[v2,3/5] gdb: Migrate frame unwinders to use C++ classes

Message ID 20240408201915.1482831-4-blarsen@redhat.com
State New
Headers
Series Modernize frame unwinders and add disable feature |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gdb_build--master-aarch64 success Testing passed
linaro-tcwg-bot/tcwg_gdb_build--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gdb_check--master-arm fail Testing failed
linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 success Testing passed

Commit Message

Guinevere Larsen April 8, 2024, 8:19 p.m. UTC
  Frame unwinders have historically been a structure populated with
callback pointers, so that architectures (or other specific unwinders)
could install their own way to handle the inferior. However, since
moving to c++, we could use polymorphism to get the same functionality
in a more readable way. Polymorphism also makes it simpler to add new
functionality to all frame unwinders, since all that's required is
adding it to the base class.

As part of the changes to add support to disabling frame unwinders,
this commit makes the first baby step in  using polymorphism for the
frame unwinders, by making frame_unwind a virtual class, and adds a
couple of new classes. The main class added is frame_unwind_legacy,
which works the same as the previous structs, using function pointers
as callbacks. This class was added to allow the transition to happen
piecemeal. New unwinders should instead follow the lead of the other
classes implemented.

2 of the others, frame_unwind_python and frame_unwind_trampoline, were added
because it seemed simpler at the moment to do that instead of reworking
the dynamic allocation to work with the legacy class, and can be used as
an example to future implementations.

Finally, the cygwin unwinder was converted to a class since it was most
of the way there already.
---
 gdb/aarch64-tdep.c          |  10 +--
 gdb/alpha-mdebug-tdep.c     |   5 +-
 gdb/alpha-tdep.c            |  10 +--
 gdb/amd64-obsd-tdep.c       |   5 +-
 gdb/amd64-tdep.c            |  20 ++---
 gdb/amd64-windows-tdep.c    |   5 +-
 gdb/amdgpu-tdep.c           |   6 +-
 gdb/arc-tdep.c              |   8 +-
 gdb/arm-tdep.c              |  24 +++---
 gdb/avr-tdep.c              |   4 +-
 gdb/bfin-tdep.c             |   5 +-
 gdb/bpf-tdep.c              |   5 +-
 gdb/cris-tdep.c             |  10 +--
 gdb/csky-tdep.c             |   8 +-
 gdb/dummy-frame.c           |   7 +-
 gdb/dummy-frame.h           |   2 +-
 gdb/dwarf2/frame-tailcall.c |   5 +-
 gdb/dwarf2/frame-tailcall.h |   2 +-
 gdb/dwarf2/frame.c          |  14 ++--
 gdb/frame-unwind.c          |  61 ++++++++++++++-
 gdb/frame-unwind.h          | 150 +++++++++++++++++++++++++++++++++---
 gdb/frame.c                 |  28 +++----
 gdb/frv-linux-tdep.c        |   5 +-
 gdb/frv-tdep.c              |   4 +-
 gdb/ft32-tdep.c             |   5 +-
 gdb/h8300-tdep.c            |   4 +-
 gdb/hppa-linux-tdep.c       |   4 +-
 gdb/hppa-tdep.c             |  14 ++--
 gdb/i386-obsd-tdep.c        |   4 +-
 gdb/i386-tdep.c             |  25 +++---
 gdb/ia64-tdep.c             |  20 ++---
 gdb/inline-frame.c          |   4 +-
 gdb/inline-frame.h          |   2 +-
 gdb/iq2000-tdep.c           |   4 +-
 gdb/jit.c                   |   5 +-
 gdb/lm32-tdep.c             |   4 +-
 gdb/loongarch-tdep.c        |   6 +-
 gdb/m32c-tdep.c             |   4 +-
 gdb/m32r-linux-tdep.c       |   4 +-
 gdb/m32r-tdep.c             |   4 +-
 gdb/m68hc11-tdep.c          |   4 +-
 gdb/m68k-linux-tdep.c       |   5 +-
 gdb/m68k-tdep.c             |   5 +-
 gdb/mep-tdep.c              |   4 +-
 gdb/microblaze-tdep.c       |   5 +-
 gdb/mips-sde-tdep.c         |   5 +-
 gdb/mips-tdep.c             |  20 ++---
 gdb/mn10300-tdep.c          |   4 +-
 gdb/moxie-tdep.c            |   4 +-
 gdb/msp430-tdep.c           |   4 +-
 gdb/nds32-tdep.c            |  12 ++-
 gdb/nios2-tdep.c            |  10 +--
 gdb/or1k-tdep.c             |   6 +-
 gdb/ppc-fbsd-tdep.c         |   4 +-
 gdb/ppc-obsd-tdep.c         |   4 +-
 gdb/python/py-unwind.c      |  51 +++++++++---
 gdb/record-btrace.c         |  10 +--
 gdb/record.h                |   4 +-
 gdb/riscv-tdep.c            |   7 +-
 gdb/rl78-tdep.c             |   5 +-
 gdb/rs6000-aix-tdep.c       |   4 +-
 gdb/rs6000-tdep.c           |  10 +--
 gdb/rx-tdep.c               |   8 +-
 gdb/s12z-tdep.c             |   6 +-
 gdb/s390-linux-tdep.c       |   4 +-
 gdb/s390-tdep.c             |   8 +-
 gdb/sentinel-frame.c        |   7 +-
 gdb/sentinel-frame.h        |   2 +-
 gdb/sh-tdep.c               |   9 +--
 gdb/sparc-netbsd-tdep.c     |   5 +-
 gdb/sparc-obsd-tdep.c       |   5 +-
 gdb/sparc-sol2-tdep.c       |   5 +-
 gdb/sparc-tdep.c            |   5 +-
 gdb/sparc64-fbsd-tdep.c     |   5 +-
 gdb/sparc64-netbsd-tdep.c   |   5 +-
 gdb/sparc64-obsd-tdep.c     |  10 +--
 gdb/sparc64-sol2-tdep.c     |   5 +-
 gdb/sparc64-tdep.c          |   5 +-
 gdb/tic6x-tdep.c            |  10 +--
 gdb/tilegx-tdep.c           |   4 +-
 gdb/tramp-frame.c           |  57 +++++++++++---
 gdb/v850-tdep.c             |   4 +-
 gdb/vax-tdep.c              |   5 +-
 gdb/windows-tdep.c          |  33 ++++----
 gdb/windows-tdep.h          |  16 +++-
 gdb/xstormy16-tdep.c        |   4 +-
 gdb/xtensa-tdep.c           |   6 +-
 gdb/z80-tdep.c              |   6 +-
 88 files changed, 561 insertions(+), 381 deletions(-)
  

