; LLVM IR from bqi343/cp-notebook :: Contests/USACO Solutions/2015-16/Dec 2015/Gold/15 Dec G2.ll (Z7findmaxi)

; 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"

@array1 = external dso_local global [5000001 x i32], align 16

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef i32 @_Z7findmaxi(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #2
  %6 = load i32, ptr %3, align 4, !tbaa !5
  store i32 %6, ptr %4, align 4, !tbaa !5
  br label %7

7:                                                ; preds = %20, %1
  %8 = load i32, ptr %4, align 4, !tbaa !5
  %9 = icmp sge i32 %8, 0
  br i1 %9, label %11, label %10

10:                                               ; preds = %7
  store i32 2, ptr %5, align 4
  br label %23

11:                                               ; preds = %7
  %12 = load i32, ptr %4, align 4, !tbaa !5
  %13 = sext i32 %12 to i64
  %14 = getelementptr inbounds [5000001 x i32], ptr @array1, i64 0, i64 %13
  %15 = load i32, ptr %14, align 4, !tbaa !5
  %16 = icmp ne i32 %15, 0
  br i1 %16, label %17, label %19

17:                                               ; preds = %11
  %18 = load i32, ptr %4, align 4, !tbaa !5
  store i32 %18, ptr %2, align 4
  store i32 1, ptr %5, align 4
  br label %23

19:                                               ; preds = %11
  br label %20

20:                                               ; preds = %19
  %21 = load i32, ptr %4, align 4, !tbaa !5
  %22 = add nsw i32 %21, -1
  store i32 %22, ptr %4, align 4, !tbaa !5
  br label %7, !llvm.loop !9

23:                                               ; preds = %17, %10
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #2
  %24 = load i32, ptr %5, align 4
  switch i32 %24, label %28 [
    i32 2, label %25
    i32 1, label %26
  ]

25:                                               ; preds = %23
  store i32 0, ptr %2, align 4
  br label %26

26:                                               ; preds = %25, %23
  %27 = load i32, ptr %2, align 4
  ret i32 %27

28:                                               ; preds = %23
  unreachable
}

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

@array1 = external dso_local local_unnamed_addr global [5000001 x i32], align 16

; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(read, argmem: none, inaccessiblemem: none) uwtable
define dso_local noundef i32 @_Z7findmaxi(i32 noundef %0) local_unnamed_addr #0 {
  %2 = icmp slt i32 %0, 0
  br i1 %2, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %1, %6
  %.079 = phi i32 [ %7, %6 ], [ %0, %1 ]
  %3 = zext nneg i32 %.079 to i64
  %4 = getelementptr inbounds [5000001 x i32], ptr @array1, i64 0, i64 %3
  %5 = load i32, ptr %4, align 4, !tbaa !5
  %.not = icmp eq i32 %5, 0
  br i1 %.not, label %6, label %._crit_edge

6:                                                ; preds = %.lr.ph
  %7 = add nsw i32 %.079, -1
  %8 = icmp slt i32 %.079, 1
  br i1 %8, label %._crit_edge, label %.lr.ph, !llvm.loop !9

._crit_edge:                                      ; preds = %6, %.lr.ph, %1
  %.07.lcssa = phi i32 [ %0, %1 ], [ %.079, %.lr.ph ], [ -1, %6 ]
  %spec.select = tail call i32 @llvm.smax.i32(i32 %.07.lcssa, i32 0)
  ret i32 %spec.select
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i32 @llvm.smax.i32(i32, i32) #1

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(read, 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" }
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)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}


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