Hi!
Before r251949 the debug info for Fortran array descriptors looked correct,
for arrays that had GFC_TYPE_ARRAY_SPAN NULL would use for DW_AT_byte_stride
DW_OP_push_object_address DW_OP_plus_uconst offsetof (, dim[0].__stride)
DW_OP_deref DW_OP_litN DW_OP_mul (where N is the element size in bytes
constant),
and if GFC_TYPE_ARRAY_SPAN is non-NULL, some span.NN variable, then
DW_OP_push_object_address DW_OP_plus_uconst offsetof (, dim[0].__stride)
DW_OP_deref DW_OP_addr span.NN DW_OP_deref DW_OP_mul
Thus, e.g. first dimension's stride in bytes was computed as
descr->dim[0].__stride * element_size or
descr->dim[0].__stride * span.NN
With that change, the span field has been added to descriptors, but now we
always emit the
DW_OP_push_object_address DW_OP_plus_uconst offsetof (, dim[0].__stride)
DW_OP_deref DW_OP_litN DW_OP_mul (where N is the element size in bytes
constant),
aka
descr->dim[0].__stride * element_size
which is incorrect for arrays where descr->span is different from
element_size.
I unfortunately don't see in TYPE_LANG_SPECIFIC anything left that would
record whether the compiler knows the type will certainly have descr->span
equal to element_size, or when it might not, so the following patch always
uses
DW_OP_push_object_address DW_OP_plus_uconst offsetof (, dim[0].__stride)
DW_OP_deref DW_OP_push_object_address DW_OP_plus_uconst offsetof (, span)
DW_OP_deref DW_OP_mul
aka
descr->dim[0].__stride * descr->span
which should be always? correct, but in the common case is 3 bytes longer
than really needed.
Unfortunately, I don't know Fortran enough to find out when exactly the
compiler knows that descr->span will be always equal to element_size, if
somebody could add a bool or unsigned : 1 field into struct lang_type,
corresponding macro and make sure it is set correctly, should be trivial to
tweak the patch so that if the compiler knows for sure it is a waste to
look up descr->span as it must be equal to elem_size to just
compute
elem_size = fold_convert (gfc_array_index_type, TYPE_SIZE_UNIT (etype));
the way it used to be before. Just it needs to be something stored on the
TYPE_LANG_SPECIFIC, as the type is all this hook is called with.
In the meantime, I think it is better to go for correct debug info over
saving the 3 bytes in .debug_info per dimension.
The patch also removes fields/macros that aren't ever used since r251949
and just waste compile time memory.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2019-12-06 Jakub Jelinek <ja...@redhat.com>
PR fortran/92775
* trans.h (struct lang_type, struct lang_decl): Remove span member.
(GFC_DECL_SPAN, GFC_TYPE_ARRAY_SPAN): Remove macros.
* trans-array.h (gfc_get_descriptor_offsets_for_info): Add another
argument.
* trans-array.c (gfc_get_descriptor_offsets_for_info): Add SPAN_OFF
argument and initialize *SPAN_OFF to the offset of span field.
* trans-types.c (gfc_get_array_descr_info): Adjust
gfc_get_descriptor_offsets_for_info caller. Compute elem_size
as base->span instead of TYPE_SIZE_UNIT (etype) constant.
