; LLVM IR from s-matyukevich/raspberry-pi-os :: exercises/lesson01/1/H-4ND-H/src (mini_uart)

; 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
declare dso_local void @uart_send(i8 noundef signext) #0

; Function Attrs: nounwind uwtable
define dso_local void @uart_send_string(ptr noundef %0) #0 {
  %2 = alloca ptr, align 8
  %3 = alloca i32, align 4
  store ptr %0, ptr %2, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #2
  store i32 0, ptr %3, align 4, !tbaa !9
  br label %4

4:                                                ; preds = %19, %1
  %5 = load ptr, ptr %2, align 8, !tbaa !5
  %6 = load i32, ptr %3, align 4, !tbaa !9
  %7 = sext i32 %6 to i64
  %8 = getelementptr inbounds i8, ptr %5, i64 %7
  %9 = load i8, ptr %8, align 1, !tbaa !11
  %10 = sext i8 %9 to i32
  %11 = icmp ne i32 %10, 0
  br i1 %11, label %13, label %12

12:                                               ; preds = %4
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #2
  br label %22

13:                                               ; preds = %4
  %14 = load ptr, ptr %2, align 8, !tbaa !5
  %15 = load i32, ptr %3, align 4, !tbaa !9
  %16 = sext i32 %15 to i64
  %17 = getelementptr inbounds i8, ptr %14, i64 %16
  %18 = load i8, ptr %17, align 1, !tbaa !11
  call void @uart_send(i8 noundef signext %18)
  br label %19

19:                                               ; preds = %13
  %20 = load i32, ptr %3, align 4, !tbaa !9
  %21 = add nsw i32 %20, 1
  store i32 %21, ptr %3, align 4, !tbaa !9
  br label %4, !llvm.loop !12

22:                                               ; preds = %12
  ret void
}

; 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 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"int", !7, i64 0}
!11 = !{!7, !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"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: nounwind uwtable
declare dso_local void @uart_send(i8 noundef signext) local_unnamed_addr #0

; Function Attrs: nounwind uwtable
define dso_local void @uart_send_string(ptr nocapture noundef readonly %0) local_unnamed_addr #0 {
  %2 = load i8, ptr %0, align 1, !tbaa !5
  %.not4 = icmp eq i8 %2, 0
  br i1 %.not4, label %._crit_edge, label %.lr.ph

._crit_edge:                                      ; preds = %.lr.ph, %1
  ret void

.lr.ph:                                           ; preds = %1, %.lr.ph
  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %1 ]
  %3 = phi i8 [ %5, %.lr.ph ], [ %2, %1 ]
  tail call void @uart_send(i8 noundef signext %3)
  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
  %4 = getelementptr inbounds i8, ptr %0, i64 %indvars.iv.next
  %5 = load i8, ptr %4, align 1, !tbaa !5
  %.not = icmp eq i8 %5, 0
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !8
}

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" }

!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 = !{!"omnipotent char", !7, i64 0}
!7 = !{!"Simple C/C++ TBAA"}
!8 = distinct !{!8, !9}
!9 = !{!"llvm.loop.mustprogress"}


; Effective O3 passes: EarlyCSEPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass