; LLVM IR from Shah-Shishir/Codeforces-Solutions :: 1093B. Letters Rearranging.ll (Z12isPalindromePci)

; 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 nounwind uwtable
define dso_local noundef zeroext i1 @_Z12isPalindromePci(ptr noundef %0, i32 noundef %1) #0 {
  %3 = alloca i1, align 1
  %4 = alloca ptr, align 8
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  %7 = alloca i32, align 4
  %8 = alloca i32, align 4
  store ptr %0, ptr %4, align 8, !tbaa !5
  store i32 %1, ptr %5, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #2
  call void @llvm.lifetime.start.p0(i64 4, ptr %7) #2
  %9 = load i32, ptr %5, align 4, !tbaa !9
  %10 = sdiv i32 %9, 2
  store i32 %10, ptr %7, align 4, !tbaa !9
  %11 = load i32, ptr %5, align 4, !tbaa !9
  %12 = add nsw i32 %11, -1
  store i32 %12, ptr %5, align 4, !tbaa !9
  store i32 0, ptr %6, align 4, !tbaa !9
  br label %13

13:                                               ; preds = %35, %2
  %14 = load i32, ptr %6, align 4, !tbaa !9
  %15 = load i32, ptr %7, align 4, !tbaa !9
  %16 = icmp slt i32 %14, %15
  br i1 %16, label %17, label %38

17:                                               ; preds = %13
  %18 = load ptr, ptr %4, align 8, !tbaa !5
  %19 = load i32, ptr %6, align 4, !tbaa !9
  %20 = sext i32 %19 to i64
  %21 = getelementptr inbounds i8, ptr %18, i64 %20
  %22 = load i8, ptr %21, align 1, !tbaa !11
  %23 = sext i8 %22 to i32
  %24 = load ptr, ptr %4, align 8, !tbaa !5
  %25 = load i32, ptr %5, align 4, !tbaa !9
  %26 = load i32, ptr %6, align 4, !tbaa !9
  %27 = sub nsw i32 %25, %26
  %28 = sext i32 %27 to i64
  %29 = getelementptr inbounds i8, ptr %24, i64 %28
  %30 = load i8, ptr %29, align 1, !tbaa !11
  %31 = sext i8 %30 to i32
  %32 = icmp ne i32 %23, %31
  br i1 %32, label %33, label %34

33:                                               ; preds = %17
  store i1 false, ptr %3, align 1
  store i32 1, ptr %8, align 4
  br label %39

34:                                               ; preds = %17
  br label %35

35:                                               ; preds = %34
  %36 = load i32, ptr %6, align 4, !tbaa !9
  %37 = add nsw i32 %36, 1
  store i32 %37, ptr %6, align 4, !tbaa !9
  br label %13, !llvm.loop !12

38:                                               ; preds = %13
  store i1 true, ptr %3, align 1
  store i32 1, ptr %8, align 4
  br label %39

39:                                               ; preds = %38, %33
  call void @llvm.lifetime.end.p0(i64 4, ptr %7) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #2
  %40 = load i1, ptr %3, align 1
  ret i1 %40
}

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

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

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 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
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++ 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 nofree norecurse nosync nounwind willreturn memory(argmem: read) uwtable
define dso_local noundef zeroext i1 @_Z12isPalindromePci(ptr nocapture noundef readonly %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = icmp slt i32 %1, 2
  br i1 %3, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %2
  %4 = lshr i32 %1, 1
  %5 = zext nneg i32 %4 to i64
  %wide.trip.count = zext nneg i32 %4 to i64
  %6 = load i8, ptr %0, align 1, !tbaa !5
  %7 = zext nneg i32 %1 to i64
  %8 = getelementptr i8, ptr %0, i64 %7
  %9 = getelementptr i8, ptr %8, i64 -1
  %10 = load i8, ptr %9, align 1, !tbaa !5
  %.not14 = icmp eq i8 %6, %10
  br i1 %.not14, label %.lr.ph16, label %._crit_edge

.lr.ph16:                                         ; preds = %.lr.ph.preheader, %.lr.ph
  %indvars.iv15 = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %.lr.ph.preheader ]
  %indvars.iv.next = add nuw nsw i64 %indvars.iv15, 1
  %exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
  br i1 %exitcond, label %._crit_edge.loopexit, label %.lr.ph, !llvm.loop !8

.lr.ph:                                           ; preds = %.lr.ph16
  %11 = getelementptr inbounds i8, ptr %0, i64 %indvars.iv.next
  %12 = load i8, ptr %11, align 1, !tbaa !5
  %13 = trunc i64 %indvars.iv.next to i32
  %14 = xor i32 %13, -1
  %15 = add i32 %14, %1
  %16 = sext i32 %15 to i64
  %17 = getelementptr inbounds i8, ptr %0, i64 %16
  %18 = load i8, ptr %17, align 1, !tbaa !5
  %.not = icmp eq i8 %12, %18
  br i1 %.not, label %.lr.ph16, label %._crit_edge.loopexit, !llvm.loop !8

._crit_edge.loopexit:                             ; preds = %.lr.ph, %.lr.ph16
  %19 = icmp uge i64 %indvars.iv.next, %5
  br label %._crit_edge

._crit_edge:                                      ; preds = %._crit_edge.loopexit, %.lr.ph.preheader, %2
  %.lcssa = phi i1 [ true, %2 ], [ false, %.lr.ph.preheader ], [ %19, %._crit_edge.loopexit ]
  ret i1 %.lcssa
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn 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" }

!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