--- gcc/fortran/trans.h.jj 2019-11-11 21:04:05.210259346 +0100
+++ gcc/fortran/trans.h 2019-12-05 11:23:55.935237355 +0100
@@ -981,7 +981,6 @@ struct GTY(()) lang_type {
tree offset;
tree dtype;
tree dataptr_type;
- tree span;
tree base_decl[2];
tree nonrestricted_type;
tree caf_token;
@@ -997,7 +996,6 @@ struct GTY(()) lang_decl {
address of target label. */
tree stringlen;
tree addr;
- tree span;
/* For assumed-shape coarrays. */
tree token, caf_offset;
unsigned int scalar_allocatable : 1;
@@ -1008,7 +1006,6 @@ struct GTY(()) lang_decl {
#define GFC_DECL_ASSIGN_ADDR(node) DECL_LANG_SPECIFIC(node)->addr
#define GFC_DECL_STRING_LEN(node) DECL_LANG_SPECIFIC(node)->stringlen
-#define GFC_DECL_SPAN(node) DECL_LANG_SPECIFIC(node)->span
#define GFC_DECL_TOKEN(node) DECL_LANG_SPECIFIC(node)->token
#define GFC_DECL_CAF_OFFSET(node) DECL_LANG_SPECIFIC(node)->caf_offset
#define GFC_DECL_SAVED_DESCRIPTOR(node) \
@@ -1059,7 +1056,6 @@ struct GTY(()) lang_decl {
#define GFC_TYPE_ARRAY_DTYPE(node) (TYPE_LANG_SPECIFIC(node)->dtype)
#define GFC_TYPE_ARRAY_DATAPTR_TYPE(node) \
(TYPE_LANG_SPECIFIC(node)->dataptr_type)
-#define GFC_TYPE_ARRAY_SPAN(node) (TYPE_LANG_SPECIFIC(node)->span)
#define GFC_TYPE_ARRAY_BASE_DECL(node, internal) \
(TYPE_LANG_SPECIFIC(node)->base_decl[(internal)])
--- gcc/fortran/trans-array.h.jj 2019-09-26 22:02:40.236457478 +0200
+++ gcc/fortran/trans-array.h 2019-12-05 11:07:52.255125510 +0100
@@ -163,7 +163,7 @@ void gfc_trans_array_cobounds (tree, stm
/* Build expressions for accessing components of an array descriptor. */
void gfc_get_descriptor_offsets_for_info (const_tree, tree *, tree *, tree *,
tree *,
- tree *, tree *, tree *);
+ tree *, tree *, tree *, tree *);
tree gfc_conv_descriptor_data_get (tree);
tree gfc_conv_descriptor_data_addr (tree);
--- gcc/fortran/trans-array.c.jj 2019-11-01 09:01:50.111998535 +0100
+++ gcc/fortran/trans-array.c 2019-12-05 11:09:38.545483494 +0100
@@ -540,9 +540,10 @@ gfc_conv_shift_descriptor_lbound (stmtbl
void
gfc_get_descriptor_offsets_for_info (const_tree desc_type, tree *data_off,
- tree *dtype_off, tree *dim_off,
- tree *dim_size, tree *stride_suboff,
- tree *lower_suboff, tree *upper_suboff)
+ tree *dtype_off, tree *span_off,
+ tree *dim_off, tree *dim_size,
+ tree *stride_suboff, tree *lower_suboff,
+ tree *upper_suboff)
{
tree field;
tree type;
@@ -552,6 +553,8 @@ gfc_get_descriptor_offsets_for_info (con
*data_off = byte_position (field);
field = gfc_advance_chain (TYPE_FIELDS (type), DTYPE_FIELD);
*dtype_off = byte_position (field);
+ field = gfc_advance_chain (TYPE_FIELDS (type), SPAN_FIELD);
+ *span_off = byte_position (field);
field = gfc_advance_chain (TYPE_FIELDS (type), DIMENSION_FIELD);
*dim_off = byte_position (field);
type = TREE_TYPE (TREE_TYPE (field));
--- gcc/fortran/trans-types.c.jj 2019-08-27 12:27:05.678497543 +0200
+++ gcc/fortran/trans-types.c 2019-12-05 11:39:33.868747876 +0100
@@ -3266,7 +3266,7 @@ gfc_get_array_descr_info (const_tree typ
int rank, dim;
bool indirect = false;
tree etype, ptype, t, base_decl;
- tree data_off, dim_off, dtype_off, dim_size, elem_size;
+ tree data_off, span_off, dim_off, dtype_off, dim_size, elem_size;
tree lower_suboff, upper_suboff, stride_suboff;
tree dtype, field, rank_off;
@@ -3323,12 +3323,13 @@ gfc_get_array_descr_info (const_tree typ
if (indirect)
base_decl = build1 (INDIRECT_REF, ptype, base_decl);
- elem_size = fold_convert (gfc_array_index_type, TYPE_SIZE_UNIT (etype));
-
- gfc_get_descriptor_offsets_for_info (type, &data_off, &dtype_off, &dim_off,
- &dim_size, &stride_suboff,
+ gfc_get_descriptor_offsets_for_info (type, &data_off, &dtype_off, &span_off,
+ &dim_off, &dim_size, &stride_suboff,
&lower_suboff, &upper_suboff);
+ t = fold_build_pointer_plus (base_decl, span_off);
+ elem_size = build1 (INDIRECT_REF, gfc_array_index_type, t);
+
t = base_decl;
if (!integer_zerop (data_off))
t = fold_build_pointer_plus (t, data_off);
Jakub
