NFC: Introduce V_rnull to replace maybe_decay_untracked(V_null)

src/cgutils.cpp

@@ -2386,8 +2386,7 @@ static Value *box_union(jl_codectx_t &ctx, const jl_cgval_t &vinfo, const SmallB
  ctx.builder.SetInsertPoint(defaultBB);
  if (skip.size() > 0) {
  assert(skip[0]);
- Value *box = maybe_decay_untracked(V_null);
- box_merge->addIncoming(box, defaultBB);
+ box_merge->addIncoming(V_rnull, defaultBB);
  ctx.builder.CreateBr(postBB);
  }
  else if (!vinfo.Vboxed) {

src/codegen.cpp

@@ -235,6 +235,7 @@ static DISubroutineType *jl_di_func_null_sig;
 
 // constants
 static Constant *V_null;
+static Constant *V_rnull;
 static bool type_is_ghost(Type *ty)
 {
  return (ty == T_void || ty->isEmptyTy());
@@ -1162,10 +1163,9 @@ static void undef_derived_strct(IRBuilder<> &irbuilder, Value *ptr, jl_datatype_
  if (np == 0)
  return;
  ptr = irbuilder.CreateBitCast(ptr, T_prjlvalue->getPointerTo(ptr->getType()->getPointerAddressSpace()));
- Value *V_null = ConstantPointerNull::get(cast<PointerType>(T_prjlvalue));
  for (i = 0; i < np; i++) {
  Value *fld = irbuilder.CreateConstInBoundsGEP1_32(T_prjlvalue, ptr, jl_ptr_offset(sty, i));
- tbaa_decorate(tbaa, irbuilder.CreateStore(V_null, fld));
+ tbaa_decorate(tbaa, irbuilder.CreateStore(V_rnull, fld));
  }
 }
 
@@ -2278,7 +2278,7 @@ static jl_cgval_t emit_getfield(jl_codectx_t &ctx, const jl_cgval_t &strct, jl_s
  strct,
  mark_julia_const((jl_value_t*)name)
  };
- Value *result = emit_jlcall(ctx, jlgetfield_func, maybe_decay_untracked(V_null), myargs_array, 2, JLCALL_F_CC);
+ Value *result = emit_jlcall(ctx, jlgetfield_func, V_rnull, myargs_array, 2, JLCALL_F_CC);
  return mark_julia_type(ctx, result, true, jl_any_type);
 }
 
@@ -3430,7 +3430,7 @@ static jl_cgval_t emit_call(jl_codectx_t &ctx, jl_expr_t *ex, jl_value_t *rt)
  // special case for known builtin not handled by emit_builtin_call
  auto it = builtin_func_map.find(jl_get_builtin_fptr(f.constant));
  if (it != builtin_func_map.end()) {
- Value *ret = emit_jlcall(ctx, it->second, maybe_decay_untracked(V_null), &argv[1], nargs - 1, JLCALL_F_CC);
+ Value *ret = emit_jlcall(ctx, it->second, V_rnull, &argv[1], nargs - 1, JLCALL_F_CC);
  return mark_julia_type(ctx, ret, true, rt);
  }
  }
@@ -3578,7 +3578,7 @@ static jl_cgval_t emit_isdefined(jl_codectx_t &ctx, jl_value_t *sym)
  }
  if (vi.boxroot != NULL) {
  Value *boxed = ctx.builder.CreateAlignedLoad(T_prjlvalue, vi.boxroot, sizeof(void*), vi.isVolatile);
- Value *box_isnull = ctx.builder.CreateICmpNE(boxed, maybe_decay_untracked(V_null));
+ Value *box_isnull = ctx.builder.CreateICmpNE(boxed, V_rnull);
  if (vi.pTIndex) {
  // value is either boxed in the stack slot, or unboxed in value
  // as indicated by testing (pTIndex & 0x80)
@@ -3631,7 +3631,7 @@ static jl_cgval_t emit_isdefined(jl_codectx_t &ctx, jl_value_t *sym)
  LoadInst *v = ctx.builder.CreateAlignedLoad(T_prjlvalue, bp, sizeof(void*));
  tbaa_decorate(tbaa_binding, v);
  v->setOrdering(AtomicOrdering::Unordered);
- isnull = ctx.builder.CreateICmpNE(v, maybe_decay_untracked(V_null));
+ isnull = ctx.builder.CreateICmpNE(v, V_rnull);
  }
  else {
  Value *v = ctx.builder.CreateCall(prepare_call(jlboundp_func), {
@@ -3686,7 +3686,7 @@ static jl_cgval_t emit_varinfo(jl_codectx_t &ctx, jl_varinfo_t &vi, jl_sym_t *va
  Instruction *boxed = ctx.builder.CreateAlignedLoad(T_prjlvalue, vi.boxroot, sizeof(void*), vi.isVolatile);
  Value *box_isnull = NULL;
  if (vi.usedUndef)
- box_isnull = ctx.builder.CreateICmpNE(boxed, maybe_decay_untracked(V_null));
+ box_isnull = ctx.builder.CreateICmpNE(boxed, V_rnull);
  maybe_mark_load_dereferenceable(boxed, vi.usedUndef || vi.pTIndex, typ);
  if (vi.pTIndex) {
  // value is either boxed in the stack slot, or unboxed in value
@@ -4057,7 +4057,7 @@ static void emit_stmtpos(jl_codectx_t &ctx, jl_value_t *expr, int ssaval_result)
  // create a new uninitialized variable
  Value *lv = vi.boxroot;
  if (lv != NULL)
- ctx.builder.CreateStore(maybe_decay_untracked(V_null), lv);
+ ctx.builder.CreateStore(V_rnull, lv);
  if (lv == NULL || vi.pTIndex != NULL)
  store_def_flag(ctx, vi, false);
  }
@@ -6190,7 +6190,7 @@ static std::pair<std::unique_ptr<Module>, jl_llvm_functions_t>
  emit_varinfo_assign(ctx, vi, tuple);
  }
  else {
- restTuple = emit_jlcall(ctx, jltuple_func, maybe_decay_untracked(V_null),
+ restTuple = emit_jlcall(ctx, jltuple_func, V_rnull,
  vargs, ctx.nvargs, JLCALL_F_CC);
  jl_cgval_t tuple = mark_julia_type(ctx, restTuple, true, vi.value.typ);
  emit_varinfo_assign(ctx, vi, tuple);
@@ -6201,7 +6201,7 @@ static std::pair<std::unique_ptr<Module>, jl_llvm_functions_t>
  Function *F = prepare_call(jltuple_func);
  restTuple =
  ctx.builder.CreateCall(F,
- { maybe_decay_untracked(V_null),
+ { V_rnull,
  ctx.builder.CreateInBoundsGEP(T_prjlvalue, argArray,
  ConstantInt::get(T_size, nreq - 1)),
  ctx.builder.CreateSub(argCount,
@@ -6519,21 +6519,18 @@ static std::pair<std::unique_ptr<Module>, jl_llvm_functions_t>
  Value *data, *tindex;
  if (retvalinfo.TIndex) {
  tindex = retvalinfo.TIndex;
+ data = V_rnull;
  if (retvalinfo.V == NULL) {
  // treat this as a simple Ghosts
- data = maybe_decay_untracked(V_null);
  sret = NULL;
  }
- else {
- data = maybe_decay_untracked(V_null);
- if (retvalinfo.Vboxed) {
- // also need to account for the possibility the return object is boxed
- // and avoid / skip copying it to the stack
- isboxed_union = ctx.builder.CreateICmpNE(
- ctx.builder.CreateAnd(tindex, ConstantInt::get(T_int8, 0x80)),
- ConstantInt::get(T_int8, 0));
- data = ctx.builder.CreateSelect(isboxed_union, retvalinfo.Vboxed, data);
- }
+ else if (retvalinfo.Vboxed) {
+ // also need to account for the possibility the return object is boxed
+ // and avoid / skip copying it to the stack
+ isboxed_union = ctx.builder.CreateICmpNE(
+ ctx.builder.CreateAnd(tindex, ConstantInt::get(T_int8, 0x80)),
+ ConstantInt::get(T_int8, 0));
+ data = ctx.builder.CreateSelect(isboxed_union, retvalinfo.Vboxed, data);
  }
  }
  else {
@@ -7335,6 +7332,7 @@ static void init_julia_llvm_env(Module *m)
  T_ppjlvalue = PointerType::get(T_pjlvalue, 0);
  T_pprjlvalue = PointerType::get(T_prjlvalue, 0);
  V_null = Constant::getNullValue(T_pjlvalue);
+ V_rnull = Constant::getNullValue(T_prjlvalue);
 
  std::vector<Type*> ftargs(0);
  ftargs.push_back(T_prjlvalue); // function

src/llvm-late-gc-lowering.cpp

@@ -600,12 +600,12 @@ Value *LateLowerGCFrame::MaybeExtractScalar(State &S, std::pair<Value*,int> ValE
 std::vector<Value*> LateLowerGCFrame::MaybeExtractVector(State &S, Value *BaseVec, Instruction *InsertBefore) {
  auto Numbers = NumberAllBase(S, BaseVec);
  std::vector<Value*> V{Numbers.size()};
- Value *V_null = ConstantPointerNull::get(cast<PointerType>(T_prjlvalue));
+ Value *V_rnull = ConstantPointerNull::get(cast<PointerType>(T_prjlvalue));
  for (unsigned i = 0; i < V.size(); ++i) {
  if (Numbers[i] >= 0)
  V[i] = GetPtrForNumber(S, Numbers[i], InsertBefore);
  else
- V[i] = V_null;
+ V[i] = V_rnull;
  }
  return V;
 }