; LLVM IR from next-step-for-interview-prep/Coding-Ninjas-DSA-course_code_and_notes_cpp :: Milestone-2=Intro_to_C++/questions and solutions/Lec-10=Character-arrays_and_2D-arra_799495fa/Z15checkPalindromeNSt7 (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 @_Z15checkPalindromeNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE(ptr noundef %0) #0 {
  %2 = alloca ptr, align 8
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i8, align 1
  store ptr %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #3
  store i32 0, ptr %3, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #3
  %6 = call noundef i64 @_ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE4sizeEv(ptr noundef nonnull align 8 dereferenceable(32) %0) #3
  %7 = sub i64 %6, 1
  %8 = trunc i64 %7 to i32
  store i32 %8, ptr %4, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 1, ptr %5) #3
  store i8 1, ptr %5, align 1, !tbaa !11
  br label %9

9:                                                ; preds = %26, %1
  %10 = load i32, ptr %3, align 4, !tbaa !9
  %11 = load i32, ptr %4, align 4, !tbaa !9
  %12 = icmp slt i32 %10, %11
  br i1 %12, label %13, label %31

13:                                               ; preds = %9
  %14 = load i32, ptr %3, align 4, !tbaa !9
  %15 = sext i32 %14 to i64
  %16 = 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 !13
  %18 = sext i8 %17 to i32
  %19 = load i32, ptr %4, align 4, !tbaa !9
  %20 = sext i32 %19 to i64
  %21 = call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %0, i64 noundef %20)
  %22 = load i8, ptr %21, align 1, !tbaa !13
  %23 = sext i8 %22 to i32
  %24 = icmp ne i32 %18, %23
  br i1 %24, label %25, label %26

25:                                               ; preds = %13
  store i8 0, ptr %5, align 1, !tbaa !11
  br label %31

26:                                               ; preds = %13
  %27 = load i32, ptr %3, align 4, !tbaa !9
  %28 = add nsw i32 %27, 1
  store i32 %28, ptr %3, align 4, !tbaa !9
  %29 = load i32, ptr %4, align 4, !tbaa !9
  %30 = add nsw i32 %29, -1
  store i32 %30, ptr %4, align 4, !tbaa !9
  br label %9, !llvm.loop !14

31:                                               ; preds = %25, %9
  %32 = load i8, ptr %5, align 1, !tbaa !11, !range !16, !noundef !17
  %33 = trunc i8 %32 to i1
  call void @llvm.lifetime.end.p0(i64 1, ptr %5) #3
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #3
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #3
  ret i1 %33
}

; 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 = !{!12, !12, i64 0}
!12 = !{!"bool", !7, i64 0}
!13 = !{!7, !7, i64 0}
!14 = distinct !{!14, !15}
!15 = !{!"llvm.loop.mustprogress"}
!16 = !{i8 0, i8 2}
!17 = !{}


; 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 @_Z15checkPalindromeNSt7__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
  %.079 = add i32 %3, -1
  %4 = icmp slt i32 %.079, 1
  br i1 %4, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %1
  %5 = zext nneg i32 %.079 to i64
  br label %.lr.ph

6:                                                ; preds = %.lr.ph
  %indvars.iv.next15 = add nuw nsw i64 %indvars.iv14, 1
  %indvars.iv.next = add nsw i64 %indvars.iv, -1
  %.not16 = icmp slt i64 %indvars.iv.next15, %indvars.iv.next
  br i1 %.not16, label %.lr.ph, label %._crit_edge, !llvm.loop !5

.lr.ph:                                           ; preds = %.lr.ph.preheader, %6
  %indvars.iv14 = phi i64 [ 0, %.lr.ph.preheader ], [ %indvars.iv.next15, %6 ]
  %indvars.iv = phi i64 [ %5, %.lr.ph.preheader ], [ %indvars.iv.next, %6 ]
  %7 = tail call noundef nonnull align 1 dereferenceable(1) ptr @_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEixEm(ptr noundef nonnull align 8 dereferenceable(32) %0, i64 noundef %indvars.iv14)
  %8 = load i8, ptr %7, align 1, !tbaa !7
  %9 = 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)
  %10 = load i8, ptr %9, align 1, !tbaa !7
  %.not = icmp eq i8 %8, %10
  br i1 %.not, label %6, label %._crit_edge

._crit_edge:                                      ; preds = %6, %.lr.ph, %1
  %.lcssa = phi i1 [ true, %1 ], [ %.not, %.lr.ph ], [ %.not, %6 ]
  ret i1 %.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 = distinct !{!5, !6}
!6 = !{!"llvm.loop.mustprogress"}
!7 = !{!8, !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C++ TBAA"}


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