Fix getfield of potentially undef inline immutable field (JuliaLang#3…

…7511)

The undef ref error may be thrown at the wrong time or not at all and may cause crashes.

src/cgutils.cpp

@@ -1687,16 +1687,18 @@ static bool emit_getfield_unknownidx(jl_codectx_t &ctx,
  else if (is_tupletype_homogeneous(stt->types)) {
  assert(nfields > 0); // nf == 0 trapped by all_pointers case
  jl_value_t *jft = jl_svecref(stt->types, 0);
+ assert(jl_is_concrete_type(jft));
  idx = idx0();
  Value *ptr = maybe_decay_tracked(ctx, data_pointer(ctx, strct));
- if (!stt->mutabl && !(maybe_null && jft == (jl_value_t*)jl_bool_type)) {
+ if (!stt->mutabl && !(maybe_null && (jft == (jl_value_t*)jl_bool_type ||
+ ((jl_datatype_t*)jft)->layout->npointers))) {
  // just compute the pointer and let user load it when necessary
  Type *fty = julia_type_to_llvm(ctx, jft);
  Value *addr = ctx.builder.CreateInBoundsGEP(fty, emit_bitcast(ctx, ptr, PointerType::get(fty, 0)), idx);
  *ret = mark_julia_slot(addr, jft, NULL, strct.tbaa);
  return true;
  }
- *ret = typed_load(ctx, ptr, idx, jft, strct.tbaa, nullptr, false);
+ *ret = typed_load(ctx, ptr, idx, jft, strct.tbaa, nullptr, maybe_null);
  return true;
  }
  else if (strct.isboxed) {
@@ -1787,12 +1789,14 @@ static jl_cgval_t emit_getfield_knownidx(jl_codectx_t &ctx, const jl_cgval_t &st
  }
  return mark_julia_slot(addr, jfty, tindex, tbaa);
  }
- else if (!jt->mutabl && !(maybe_null && jfty == (jl_value_t*)jl_bool_type)) {
+ assert(jl_is_concrete_type(jfty));
+ if (!jt->mutabl && !(maybe_null && (jfty == (jl_value_t*)jl_bool_type ||
+ ((jl_datatype_t*)jfty)->layout->npointers))) {
  // just compute the pointer and let user load it when necessary
  return mark_julia_slot(addr, jfty, NULL, tbaa);
  }
  unsigned align = jl_field_align(jt, idx);
- return typed_load(ctx, addr, NULL, jfty, tbaa, nullptr, true, align);
+ return typed_load(ctx, addr, NULL, jfty, tbaa, nullptr, maybe_null, align);
  }
  else if (isa<UndefValue>(strct.V)) {
  return jl_cgval_t();

test/core.jl

@@ -7330,3 +7330,69 @@ function c37265_2(d)
  e
 end
 @test_throws TypeError c37265_2(0)
+
+struct PointerImmutable
+ a::Any
+ b::Int
+end
+struct NullableHomogeneousPointerImmutable
+ x1::PointerImmutable
+ x2::PointerImmutable
+ x3::PointerImmutable
+ NullableHomogeneousPointerImmutable() = new()
+ NullableHomogeneousPointerImmutable(x1) = new(x1)
+ NullableHomogeneousPointerImmutable(x1, x2) = new(x1, x2)
+ NullableHomogeneousPointerImmutable(x1, x2, x3) = new(x1, x2, x3)
+end
+
+function getfield_knownindex_unused(v)
+ v.x1
+ return
+end
+
+function getfield_unknownindex_unused(v, n)
+ getfield(v, n)
+ return
+end
+
+function getfield_knownindex_used1(r, v)
+ fld = v.x1
+ r[] += 1
+ return fld
+end
+
+function getfield_knownindex_used2(r, v)
+ fld = v.x1
+ r[] += 1
+ return fld.a
+end
+
+function getfield_knownindex_used3(r, v)
+ fld = v.x1
+ r[] += 1
+ return fld.b
+end
+
+let v = NullableHomogeneousPointerImmutable(),
+ v2 = NullableHomogeneousPointerImmutable(PointerImmutable(1, 2)),
+ r = Ref(0)
+ @test_throws UndefRefError getfield_knownindex_unused(v)
+ @test_throws UndefRefError getfield_unknownindex_unused(v, 1)
+ @test_throws UndefRefError getfield_unknownindex_unused(v, :x1)
+ @test_throws UndefRefError getfield_knownindex_used1(r, v)
+ @test r[] == 0
+ @test_throws UndefRefError getfield_knownindex_used2(r, v)
+ @test r[] == 0
+ @test_throws UndefRefError getfield_knownindex_used3(r, v)
+ @test r[] == 0
+
+ @test getfield_knownindex_unused(v2) === nothing
+ @test getfield_unknownindex_unused(v2, 1) === nothing
+ @test getfield_unknownindex_unused(v2, :x1) === nothing
+ @test getfield_knownindex_used1(r, v2) === PointerImmutable(1, 2)
+ @test r[] == 1
+ @test getfield_knownindex_used2(r, v2) === 1
+ @test r[] == 2
+ @test getfield_knownindex_used3(r, v2) === 2
+ @test r[] == 3
+end