; LLVM IR from nonstriater/Learn-Algorithms :: 9 Algorithms Job Interview/codes/1 string (string)

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

; Function Attrs: nounwind uwtable
define dso_local i32 @symmetrical(ptr noundef %0, i32 noundef %1) #1 {
  %3 = alloca ptr, align 8
  %4 = alloca i32, align 4
  %5 = alloca ptr, align 8
  %6 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  store i32 %1, ptr %4, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  %7 = load ptr, ptr %3, align 8, !tbaa !5
  %8 = load i32, ptr %4, align 4, !tbaa !9
  %9 = sext i32 %8 to i64
  %10 = getelementptr inbounds i8, ptr %7, i64 %9
  %11 = getelementptr inbounds i8, ptr %10, i64 -1
  store ptr %11, ptr %5, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #2
  store i32 1, ptr %6, align 4, !tbaa !9
  br label %12

12:                                               ; preds = %27, %2
  %13 = load ptr, ptr %5, align 8, !tbaa !5
  %14 = load ptr, ptr %3, align 8, !tbaa !5
  %15 = icmp ugt ptr %13, %14
  br i1 %15, label %16, label %28

16:                                               ; preds = %12
  %17 = load ptr, ptr %3, align 8, !tbaa !5
  %18 = getelementptr inbounds i8, ptr %17, i32 1
  store ptr %18, ptr %3, align 8, !tbaa !5
  %19 = load i8, ptr %17, align 1, !tbaa !11
  %20 = sext i8 %19 to i32
  %21 = load ptr, ptr %5, align 8, !tbaa !5
  %22 = getelementptr inbounds i8, ptr %21, i32 -1
  store ptr %22, ptr %5, align 8, !tbaa !5
  %23 = load i8, ptr %21, align 1, !tbaa !11
  %24 = sext i8 %23 to i32
  %25 = icmp ne i32 %20, %24
  br i1 %25, label %26, label %27

26:                                               ; preds = %16
  store i32 0, ptr %6, align 4, !tbaa !9
  br label %27

27:                                               ; preds = %26, %16
  br label %12, !llvm.loop !12

28:                                               ; preds = %12
  %29 = load i32, ptr %6, align 4, !tbaa !9
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #2
  ret i32 %29
}

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 }

!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 norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local range(i32 0, 2) i32 @symmetrical(ptr noundef readonly %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = sext i32 %1 to i64
  %4 = getelementptr inbounds i8, ptr %0, i64 %3
  %.068 = getelementptr inbounds i8, ptr %4, i64 -1
  %5 = icmp ugt ptr %.068, %0
  br i1 %5, label %.lr.ph, label %._crit_edge

.lr.ph:                                           ; preds = %2, %.lr.ph
  %.0611 = phi ptr [ %.06, %.lr.ph ], [ %.068, %2 ]
  %.010 = phi i32 [ %spec.select, %.lr.ph ], [ 1, %2 ]
  %.079 = phi ptr [ %6, %.lr.ph ], [ %0, %2 ]
  %6 = getelementptr inbounds i8, ptr %.079, i64 1
  %7 = load i8, ptr %.079, align 1, !tbaa !5
  %8 = load i8, ptr %.0611, align 1, !tbaa !5
  %.not = icmp eq i8 %7, %8
  %spec.select = select i1 %.not, i32 %.010, i32 0
  %.06 = getelementptr inbounds i8, ptr %.0611, i64 -1
  %9 = icmp ugt ptr %.06, %6
  br i1 %9, label %.lr.ph, label %._crit_edge, !llvm.loop !8

._crit_edge:                                      ; preds = %.lr.ph, %2
  %.0.lcssa = phi i32 [ 1, %2 ], [ %spec.select, %.lr.ph ]
  ret i32 %.0.lcssa
}

attributes #0 = { nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) 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/C++ TBAA"}
!8 = distinct !{!8, !9}
!9 = !{!"llvm.loop.mustprogress"}


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