From e029b9300c58a0ffbfa1b7f81381a937a60b27fd Mon Sep 17 00:00:00 2001
From: Pierre-Marie de Rodat <derodat@adacore.com>
Date: Wed, 3 Sep 2014 09:46:32 +0200
Subject: [PATCH 5/5] dwarf2out.c: do not short-circuit add_bound_info in array
lang-hook
gcc/
* dwarf2out.h (struct array_descr_info): Remove the base_decl field.
* dwarf2out.c (init_array_descr_info): Update accordingly.
(enum dw_scalar_form): New.
(add_scalar_info): New.
(loc_list_from_tree): Handle PLACEHOLDER_EXPR nodes for
type-related expressions.
(add_bound_info): Use add_scalar_info.
(descr_info_loc): Remove.
(add_descr_info_field): Remove.
(gen_descr_array_type_die): Switch add_descr_info_field calls
into add_scalar_info/add_bound_info ones.
gcc/ada/
* gcc-interface/misc.c (gnat_get_array_descr_info): Remove base_decl
initialization.
gcc/fortran/
* trans-types.c (gfc_get_array_descr_info): Use PLACEHOLDER_EXPR nodes
instead of VAR_DECL ones in type-related expressions. Remove base_decl
initialization.
---
gcc/ada/gcc-interface/misc.c | 1 -
gcc/dwarf2out.c | 434 ++++++++++++++++++++-----------------------
gcc/dwarf2out.h | 1 -
gcc/fortran/trans-types.c | 5 +-
4 files changed, 203 insertions(+), 238 deletions(-)
@@ -658,7 +658,6 @@ gnat_get_array_descr_info (const_tree type, struct array_descr_info *info)
info->ordering = (convention_fortran_p
? array_descr_ordering_column_major
: array_descr_ordering_row_major);
- info->base_decl = NULL_TREE;
info->data_location = NULL_TREE;
info->allocated = NULL_TREE;
info->associated = NULL_TREE;
@@ -2981,6 +2981,15 @@ static bool frame_pointer_fb_offset_valid;
static vec<dw_die_ref> base_types;
+/* Flags to represent a set of attribute classes for attributes that represent
+ a scalar value (bounds, pointers, ...). */
+enum dw_scalar_form
+{
+ dw_scalar_form_constant = 0x01,
+ dw_scalar_form_exprloc = 0x02,
+ dw_scalar_form_reference = 0x04
+};
+
/* Forward declarations for functions defined in this file. */
static int is_pseudo_reg (const_rtx);
@@ -3186,6 +3195,7 @@ static bool tree_add_const_value_attribute_for_decl (dw_die_ref, tree);
static void add_name_attribute (dw_die_ref, const char *);
static void add_gnat_descriptive_type_attribute (dw_die_ref, tree, dw_die_ref);
static void add_comp_dir_attribute (dw_die_ref);
+static void add_scalar_info (dw_die_ref, enum dwarf_attribute, tree, int);
static void add_bound_info (dw_die_ref, enum dwarf_attribute, tree);
static void add_subscript_info (dw_die_ref, tree, bool);
static void add_byte_size_attribute (dw_die_ref, tree);
@@ -14283,11 +14293,19 @@ loc_list_from_tree (tree loc, int want_address)
case PLACEHOLDER_EXPR:
/* This case involves extracting fields from an object to determine the
- position of other fields. We don't try to encode this here. The
- only user of this is Ada, which encodes the needed information using
- the names of types. */
- expansion_failed (loc, NULL_RTX, "PLACEHOLDER_EXPR");
- return 0;
+ position of other fields. It is supposed to appear only as the first
+ operand of COMPONENT_REF nodes. */
+ if (TREE_CODE (TREE_TYPE (loc)) == RECORD_TYPE
+ && want_address >= 1)
+ {
+ ret = new_loc_descr (DW_OP_push_object_address, 0, 0);
+ have_address = 1;
+ break;
+ }
+ else
+ expansion_failed (loc, NULL_RTX,
+ "PLACEHOLDER_EXPR for a non-structure");
+ break;
case CALL_EXPR:
expansion_failed (loc, NULL_RTX, "CALL_EXPR");
@@ -16389,6 +16407,141 @@ add_comp_dir_attribute (dw_die_ref die)
add_AT_string (die, DW_AT_comp_dir, wd);
}
+/* Given a tree node VALUE describing a scalar attribute ATTR (i.e. a bound, a
+ pointer computation, ...), output a representation for that bound according
+ to the accepted FORMS (see enum dw_scalar_form) and add it to DIE. */
+
+static void
+add_scalar_info (dw_die_ref die, enum dwarf_attribute attr, tree value,
+ int forms)
+{
+ dw_die_ref ctx, decl_die;
+ dw_loc_list_ref list;
+
+ bool pell_conversions = true;
+
+ while (pell_conversions)
+ switch (TREE_CODE (value))
+ {
+ case ERROR_MARK:
+ case SAVE_EXPR:
+ return;
+
+ CASE_CONVERT:
+ case VIEW_CONVERT_EXPR:
+ value = TREE_OPERAND (value, 0);
+ break;
+
+ default:
+ pell_conversions = false;
+ break;
+ }
+
+ /* If possible and permitted, output the attribute as a constant. */
+ if ((forms & dw_scalar_form_constant) != 0
+ && TREE_CODE (value) == INTEGER_CST)
+ {
+ unsigned int prec = simple_type_size_in_bits (TREE_TYPE (value));
+
+ /* If HOST_WIDE_INT is big enough then represent the bound as
+ a constant value. We need to choose a form based on
+ whether the type is signed or unsigned. We cannot just
+ call add_AT_unsigned if the value itself is positive
+ (add_AT_unsigned might add the unsigned value encoded as
+ DW_FORM_data[1248]). Some DWARF consumers will lookup the
+ bounds type and then sign extend any unsigned values found
+ for signed types. This is needed only for
+ DW_AT_{lower,upper}_bound, since for most other attributes,
+ consumers will treat DW_FORM_data[1248] as unsigned values,
+ regardless of the underlying type. */
+ if (prec <= HOST_BITS_PER_WIDE_INT
+ || tree_fits_uhwi_p (value))
+ {
+ if (TYPE_UNSIGNED (TREE_TYPE (value)))
+ add_AT_unsigned (die, attr, TREE_INT_CST_LOW (value));
+ else
+ add_AT_int (die, attr, TREE_INT_CST_LOW (value));
+ }
+ else
+ /* Otherwise represent the bound as an unsigned value with
+ the precision of its type. The precision and signedness
+ of the type will be necessary to re-interpret it
+ unambiguously. */
+ add_AT_wide (die, attr, value);
+ }
+
+ /* Otherwise, if it's possible and permitted too, output a reference to
+ another DIE. */
+ if ((forms & dw_scalar_form_reference) != 0)
+ {
+ tree decl = NULL_TREE;
+
+ /* Some type attributes reference an outer type. For instance, the upper
+ bound of an array may reference an embedding record (this happens in
+ Ada). */
+ if (TREE_CODE (value) == COMPONENT_REF
+ && TREE_CODE (TREE_OPERAND (value, 0)) == PLACEHOLDER_EXPR
+ && TREE_CODE (TREE_OPERAND (value, 1)) == FIELD_DECL)
+ decl = TREE_OPERAND (value, 1);
+
+ else if (TREE_CODE (value) == VAR_DECL
+ || TREE_CODE (value) == PARM_DECL
+ || TREE_CODE (value) == RESULT_DECL)
+ decl = value;
+
+ if (decl != NULL_TREE)
+ {
+ dw_die_ref decl_die = lookup_decl_die (decl);
+
+ /* ??? Can this happen, or should the variable have been bound
+ first? Probably it can, since I imagine that we try to create
+ the types of parameters in the order in which they exist in
+ the list, and won't have created a forward reference to a
+ later parameter. */
+ if (decl_die != NULL)
+ {
+ add_AT_die_ref (die, attr, decl_die);
+ return;
+ }
+ }
+ }
+
+ /* Last chance: try to create a stack operation procedure to evaluate the
+ value. Do nothing if even that is not possible or permitted. */
+ if ((forms & dw_scalar_form_exprloc) == 0)
+ return;
+
+ list = loc_list_from_tree (value, 2);
+ if (list == NULL || single_element_loc_list_p (list))
+ {
+ /* If this attribute is not a reference nor constant, it is
+ a DWARF expression rather than location description. For that
+ loc_list_from_tree (value, 0) is needed. */
+ dw_loc_list_ref list2 = loc_list_from_tree (value, 0);
+ if (list2 && single_element_loc_list_p (list2))
+ {
+ add_AT_loc (die, attr, list2->expr);
+ return;
+ }
+ }
+
+ /* If that failed to give a single element location list, fall back to
+ outputting this as a reference... still if permitted. */
+ if (list == NULL || (forms & dw_scalar_form_reference) == 0)
+ return;
+
+ if (current_function_decl == 0)
+ ctx = comp_unit_die ();
+ else
+ ctx = lookup_decl_die (current_function_decl);
+
+ decl_die = new_die (DW_TAG_variable, ctx, value);
+ add_AT_flag (decl_die, DW_AT_artificial, 1);
+ add_type_attribute (decl_die, TREE_TYPE (value), TYPE_QUAL_CONST, ctx);
+ add_AT_location_description (decl_die, DW_AT_location, list);
+ add_AT_die_ref (die, attr, decl_die);
+}
+
/* Return the default for DW_AT_lower_bound, or -1 if there is not any
default. */
@@ -16430,121 +16583,40 @@ lower_bound_default (void)
a representation for that bound. */
static void
-add_bound_info (dw_die_ref subrange_die, enum dwarf_attribute bound_attr, tree bound)
+add_bound_info (dw_die_ref subrange_die, enum dwarf_attribute bound_attr,
+ tree bound)
{
- switch (TREE_CODE (bound))
- {
- case ERROR_MARK:
- return;
+ int dflt;
- /* All fixed-bounds are represented by INTEGER_CST nodes. */
- case INTEGER_CST:
+ while (1)
+ switch (TREE_CODE (bound))
{
- unsigned int prec = simple_type_size_in_bits (TREE_TYPE (bound));
- int dflt;
+ /* Pell all conversions. */
+ CASE_CONVERT:
+ case VIEW_CONVERT_EXPR:
+ bound = TREE_OPERAND (bound, 0);
+ break;
- /* Use the default if possible. */
+ /* All fixed-bounds are represented by INTEGER_CST nodes. Lower bounds
+ are even omitted when they are the default. */
+ case INTEGER_CST:
+ /* If the value for this bound is the default one, we can even omit the
+ attribute. */
if (bound_attr == DW_AT_lower_bound
&& tree_fits_shwi_p (bound)
&& (dflt = lower_bound_default ()) != -1
&& tree_to_shwi (bound) == dflt)
- ;
-
- /* If HOST_WIDE_INT is big enough then represent the bound as
- a constant value. We need to choose a form based on
- whether the type is signed or unsigned. We cannot just
- call add_AT_unsigned if the value itself is positive
- (add_AT_unsigned might add the unsigned value encoded as
- DW_FORM_data[1248]). Some DWARF consumers will lookup the
- bounds type and then sign extend any unsigned values found
- for signed types. This is needed only for
- DW_AT_{lower,upper}_bound, since for most other attributes,
- consumers will treat DW_FORM_data[1248] as unsigned values,
- regardless of the underlying type. */
- else if (prec <= HOST_BITS_PER_WIDE_INT
- || tree_fits_uhwi_p (bound))
- {
- if (TYPE_UNSIGNED (TREE_TYPE (bound)))
- add_AT_unsigned (subrange_die, bound_attr,
- TREE_INT_CST_LOW (bound));
- else
- add_AT_int (subrange_die, bound_attr, TREE_INT_CST_LOW (bound));
- }
- else
- /* Otherwise represent the bound as an unsigned value with
- the precision of its type. The precision and signedness
- of the type will be necessary to re-interpret it
- unambiguously. */
- add_AT_wide (subrange_die, bound_attr, bound);
- }
- break;
-
- CASE_CONVERT:
- case VIEW_CONVERT_EXPR:
- add_bound_info (subrange_die, bound_attr, TREE_OPERAND (bound, 0));
