[PATCH 4/6] Dwarf: Fortran, support DW_TAG_entry_point.
Wiederhake, Tim
tim.wiederhake@intel.com
Fri Aug 4 11:03:00 GMT 2017
Hi Yao!
> -----Original Message-----
> From: gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] On Behalf Of Yao Qi
> Sent: Wednesday, August 2, 2017 3:15 PM
> To: Wiederhake, Tim <tim.wiederhake@intel.com>
> Cc: gdb-patches@sourceware.org; Bernhard Heckel
> <bernhard.heckel@intel.com>
> Subject: Re: [PATCH 4/6] Dwarf: Fortran, support DW_TAG_entry_point.
>
> Tim Wiederhake <tim.wiederhake@intel.com> writes:
>
> > Fortran provides additional entry-points to an subprogram. Those entry-
> points
> > may have only a subset of parameters of the original subprogram as well.
> >
> > Add support for parsing DW_TAG_entry_point's for Fortran.
>
> Looks gfortran doesn't generate DW_TAG_entry_point now. Could you
> confirm that this patch fix PR 8043 and PR 9279?
Tested and confirmed.
> >
> > xxxx-yy-zz Bernhard Heckel <bernhard.heckel@intel.com>
> > Tim Wiederhake <tim.wiederhake@intel.com>
> >
> > gdb/ChangeLog:
>
> PR fortran/8043
> PR fortran/9279
> > * gdb/dwarf2read.c (add_partial_symbol): Handle DW_TAG_entry_point.
> > (add_partial_entry_point): New function.
> > (add_partial_subprogram): Search for entry_points.
> > (process_die): Handle DW_TAG_entry_point.
> > (dwarf2_get_pc_bounds): Update low pc from DWARF.
> > (load_partial_dies): Save DW_TAG_entry_point's.
> > (load_partial_dies): Save DW_TAG_entry_point to hash table.
> > (load_partial_dies): Look into child's of DW_TAG_sub_program
> > for fortran.
> > (new_symbol_full): Process DW_TAG_entry_point.
> > (read_type_die_1): Handle DW_TAG_entry_point.
> >
> > gdb/testsuite/ChangeLog:
> > * gdb.fortran/entry_point.f90: New file.
> > * gdb.fortran/entry_point.exp: New file.
> >
> >
> > ---
> > gdb/dwarf2read.c | 100
> +++++++++++++++++++++++++++++-
> > gdb/testsuite/gdb.fortran/entry_point.exp | 70 +++++++++++++++++++++
> > gdb/testsuite/gdb.fortran/entry_point.f90 | 48 ++++++++++++++
> > 3 files changed, 217 insertions(+), 1 deletion(-)
> > create mode 100644 gdb/testsuite/gdb.fortran/entry_point.exp
> > create mode 100644 gdb/testsuite/gdb.fortran/entry_point.f90
> >
> > diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
> > index 6d38d70..c3c01a7 100644
> > --- a/gdb/dwarf2read.c
> > +++ b/gdb/dwarf2read.c
> > @@ -1556,6 +1556,10 @@ static void add_partial_module (struct
> partial_die_info *pdi, CORE_ADDR *lowpc,
> > static void add_partial_enumeration (struct partial_die_info *enum_pdi,
> > struct dwarf2_cu *cu);
> >
> > +static void add_partial_entry_point (struct partial_die_info *pdi,
> > + CORE_ADDR *lowpc, CORE_ADDR *highpc,
> > + int need_pc, struct dwarf2_cu *cu);
> > +
> > static void add_partial_subprogram (struct partial_die_info *pdi,
> > CORE_ADDR *lowpc, CORE_ADDR *highpc,
> > int need_pc, struct dwarf2_cu *cu);
> > @@ -7132,6 +7136,32 @@ add_partial_symbol (struct partial_die_info *pdi,
> struct dwarf2_cu *cu)
> >
> > switch (pdi->tag)
> > {
> > + case DW_TAG_entry_point:
> > + {
> > + /* Don't know any other language than fortran which is
> > + using DW_TAG_entry_point. */
> > + if (cu->language == language_fortran)
> > + {
> > + addr = gdbarch_adjust_dwarf2_addr (gdbarch, pdi->lowpc +
> baseaddr);
> > + /* DW_TAG_entry_point provides an additional entry_point to an
> > + existing sub_program. Therefore, we inherit the "external"
> > + attribute from the sub_program to which the entry_point
> > + belongs to. */
> > + if (pdi->die_parent->is_external)
> > + add_psymbol_to_list (actual_name, strlen (actual_name),
> > + built_actual_name != NULL,
> > + VAR_DOMAIN, LOC_BLOCK,
> > + &objfile->global_psymbols,
> > + addr, cu->language, objfile);
> > + else
> > + add_psymbol_to_list (actual_name, strlen (actual_name),
> > + built_actual_name != NULL,
> > + VAR_DOMAIN, LOC_BLOCK,
> > + &objfile->static_psymbols,
> > + addr, cu->language, objfile);
>
> Nit, can you do
>
> add_psymbol_to_list (actual_name, strlen (actual_name),
> built_actual_name != NULL,
> VAR_DOMAIN, LOC_BLOCK,
> pdi->die_parent->is_external ?
