %12
  br i1 %13, label %15, label %14

14:                                               ; preds = %9
  store i32 2, ptr %6, align 4
  br label %35

15:                                               ; preds = %9
  %16 = load i32, ptr %5, align 4, !tbaa !9
  %17 = sext i32 %16 to i64
  %18 = call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %0, i64 noundef %17)
  %19 = load i8, ptr %18, align 1, !tbaa !11
  %20 = sext i8 %19 to i32
  %21 = load i32, ptr %4, align 4, !tbaa !9
  %22 = sub nsw i32 %21, 1
  %23 = load i32, ptr %5, align 4, !tbaa !9
  %24 = sub nsw i32 %22, %23
  %25 = sext i32 %24 to i64
  %26 = call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %0, i64 noundef %25)
  %27 = load i8, ptr %26, align 1, !tbaa !11
  %28 = sext i8 %27 to i32
  %29 = icmp ne i32 %20, %28
  br i1 %29, label %30, label %31

30:                                               ; preds = %15
  store i1 false, ptr %2, align 1
  store i32 1, ptr %6, align 4
  br label %35

31:                                               ; preds = %15
  br label %32

32:                                               ; preds = %31
  %33 = load i32, ptr %5, align 4, !tbaa !9
  %34 = add nsw i32 %33, 1
  store i32 %34, ptr %5, align 4, !tbaa !9
  br label %9, !llvm.loop !12

35:                                               ; preds = %30, %14
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #3
  %36 = load i32, ptr %6, align 4
  switch i32 %36, label %38 [
    i32 2, label %37
  ]

37:                                               ; preds = %35
  store i1 true, ptr %2, align 1
  store i32 1, ptr %6, align 4
  br label %38

38:                                               ; preds = %37, %35
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #3
  %39 = load i1, ptr %2, align 1
  ret i1 %39
}

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

; Function Attrs: mustprogress nounwind uwtable
declare noundef i64 @_ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE4sizeEv(ptr noundef nonnull align 8 dereferenceable(32)) #2 align 2

; Function Attrs: mustprogress nounwind uwtable
declare noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32), i64 noundef) #2 align 2

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

attributes #0 = { mustprogress 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 = { mustprogress 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 #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++ 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: mustprogress nounwind uwtable
define dso_local noundef zeroext i1 @_Z13is_palindromeNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE(ptr noundef nonnull %0) local_unnamed_addr #0 {
  %2 = tail call noundef i64 @_ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE4sizeEv(ptr noundef nonnull align 8 dereferenceable(32) %0) #1
  %3 = trunc i64 %2 to i32
  %.not910 = icmp slt i32 %3, 2
  br i1 %.not910, label %.critedge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %1
  %4 = lshr i32 %3, 1
  %5 = zext nneg i32 %4 to i64
  %wide.trip.count = zext nneg i32 %4 to i64
  %6 = tail call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %0, i64 noundef 0)
  %7 = load i8, ptr %6, align 1, !tbaa !5
  %8 = shl i64 %2, 32
  %sext15 = add nsw i64 %8, -4294967296
  %9 = ashr exact i64 %sext15, 32
  %10 = tail call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %0, i64 noundef %9)
  %11 = load i8, ptr %10, align 1, !tbaa !5
  %.not16 = icmp eq i8 %7, %11
  br i1 %.not16, label %.lr.ph18, label %.critedge

.lr.ph18:                                         ; preds = %.lr.ph.preheader, %.lr.ph
  %indvars.iv17 = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %.lr.ph.preheader ]
  %indvars.iv.next = add nuw nsw i64 %indvars.iv17, 1
  %exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
  br i1 %exitcond, label %.critedge.loopexit, label %.lr.ph, !llvm.loop !8

.lr.ph:                                           ; preds = %.lr.ph18
  %12 = tail call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %0, i64 noundef %indvars.iv.next)
  %13 = load i8, ptr %12, align 1, !tbaa !5
  %reass.sub = sub i64 %2, %indvars.iv17
  %14 = shl i64 %reass.sub, 32
  %sext = add i64 %14, -8589934592
  %15 = ashr exact i64 %sext, 32
  %16 = tail call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %0, i64 noundef %15)
  %17 = load i8, ptr %16, align 1, !tbaa !5
  %.not = icmp eq i8 %13, %17
  br i1 %.not, label %.lr.ph18, label %.critedge.loopexit, !llvm.loop !8

.critedge.loopexit:                               ; preds = %.lr.ph, %.lr.ph18
  %.not9.le = icmp uge i64 %indvars.iv.next, %5
  br label %.critedge

.critedge:                                        ; preds = %.critedge.loopexit, %.lr.ph.preheader, %1
  %.not9.lcssa = phi i1 [ true, %1 ], [ false, %.lr.ph.preheader ], [ %.not9.le, %.critedge.loopexit ]
  ret i1 %.not9.lcssa
}

; Function Attrs: mustprogress nounwind uwtable
declare noundef i64 @_ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE4sizeEv(ptr noundef nonnull align 8 dereferenceable(32)) local_unnamed_addr #0 align 2

; Function Attrs: mustprogress nounwind uwtable
declare noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32), i64 noundef) local_unnamed_addr #0 align 2

attributes #0 = { mustprogress 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 }

!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++ TBAA"}
!8 = distinct !{!8, !9}
!9 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: GVNPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LICMPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass