; LLVM IR from Saikat2407/DSA_Hacktoberfest2023 :: c++/Dynamic Programming/1_Climbing_Stairs.ll (Z12totalWaysReci)

; 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: mustprogress uwtable
define dso_local noundef i32 @_Z12totalWaysReci(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  %4 = load i32, ptr %3, align 4, !tbaa !5
  %5 = icmp sle i32 %4, 0
  br i1 %5, label %6, label %7

6:                                                ; preds = %1
  store i32 0, ptr %2, align 4
  br label %20

7:                                                ; preds = %1
  %8 = load i32, ptr %3, align 4, !tbaa !5
  %9 = icmp sle i32 %8, 2
  br i1 %9, label %10, label %12

10:                                               ; preds = %7
  %11 = load i32, ptr %3, align 4, !tbaa !5
  store i32 %11, ptr %2, align 4
  br label %20

12:                                               ; preds = %7
  %13 = load i32, ptr %3, align 4, !tbaa !5
  %14 = sub nsw i32 %13, 1
  %15 = call noundef i32 @_Z12totalWaysReci(i32 noundef %14)
  %16 = load i32, ptr %3, align 4, !tbaa !5
  %17 = sub nsw i32 %16, 2
  %18 = call noundef i32 @_Z12totalWaysReci(i32 noundef %17)
  %19 = add nsw i32 %15, %18
  store i32 %19, ptr %2, align 4
  br label %20

20:                                               ; preds = %12, %10, %6
  %21 = load i32, ptr %2, align 4
  ret i32 %21
}

attributes #0 = { mustprogress 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++ TBAA"}


; 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: mustprogress nofree nosync nounwind willreturn memory(none) uwtable
define dso_local noundef i32 @_Z12totalWaysReci(i32 noundef %0) local_unnamed_addr #0 {
  %2 = icmp slt i32 %0, 1
  br i1 %2, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %1
  %3 = icmp ult i32 %0, 3
  br i1 %3, label %._crit_edge.loopexit, label %tailrecurse

tailrecurse:                                      ; preds = %.lr.ph.preheader, %tailrecurse
  %accumulator.tr713 = phi i32 [ %7, %tailrecurse ], [ 0, %.lr.ph.preheader ]
  %.tr812 = phi i32 [ %6, %tailrecurse ], [ %0, %.lr.ph.preheader ]
  %4 = add nsw i32 %.tr812, -1
  %5 = tail call noundef i32 @_Z12totalWaysReci(i32 noundef %4)
  %6 = add nsw i32 %.tr812, -2
  %7 = add nsw i32 %5, %accumulator.tr713
  %8 = icmp ult i32 %6, 3
  br i1 %8, label %._crit_edge.loopexit, label %tailrecurse

._crit_edge.loopexit:                             ; preds = %tailrecurse, %.lr.ph.preheader
  %.tr8.lcssa = phi i32 [ %0, %.lr.ph.preheader ], [ %6, %tailrecurse ]
  %accumulator.tr7.lcssa = phi i32 [ 0, %.lr.ph.preheader ], [ %7, %tailrecurse ]
  %9 = add nsw i32 %.tr8.lcssa, %accumulator.tr7.lcssa
  br label %._crit_edge

._crit_edge:                                      ; preds = %._crit_edge.loopexit, %1
  %accumulator.ret.tr = phi i32 [ 0, %1 ], [ %9, %._crit_edge.loopexit ]
  ret i32 %accumulator.ret.tr
}

attributes #0 = { mustprogress nofree nosync nounwind willreturn memory(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)"}


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