> &objfile->global_psymbols : &objfile-
> >static_psymbols,
> addr, cu->language, objfile);
>
> or
>
> auto psymbols = pdi->die_parent->is_external ?
> &objfile->global_psymbols : &objfile-
> >static_psymbols;
>
> add_psymbol_to_list (actual_name, strlen (actual_name),
> built_actual_name != NULL,
> VAR_DOMAIN, LOC_BLOCK,
> psymbols,
> addr, cu->language, objfile);
Changed locally.
> > + }
> > + break;
> > + }
> > case DW_TAG_subprogram:
> > addr = gdbarch_adjust_dwarf2_addr (gdbarch, pdi->lowpc +
> baseaddr);
> > if (pdi->is_external || cu->language == language_ada)
> > @@ -7332,6 +7362,18 @@ add_partial_module (struct partial_die_info *pdi,
> CORE_ADDR *lowpc,
> > scan_partial_symbols (pdi->die_child, lowpc, highpc, set_addrmap,
> cu);
> > }
> >
> > +static void
> > +add_partial_entry_point (struct partial_die_info *pdi,
> > + CORE_ADDR *p_lowpc, CORE_ADDR *p_highpc,
> > + int set_addrmap, struct dwarf2_cu *cu)
> > +{
> > + if (pdi->name == NULL)
> > + complaint (&symfile_complaints,
> > + _("DW_TAG_entry_point have to have a name"));
> > + else
> > + add_partial_symbol (pdi, cu);
> > +}
> > +
> > /* Read a partial die corresponding to a subprogram and create a
> partial
> > symbol for that subprogram. When the CU language allows it, this
> > routine also defines a partial symbol for each nested subprogram
> > @@ -7402,6 +7444,16 @@ add_partial_subprogram (struct partial_die_info
> *pdi,
> > pdi = pdi->die_sibling;
> > }
> > }
> > + else if (cu->language == language_fortran)
> > + {
> > + pdi = pdi->die_child;
> > + while (pdi != NULL)
> > + {
> > + if (pdi->tag == DW_TAG_entry_point)
> > + add_partial_entry_point (pdi, lowpc, highpc, set_addrmap, cu);
>
> In Fortran, is it possible to define "nested functions" or "contained
> routines" within an entry point of a subprogram? like,
>
> subroutine bar
>
> entry foo
>
> contains
> subroutine foo_sub
> entry foo_sub_entry
> end subroutine foo_sub
> entry bar
>
> end subroutine
Will test and report.
> can gdb correctly handle these nested functions and nested entry points?
> My point is that it is better that add_partial_subprogram handles both
> DW_TAG_subprogram and DW_TAG_entry_point first, and then, recursively
> call itself to handle DIE children.
>
> add_partial_subprogram ()
> {
> if (pdi->tag == DW_TAG_subprogram)
> {}
> else if (pdi->tag == DW_TAG_entry_point)
> {}
>
> if (! pdi->has_children)
> return;
>
> if (cu->language == language_ada || cu->language == language_fortran)
> {
> pdi = pdi->die_child;
> while (pdi != NULL)
> {
> fixup_partial_die (pdi, cu);
> if (pdi->tag == DW_TAG_subprogram
> || pdi->tag == DW_TAG_lexical_block
> || pdi->tag == DW_TAG_entry_point)
> add_partial_subprogram (pdi, lowpc, highpc, set_addrmap, cu);
> pdi = pdi->die_sibling;
> }
> }
> }
>
> > + pdi = pdi->die_sibling;
> > + }
> > + }
> > }
> >
> > /* Read a partial die corresponding to an enumeration type. */
> > @@ -8508,6 +8560,7 @@ process_die (struct die_info *die, struct
> dwarf2_cu *cu)
> > case DW_TAG_type_unit:
> > read_type_unit_scope (die, cu);
> > break;
> > + case DW_TAG_entry_point:
> > case DW_TAG_subprogram:
> > case DW_TAG_inlined_subroutine:
> > read_func_scope (die, cu);
> > @@ -12499,6 +12552,27 @@ dwarf2_get_pc_bounds (struct die_info *die,
> CORE_ADDR *lowpc,
> > CORE_ADDR high = 0;
> > enum pc_bounds_kind ret;
> >
> > + if (die->tag == DW_TAG_entry_point)
> > + {
> > + /* Entry_point is embedded in an subprogram. Therefore, we can
> use the
> > + highpc from its enveloping subprogram and get the lowpc from DWARF.
> */
> > + ret = dwarf2_get_pc_bounds (die->parent, lowpc, highpc, cu, pst);
> > + if (ret == PC_BOUNDS_NOT_PRESENT || ret == PC_BOUNDS_INVALID)
> > + return ret;
> > +
> > + attr = dwarf2_attr (die, DW_AT_low_pc, cu);
> > + if (!attr)
> > + {
> > + complaint (&symfile_complaints,
> > + _("DW_TAG_entry_point is missing DW_AT_low_pc"));
> > + return PC_BOUNDS_INVALID;
> > + }
> > + low = attr_value_as_address (attr);
> > + *lowpc = low;
> > +
> > + return PC_BOUNDS_HIGH_LOW;
>
> Why return PC_BOUNDS_HIGH_LOW, which means both DW_AT_low_pc and
> DW_AT_high_pc are found. However, DW_TAG_entry_point doesn't have
> DW_AT_high_pc. The question is why do we call dwarf2_get_pc_bounds for
> DW_TAG_entry_point. Is it because we call read_func_scope for
> DW_TAG_entry_point?
I may be misunderstanding you here. Yes, DW_TAG_entry_point doesn't
have DW_AT_high_pc but we know that value implicitly from the surrounding
subprogram, as explained in the comment above.
> > + }
> > +
> > attr_high = dwarf2_attr (die, DW_AT_high_pc, cu);
> > if (attr_high)
> > {
> > @@ -16029,6 +16103,7 @@ load_partial_dies (const struct die_reader_specs
> *reader,
> > && abbrev->tag != DW_TAG_constant
> > && abbrev->tag != DW_TAG_enumerator
> > && abbrev->tag != DW_TAG_subprogram
> > + && abbrev->tag != DW_TAG_entry_point
> > && abbrev->tag != DW_TAG_lexical_block
> > && abbrev->tag != DW_TAG_variable
> > && abbrev->tag != DW_TAG_namespace
> > @@ -16155,6 +16230,7 @@ load_partial_dies (const struct die_reader_specs
> *reader,
> > if (load_all
> > || abbrev->tag == DW_TAG_constant
> > || abbrev->tag == DW_TAG_subprogram
> > + || abbrev->tag == DW_TAG_entry_point
>
> Could you update the comments above this block?
Sorry, which comments specifically?
The comment directly above the last block states:
DW_AT_abstract_origin refers to functions (and many things under the function DIE [...])"
> > || abbrev->tag == DW_TAG_variable
> > || abbrev->tag == DW_TAG_namespace
> > || part_die->is_declaration)
> > @@ -16197,7 +16273,9 @@ load_partial_dies (const struct die_reader_specs
> *reader,
> > || last_die->tag == DW_TAG_union_type))
> > || (cu->language == language_ada
> > && (last_die->tag == DW_TAG_subprogram
> > - || last_die->tag == DW_TAG_lexical_block))))
> > + || last_die->tag == DW_TAG_lexical_block))
> > + || (cu->language == language_fortran
> > + && last_die->tag == DW_TAG_subprogram)))
>
> Likewise, update comments above. Do we need to check both
> DW_TAG_subprogram and DW_TAG_entry_point?
Changed locally.
> > {
> > nesting_level++;
> > parent_die = last_die;
> > @@ -19058,6 +19136,25 @@ new_symbol_full (struct die_info *die, struct
> type *type, struct dwarf2_cu *cu,
> > SYMBOL_ACLASS_INDEX (sym) = LOC_LABEL;
> > add_symbol_to_list (sym, cu->list_in_scope);
> > break;
> > + case DW_TAG_entry_point:
> > + /* Don't know any other language than fortran which is
> > + using DW_TAG_entry_point. */
> > + if (cu->language == language_fortran)
> > + {
> > + /* SYMBOL_BLOCK_VALUE (sym) will be filled in later by
> > + finish_block. */
> > + SYMBOL_ACLASS_INDEX (sym) = LOC_BLOCK;
> > + /* DW_TAG_entry_point provides an additional entry_point to an
> > + existing sub_program. Therefore, we inherit the "external"
> > + attribute from the sub_program to which the entry_point
> > + belongs to. */
> > + attr2 = dwarf2_attr (die->parent, DW_AT_external, cu);
> > + if (attr2 && (DW_UNSND (attr2) != 0))
>
> if (attr2 != NULL && DW_UNSND (attr2) != 0)
Changed locally.
> > + list_to_add = &global_symbols;
> > + else
> > + list_to_add = cu->list_in_scope;
> > + }
> > + break;
> > case DW_TAG_subprogram:
>
>
> Can we merge to case block for DW_TAG_subprogram and DW_TAG_subprogram?
> They are quite similar.
Merged locally.
>
> --
> Yao (齐尧)
Regards,
Tim
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