datatype: finish layout corrections (#43306)

We still had some discrepancies between what the code thought could be
computed for a layout, and what we actually could compute layout for.
This hopefully makes those two computations now always give the same
answers (with the assistance of the layout cache).

Fixes #43303

Author: vtjnash

src/array.c

@@ -219,51 +219,28 @@ JL_DLLEXPORT jl_array_t *jl_reshape_array(jl_value_t *atype, jl_array_t *data,
                                           jl_value_t *_dims)
 {
     jl_task_t *ct = jl_current_task;
-    jl_array_t *a;
+    assert(jl_types_equal(jl_tparam0(jl_typeof(data)), jl_tparam0(atype)));
+
     size_t ndims = jl_nfields(_dims);
     assert(is_ntuple_long(_dims));
     size_t *dims = (size_t*)_dims;
-    assert(jl_types_equal(jl_tparam0(jl_typeof(data)), jl_tparam0(atype)));
-
     int ndimwords = jl_array_ndimwords(ndims);
     int tsz = sizeof(jl_array_t) + ndimwords * sizeof(size_t) + sizeof(void*);
-    a = (jl_array_t*)jl_gc_alloc(ct->ptls, tsz, atype);
+    jl_array_t *a = (jl_array_t*)jl_gc_alloc(ct->ptls, tsz, atype);
     // No allocation or safepoint allowed after this
+    // copy data (except dims) from the old object
     a->flags.pooled = tsz <= GC_MAX_SZCLASS;
     a->flags.ndims = ndims;
     a->offset = 0;
     a->data = NULL;
     a->flags.isaligned = data->flags.isaligned;
-    jl_array_t *owner = (jl_array_t*)jl_array_owner(data);
-    jl_value_t *eltype = jl_tparam0(atype);
-    size_t elsz = 0, align = 0;
-    int isboxed = !jl_islayout_inline(eltype, &elsz, &align);
-    assert(isboxed == data->flags.ptrarray);
-    if (!isboxed) {
-        a->elsize = LLT_ALIGN(elsz, align);
-        jl_value_t *ownerty = jl_typeof(owner);
-        size_t oldelsz = 0, oldalign = 0;
-        if (ownerty == (jl_value_t*)jl_string_type) {
-            oldalign = 1;
-        }
-        else {
-            jl_islayout_inline(jl_tparam0(ownerty), &oldelsz, &oldalign);
-        }
-        if (oldalign < align)
-            jl_exceptionf(jl_argumenterror_type,
-                          "reinterpret from alignment %d bytes to alignment %d bytes not allowed",
-                          (int) oldalign, (int) align);
-        a->flags.ptrarray = 0;
-        a->flags.hasptr = data->flags.hasptr;
-    }
-    else {
-        a->elsize = sizeof(void*);
-        a->flags.ptrarray = 1;
-        a->flags.hasptr = 0;
-    }
+    a->elsize = data->elsize;
+    a->flags.ptrarray = data->flags.ptrarray;
+    a->flags.hasptr = data->flags.hasptr;
 
     // if data is itself a shared wrapper,
     // owner should point back to the original array
+    jl_array_t *owner = (jl_array_t*)jl_array_owner(data);
     jl_array_data_owner(a) = (jl_value_t*)owner;
 
     a->flags.how = 3;

src/datatype.c

@@ -248,9 +248,9 @@ int jl_struct_try_layout(jl_datatype_t *dt)
     return 1;
 }
 
-int jl_datatype_isinlinealloc(jl_datatype_t *ty, int pointerfree) JL_NOTSAFEPOINT
+int jl_datatype_isinlinealloc(jl_datatype_t *ty, int pointerfree)
 {
-    if (ty->name->mayinlinealloc && (ty->isconcretetype || ((jl_datatype_t*)jl_unwrap_unionall(ty->name->wrapper))->layout)) { // TODO: use jl_struct_try_layout(dt) (but it is a safepoint)
+    if (ty->name->mayinlinealloc && jl_struct_try_layout(ty)) {
         if (ty->layout->npointers > 0) {
             if (pointerfree)
                 return 0;
@@ -264,7 +264,7 @@ int jl_datatype_isinlinealloc(jl_datatype_t *ty, int pointerfree) JL_NOTSAFEPOIN
     return 0;
 }
 
