Re: [PATCH] gdb: add gdb_bfd_all_sections for range-based iteration

Simon Marchi
2020-08-27T12:59:42Z

On 2020-08-24 5:30 p.m., Simon Marchi via Gdb-patches wrote:
> On 2020-08-24 4:57 p.m., Tom Tromey wrote:
>>>> I also did this kind of thing -- I have some patches to remove many uses
>>>> of bfd_map_over_sections, though not all of them, since some seem hard
>>>> to test.
>>
>> Simon> What approach did you take?
>>
>> Almost exactly identical to yours -- I named the adapter
>> "gdb_bfd_sections". I can resurrect some of my patches after yours
>> lands.
>>
>> Tom
>>
>
> I modeled the "gdb_bfd_all_sections" on "all_threads" and "all_inferiors". But honestly
> the "all" sounds superfluous now that I re-read it.
>
> I'll push the patch with "all" removed from the name.
>
> Thanks!
>
> Simon
>

I finally did this. I fixed some formatting issues at the same time and made the
print_data parameters references. Here's what I pushed:

From b886559f31fabb8bf234c1818dd01f8987e3c190 Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Thu, 27 Aug 2020 08:58:43 -0400
Subject: [PATCH] gdb: add gdb_bfd_sections for range-based iteration

I wanted to make a nicer / type-safe interface for
bfd_map_over_sections, avoiding the `void *` data parameter.

My first shot was to make a wrapper for bfd_map_over_sections,
gdb_bfd_map_over_sections that took a gdb::function_view.

However, I think that a range adapter gives nicer and simpler code, as a
simple for loop is easier to read than a callback / lambda function. So
here it is, it uses next_iterator and next_adapter, so it's not much
code.

As an example, I ported maintenance_info_sections and friends to use it.
The maint_print_section_data type could probably be removed now, but I
didn't want to do too much in one patch.

gdb/ChangeLog:

* gdb_bfd.h (gdb_bfd_section_iterator, gdb_bfd_section_range,
gdb_bfd_sections): New.
* maint.c (print_bfd_section_info): Change param type to
maint_print_section_data.
(print_objfile_section_info): Likewise.
(print_bfd_section_info_maybe_relocated): Likewise.
(maintenance_info_sections): Use gdb_bfd_sections.

Change-Id: Ib496f6b0a0eb7aadb10da1dd381304014d934ea0
---
gdb/ChangeLog | 10 ++++++++++
gdb/gdb_bfd.h | 18 ++++++++++++++++++
gdb/maint.c | 48 ++++++++++++++++++++++--------------------------
3 files changed, 50 insertions(+), 26 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ceff808d8296..4fd89745713d 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,13 @@
+2020-08-27 Simon Marchi <simon.marchi@polymtl.ca>
+
+ * gdb_bfd.h (gdb_bfd_section_iterator, gdb_bfd_section_range,
+ gdb_bfd_sections): New.
+ * maint.c (print_bfd_section_info): Change param type to
+ maint_print_section_data.
+ (print_objfile_section_info): Likewise.
+ (print_bfd_section_info_maybe_relocated): Likewise.
+ (maintenance_info_sections): Use gdb_bfd_sections.
+
2020-08-25 Shahab Vahedi <shahab@synopsys.com>

* MAINTAINERS: Add ARC target and maintainer.
diff --git a/gdb/gdb_bfd.h b/gdb/gdb_bfd.h
index a941b79fe734..0f450567d50e 100644
--- a/gdb/gdb_bfd.h
+++ b/gdb/gdb_bfd.h
@@ -23,6 +23,7 @@
#include "registry.h"
#include "gdbsupport/byte-vector.h"
#include "gdbsupport/gdb_ref_ptr.h"
+#include "gdbsupport/next-iterator.h"

DECLARE_REGISTRY (bfd);

@@ -193,4 +194,21 @@ int gdb_bfd_requires_relocations (bfd *abfd);
bool gdb_bfd_get_full_section_contents (bfd *abfd, asection *section,
gdb::byte_vector *contents);

+/* Range adapter for a BFD's sections.
+
+ To be used as:
+
+ for (asection *sect : gdb_bfd_all_sections (bfd))
+ ... use SECT ...
+ */
+
+using gdb_bfd_section_iterator = next_iterator<asection>;
+using gdb_bfd_section_range = next_adapter<asection, gdb_bfd_section_iterator>;
+
+static inline
+gdb_bfd_section_range gdb_bfd_sections (bfd *abfd)
+{
+ return gdb_bfd_section_range (abfd->sections);
+}
+
#endif /* GDB_BFD_H */
diff --git a/gdb/maint.c b/gdb/maint.c
index 3368769ad96f..be0b1605159a 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -266,7 +266,7 @@ struct maint_print_section_data
maint_print_section_data (struct objfile *objfile, const char *arg,
bfd *abfd)
: objfile (objfile),
- arg(arg)
+ arg (arg)
{
int section_count = gdb_bfd_count_sections (abfd);
index_digits = ((int) log10 ((float) section_count)) + 1;
@@ -292,21 +292,19 @@ print_section_index (bfd *abfd,
printf_filtered ("%-*s", (index_digits + 4), result.c_str ());
}