Comments

Guinevere Larsen April 12, 2024, 2:40 p.m. UTC | #1
I mentioned as a reply to the cover letter that this patch series had a 
crash in arm32 bit. This patch had the problem and a quick fix I inlined.

Trimming the diff for readability.

On 4/8/24 17:19, Guinevere Larsen wrote:
> diff --git a/gdb/tramp-frame.c b/gdb/tramp-frame.c
> index 2fcc3814e59..7fee4d5c71d 100644
> --- a/gdb/tramp-frame.c
> +++ b/gdb/tramp-frame.c
> @@ -123,7 +123,7 @@ tramp_frame_sniffer (const struct frame_unwind *self,
>   		     const frame_info_ptr &this_frame,
>   		     void **this_cache)
>   {
> -  const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
> +  const struct tramp_frame *tramp = self->unwind_data ()->tramp_frame;
>     CORE_ADDR pc = get_frame_pc (this_frame);
>     CORE_ADDR func;
>     struct tramp_frame_cache *tramp_cache;
> @@ -142,6 +142,46 @@ tramp_frame_sniffer (const struct frame_unwind *self,
>     return 1;
>   }
>   
> +class frame_unwind_trampoline : public frame_unwind
> +{
> +private:
> +  frame_prev_arch_ftype *prev_arch_p;
> +public:
> +  frame_unwind_trampoline (enum frame_type t, const struct frame_data *d,
> +			   frame_prev_arch_ftype *pa)
> +    : frame_unwind ("trampoline", t, FRAME_UNWIND_GDB, d), prev_arch_p (pa)
> +  { }
> +
> +  int sniffer(const frame_unwind *self, const frame_info_ptr &this_frame,
> +	      void **this_prologue_cache) const override
> +  {
> +    return tramp_frame_sniffer (self, this_frame, this_prologue_cache);
> +  }
> +  void this_id (const frame_info_ptr &this_frame, void **this_prologue_cache,
> +		struct frame_id *id) const override
> +  {
> +    tramp_frame_this_id (this_frame, this_prologue_cache, id);
> +  }
> +  struct value *prev_register (const frame_info_ptr &this_frame,
> +			       void **this_prologue_cache,
> +			       int regnum) const override
> +  {
> +    return tramp_frame_prev_register (this_frame, this_prologue_cache, regnum);
> +  }
> +
> +  struct gdbarch *prev_arch (const frame_info_ptr &this_frame,
> +			     void **this_prologue_cache) const override
> +  {

