; LLVM IR from ahiralesc/RTOS :: F767ZIT6/SEN_T6713_C02_F7/Core/Src (crccalc)

; 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"

@table_crc_hi = external hidden constant [256 x i8], align 16
@table_crc_lo = external hidden constant [256 x i8], align 16

; Function Attrs: nounwind uwtable
define dso_local zeroext i16 @crc16(ptr noundef %0, i16 noundef zeroext %1) #0 {
  %3 = alloca ptr, align 8
  %4 = alloca i16, align 2
  %5 = alloca i8, align 1
  %6 = alloca i8, align 1
  %7 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  store i16 %1, ptr %4, align 2, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 1, ptr %5) #2
  store i8 -1, ptr %5, align 1, !tbaa !11
  call void @llvm.lifetime.start.p0(i64 1, ptr %6) #2
  store i8 -1, ptr %6, align 1, !tbaa !11
  call void @llvm.lifetime.start.p0(i64 4, ptr %7) #2
  br label %8

8:                                                ; preds = %12, %2
  %9 = load i16, ptr %4, align 2, !tbaa !9
  %10 = add i16 %9, -1
  store i16 %10, ptr %4, align 2, !tbaa !9
  %11 = icmp ne i16 %9, 0
  br i1 %11, label %12, label %33

12:                                               ; preds = %8
  %13 = load i8, ptr %6, align 1, !tbaa !11
  %14 = zext i8 %13 to i32
  %15 = load ptr, ptr %3, align 8, !tbaa !5
  %16 = getelementptr inbounds i8, ptr %15, i32 1
  store ptr %16, ptr %3, align 8, !tbaa !5
  %17 = load i8, ptr %15, align 1, !tbaa !11
  %18 = zext i8 %17 to i32
  %19 = xor i32 %14, %18
  store i32 %19, ptr %7, align 4, !tbaa !12
  %20 = load i8, ptr %5, align 1, !tbaa !11
  %21 = zext i8 %20 to i32
  %22 = load i32, ptr %7, align 4, !tbaa !12
  %23 = zext i32 %22 to i64
  %24 = getelementptr inbounds [256 x i8], ptr @table_crc_hi, i64 0, i64 %23
  %25 = load i8, ptr %24, align 1, !tbaa !11
  %26 = zext i8 %25 to i32
  %27 = xor i32 %21, %26
  %28 = trunc i32 %27 to i8
  store i8 %28, ptr %6, align 1, !tbaa !11
  %29 = load i32, ptr %7, align 4, !tbaa !12
  %30 = zext i32 %29 to i64
  %31 = getelementptr inbounds [256 x i8], ptr @table_crc_lo, i64 0, i64 %30
  %32 = load i8, ptr %31, align 1, !tbaa !11
  store i8 %32, ptr %5, align 1, !tbaa !11
  br label %8, !llvm.loop !14

33:                                               ; preds = %8
  %34 = load i8, ptr %5, align 1, !tbaa !11
  %35 = zext i8 %34 to i32
  %36 = shl i32 %35, 8
  %37 = load i8, ptr %6, align 1, !tbaa !11
  %38 = zext i8 %37 to i32
  %39 = or i32 %36, %38
  %40 = trunc i32 %39 to i16
  call void @llvm.lifetime.end.p0(i64 4, ptr %7) #2
  call void @llvm.lifetime.end.p0(i64 1, ptr %6) #2
  call void @llvm.lifetime.end.p0(i64 1, ptr %5) #2
  ret i16 %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 = !{!"short", !7, i64 0}
!11 = !{!7, !7, i64 0}
!12 = !{!13, !13, i64 0}
!13 = !{!"int", !7, i64 0}
!14 = distinct !{!14, !15}
!15 = !{!"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"

@table_crc_hi = external hidden local_unnamed_addr constant [256 x i8], align 16
@table_crc_lo = external hidden local_unnamed_addr constant [256 x i8], align 16

; Function Attrs: nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local zeroext i16 @crc16(ptr nocapture noundef readonly %0, i16 noundef zeroext %1) local_unnamed_addr #0 {
  %.not10 = icmp eq i16 %1, 0
  br i1 %.not10, label %._crit_edge, label %.lr.ph.preheader

.lr.ph.preheader:                                 ; preds = %2
  %xtraiter = and i16 %1, 1
  %3 = icmp eq i16 %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 i16 %1, -2
  br label %.lr.ph

.lr.ph:                                           ; preds = %.lr.ph, %.lr.ph.preheader.new
  %.014 = phi ptr [ %0, %.lr.ph.preheader.new ], [ %13, %.lr.ph ]
  %.0713 = phi i8 [ -1, %.lr.ph.preheader.new ], [ %19, %.lr.ph ]
  %.0812 = phi i8 [ -1, %.lr.ph.preheader.new ], [ %21, %.lr.ph ]
  %niter = phi i16 [ 0, %.lr.ph.preheader.new ], [ %niter.next.1, %.lr.ph ]
  %4 = getelementptr inbounds i8, ptr %.014, i64 1
  %5 = load i8, ptr %.014, align 1, !tbaa !5
  %6 = xor i8 %5, %.0713
  %7 = zext i8 %6 to i64
  %8 = getelementptr inbounds [256 x i8], ptr @table_crc_hi, i64 0, i64 %7
  %9 = load i8, ptr %8, align 1, !tbaa !5
  %10 = xor i8 %9, %.0812
  %11 = getelementptr inbounds [256 x i8], ptr @table_crc_lo, i64 0, i64 %7
  %12 = load i8, ptr %11, align 1, !tbaa !5
  %13 = getelementptr inbounds i8, ptr %.014, i64 2
  %14 = load i8, ptr %4, align 1, !tbaa !5
  %15 = xor i8 %14, %10
  %16 = zext i8 %15 to i64
  %17 = getelementptr inbounds [256 x i8], ptr @table_crc_hi, i64 0, i64 %16
  %18 = load i8, ptr %17, align 1, !tbaa !5
  %19 = xor i8 %18, %12
  %20 = getelementptr inbounds [256 x i8], ptr @table_crc_lo, i64 0, i64 %16
  %21 = load i8, ptr %20, align 1, !tbaa !5
  %niter.next.1 = add i16 %niter, 2
  %niter.ncmp.1 = icmp eq i16 %niter.next.1, %unroll_iter
  br i1 %niter.ncmp.1, label %._crit_edge.loopexit.unr-lcssa, label %.lr.ph, !llvm.loop !8

._crit_edge.loopexit.unr-lcssa:                   ; preds = %.lr.ph, %.lr.ph.preheader
  %.lcssa19.ph = phi i8 [ poison, %.lr.ph.preheader ], [ %19, %.lr.ph ]
  %.lcssa.ph = phi i8 [ poison, %.lr.ph.preheader ], [ %21, %.lr.ph ]
  %.014.unr = phi ptr [ %0, %.lr.ph.preheader ], [ %13, %.lr.ph ]
  %.0713.unr = phi i8 [ -1, %.lr.ph.preheader ], [ %19, %.lr.ph ]
  %.0812.unr = phi i8 [ -1, %.lr.ph.preheader ], [ %21, %.lr.ph ]
  %lcmp.mod.not = icmp eq i16 %xtraiter, 0
  br i1 %lcmp.mod.not, label %._crit_edge.loopexit, label %.lr.ph.epil

.lr.ph.epil:                                      ; preds = %._crit_edge.loopexit.unr-lcssa
  %22 = load i8, ptr %.014.unr, align 1, !tbaa !5
  %23 = xor i8 %22, %.0713.unr
  %24 = zext i8 %23 to i64
  %25 = getelementptr inbounds [256 x i8], ptr @table_crc_hi, i64 0, i64 %24
  %26 = load i8, ptr %25, align 1, !tbaa !5
  %27 = xor i8 %26, %.0812.unr
  %28 = getelementptr inbounds [256 x i8], ptr @table_crc_lo, i64 0, i64 %24
  %29 = load i8, ptr %28, align 1, !tbaa !5
  br label %._crit_edge.loopexit

._crit_edge.loopexit:                             ; preds = %._crit_edge.loopexit.unr-lcssa, %.lr.ph.epil
  %.lcssa19 = phi i8 [ %.lcssa19.ph, %._crit_edge.loopexit.unr-lcssa ], [ %27, %.lr.ph.epil ]
  %.lcssa = phi i8 [ %.lcssa.ph, %._crit_edge.loopexit.unr-lcssa ], [ %29, %.lr.ph.epil ]
  %30 = zext i8 %.lcssa to i16
  %31 = shl nuw i16 %30, 8
  %32 = zext i8 %.lcssa19 to i16
  %33 = or disjoint i16 %31, %32
  br label %._crit_edge

._crit_edge:                                      ; preds = %._crit_edge.loopexit, %2
  %34 = phi i16 [ -1, %2 ], [ %33, %._crit_edge.loopexit ]
  ret i16 %34
}

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 = distinct !{!8, !9}
!9 = !{!"llvm.loop.mustprogress"}


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