- break;
-
- case SAVE_EXPR:
- break;
-
- case VAR_DECL:
- case PARM_DECL:
- case RESULT_DECL:
- {
- dw_die_ref decl_die = lookup_decl_die (bound);
-
- /* ??? Can this happen, or should the variable have been bound
- first? Probably it can, since I imagine that we try to create
- the types of parameters in the order in which they exist in
- the list, and won't have created a forward reference to a
- later parameter. */
- if (decl_die != NULL)
- {
- add_AT_die_ref (subrange_die, bound_attr, decl_die);
- break;
- }
- }
- /* FALLTHRU */
-
- default:
- {
- /* Otherwise try to create a stack operation procedure to
- evaluate the value of the array bound. */
-
- dw_die_ref ctx, decl_die;
- dw_loc_list_ref list;
-
- list = loc_list_from_tree (bound, 2);
- if (list == NULL || single_element_loc_list_p (list))
- {
- /* If DW_AT_*bound is not a reference nor constant, it is
- a DWARF expression rather than location description.
- For that loc_list_from_tree (bound, 0) is needed.
- If that fails to give a single element list,
- fall back to outputting this as a reference anyway. */
- dw_loc_list_ref list2 = loc_list_from_tree (bound, 0);
- if (list2 && single_element_loc_list_p (list2))
- {
- add_AT_loc (subrange_die, bound_attr, list2->expr);
- break;
- }
- }
- if (list == NULL)
- break;
+ return;
- if (current_function_decl == 0)
- ctx = comp_unit_die ();
- else
- ctx = lookup_decl_die (current_function_decl);
+ /* FALLTHRU */
- decl_die = new_die (DW_TAG_variable, ctx, bound);
- add_AT_flag (decl_die, DW_AT_artificial, 1);
- add_type_attribute (decl_die, TREE_TYPE (bound), TYPE_QUAL_CONST, ctx);
- add_AT_location_description (decl_die, DW_AT_location, list);
- add_AT_die_ref (subrange_die, bound_attr, decl_die);
- break;
+ default:
+ add_scalar_info (subrange_die, bound_attr, bound,
+ dw_scalar_form_constant
+ | dw_scalar_form_exprloc
+ | dw_scalar_form_reference);
+ return;
}
- }
}
/* Add subscript info to TYPE_DIE, describing an array TYPE, collapsing
@@ -17332,99 +17404,6 @@ gen_array_type_die (tree type, dw_die_ref context_die)
add_pubtype (type, array_die);
}
-static dw_loc_descr_ref
-descr_info_loc (tree val, tree base_decl)
-{
- HOST_WIDE_INT size;
- dw_loc_descr_ref loc, loc2;
- enum dwarf_location_atom op;
-
- if (val == base_decl)
- return new_loc_descr (DW_OP_push_object_address, 0, 0);
-
- switch (TREE_CODE (val))
- {
- CASE_CONVERT:
- return descr_info_loc (TREE_OPERAND (val, 0), base_decl);
- case VAR_DECL:
- return loc_descriptor_from_tree (val, 0);
- case INTEGER_CST:
- if (tree_fits_shwi_p (val))
- return int_loc_descriptor (tree_to_shwi (val));
- break;
- case INDIRECT_REF:
- size = int_size_in_bytes (TREE_TYPE (val));
- if (size < 0)
- break;
- loc = descr_info_loc (TREE_OPERAND (val, 0), base_decl);
- if (!loc)
- break;
- if (size == DWARF2_ADDR_SIZE)
- add_loc_descr (&loc, new_loc_descr (DW_OP_deref, 0, 0));
- else
- add_loc_descr (&loc, new_loc_descr (DW_OP_deref_size, size, 0));
- return loc;
- case POINTER_PLUS_EXPR:
- case PLUS_EXPR:
- if (tree_fits_uhwi_p (TREE_OPERAND (val, 1))
- && tree_to_uhwi (TREE_OPERAND (val, 1)) < 16384)
- {
- loc = descr_info_loc (TREE_OPERAND (val, 0), base_decl);
- if (!loc)
- break;
- loc_descr_plus_const (&loc, tree_to_shwi (TREE_OPERAND (val, 1)));
- }
- else
- {
- op = DW_OP_plus;
- do_binop:
- loc = descr_info_loc (TREE_OPERAND (val, 0), base_decl);
- if (!loc)
- break;
