; LLVM IR from Hunterdii/GeeksforGeeks-POTD :: December 2024 GFG SOLUTION (December-15)

; 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
define dso_local i32 @peakElement(ptr noundef %0, i32 noundef %1) #0 {
  %3 = alloca ptr, align 8
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  %7 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  store i32 %1, ptr %4, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  store i32 0, ptr %5, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #2
  %8 = load i32, ptr %4, align 4, !tbaa !9
  %9 = sub nsw i32 %8, 1
  store i32 %9, ptr %6, align 4, !tbaa !9
  br label %10

10:                                               ; preds = %38, %2
  %11 = load i32, ptr %5, align 4, !tbaa !9
  %12 = load i32, ptr %6, align 4, !tbaa !9
  %13 = icmp slt i32 %11, %12
  br i1 %13, label %14, label %39

14:                                               ; preds = %10
  call void @llvm.lifetime.start.p0(i64 4, ptr %7) #2
  %15 = load i32, ptr %5, align 4, !tbaa !9
  %16 = load i32, ptr %6, align 4, !tbaa !9
  %17 = load i32, ptr %5, align 4, !tbaa !9
  %18 = sub nsw i32 %16, %17
  %19 = sdiv i32 %18, 2
  %20 = add nsw i32 %15, %19
  store i32 %20, ptr %7, align 4, !tbaa !9
  %21 = load ptr, ptr %3, align 8, !tbaa !5
  %22 = load i32, ptr %7, align 4, !tbaa !9
  %23 = sext i32 %22 to i64
  %24 = getelementptr inbounds i32, ptr %21, i64 %23
  %25 = load i32, ptr %24, align 4, !tbaa !9
  %26 = load ptr, ptr %3, align 8, !tbaa !5
  %27 = load i32, ptr %7, align 4, !tbaa !9
  %28 = add nsw i32 %27, 1
  %29 = sext i32 %28 to i64
  %30 = getelementptr inbounds i32, ptr %26, i64 %29
  %31 = load i32, ptr %30, align 4, !tbaa !9
  %32 = icmp sgt i32 %25, %31
  br i1 %32, label %33, label %35

33:                                               ; preds = %14
  %34 = load i32, ptr %7, align 4, !tbaa !9
  store i32 %34, ptr %6, align 4, !tbaa !9
  br label %38

35:                                               ; preds = %14
  %36 = load i32, ptr %7, align 4, !tbaa !9
  %37 = add nsw i32 %36, 1
  store i32 %37, ptr %5, align 4, !tbaa !9
  br label %38

38:                                               ; preds = %35, %33
  call void @llvm.lifetime.end.p0(i64 4, ptr %7) #2
  br label %10, !llvm.loop !11

39:                                               ; preds = %10
  %40 = load i32, ptr %5, align 4, !tbaa !9
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  ret i32 %40
}

; 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 = 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"

; Function Attrs: nofree norecurse nosync nounwind memory(argmem: read) uwtable
define dso_local i32 @peakElement(ptr nocapture noundef readonly %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = icmp sgt i32 %1, 1
  br i1 %3, label %.lr.ph.preheader, label %._crit_edge

.lr.ph.preheader:                                 ; preds = %2
  %4 = add nsw i32 %1, -1
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph.preheader, %.lr.ph
  %.015 = phi i32 [ %.0., %.lr.ph ], [ 0, %.lr.ph.preheader ]
  %.01214 = phi i32 [ %..012, %.lr.ph ], [ %4, %.lr.ph.preheader ]
  %5 = sub nsw i32 %.01214, %.015
  %6 = sdiv i32 %5, 2
  %7 = add nsw i32 %6, %.015
  %8 = sext i32 %7 to i64
  %9 = getelementptr inbounds i32, ptr %0, i64 %8
  %10 = load i32, ptr %9, align 4, !tbaa !5
  %11 = add nsw i32 %7, 1
  %12 = sext i32 %11 to i64
  %13 = getelementptr inbounds i32, ptr %0, i64 %12
  %14 = load i32, ptr %13, align 4, !tbaa !5
  %15 = icmp sgt i32 %10, %14
  %..012 = select i1 %15, i32 %7, i32 %.01214
  %.0. = select i1 %15, i32 %.015, i32 %11
  %16 = icmp slt i32 %.0., %..012
  br i1 %16, label %.lr.ph, label %._crit_edge, !llvm.loop !9

._crit_edge:                                      ; preds = %.lr.ph, %2
  %.0.lcssa = phi i32 [ 0, %2 ], [ %.0., %.lr.ph ]
  ret i32 %.0.lcssa
}

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


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