; LLVM IR from devicehive/esp8266-firmware :: firmware-src/sources (crc32)

; 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"

@crc32_tab = external hidden constant [256 x i32], align 4

; Function Attrs: nounwind uwtable
define dso_local i32 @crc32(ptr noundef %0, i32 noundef %1) #0 {
  %3 = alloca ptr, align 8
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca ptr, align 8
  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 -1, ptr %5, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 8, ptr %6) #2
  %7 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %7, ptr %6, align 8, !tbaa !5
  br label %8

8:                                                ; preds = %12, %2
  %9 = load i32, ptr %4, align 4, !tbaa !9
  %10 = add i32 %9, -1
  store i32 %10, ptr %4, align 4, !tbaa !9
  %11 = icmp ne i32 %9, 0
  br i1 %11, label %12, label %26

12:                                               ; preds = %8
  %13 = load i32, ptr %5, align 4, !tbaa !9
  %14 = load ptr, ptr %6, align 8, !tbaa !5
  %15 = getelementptr inbounds i8, ptr %14, i32 1
  store ptr %15, ptr %6, align 8, !tbaa !5
  %16 = load i8, ptr %14, align 1, !tbaa !11
  %17 = zext i8 %16 to i32
  %18 = xor i32 %13, %17
  %19 = and i32 %18, 255
  %20 = zext i32 %19 to i64
  %21 = getelementptr inbounds [256 x i32], ptr @crc32_tab, i64 0, i64 %20
  %22 = load i32, ptr %21, align 4, !tbaa !9
  %23 = load i32, ptr %5, align 4, !tbaa !9
  %24 = lshr i32 %23, 8
  %25 = xor i32 %22, %24
  store i32 %25, ptr %5, align 4, !tbaa !9
  br label %8, !llvm.loop !12

26:                                               ; preds = %8
  %27 = load i32, ptr %5, align 4, !tbaa !9
  %28 = xor i32 %27, -1
  call void @llvm.lifetime.end.p0(i64 8, ptr %6) #2
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #2
  ret i32 %28
}

; 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 = !{!7, !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"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"

@crc32_tab = external hidden local_unnamed_addr constant [256 x i32], align 4

; Function Attrs: nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local i32 @crc32(ptr nocapture noundef readonly %0, i32 noundef %1) local_unnamed_addr #0 {
  %.not7 = icmp eq i32 %1, 0
  br i1 %.not7, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %2
  %xtraiter = and i32 %1, 1
  %3 = icmp eq i32 %1, 1
  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, -2
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph, %.lr.ph.preheader.new
  %.010 = phi ptr [ %0, %.lr.ph.preheader.new ], [ %11, %.lr.ph ]
  %.059 = phi i32 [ -1, %.lr.ph.preheader.new ], [ %17, %.lr.ph ]
  %niter = phi i32 [ 0, %.lr.ph.preheader.new ], [ %niter.next.1, %.lr.ph ]
  %4 = getelementptr inbounds i8, ptr %.010, i64 1
  %5 = load i8, ptr %.010, align 1, !tbaa !5
  %.05.tr = trunc i32 %.059 to i8
  %.narrow = xor i8 %5, %.05.tr
  %6 = zext i8 %.narrow to i64
  %7 = getelementptr inbounds [256 x i32], ptr @crc32_tab, i64 0, i64 %6
  %8 = load i32, ptr %7, align 4, !tbaa !8
  %9 = lshr i32 %.059, 8
  %10 = xor i32 %8, %9
  %11 = getelementptr inbounds i8, ptr %.010, i64 2
  %12 = load i8, ptr %4, align 1, !tbaa !5
  %.05.tr.1 = trunc i32 %10 to i8
  %.narrow.1 = xor i8 %12, %.05.tr.1
  %13 = zext i8 %.narrow.1 to i64
  %14 = getelementptr inbounds [256 x i32], ptr @crc32_tab, i64 0, i64 %13
  %15 = load i32, ptr %14, align 4, !tbaa !8
  %16 = lshr i32 %10, 8
  %17 = xor i32 %15, %16
  %niter.next.1 = add i32 %niter, 2
  %niter.ncmp.1 = icmp eq i32 %niter.next.1, %unroll_iter
  br i1 %niter.ncmp.1, label %._crit_edge.loopexit.unr-lcssa, label %.lr.ph, !llvm.loop !10

._crit_edge.loopexit.unr-lcssa:                   ; preds = %.lr.ph, %.lr.ph.preheader
  %.lcssa.ph = phi i32 [ poison, %.lr.ph.preheader ], [ %17, %.lr.ph ]
  %.010.unr = phi ptr [ %0, %.lr.ph.preheader ], [ %11, %.lr.ph ]
  %.059.unr = phi i32 [ -1, %.lr.ph.preheader ], [ %17, %.lr.ph ]
  %lcmp.mod.not = icmp eq i32 %xtraiter, 0
  br i1 %lcmp.mod.not, label %._crit_edge.loopexit, label %.lr.ph.epil

.lr.ph.epil:                                      ; preds = %._crit_edge.loopexit.unr-lcssa
  %18 = load i8, ptr %.010.unr, align 1, !tbaa !5
  %.05.tr.epil = trunc i32 %.059.unr to i8
  %.narrow.epil = xor i8 %18, %.05.tr.epil
  %19 = zext i8 %.narrow.epil to i64
  %20 = getelementptr inbounds [256 x i32], ptr @crc32_tab, i64 0, i64 %19
  %21 = load i32, ptr %20, align 4, !tbaa !8
  %22 = lshr i32 %.059.unr, 8
  %23 = xor i32 %21, %22
  br label %._crit_edge.loopexit

._crit_edge.loopexit:                             ; preds = %._crit_edge.loopexit.unr-lcssa, %.lr.ph.epil
  %.lcssa = phi i32 [ %.lcssa.ph, %._crit_edge.loopexit.unr-lcssa ], [ %23, %.lr.ph.epil ]
  %24 = xor i32 %.lcssa, -1
  br label %._crit_edge

._crit_edge:                                      ; preds = %._crit_edge.loopexit, %2
  %.05.lcssa = phi i32 [ 0, %2 ], [ %24, %._crit_edge.loopexit ]
  ret i32 %.05.lcssa
}

attributes #0 = { nofree norecurse nosync nounwind memory(read, 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 = !{!"omnipotent char", !7, i64 0}
!7 = !{!"Simple C/C++ TBAA"}
!8 = !{!9, !9, i64 0}
!9 = !{!"int", !6, i64 0}
!10 = distinct !{!10, !11}
!11 = !{!"llvm.loop.mustprogress"}


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