This place should have:

     if (prev_arch_p == nullptr)
       error (_("No prev_arch callback installed"));


I've fixed this locally, but since this patch is over 100Kb, I would 
prefer to not spam the list :)
  

Patch

diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
index 4c22d3705f5..c1a9ad67193 100644
--- a/gdb/aarch64-tdep.c
+++ b/gdb/aarch64-tdep.c
@@ -1203,8 +1203,7 @@  aarch64_prologue_prev_register (const frame_info_ptr &this_frame,
 }
 
 /* AArch64 prologue unwinder.  */
-static frame_unwind aarch64_prologue_unwind =
-{
+static const frame_unwind_legacy aarch64_prologue_unwind (
   "aarch64 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1213,7 +1212,7 @@  static frame_unwind aarch64_prologue_unwind =
   aarch64_prologue_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Allocate and fill in *THIS_CACHE with information about the prologue of
    *THIS_FRAME.  Do not do this is if *THIS_CACHE was already allocated.
@@ -1299,8 +1298,7 @@  aarch64_stub_unwind_sniffer (const struct frame_unwind *self,
 }
 
 /* AArch64 stub unwinder.  */
-static frame_unwind aarch64_stub_unwind =
-{
+static const frame_unwind_legacy aarch64_stub_unwind (
   "aarch64 stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1309,7 +1307,7 @@  static frame_unwind aarch64_stub_unwind =
   aarch64_prologue_prev_register,
   NULL,
   aarch64_stub_unwind_sniffer
-};
+);
 
 /* Return the frame base address of *THIS_FRAME.  */
 
diff --git a/gdb/alpha-mdebug-tdep.c b/gdb/alpha-mdebug-tdep.c
index b087afabae7..b43849c203d 100644
--- a/gdb/alpha-mdebug-tdep.c
+++ b/gdb/alpha-mdebug-tdep.c
@@ -330,8 +330,7 @@  alpha_mdebug_frame_sniffer (const struct frame_unwind *self,
   return 1;
 }
 
-static const struct frame_unwind alpha_mdebug_frame_unwind =
-{
+static const struct frame_unwind_legacy alpha_mdebug_frame_unwind (
   "alpha mdebug",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -340,7 +339,7 @@  static const struct frame_unwind alpha_mdebug_frame_unwind =
   alpha_mdebug_frame_prev_register,
   NULL,
   alpha_mdebug_frame_sniffer
-};
+);
 
 static CORE_ADDR
 alpha_mdebug_frame_base_address (const frame_info_ptr &this_frame,
diff --git a/gdb/alpha-tdep.c b/gdb/alpha-tdep.c
index dd3556d6ae0..4f7526e5b19 100644
--- a/gdb/alpha-tdep.c
+++ b/gdb/alpha-tdep.c
@@ -1006,8 +1006,7 @@  alpha_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind alpha_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy alpha_sigtramp_frame_unwind (
   "alpha sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1016,7 +1015,7 @@  static const struct frame_unwind alpha_sigtramp_frame_unwind =
   alpha_sigtramp_frame_prev_register,
   NULL,
   alpha_sigtramp_frame_sniffer
-};
+);
 
 
 
@@ -1426,8 +1425,7 @@  alpha_heuristic_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 }
 
-static const struct frame_unwind alpha_heuristic_frame_unwind =
-{
+static const struct frame_unwind_legacy alpha_heuristic_frame_unwind (
   "alpha prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1436,7 +1434,7 @@  static const struct frame_unwind alpha_heuristic_frame_unwind =
   alpha_heuristic_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 alpha_heuristic_frame_base_address (const frame_info_ptr &this_frame,
diff --git a/gdb/amd64-obsd-tdep.c b/gdb/amd64-obsd-tdep.c
index 059628cd7f0..b4ff53eeab4 100644
--- a/gdb/amd64-obsd-tdep.c
+++ b/gdb/amd64-obsd-tdep.c
@@ -401,8 +401,7 @@  amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 		   || (startswith (name, "Xintr"))));
 }
 
-static const struct frame_unwind amd64obsd_trapframe_unwind =
-{
+static const struct frame_unwind_legacy amd64obsd_trapframe_unwind (
   /* FIXME: kettenis/20051219: This really is more like an interrupt
      frame, but SIGTRAMP_FRAME would print <signal handler called>,
      which really is not what we want here.  */
@@ -414,7 +413,7 @@  static const struct frame_unwind amd64obsd_trapframe_unwind =
   amd64obsd_trapframe_prev_register,
   NULL,
   amd64obsd_trapframe_sniffer
-};
+);
 
 
 static void
diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index b3be7dbed82..1b18b67c9ee 100644
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -2677,8 +2677,7 @@  amd64_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind amd64_frame_unwind =
-{
+static const struct frame_unwind_legacy amd64_frame_unwind (
   "amd64 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2687,7 +2686,7 @@  static const struct frame_unwind amd64_frame_unwind =
   amd64_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Generate a bytecode expression to get the value of the saved PC.  */
 
@@ -2824,8 +2823,7 @@  amd64_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind amd64_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy amd64_sigtramp_frame_unwind (
   "amd64 sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2834,7 +2832,7 @@  static const struct frame_unwind amd64_sigtramp_frame_unwind =
   amd64_sigtramp_frame_prev_register,
   NULL,
   amd64_sigtramp_frame_sniffer
-};
+);
 
 
 static CORE_ADDR
@@ -3017,8 +3015,7 @@  amd64_epilogue_frame_this_id (const frame_info_ptr &this_frame,
     (*this_id) = frame_id_build (cache->base + 16, cache->pc);
 }
 
-static const struct frame_unwind amd64_epilogue_override_frame_unwind =
-{
+static const struct frame_unwind_legacy amd64_epilogue_override_frame_unwind (
   "amd64 epilogue override",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3027,10 +3024,9 @@  static const struct frame_unwind amd64_epilogue_override_frame_unwind =
   amd64_frame_prev_register,
   NULL,
   amd64_epilogue_override_frame_sniffer
-};
+);
 
-static const struct frame_unwind amd64_epilogue_frame_unwind =
-{
+static const struct frame_unwind_legacy amd64_epilogue_frame_unwind (
   "amd64 epilogue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3039,7 +3035,7 @@  static const struct frame_unwind amd64_epilogue_frame_unwind =
   amd64_frame_prev_register,
   NULL, 
   amd64_epilogue_frame_sniffer
-};
+);
 
 static struct frame_id
 amd64_dummy_id (struct gdbarch *gdbarch, const frame_info_ptr &this_frame)
diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index d395e3a73f2..fecce06fefa 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -1180,8 +1180,7 @@  amd64_windows_frame_this_id (const frame_info_ptr &this_frame, void **this_cache
 
 /* Windows x64 SEH unwinder.  */
 
-static const struct frame_unwind amd64_windows_frame_unwind =
-{
+static const struct frame_unwind_legacy amd64_windows_frame_unwind (
   "amd64 windows",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1190,7 +1189,7 @@  static const struct frame_unwind amd64_windows_frame_unwind =
   &amd64_windows_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Implement the "skip_prologue" gdbarch method.  */
 
diff --git a/gdb/amdgpu-tdep.c b/gdb/amdgpu-tdep.c
index 679098a778f..4f02a7efd63 100644
--- a/gdb/amdgpu-tdep.c
+++ b/gdb/amdgpu-tdep.c
@@ -891,7 +891,7 @@  amdgpu_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const frame_unwind amdgpu_frame_unwind = {
+static const frame_unwind_legacy amdgpu_frame_unwind (
   "amdgpu",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -901,8 +901,8 @@  static const frame_unwind amdgpu_frame_unwind = {
   nullptr,
   default_frame_sniffer,
   nullptr,
-  nullptr,
-};
+  nullptr
+);
 
 static int
 print_insn_amdgpu (bfd_vma memaddr, struct disassemble_info *info)
diff --git a/gdb/arc-tdep.c b/gdb/arc-tdep.c
index 373c392f700..d25c577b62d 100644
--- a/gdb/arc-tdep.c
+++ b/gdb/arc-tdep.c
@@ -1909,7 +1909,7 @@  arc_sigtramp_frame_sniffer (const struct frame_unwind *self,
    the fallback unwinder, we use the default frame sniffer, which always
    accepts the frame.  */
 
-static const struct frame_unwind arc_frame_unwind = {
+static const struct frame_unwind_legacy arc_frame_unwind (
   "arc prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1920,13 +1920,13 @@  static const struct frame_unwind arc_frame_unwind = {
   default_frame_sniffer,
   NULL,
   NULL
-};
+);
 
 /* Structure defining the ARC signal frame unwind functions.  Custom
    sniffer is used, because this frame must be accepted only in the right
    context.  */
 
-static const struct frame_unwind arc_sigtramp_frame_unwind = {
+static const struct frame_unwind_legacy arc_sigtramp_frame_unwind (
   "arc sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1937,7 +1937,7 @@  static const struct frame_unwind arc_sigtramp_frame_unwind = {
   arc_sigtramp_frame_sniffer,
   NULL,
   NULL
-};
+);
 
 
 static const struct frame_base arc_normal_base = {
diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index acee2d5b95f..a2785ae3358 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -2468,7 +2468,7 @@  arm_prologue_prev_register (const frame_info_ptr &this_frame,
 				       prev_regnum);
 }
 
-static frame_unwind arm_prologue_unwind = {
+static const frame_unwind_legacy arm_prologue_unwind (
   "arm prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2477,7 +2477,7 @@  static frame_unwind arm_prologue_unwind = {
   arm_prologue_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Maintain a list of ARM exception table entries per objfile, similar to the
    list of mapping symbols.  We only cache entries for standard ARM-defined
@@ -3188,7 +3188,7 @@  arm_exidx_unwind_sniffer (const struct frame_unwind *self,
   return 1;
 }
 
-struct frame_unwind arm_exidx_unwind = {
+struct frame_unwind_legacy arm_exidx_unwind (
   "arm exidx",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3197,7 +3197,7 @@  struct frame_unwind arm_exidx_unwind = {
   arm_prologue_prev_register,
   NULL,
   arm_exidx_unwind_sniffer
-};
+);
 
 static struct arm_prologue_cache *
 arm_make_epilogue_frame_cache (const frame_info_ptr &this_frame)
@@ -3298,8 +3298,7 @@  arm_epilogue_frame_sniffer (const struct frame_unwind *self,
 
 /* Frame unwinder from epilogue.  */
 
-static const struct frame_unwind arm_epilogue_frame_unwind =
-{
+static const struct frame_unwind_legacy arm_epilogue_frame_unwind (
   "arm epilogue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3307,8 +3306,8 @@  static const struct frame_unwind arm_epilogue_frame_unwind =
   arm_epilogue_frame_this_id,
   arm_epilogue_frame_prev_register,
   NULL,
-  arm_epilogue_frame_sniffer,
-};
+  arm_epilogue_frame_sniffer
+);
 
 /* Recognize GCC's trampoline for thumb call-indirect.  If we are in a
    trampoline, return the target PC.  Otherwise return 0.
@@ -3429,7 +3428,7 @@  arm_stub_unwind_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-struct frame_unwind arm_stub_unwind = {
+struct frame_unwind_legacy arm_stub_unwind (
   "arm stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3438,7 +3437,7 @@  struct frame_unwind arm_stub_unwind = {
   arm_prologue_prev_register,
   NULL,
   arm_stub_unwind_sniffer
-};
+);
 
 /* Put here the code to store, into CACHE->saved_regs, the addresses
    of the saved registers of frame described by THIS_FRAME.  CACHE is
@@ -3955,8 +3954,7 @@  arm_m_exception_unwind_sniffer (const struct frame_unwind *self,
 /* Frame unwinder for M-profile exceptions (EXC_RETURN on stack),
    lockup and secure/nonsecure interstate function calls (FNC_RETURN).  */
 
