; LLVM IR from o0o0o0o0o0o0o/image-processing-from-scratch :: ImageMatting/Eigen/bench/analyze-blocking-sizes.ll (Z8log2_potm)

; 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 i8 @_Z8log2_potm(i64 noundef %0) #0 {
  %2 = alloca i64, align 8
  %3 = alloca i64, align 8
  store i64 %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  store i64 0, ptr %3, align 8, !tbaa !5
  br label %4

4:                                                ; preds = %8, %1
  %5 = load i64, ptr %2, align 8, !tbaa !5
  %6 = lshr i64 %5, 1
  store i64 %6, ptr %2, align 8, !tbaa !5
  %7 = icmp ne i64 %6, 0
  br i1 %7, label %8, label %11

8:                                                ; preds = %4
  %9 = load i64, ptr %3, align 8, !tbaa !5
  %10 = add i64 %9, 1
  store i64 %10, ptr %3, align 8, !tbaa !5
  br label %4, !llvm.loop !9

11:                                               ; preds = %4
  %12 = load i64, ptr %3, align 8, !tbaa !5
  %13 = trunc i64 %12 to i8
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  ret i8 %13
}

; 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 = !{!"long", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = distinct !{!9, !10}
!10 = !{!"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(none) uwtable
define dso_local noundef zeroext i8 @_Z8log2_potm(i64 noundef %0) local_unnamed_addr #0 {
._crit_edge:
  %.not5 = icmp ult i64 %0, 2
  %1 = tail call range(i64 0, 65) i64 @llvm.ctlz.i64(i64 %0, i1 true)
  %2 = trunc nuw nsw i64 %1 to i8
  %3 = xor i8 %2, 63
  %.0.lcssa = select i1 %.not5, i8 0, i8 %3
  ret i8 %.0.lcssa
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i64 @llvm.ctlz.i64(i64, i1 immarg) #1

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(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" }
attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }

!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)"}


; Effective O3 passes: AggressiveInstCombinePass,GVNPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,LCSSAPass,LoopIdiomRecognizePass,LoopRotatePass,LoopSimplifyPass,PostOrderFunctionAttrsPass,SCCPPass,SROAPass,SimplifyCFGPass,TailCallElimPass