; LLVM IR from BrunoLevy/learn-fpga :: FemtoRV/FIRMWARE/LIBFEMTOC/missing/clz.ll_ (clzsi2)

; 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: nounwind uwtable
define dso_local i32 @__clzsi2(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  store i32 -2147483648, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  store i32 0, ptr %5, align 4, !tbaa !5
  br label %7

7:                                                ; preds = %21, %1
  %8 = load i32, ptr %5, align 4, !tbaa !5
  %9 = icmp slt i32 %8, 32
  br i1 %9, label %11, label %10

10:                                               ; preds = %7
  store i32 2, ptr %6, align 4
  br label %24

11:                                               ; preds = %7
  %12 = load i32, ptr %3, align 4, !tbaa !5
  %13 = load i32, ptr %4, align 4, !tbaa !5
  %14 = and i32 %12, %13
  %15 = icmp ne i32 %14, 0
  br i1 %15, label %16, label %18

16:                                               ; preds = %11
  %17 = load i32, ptr %5, align 4, !tbaa !5
  store i32 %17, ptr %2, align 4
  store i32 1, ptr %6, align 4
  br label %24

18:                                               ; preds = %11
  %19 = load i32, ptr %4, align 4, !tbaa !5
  %20 = lshr i32 %19, 1
  store i32 %20, ptr %4, align 4, !tbaa !5
  br label %21

21:                                               ; preds = %18
  %22 = load i32, ptr %5, align 4, !tbaa !5
  %23 = add nsw i32 %22, 1
  store i32 %23, ptr %5, align 4, !tbaa !5
  br label %7, !llvm.loop !9

24:                                               ; preds = %16, %10
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  %25 = load i32, ptr %6, align 4
  switch i32 %25, label %27 [
    i32 2, label %26
  ]

26:                                               ; preds = %24
  store i32 32, ptr %2, align 4
  store i32 1, ptr %6, align 4
  br label %27

27:                                               ; preds = %26, %24
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  %28 = load i32, ptr %2, align 4
  ret i32 %28
}

; 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 = { 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 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/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: nofree norecurse nosync nounwind memory(none) uwtable
define dso_local i32 @__clzsi2(i32 noundef %0) local_unnamed_addr #0 {
  %.not12 = icmp sgt i32 %0, -1
  br i1 %.not12, label %.lr.ph, label %._crit_edge

.lr.ph:                                           ; preds = %1, %.lr.ph
  %.0814 = phi i32 [ %3, %.lr.ph ], [ 0, %1 ]
  %.0913 = phi i32 [ %2, %.lr.ph ], [ -2147483648, %1 ]
  %2 = lshr i32 %.0913, 1
  %3 = add nuw nsw i32 %.0814, 1
  %4 = icmp ult i32 %.0814, 31
  %5 = and i32 %2, %0
  %.not = icmp eq i32 %5, 0
  %or.cond = select i1 %4, i1 %.not, i1 false
  br i1 %or.cond, label %.lr.ph, label %._crit_edge, !llvm.loop !5

._crit_edge:                                      ; preds = %.lr.ph, %1
  %.08.lcssa = phi i32 [ 0, %1 ], [ %3, %.lr.ph ]
  ret i32 %.08.lcssa
}

attributes #0 = { nofree norecurse nosync nounwind 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)"}
!5 = distinct !{!5, !6}
!6 = !{!"llvm.loop.mustprogress"}


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