; LLVM IR from jgaeddert/liquid-dsp :: src/fft/src (fft_utilities)

; 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: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: nounwind uwtable
define dso_local i32 @fft_reverse_index(i32 noundef %0, i32 noundef %1) #1 {
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  store i32 %0, ptr %3, align 4, !tbaa !5
  store i32 %1, ptr %4, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #2
  store i32 0, ptr %5, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #2
  store i32 0, ptr %6, align 4, !tbaa !5
  br label %7

7:                                                ; preds = %20, %2
  %8 = load i32, ptr %6, align 4, !tbaa !5
  %9 = load i32, ptr %4, align 4, !tbaa !5
  %10 = icmp ult i32 %8, %9
  br i1 %10, label %11, label %23

11:                                               ; preds = %7
  %12 = load i32, ptr %5, align 4, !tbaa !5
  %13 = shl i32 %12, 1
  store i32 %13, ptr %5, align 4, !tbaa !5
  %14 = load i32, ptr %3, align 4, !tbaa !5
  %15 = and i32 %14, 1
  %16 = load i32, ptr %5, align 4, !tbaa !5
  %17 = or i32 %16, %15
  store i32 %17, ptr %5, align 4, !tbaa !5
  %18 = load i32, ptr %3, align 4, !tbaa !5
  %19 = lshr i32 %18, 1
  store i32 %19, ptr %3, align 4, !tbaa !5
  br label %20

20:                                               ; preds = %11
  %21 = load i32, ptr %6, align 4, !tbaa !5
  %22 = add i32 %21, 1
  store i32 %22, ptr %6, align 4, !tbaa !5
  br label %7, !llvm.loop !9

23:                                               ; preds = %7
  %24 = load i32, ptr %5, align 4, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  ret i32 %24
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { 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 #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 = 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"

; Function Attrs: nofree norecurse nosync nounwind memory(none) uwtable
define dso_local i32 @fft_reverse_index(i32 noundef %0, i32 noundef %1) local_unnamed_addr #0 {
  %.not = icmp eq i32 %1, 0
  br i1 %.not, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %2
  %xtraiter = and i32 %1, 3
  %3 = icmp ult i32 %1, 4
  br i1 %3, label %._crit_edge.loopexit.unr-lcssa, label %.lr.ph.preheader.new

.lr.ph.preheader.new:                             ; preds = %.lr.ph.preheader
  %unroll_iter = and i32 %1, -4
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph, %.lr.ph.preheader.new
  %.0811 = phi i32 [ 0, %.lr.ph.preheader.new ], [ %16, %.lr.ph ]
  %.0910 = phi i32 [ %0, %.lr.ph.preheader.new ], [ %17, %.lr.ph ]
  %niter = phi i32 [ 0, %.lr.ph.preheader.new ], [ %niter.next.3, %.lr.ph ]
  %4 = shl i32 %.0811, 3
  %5 = shl i32 %.0910, 2
  %6 = and i32 %5, 4
  %7 = or disjoint i32 %4, %6
  %8 = and i32 %.0910, 2
  %9 = or disjoint i32 %7, %8
  %10 = lshr i32 %.0910, 2
  %11 = and i32 %10, 1
  %12 = or disjoint i32 %9, %11
  %13 = lshr i32 %.0910, 3
  %14 = shl i32 %12, 1
  %15 = and i32 %13, 1
  %16 = or disjoint i32 %14, %15
  %17 = lshr i32 %.0910, 4
  %niter.next.3 = add i32 %niter, 4
  %niter.ncmp.3 = icmp eq i32 %niter.next.3, %unroll_iter
  br i1 %niter.ncmp.3, label %._crit_edge.loopexit.unr-lcssa, label %.lr.ph, !llvm.loop !5

._crit_edge.loopexit.unr-lcssa:                   ; preds = %.lr.ph, %.lr.ph.preheader
  %.lcssa.ph = phi i32 [ poison, %.lr.ph.preheader ], [ %16, %.lr.ph ]
  %.0811.unr = phi i32 [ 0, %.lr.ph.preheader ], [ %16, %.lr.ph ]
  %.0910.unr = phi i32 [ %0, %.lr.ph.preheader ], [ %17, %.lr.ph ]
  %lcmp.mod.not = icmp eq i32 %xtraiter, 0
  br i1 %lcmp.mod.not, label %._crit_edge, label %.lr.ph.epil

.lr.ph.epil:                                      ; preds = %._crit_edge.loopexit.unr-lcssa, %.lr.ph.epil
  %.0811.epil = phi i32 [ %20, %.lr.ph.epil ], [ %.0811.unr, %._crit_edge.loopexit.unr-lcssa ]
  %.0910.epil = phi i32 [ %21, %.lr.ph.epil ], [ %.0910.unr, %._crit_edge.loopexit.unr-lcssa ]
  %epil.iter = phi i32 [ %epil.iter.next, %.lr.ph.epil ], [ 0, %._crit_edge.loopexit.unr-lcssa ]
  %18 = shl i32 %.0811.epil, 1
  %19 = and i32 %.0910.epil, 1
  %20 = or disjoint i32 %18, %19
  %21 = lshr i32 %.0910.epil, 1
  %epil.iter.next = add i32 %epil.iter, 1
  %epil.iter.cmp.not = icmp eq i32 %epil.iter.next, %xtraiter
  br i1 %epil.iter.cmp.not, label %._crit_edge, label %.lr.ph.epil, !llvm.loop !7

._crit_edge:                                      ; preds = %._crit_edge.loopexit.unr-lcssa, %.lr.ph.epil, %2
  %.08.lcssa = phi i32 [ 0, %2 ], [ %.lcssa.ph, %._crit_edge.loopexit.unr-lcssa ], [ %20, %.lr.ph.epil ]
  ret i32 %.08.lcssa
}

attributes #0 = { nofree norecurse nosync nounwind 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)"}
!5 = distinct !{!5, !6}
!6 = !{!"llvm.loop.mustprogress"}
!7 = distinct !{!7, !8}
!8 = !{!"llvm.loop.unroll.disable"}


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