; LLVM IR from cpq/bare-metal-programming-guide :: steps/step-4-printf/syscalls.ll (sbrk)

; 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"

@_sbrk.heap = external hidden global ptr, align 8
@_end = external global i8, align 1

; Function Attrs: nounwind uwtable
define dso_local ptr @_sbrk(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca ptr, align 8
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #2
  %4 = load ptr, ptr @_sbrk.heap, align 8, !tbaa !9
  %5 = icmp eq ptr %4, null
  br i1 %5, label %6, label %7

6:                                                ; preds = %1
  store ptr @_end, ptr @_sbrk.heap, align 8, !tbaa !9
  br label %7

7:                                                ; preds = %6, %1
  %8 = load ptr, ptr @_sbrk.heap, align 8, !tbaa !9
  store ptr %8, ptr %3, align 8, !tbaa !9
  %9 = load i32, ptr %2, align 4, !tbaa !5
  %10 = load ptr, ptr @_sbrk.heap, align 8, !tbaa !9
  %11 = sext i32 %9 to i64
  %12 = getelementptr inbounds i8, ptr %10, i64 %11
  store ptr %12, ptr @_sbrk.heap, align 8, !tbaa !9
  %13 = load ptr, ptr %3, align 8, !tbaa !9
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #2
  ret ptr %13
}

; 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 = !{!10, !10, i64 0}
!10 = !{!"any pointer", !7, i64 0}


; 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"

@_sbrk.heap = external hidden local_unnamed_addr global ptr, align 8
@_end = external global i8, align 1

; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(readwrite, argmem: none, inaccessiblemem: none) uwtable
define dso_local nonnull ptr @_sbrk(i32 noundef %0) local_unnamed_addr #0 {
  %2 = load ptr, ptr @_sbrk.heap, align 8, !tbaa !5
  %3 = icmp eq ptr %2, null
  %spec.select = select i1 %3, ptr @_end, ptr %2
  %4 = sext i32 %0 to i64
  %5 = getelementptr inbounds i8, ptr %spec.select, i64 %4
  store ptr %5, ptr @_sbrk.heap, align 8, !tbaa !5
  ret ptr %spec.select
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(readwrite, argmem: none, inaccessiblemem: 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 = !{!6, !6, i64 0}
!6 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}


; Effective O3 passes: DSEPass,EarlyCSEPass,GVNPass,GlobalOptPass,InferFunctionAttrsPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass