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gdb: make gdbarch store a vector of frame unwinders

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Before this commit, all frame unwinders would be stored in the obstack
of a gdbarch and accessed by using the registry system. This made for
unwieldy code, and unnecessarily complex logic in the frame_unwinder
implementation, along with making frame_unwind structs be unable to have
non-trivial constructors.

Seeing as a future patch of this series wants to refactor the
frame_unwind struct to use inheritance, obstack storage would no longer
be viable. In preparation for that change, this commit adds an
std::vector to gdbarch to store the unwinders in.

There should be no user-visible changes.
This commit is contained in:
Guinevere Larsen
2024-01-18 14:25:14 +01:00
parent b235e90e74
commit e961aad01f
5 changed files with 61 additions and 69 deletions
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8
gdb/arch-utils.c
View File

@@ -1218,6 +1218,14 @@ obstack *gdbarch_obstack (gdbarch *arch)
/* See gdbarch.h. */
std::vector<const frame_unwind*>&
gdbarch_get_unwinder_list (struct gdbarch *arch)
{
return arch->unwinders;
}
/* See gdbarch.h. */
char *
gdbarch_obstack_strdup (struct gdbarch *arch, const char *string)
{

111
gdb/frame-unwind.c
View File

@@ -31,49 +31,16 @@
#include "cli/cli-cmds.h"
#include "inferior.h"
struct frame_unwind_table_entry
/* If an unwinder should be prepended to the list, this is the
index in which it should be inserted. */
static int osabi_start = -1;
/* Start the table out with a few default sniffers. OSABI code
can't override this. */
static void
initialize_frame_unwind_table (std::vector<const frame_unwind*>& table)
{
const struct frame_unwind *unwinder;
struct frame_unwind_table_entry *next;
};
struct frame_unwind_table
{
struct frame_unwind_table_entry *list = nullptr;
/* The head of the OSABI part of the search list. */
struct frame_unwind_table_entry **osabi_head = nullptr;
};
static const registry<gdbarch>::key<struct frame_unwind_table>
frame_unwind_data;
/* A helper function to add an unwinder to a list. LINK says where to
install the new unwinder. The new link is returned. */
static struct frame_unwind_table_entry **
add_unwinder (struct obstack *obstack, const struct frame_unwind *unwinder,
struct frame_unwind_table_entry **link)
{
*link = OBSTACK_ZALLOC (obstack, struct frame_unwind_table_entry);
(*link)->unwinder = unwinder;
return &(*link)->next;
}
static struct frame_unwind_table *
get_frame_unwind_table (struct gdbarch *gdbarch)
{
struct frame_unwind_table *table = frame_unwind_data.get (gdbarch);
if (table != nullptr)
return table;
table = new frame_unwind_table;
/* Start the table out with a few default sniffers. OSABI code
can't override this. */
struct frame_unwind_table_entry **link = &table->list;
struct obstack *obstack = gdbarch_obstack (gdbarch);
link = add_unwinder (obstack, &dummy_frame_unwind, link);
table.push_back (&dummy_frame_unwind);
/* The DWARF tailcall sniffer must come before the inline sniffer.
Otherwise, we can end up in a situation where a DWARF frame finds
tailcall information, but then the inline sniffer claims a frame
@@ -81,12 +48,22 @@ get_frame_unwind_table (struct gdbarch *gdbarch)
safe to do always because the tailcall sniffer can only ever be
activated if the newer frame was created using the DWARF
unwinder, and it also found tailcall information. */
link = add_unwinder (obstack, &dwarf2_tailcall_frame_unwind, link);
link = add_unwinder (obstack, &inline_frame_unwind, link);
table.push_back (&dwarf2_tailcall_frame_unwind);
table.push_back (&inline_frame_unwind);
/* The insertion point for OSABI sniffers. */
table->osabi_head = link;
frame_unwind_data.set (gdbarch, table);
osabi_start = table.size ();
}
/* This function call retrieves the list of frame unwinders available in
GDBARCH. If this list is empty, it is initialized before being
returned. */
static std::vector<const frame_unwind*>&
get_frame_unwind_table (struct gdbarch *gdbarch)
{
std::vector<const frame_unwind*>& table = gdbarch_get_unwinder_list (gdbarch);
if (table.size () == 0)
initialize_frame_unwind_table (table);
return table;
}
@@ -95,27 +72,25 @@ void
frame_unwind_prepend_unwinder (struct gdbarch *gdbarch,
const struct frame_unwind *unwinder)
{
struct frame_unwind_table *table = get_frame_unwind_table (gdbarch);
struct frame_unwind_table_entry *entry;
std::vector<const frame_unwind*>& table = get_frame_unwind_table (gdbarch);
/* Insert the new entry at the start of the list. */
entry = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry);
entry->unwinder = unwinder;
entry->next = (*table->osabi_head);
(*table->osabi_head) = entry;
gdb_assert (osabi_start >= 0);
table.push_back (unwinder);
/* Bubble the new entry up to where new unwinders are allowed to be
inserterd. */
for (int i = table.size() - 1; i > osabi_start; i--)
std::swap(table[i], table[i-1]);
}
void
frame_unwind_append_unwinder (struct gdbarch *gdbarch,
const struct frame_unwind *unwinder)
{
struct frame_unwind_table *table = get_frame_unwind_table (gdbarch);
struct frame_unwind_table_entry **ip;
std::vector<const frame_unwind*>& table = get_frame_unwind_table (gdbarch);
/* Find the end of the list and insert the new entry there. */
for (ip = table->osabi_head; (*ip) != NULL; ip = &(*ip)->next);
(*ip) = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry);
(*ip)->unwinder = unwinder;
table.push_back (unwinder);
}
/* Call SNIFFER from UNWINDER. If it succeeded set UNWINDER for
@@ -188,9 +163,6 @@ frame_unwind_find_by_frame (frame_info_ptr this_frame, void **this_cache)
FRAME_SCOPED_DEBUG_ENTER_EXIT;
frame_debug_printf ("this_frame=%d", frame_relative_level (this_frame));
struct gdbarch *gdbarch = get_frame_arch (this_frame);
struct frame_unwind_table *table = get_frame_unwind_table (gdbarch);
struct frame_unwind_table_entry *entry;
const struct frame_unwind *unwinder_from_target;
unwinder_from_target = target_get_unwinder ();
@@ -205,8 +177,10 @@ frame_unwind_find_by_frame (frame_info_ptr this_frame, void **this_cache)
unwinder_from_target))
return;
for (entry = table->list; entry != NULL; entry = entry->next)
if (frame_unwind_try_unwinder (this_frame, this_cache, entry->unwinder))
struct gdbarch *gdbarch = get_frame_arch (this_frame);
std::vector<const frame_unwind*> table = get_frame_unwind_table (gdbarch);
for (auto unwinder: table)
if (frame_unwind_try_unwinder (this_frame, this_cache, unwinder))
return;
internal_error (_("frame_unwind_find_by_frame failed"));
@@ -347,7 +321,7 @@ static void
maintenance_info_frame_unwinders (const char *args, int from_tty)
{
gdbarch *gdbarch = current_inferior ()->arch ();
struct frame_unwind_table *table = get_frame_unwind_table (gdbarch);
std::vector<const frame_unwind*> table = get_frame_unwind_table (gdbarch);
ui_out *uiout = current_uiout;
ui_out_emit_table table_emitter (uiout, 2, -1, "FrameUnwinders");
@@ -355,11 +329,10 @@ maintenance_info_frame_unwinders (const char *args, int from_tty)
uiout->table_header (25, ui_left, "type", "Type");
uiout->table_body ();
for (struct frame_unwind_table_entry *entry = table->list; entry != NULL;
entry = entry->next)
for (const struct frame_unwind* unwinder: table)
{
const char *name = entry->unwinder->name;
const char *type = frame_type_str (entry->unwinder->type);
const char *name = unwinder->name;
const char *type = frame_type_str (unwinder->type);
ui_out_emit_list tuple_emitter (uiout, nullptr);
uiout->field_string ("name", name);