-/* Print information about ASECT from ABFD. DATUM holds a pointer to a
- maint_print_section_data object. The section will be printed using the
- VMA's from the bfd, which will not be the relocated addresses for bfds
- that should be relocated. The information must be printed with the
- same layout as PRINT_OBJFILE_SECTION_INFO below. */
+/* Print information about ASECT from ABFD. The section will be printed using
+ the VMA's from the bfd, which will not be the relocated addresses for bfds
+ that should be relocated. The information must be printed with the same
+ layout as PRINT_OBJFILE_SECTION_INFO below. */

static void
print_bfd_section_info (bfd *abfd,
asection *asect,
- void *datum)
+ const maint_print_section_data &print_data)
{
flagword flags = bfd_section_flags (asect);
const char *name = bfd_section_name (asect);
- maint_print_section_data *print_data = (maint_print_section_data *) datum;
- const char *arg = print_data->arg;
+ const char *arg = print_data.arg;

if (arg == NULL || *arg == '\0'
|| match_substring (arg, name)
@@ -318,7 +316,7 @@ print_bfd_section_info (bfd *abfd,

addr = bfd_section_vma (asect);
endaddr = addr + bfd_section_size (asect);
- print_section_index (abfd, asect, print_data->index_digits);
+ print_section_index (abfd, asect, print_data.index_digits);
maint_print_section_info (name, flags, addr, endaddr,
asect->filepos, addr_size);
}
@@ -332,11 +330,11 @@ print_bfd_section_info (bfd *abfd,
static void
print_objfile_section_info (bfd *abfd,
struct obj_section *asect,
- maint_print_section_data *print_data)
+ const maint_print_section_data &print_data)
{
flagword flags = bfd_section_flags (asect->the_bfd_section);
const char *name = bfd_section_name (asect->the_bfd_section);
- const char *string = print_data->arg;
+ const char *string = print_data.arg;

if (string == NULL || *string == '\0'
|| match_substring (string, name)
@@ -346,7 +344,7 @@ print_objfile_section_info (bfd *abfd,
int addr_size = gdbarch_addr_bit (gdbarch) / 8;

print_section_index (abfd, asect->the_bfd_section,
- print_data->index_digits);
+ print_data.index_digits);
maint_print_section_info (name, flags,
obj_section_addr (asect),
obj_section_endaddr (asect),
@@ -376,24 +374,21 @@ maint_obj_section_from_bfd_section (bfd *abfd,
return osect;
}

-/* Print information about ASECT from ABFD. DATUM holds a pointer to a
- maint_print_section_data object. Where possible the information for
+/* Print information about ASECT from ABFD. Where possible the information for
ASECT will print the relocated addresses of the section. */

static void
-print_bfd_section_info_maybe_relocated (bfd *abfd,
- asection *asect,
- void *datum)
+print_bfd_section_info_maybe_relocated
+ (bfd *abfd, asection *asect, const maint_print_section_data &print_data)
{
- maint_print_section_data *print_data = (maint_print_section_data *) datum;
- objfile *objfile = print_data->objfile;
+ objfile *objfile = print_data.objfile;

gdb_assert (objfile->sections != NULL);
obj_section *osect
= maint_obj_section_from_bfd_section (abfd, asect, objfile);

if (osect->the_bfd_section == NULL)
- print_bfd_section_info (abfd, asect, datum);
+ print_bfd_section_info (abfd, asect, print_data);
else
print_objfile_section_info (abfd, osect, print_data);
}
@@ -432,9 +427,9 @@ maintenance_info_sections (const char *arg, int from_tty)

maint_print_section_data print_data (ofile, arg, ofile->obfd);

- bfd_map_over_sections (ofile->obfd,
- print_bfd_section_info_maybe_relocated,
- (void *) &print_data);
+ for (asection *sect : gdb_bfd_sections (ofile->obfd))
+ print_bfd_section_info_maybe_relocated (ofile->obfd, sect,
+ print_data);
}
}

@@ -446,8 +441,9 @@ maintenance_info_sections (const char *arg, int from_tty)
printf_filtered (" `%s', ", bfd_get_filename (core_bfd));
wrap_here (" ");
printf_filtered (_("file type %s.\n"), bfd_get_target (core_bfd));
- bfd_map_over_sections (core_bfd, print_bfd_section_info,
- (void *) &print_data);
+
+ for (asection *sect : gdb_bfd_sections (core_bfd))
+ print_bfd_section_info (core_bfd, sect, print_data);
}
}

--
2.28.0