- loc2 = descr_info_loc (TREE_OPERAND (val, 1), base_decl);
- if (!loc2)
- break;
- add_loc_descr (&loc, loc2);
- add_loc_descr (&loc2, new_loc_descr (op, 0, 0));
- }
- return loc;
- case MINUS_EXPR:
- op = DW_OP_minus;
- goto do_binop;
- case MULT_EXPR:
- op = DW_OP_mul;
- goto do_binop;
- case EQ_EXPR:
- op = DW_OP_eq;
- goto do_binop;
- case NE_EXPR:
- op = DW_OP_ne;
- goto do_binop;
- default:
- break;
- }
- return NULL;
-}
-
-static void
-add_descr_info_field (dw_die_ref die, enum dwarf_attribute attr,
- tree val, tree base_decl)
-{
- dw_loc_descr_ref loc;
-
- if (tree_fits_shwi_p (val))
- {
- add_AT_unsigned (die, attr, tree_to_shwi (val));
- return;
- }
-
- loc = descr_info_loc (val, base_decl);
- if (!loc)
- return;
-
- add_AT_loc (die, attr, loc);
-}
-
/* This routine generates DIE for array with hidden descriptor, details
are filled into *info by a langhook. */
@@ -17466,15 +17445,18 @@ gen_descr_array_type_die (tree type, struct array_descr_info *info,
if (dwarf_version >= 3 || !dwarf_strict)
{
if (info->data_location)
- add_descr_info_field (array_die, DW_AT_data_location,
- info->data_location,
- info->base_decl);
+ add_scalar_info (array_die, DW_AT_data_location, info->data_location,
+ dw_scalar_form_exprloc);
if (info->associated)
- add_descr_info_field (array_die, DW_AT_associated, info->associated,
- info->base_decl);
+ add_scalar_info (array_die, DW_AT_associated, info->associated,
+ dw_scalar_form_constant
+ | dw_scalar_form_exprloc
+ | dw_scalar_form_reference);
if (info->allocated)
- add_descr_info_field (array_die, DW_AT_allocated, info->allocated,
- info->base_decl);
+ add_scalar_info (array_die, DW_AT_allocated, info->allocated,
+ dw_scalar_form_constant
+ | dw_scalar_form_exprloc
+ | dw_scalar_form_reference);
}
add_gnat_descriptive_type_attribute (array_die, type, context_die);
@@ -17489,30 +17471,17 @@ gen_descr_array_type_die (tree type, struct array_descr_info *info,
info->dimen[dim].bounds_type, 0,
context_die);
if (info->dimen[dim].lower_bound)
- {
- /* If it is the default value, omit it. */
- int dflt;
-
- if (tree_fits_shwi_p (info->dimen[dim].lower_bound)
- && (dflt = lower_bound_default ()) != -1
- && tree_to_shwi (info->dimen[dim].lower_bound) == dflt)
- ;
- else
- add_descr_info_field (subrange_die, DW_AT_lower_bound,
- info->dimen[dim].lower_bound,
- info->base_decl);
- }
+ add_bound_info (subrange_die, DW_AT_lower_bound,
+ info->dimen[dim].lower_bound);
if (info->dimen[dim].upper_bound)
- add_descr_info_field (subrange_die, DW_AT_upper_bound,
- info->dimen[dim].upper_bound,
- info->base_decl);
- if (dwarf_version >= 3 || !dwarf_strict)
- {
- if (info->dimen[dim].stride)
- add_descr_info_field (subrange_die, DW_AT_byte_stride,
- info->dimen[dim].stride,
- info->base_decl);
- }
+ add_bound_info (subrange_die, DW_AT_upper_bound,
+ info->dimen[dim].upper_bound);
+ if ((dwarf_version >= 3 || !dwarf_strict) && info->dimen[dim].stride)
+ add_scalar_info (subrange_die, DW_AT_byte_stride,
+ info->dimen[dim].stride,
+ dw_scalar_form_constant
+ | dw_scalar_form_exprloc
+ | dw_scalar_form_reference);
}
gen_type_die (info->element_type, context_die);
@@ -19999,7 +19968,6 @@ init_array_descr_info (struct array_descr_info *info)
info->ndimensions = 0;
info->ordering = array_descr_ordering_default;
info->element_type = NULL_TREE;
- info->base_decl = NULL_TREE;
info->data_location = NULL_TREE;
info->allocated = NULL_TREE;
info->associated = NULL_TREE;
