; LLVM IR from thalium/icebox :: third_party/virtualbox/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Core (ReverseBits)

; 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 @ReverseBits(i32 noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca i64, align 8
  %4 = alloca i32, align 4
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  store i32 0, ptr %4, align 4, !tbaa !5
  store i64 0, ptr %3, align 8, !tbaa !9
  br label %5

5:                                                ; preds = %23, %1
  %6 = load i64, ptr %3, align 8, !tbaa !9
  %7 = icmp ult i64 %6, 32
  br i1 %7, label %8, label %26

8:                                                ; preds = %5
  %9 = load i32, ptr %2, align 4, !tbaa !5
  %10 = load i64, ptr %3, align 8, !tbaa !9
  %11 = trunc i64 %10 to i32
  %12 = shl i32 1, %11
  %13 = and i32 %9, %12
  %14 = icmp ne i32 %13, 0
  br i1 %14, label %15, label %22

15:                                               ; preds = %8
  %16 = load i32, ptr %4, align 4, !tbaa !5
  %17 = load i64, ptr %3, align 8, !tbaa !9
  %18 = sub i64 31, %17
  %19 = trunc i64 %18 to i32
  %20 = shl i32 1, %19
  %21 = or i32 %16, %20
  store i32 %21, ptr %4, align 4, !tbaa !5
  br label %22

22:                                               ; preds = %15, %8
  br label %23

23:                                               ; preds = %22
  %24 = load i64, ptr %3, align 8, !tbaa !9
  %25 = add i64 %24, 1
  store i64 %25, ptr %3, align 8, !tbaa !9
  br label %5, !llvm.loop !11

26:                                               ; preds = %5
  %27 = load i32, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  ret i32 %27
}

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 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"long long", !7, i64 0}
!11 = distinct !{!11, !12}
!12 = !{!"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 @ReverseBits(i32 noundef %0) local_unnamed_addr #0 {
  %.1.31 = tail call i32 @llvm.bitreverse.i32(i32 %0)
  ret i32 %.1.31
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i32 @llvm.bitreverse.i32(i32) #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: EarlyCSEPass,GVNPass,GlobalOptPass,IPSCCPPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,LCSSAPass,LoopRotatePass,PostOrderFunctionAttrsPass,ReassociatePass,SROAPass,SimplifyCFGPass,TailCallElimPass