3
gdb/gdbarch.c
View File

@@ -27,6 +27,7 @@
/* Maintain the struct gdbarch object. */
#include <vector>
struct gdbarch
{
/* Has this architecture been fully initialized? */
@@ -36,6 +37,8 @@ struct gdbarch
auto_obstack obstack;
/* Registry. */
registry<gdbarch> registry_fields;
/* list of frame unwinders. */
std::vector<const frame_unwind *> unwinders;
/* basic architectural information. */
const struct bfd_arch_info * bfd_arch_info;

5
gdb/gdbarch.h
View File

@@ -30,6 +30,7 @@
#include "displaced-stepping.h"
#include "gdbsupport/gdb-checked-static-cast.h"
#include "registry.h"
#include "frame-unwind.h"
struct floatformat;
struct ui_file;
@@ -310,6 +311,10 @@ extern obstack *gdbarch_obstack (gdbarch *arch);
#define GDBARCH_OBSTACK_ZALLOC(GDBARCH, TYPE) obstack_zalloc<TYPE> (gdbarch_obstack ((GDBARCH)))
/* Return the vector of unwinders stored in a gdbarch object. */
std::vector<const frame_unwind*>& gdbarch_get_unwinder_list (struct gdbarch *arch);
/* Duplicate STRING, returning an equivalent string that's allocated on the
obstack associated with GDBARCH. The string is freed when the corresponding
architecture is also freed. */

3
gdb/gdbarch.py
View File

@@ -125,6 +125,7 @@ with open("gdbarch.c", "w") as f:
print(file=f)
print("/* Maintain the struct gdbarch object. */", file=f)
print(file=f)
print("#include <vector>",file=f)
#
# The struct definition body.
#
@@ -137,6 +138,8 @@ with open("gdbarch.c", "w") as f:
print(" auto_obstack obstack;", file=f)
print(" /* Registry. */", file=f)
print(" registry<gdbarch> registry_fields;", file=f)
print(" /* list of frame unwinders. */", file=f)
print(" std::vector<const frame_unwind *> unwinders;", file=f)
print(file=f)
print(" /* basic architectural information. */", file=f)
for c in filter(info, components):