; LLVM IR from alekras/ao.rtos.cpp :: Tools/ARM-Raspberry_Pi/Initial_Interactive_Loader (periph)

; 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"

@pAUX_MU_LSR_REG = external dso_local global ptr, align 8
@pAUX_MU_IO_REG = external dso_local global ptr, align 8

; Function Attrs: mustprogress nounwind uwtable
define dso_local zeroext i8 @uart_recv() #0 {
  %1 = alloca i8, align 1
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  call void @llvm.lifetime.start.p0(i64 4, ptr %2) #2
  br label %4

4:                                                ; preds = %12, %0
  %5 = load ptr, ptr @pAUX_MU_LSR_REG, align 8, !tbaa !5
  %6 = load volatile i32, ptr %5, align 4, !tbaa !9
  store volatile i32 %6, ptr %2, align 4, !tbaa !9
  %7 = load volatile i32, ptr %2, align 4, !tbaa !9
  %8 = and i32 %7, 2
  %9 = icmp ne i32 %8, 0
  br i1 %9, label %10, label %11

10:                                               ; preds = %4
  store i8 42, ptr %1, align 1
  store i32 1, ptr %3, align 4
  br label %21

11:                                               ; preds = %4
  br label %12

12:                                               ; preds = %11
  %13 = load volatile i32, ptr %2, align 4, !tbaa !9
  %14 = and i32 %13, 1
  %15 = icmp eq i32 %14, 0
  br i1 %15, label %4, label %16, !llvm.loop !11

16:                                               ; preds = %12
  %17 = load ptr, ptr @pAUX_MU_IO_REG, align 8, !tbaa !5
  %18 = load volatile i32, ptr %17, align 4, !tbaa !9
  %19 = and i32 %18, 255
  %20 = trunc i32 %19 to i8
  store i8 %20, ptr %1, align 1
  store i32 1, ptr %3, align 4
  br label %21

21:                                               ; preds = %16, %10
  call void @llvm.lifetime.end.p0(i64 4, ptr %2) #2
  %22 = load i8, ptr %1, align 1
  ret i8 %22
}

; 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 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"int", !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"

@pAUX_MU_LSR_REG = external dso_local local_unnamed_addr global ptr, align 8
@pAUX_MU_IO_REG = external dso_local local_unnamed_addr global ptr, align 8

; Function Attrs: mustprogress nofree norecurse nounwind uwtable
define dso_local zeroext i8 @uart_recv() local_unnamed_addr #0 {
  %1 = alloca i32, align 4
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %1)
  %2 = load ptr, ptr @pAUX_MU_LSR_REG, align 8, !tbaa !5
  br label %3

3:                                                ; preds = %6, %0
  %4 = load volatile i32, ptr %2, align 4, !tbaa !9
  store volatile i32 %4, ptr %1, align 4, !tbaa !9
  %.0..0..0..0. = load volatile i32, ptr %1, align 4, !tbaa !9
  %5 = and i32 %.0..0..0..0., 2
  %.not = icmp eq i32 %5, 0
  br i1 %.not, label %6, label %.loopexit

6:                                                ; preds = %3
  %.0..0..0..0.1 = load volatile i32, ptr %1, align 4, !tbaa !9
  %7 = and i32 %.0..0..0..0.1, 1
  %8 = icmp eq i32 %7, 0
  br i1 %8, label %3, label %9, !llvm.loop !11

9:                                                ; preds = %6
  %10 = load ptr, ptr @pAUX_MU_IO_REG, align 8, !tbaa !5
  %11 = load volatile i32, ptr %10, align 4, !tbaa !9
  %12 = trunc i32 %11 to i8
  br label %.loopexit

.loopexit:                                        ; preds = %3, %9
  %.0 = phi i8 [ %12, %9 ], [ 42, %3 ]
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %1)
  ret i8 %.0
}

; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

attributes #0 = { mustprogress 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" }
attributes #1 = { mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }

!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++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"int", !7, i64 0}
!11 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: CorrelatedValuePropagationPass,GlobalOptPass,IPSCCPPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LICMPass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass