gdb/solib-rocm: avoid expensive gdbarch_from_bfd call in rocm_solib_relocate_section_addresses

Loading a library containing a lot (> 100k) sections proved very slow
with whenever the support for ROCm was built into gdb.  The culprit is
the gdbarch_from_bfd call in rocm_solib_relocate_section_addresses:

    if (!is_amdgpu_arch (gdbarch_from_bfd (so.abfd.get ())))

This function gets called for every section, and gdbarch_from_bfd is
somewhat slow.  It turns out that we can skip the gdbarch_from_bfd call,
since all is_amdgpu_arch needs is the bfd_architecture value, which we
can directly extract from the `bfd *`, without going through the
gdbarch.

Add an overload of is_amdgpu_arch that takes a `bfd *`, and use it in
rocm_solib_relocate_section_addresses.

Update a call site in rocm_solib_bfd_open to use the new overload as
well.  That call site is not as much in a hot path, but there is no
point in paying the extra cost of looking up the gdbarch there.  I
removed the other assert that checked that gdbarch_from_bfd returned a
non-nullptr value.  If that was the case, something would be very wrong
with ROCgdb, and the problem would manifest very soon after anyway.

Change-Id: I55e9e68af59903b1b9727ff57388f9469d0e0002
Approved-by: Lancelot Six <lancelot.six@amd.com> (AMDGPU)
This commit is contained in:
Simon Marchi
2025-10-27 15:41:51 -04:00
parent 20adfa53dc
commit 338796db76
3 changed files with 24 additions and 5 deletions

View File

@@ -31,13 +31,28 @@
#include "producer.h"
#include "reggroups.h"
/* Return true if INFO is of an AMDGPU architecture. */
static bool
is_amdgpu_arch (const bfd_arch_info *info)
{
return info->arch == bfd_arch_amdgcn;
}
/* See amdgpu-tdep.h. */
bool
is_amdgpu_arch (struct gdbarch *arch)
{
gdb_assert (arch != nullptr);
return gdbarch_bfd_arch_info (arch)->arch == bfd_arch_amdgcn;
return is_amdgpu_arch (gdbarch_bfd_arch_info (arch));
}
/* See amdgpu-tdep.h. */
bool
is_amdgpu_arch (bfd *abfd)
{
return is_amdgpu_arch (abfd->arch_info);
}
/* See amdgpu-tdep.h. */

View File

@@ -84,8 +84,13 @@ struct amdgpu_gdbarch_tdep : gdbarch_tdep_base
};
/* Return true if GDBARCH is of an AMDGPU architecture. */
bool is_amdgpu_arch (struct gdbarch *gdbarch);
/* Return true if ABFD is of an AMDGPU architecture. */
bool is_amdgpu_arch (bfd *abfd);
/* Return the amdgpu-specific data associated to ARCH. */
amdgpu_gdbarch_tdep *get_amdgpu_gdbarch_tdep (gdbarch *arch);

View File

@@ -245,7 +245,7 @@ void
rocm_solib_ops::relocate_section_addresses (solib &so,
struct target_section *sec) const
{
if (!is_amdgpu_arch (gdbarch_from_bfd (so.abfd.get ())))
if (!is_amdgpu_arch (so.abfd.get ()))
{
m_host_ops->relocate_section_addresses (so, sec);
return;
@@ -728,8 +728,7 @@ rocm_solib_ops::bfd_open (const char *pathname) const
}
}
gdb_assert (gdbarch_from_bfd (abfd.get ()) != nullptr);
gdb_assert (is_amdgpu_arch (gdbarch_from_bfd (abfd.get ())));
gdb_assert (is_amdgpu_arch (abfd.get ()));
return abfd;
}