; LLVM IR from Dovyski/opengl-demos :: libs/glm-0.9.9.3/test/core/core_func_integer_find_msb.ll (Z5nlz2aj)

; 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: mustprogress nounwind uwtable
define dso_local noundef i32 @_Z5nlz2aj(i32 noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  store i32 32, ptr %4, align 4, !tbaa !5
  store i32 16, ptr %5, align 4, !tbaa !5
  br label %6

6:                                                ; preds = %20, %1
  %7 = load i32, ptr %2, align 4, !tbaa !5
  %8 = load i32, ptr %5, align 4, !tbaa !5
  %9 = lshr i32 %7, %8
  store i32 %9, ptr %3, align 4, !tbaa !5
  %10 = load i32, ptr %3, align 4, !tbaa !5
  %11 = icmp ne i32 %10, 0
  br i1 %11, label %12, label %17

12:                                               ; preds = %6
  %13 = load i32, ptr %4, align 4, !tbaa !5
  %14 = load i32, ptr %5, align 4, !tbaa !5
  %15 = sub nsw i32 %13, %14
  store i32 %15, ptr %4, align 4, !tbaa !5
  %16 = load i32, ptr %3, align 4, !tbaa !5
  store i32 %16, ptr %2, align 4, !tbaa !5
  br label %17

17:                                               ; preds = %12, %6
  %18 = load i32, ptr %5, align 4, !tbaa !5
  %19 = ashr i32 %18, 1
  store i32 %19, ptr %5, align 4, !tbaa !5
  br label %20

20:                                               ; preds = %17
  %21 = load i32, ptr %5, align 4, !tbaa !5
  %22 = icmp ne i32 %21, 0
  br i1 %22, label %6, label %23, !llvm.loop !9

23:                                               ; preds = %20
  %24 = load i32, ptr %4, align 4, !tbaa !5
  %25 = load i32, ptr %2, align 4, !tbaa !5
  %26 = sub i32 %24, %25
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  ret i32 %26
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { 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 #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 = !{!"int", !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 i32 @_Z5nlz2aj(i32 noundef %0) local_unnamed_addr #0 {
  %2 = lshr i32 %0, 16
  %.not = icmp ult i32 %0, 65536
  %spec.select = select i1 %.not, i32 %0, i32 %2
  %spec.select16 = select i1 %.not, i32 32, i32 16
  %3 = lshr i32 %spec.select, 8
  %.not.1 = icmp ult i32 %spec.select, 256
  %spec.select.1 = select i1 %.not.1, i32 %spec.select, i32 %3
  %.neg = select i1 %.not.1, i32 0, i32 -8
  %spec.select16.1 = add nsw i32 %.neg, %spec.select16
  %4 = lshr i32 %spec.select.1, 4
  %.not.2 = icmp ult i32 %spec.select.1, 16
  %spec.select.2 = select i1 %.not.2, i32 %spec.select.1, i32 %4
  %.neg17 = select i1 %.not.2, i32 0, i32 -4
  %spec.select16.2 = add nsw i32 %.neg17, %spec.select16.1
  %5 = lshr i32 %spec.select.2, 2
  %.not.3 = icmp ult i32 %spec.select.2, 4
  %spec.select.3 = select i1 %.not.3, i32 %spec.select.2, i32 %5
  %.neg18 = select i1 %.not.3, i32 0, i32 -2
  %spec.select16.3 = add nsw i32 %.neg18, %spec.select16.2
  %.not.4 = icmp ugt i32 %spec.select.3, 1
  %6 = zext i1 %.not.4 to i32
  %spec.select.4 = lshr i32 %spec.select.3, %6
  %.neg19 = sext i1 %.not.4 to i32
  %spec.select16.4 = add nsw i32 %spec.select16.3, %.neg19
  %7 = sub nsw i32 %spec.select16.4, %spec.select.4
  ret i32 %7
}

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" }

!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: GVNPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,LCSSAPass,PostOrderFunctionAttrsPass,SCCPPass,SROAPass,SimplifyCFGPass