; LLVM IR from alekras/ao.rtos.cpp :: Porting/ARM-Raspberry_Pi (rpi-mailbox)

; 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"

%struct.mailbox_t = type { i32, [3 x i32], i32, i32, i32, i32, i32 }

@mailbox = external global ptr, align 8

; 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 @RPI_Mailbox0Read(i32 noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca ptr, 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
  %5 = load ptr, ptr @mailbox, align 8, !tbaa !9
  store ptr %5, ptr %3, align 8, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  store i32 -1, ptr %4, align 4, !tbaa !5
  br label %6

6:                                                ; preds = %19, %1
  %7 = load i32, ptr %4, align 4, !tbaa !5
  %8 = and i32 %7, 15
  %9 = load i32, ptr %2, align 4, !tbaa !5
  %10 = icmp ne i32 %8, %9
  br i1 %10, label %11, label %23

11:                                               ; preds = %6
  br label %12

12:                                               ; preds = %18, %11
  %13 = load ptr, ptr %3, align 8, !tbaa !9
  %14 = getelementptr inbounds %struct.mailbox_t, ptr %13, i32 0, i32 4
  %15 = load volatile i32, ptr %14, align 4, !tbaa !11
  %16 = and i32 %15, 1073741824
  %17 = icmp ne i32 %16, 0
  br i1 %17, label %18, label %19

18:                                               ; preds = %12
  br label %12, !llvm.loop !13

19:                                               ; preds = %12
  %20 = load ptr, ptr %3, align 8, !tbaa !9
  %21 = getelementptr inbounds %struct.mailbox_t, ptr %20, i32 0, i32 0
  %22 = load volatile i32, ptr %21, align 4, !tbaa !15
  store i32 %22, ptr %4, align 4, !tbaa !5
  br label %6, !llvm.loop !16

23:                                               ; preds = %6
  %24 = load i32, ptr %4, align 4, !tbaa !5
  %25 = ashr i32 %24, 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  ret i32 %25
}

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 = !{!"any pointer", !7, i64 0}
!11 = !{!12, !6, i64 24}
!12 = !{!"", !6, i64 0, !7, i64 4, !6, i64 16, !6, i64 20, !6, i64 24, !6, i64 28, !6, i64 32}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}
!15 = !{!12, !6, i64 0}
!16 = distinct !{!16, !14}


; 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"

@mailbox = external local_unnamed_addr global ptr, align 8

; Function Attrs: nofree norecurse nounwind uwtable
define dso_local range(i32 -134217728, 134217728) i32 @RPI_Mailbox0Read(i32 noundef %0) local_unnamed_addr #0 {
  %2 = load ptr, ptr @mailbox, align 8, !tbaa !5
  %.not5 = icmp eq i32 %0, 15
  br i1 %.not5, label %._crit_edge, label %.preheader.lr.ph

.preheader.lr.ph:                                 ; preds = %1
  %3 = getelementptr inbounds i8, ptr %2, i64 24
  br label %.preheader

.preheader:                                       ; preds = %.preheader.backedge, %.preheader.lr.ph
  %4 = load volatile i32, ptr %3, align 4, !tbaa !9
  %5 = and i32 %4, 1073741824
  %.not4 = icmp eq i32 %5, 0
  br i1 %.not4, label %6, label %.preheader.backedge

.preheader.backedge:                              ; preds = %.preheader, %6
  br label %.preheader, !llvm.loop !12

6:                                                ; preds = %.preheader
  %7 = load volatile i32, ptr %2, align 4, !tbaa !14
  %8 = and i32 %7, 15
  %.not = icmp eq i32 %8, %0
  br i1 %.not, label %._crit_edge.loopexit, label %.preheader.backedge

._crit_edge.loopexit:                             ; preds = %6
  %9 = ashr i32 %7, 4
  br label %._crit_edge

._crit_edge:                                      ; preds = %._crit_edge.loopexit, %1
  %.0.lcssa = phi i32 [ -1, %1 ], [ %9, %._crit_edge.loopexit ]
  ret i32 %.0.lcssa
}

attributes #0 = { nofree norecurse 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" }

!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, !11, i64 24}
!10 = !{!"", !11, i64 0, !7, i64 4, !11, i64 16, !11, i64 20, !11, i64 24, !11, i64 28, !11, i64 32}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}
!14 = !{!10, !11, i64 0}


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