mitigate JuliaLang#6097

the general problem was that one place in the code had a larger type for
a tuple than another. I don't know why, but we can at least generate
correct code instead of crashing. there was already some code in boxed()
towards handling this kind of thing, but it needed to be rearranged a bit.

src/cgutils.cpp

@@ -1457,9 +1457,19 @@ static jl_value_t *static_constant_instance(Constant *constant, jl_value_t *jt)
 static Value *boxed(Value *v, jl_codectx_t *ctx, jl_value_t *jt)
 {
  Type *t = (v == NULL) ? NULL : v->getType();
+
+ if (jt == NULL) {
+ jt = julia_type_of(v);
+ }
+ else if (!jl_is_leaf_type(jt)) {
+ // we can get a sharper type from julia_type_of than expr_type in some
+ // cases, due to ccall's compile-time evaluations of types. see issue #5752
+ jl_value_t *jt2 = julia_type_of(v);
+ if (jl_subtype(jt2, jt, 0))
+ jt = jt2;
+ }
+
  if (v == NULL || dyn_cast<UndefValue>(v) != 0 || t == NoopType) {
- if (jt == NULL || jl_is_uniontype(jt) || jl_is_abstracttype(jt))
- jt = julia_type_of(v);
  jl_value_t *s = static_void_instance(jt);
  if (jl_is_tuple(jt) && jl_tuple_len(jt) > 0)
  jl_add_linfo_root(ctx->linfo, s);
@@ -1468,8 +1478,6 @@ static Value *boxed(Value *v, jl_codectx_t *ctx, jl_value_t *jt)
  if (t == jl_pvalue_llvmt)
  return v;
  if (t == T_int1) return julia_bool(v);
- if (jt == NULL || jl_is_uniontype(jt) || jl_is_abstracttype(jt))
- jt = julia_type_of(v);
  if (t == T_void || t->isEmptyTy()) {
  jl_value_t *s = static_void_instance(jt);
  if (jl_is_tuple(jt) && jl_tuple_len(jt) > 0)
@@ -1489,12 +1497,14 @@ static Value *boxed(Value *v, jl_codectx_t *ctx, jl_value_t *jt)
  make_gcroot(tpl,ctx);
  for (size_t i = 0; i < n; ++i) {
  jl_value_t *jti = jl_tupleref(jt,i);
- Value *vi = emit_tupleref(v,ConstantInt::get(T_size,i+1),jt,ctx);
- emit_tupleset(tpl,ConstantInt::get(T_size,i+1),boxed(vi,ctx,jti),jt,ctx);
+ Value *vi = emit_tupleref(v, ConstantInt::get(T_size,i+1), jt, ctx);
+ Value *boxedvi = boxed(vi, ctx, jti);
+ emit_tupleset(tpl, ConstantInt::get(T_size,i+1), boxedvi, jt, ctx);
  }
  ctx->argDepth = last_depth;
  return tpl;
  }
+
  jl_datatype_t *jb = (jl_datatype_t*)jt;
  assert(jl_is_datatype(jb));
  if (jb == jl_int8_type)
@@ -1522,18 +1532,11 @@ static Value *boxed(Value *v, jl_codectx_t *ctx, jl_value_t *jt)
  if (jb == jl_uint64_type) return builder.CreateCall(prepare_call(box_uint64_func), v);
  if (jb == jl_char_type) return builder.CreateCall(prepare_call(box_char_func), v);
 
- if (!jl_is_leaf_type(jt)) {
- // we can get a sharper type from julia_type_of than expr_type in some
- // cases, due to ccall's compile-time evaluations of types. see issue #5752
- jl_value_t *jt2 = julia_type_of(v);
- if (jl_subtype(jt2, jt, 0))
- jt = jt2;
- }
-
  if (!jl_isbits(jt) || !jl_is_leaf_type(jt)) {
  assert("Don't know how to box this type" && false);
  return NULL;
  }
+
  if (!jb->abstract && jb->size == 0) {
  if (jb->instance == NULL)
  jl_new_struct_uninit(jb);