-static unsigned union_isinlinable(jl_value_t *ty, int pointerfree, size_t *nbytes, size_t *align, int asfield) JL_NOTSAFEPOINT
+static unsigned union_isinlinable(jl_value_t *ty, int pointerfree, size_t *nbytes, size_t *align, int asfield)
 {
     if (jl_is_uniontype(ty)) {
         unsigned na = union_isinlinable(((jl_uniontype_t*)ty)->a, 1, nbytes, align, asfield);
@@ -290,19 +290,19 @@ static unsigned union_isinlinable(jl_value_t *ty, int pointerfree, size_t *nbyte
     return 0;
 }
 
-int jl_uniontype_size(jl_value_t *ty, size_t *sz) JL_NOTSAFEPOINT
+int jl_uniontype_size(jl_value_t *ty, size_t *sz)
 {
     size_t al = 0;
     return union_isinlinable(ty, 0, sz, &al, 0) != 0;
 }
 
-JL_DLLEXPORT int jl_islayout_inline(jl_value_t *eltype, size_t *fsz, size_t *al) JL_NOTSAFEPOINT
+JL_DLLEXPORT int jl_islayout_inline(jl_value_t *eltype, size_t *fsz, size_t *al)
 {
     unsigned countbits = union_isinlinable(eltype, 0, fsz, al, 1);
     return (countbits > 0 && countbits < 127) ? countbits : 0;
 }
 
-JL_DLLEXPORT int jl_stored_inline(jl_value_t *eltype) JL_NOTSAFEPOINT
+JL_DLLEXPORT int jl_stored_inline(jl_value_t *eltype)
 {
     size_t fsz = 0, al = 0;
     return jl_islayout_inline(eltype, &fsz, &al);

src/jltypes.c

@@ -46,12 +46,10 @@ static int layout_uses_free_typevars(jl_value_t *v, jl_typeenv_t *env)
                layout_uses_free_typevars(((jl_uniontype_t*)v)->b, env);
     if (jl_is_vararg(v)) {
         jl_vararg_t *vm = (jl_vararg_t*)v;
-        if (vm->T) {
-            if (layout_uses_free_typevars(vm->T, env))
-                return 1;
-            if (vm->N && layout_uses_free_typevars(vm->N, env))
-                return 1;
-        }
+        if (vm->T && layout_uses_free_typevars(vm->T, env))
+            return 1;
+        if (vm->N && layout_uses_free_typevars(vm->N, env))
+            return 1;
         return 0;
     }
     if (jl_is_unionall(v)) {

src/julia.h

@@ -1480,8 +1480,8 @@ JL_DLLEXPORT void        jl_set_nth_field(jl_value_t *v, size_t i, jl_value_t *r
 JL_DLLEXPORT int         jl_field_isdefined(jl_value_t *v, size_t i) JL_NOTSAFEPOINT;
 JL_DLLEXPORT jl_value_t *jl_get_field(jl_value_t *o, const char *fld);
 JL_DLLEXPORT jl_value_t *jl_value_ptr(jl_value_t *a);
-int jl_uniontype_size(jl_value_t *ty, size_t *sz) JL_NOTSAFEPOINT;
-JL_DLLEXPORT int jl_islayout_inline(jl_value_t *eltype, size_t *fsz, size_t *al) JL_NOTSAFEPOINT;
+int jl_uniontype_size(jl_value_t *ty, size_t *sz);
+JL_DLLEXPORT int jl_islayout_inline(jl_value_t *eltype, size_t *fsz, size_t *al);
 
 // arrays
 JL_DLLEXPORT jl_array_t *jl_new_array(jl_value_t *atype, jl_value_t *dims);

test/compiler/codegen.jl

@@ -603,6 +603,15 @@ get_llvm(g41438, ()); # cause allocation of layout
 @test S41438{Int}.layout != C_NULL
 @test !Base.datatype_pointerfree(S41438{Int})
 
+
+# issue #43303
+struct A43303{T}
+    x::Pair{Ptr{T},Ptr{T}}
+end
+@test A43303.body.layout != C_NULL
+@test isbitstype(A43303{Int})
+@test A43303.body.types[1].layout != C_NULL
+
 # issue #41157
 f41157(a, b) = a[1] = b[1]
 @test_throws BoundsError f41157(Tuple{Int}[], Tuple{Union{}}[])