@@ -274,7 +274,6 @@ struct array_descr_info
int ndimensions;
enum array_descr_ordering ordering;
tree element_type;
- tree base_decl;
tree data_location;
tree allocated;
tree associated;
@@ -3039,11 +3039,10 @@ gfc_get_array_descr_info (const_tree type, struct array_descr_info *info)
base_decl = GFC_TYPE_ARRAY_BASE_DECL (type, indirect);
if (!base_decl)
{
- base_decl = build_decl (input_location, VAR_DECL, NULL_TREE,
- indirect ? build_pointer_type (ptype) : ptype);
+ base_decl = build0 (PLACEHOLDER_EXPR,
+ indirect ? build_pointer_type (ptype) : ptype);
GFC_TYPE_ARRAY_BASE_DECL (type, indirect) = base_decl;
}
- info->base_decl = base_decl;
if (indirect)
base_decl = build1 (INDIRECT_REF, ptype, base_decl);
--
2.1.0
Hi! I'm currently working on improving the debug information output for GNAT (the Ada frontend in GCC), which currently uses non-standard DWARF to describe complex types. Lately, I focused on debug information for arrays and the attached inter-dependent patches are an attempt to do so: - they enhance the existing "array_descr_info" language hook; - they adjust the Fortran front-end accordingly (it's the only array_descr_info user currently); - they make the Ada front-end use this hook. Here are more details about what motivated each patch: 1. This first patch enhances the array_descr_info language hook so that front-end can pass more information about array types to the DWARF backend: - Array ordering (column/row major) so that the information that Fortran arrays are column major ordered comes from the Fortran front-end and so that later GNAT can decide itself for each array type (they can be both column and row major ordered). - Bounds type: Ada arrays can be indexed by integers but also characters, enumerated types, etc. However it seems that the middle-end makes the assumption that every array index is sizetype so this information is needed here for accurate debug info. It also makes the language hook generate "GNAT descriptive type" attributes for array types, just as the regular array types handling in dwarf2out.c does. Finally, it makes the DWARF back-end initialize the "array_descr_info" structure so that new fields can be added to it later without affecting existing front-ends that use this hook. 2. Currently, this language hook is enabled only when (dwarf_version >= 3 || !dwarf_strict). The hook generates information that is mostly valid for strict DWARFv2, though. The second patch enables this language hook every time and instead prevents the emission for some attributes when needed. 3. This one enables the array_descr_info hook in GNAT. 4. This one enhances debug helpers in dwarf2out.c to ease location descriptions (DWARF expressions) bugs investigation. 5. The array_descr_info hook has its own circuitry in dwarf2out.c to generate location description: add_descr_info_field. It is a duplicate of loc_list_from_tree and less powerful except that it handles "self-referencial attributes". This final patch is an attempt to merge these two circuitries so that this hook can generate more complex DWARF expressions. It also adjusts the Fortran front-end accordingly. These patches were tested on x86_64-pc-linux-gnu. They trigger no regression in the GCC DejaGNU testsuite nor in the GDB one (they fix some failures however). Ok for trunk? Thank you very much for reading until this point and thank you in advance for your review! ;-)