-struct frame_unwind arm_m_exception_unwind =
-{
+struct frame_unwind_legacy arm_m_exception_unwind (
   "arm m exception lockup sec_fnc",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3965,7 +3963,7 @@  struct frame_unwind arm_m_exception_unwind =
   arm_m_exception_prev_register,
   NULL,
   arm_m_exception_unwind_sniffer
-};
+);
 
 static CORE_ADDR
 arm_normal_frame_base (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/avr-tdep.c b/gdb/avr-tdep.c
index d3b6f949843..82ce125f1e9 100644
--- a/gdb/avr-tdep.c
+++ b/gdb/avr-tdep.c
@@ -1154,7 +1154,7 @@  avr_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 }
 
-static const struct frame_unwind avr_frame_unwind = {
+static const struct frame_unwind_legacy avr_frame_unwind (
   "avr prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1163,7 +1163,7 @@  static const struct frame_unwind avr_frame_unwind = {
   avr_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 avr_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/bfin-tdep.c b/gdb/bfin-tdep.c
index 5400857a929..3849002c40e 100644
--- a/gdb/bfin-tdep.c
+++ b/gdb/bfin-tdep.c
@@ -371,8 +371,7 @@  bfin_frame_prev_register (const frame_info_ptr &this_frame,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind bfin_frame_unwind =
-{
+static const struct frame_unwind_legacy bfin_frame_unwind (
   "bfin prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -381,7 +380,7 @@  static const struct frame_unwind bfin_frame_unwind =
   bfin_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Check for "[--SP] = <reg>;" insns.  These are appear in function
    prologues to save misc registers onto the stack.  */
diff --git a/gdb/bpf-tdep.c b/gdb/bpf-tdep.c
index 83bee2bf676..6f1ae050225 100644
--- a/gdb/bpf-tdep.c
+++ b/gdb/bpf-tdep.c
@@ -181,8 +181,7 @@  bpf_frame_prev_register (const frame_info_ptr &this_frame,
 
 /* Frame unwinder machinery for BPF.  */
 
-static const struct frame_unwind bpf_frame_unwind =
-{
+static const struct frame_unwind_legacy bpf_frame_unwind (
   "bpf prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -191,7 +190,7 @@  static const struct frame_unwind bpf_frame_unwind =
   bpf_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 
 /* Breakpoints.  */
diff --git a/gdb/cris-tdep.c b/gdb/cris-tdep.c
index 7345dd2d668..c91d3a6019d 100644
--- a/gdb/cris-tdep.c
+++ b/gdb/cris-tdep.c
@@ -434,8 +434,7 @@  cris_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind cris_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy cris_sigtramp_frame_unwind (
   "cris sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -444,7 +443,7 @@  static const struct frame_unwind cris_sigtramp_frame_unwind =
   cris_sigtramp_frame_prev_register,
   NULL,
   cris_sigtramp_frame_sniffer
-};
+);
 
 static int
 crisv32_single_step_through_delay (struct gdbarch *gdbarch,
@@ -900,8 +899,7 @@  cris_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
   return sp;
 }
 
-static const struct frame_unwind cris_frame_unwind = 
-{
+static const struct frame_unwind_legacy cris_frame_unwind (
   "cris prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -910,7 +908,7 @@  static const struct frame_unwind cris_frame_unwind =
   cris_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 cris_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/csky-tdep.c b/gdb/csky-tdep.c
index fc13865e22f..3313803c19a 100644
--- a/gdb/csky-tdep.c
+++ b/gdb/csky-tdep.c
@@ -2158,7 +2158,7 @@  csky_frame_prev_register (const frame_info_ptr &this_frame,
 /* Data structures for the normal prologue-analysis-based
    unwinder.  */
 
-static const struct frame_unwind csky_unwind_cache = {
+static const struct frame_unwind_legacy csky_unwind_cache (
   "cski prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2169,7 +2169,7 @@  static const struct frame_unwind csky_unwind_cache = {
   default_frame_sniffer,
   NULL,
   NULL
-};
+);
 
 static CORE_ADDR
 csky_check_long_branch (const frame_info_ptr &frame, CORE_ADDR pc)
@@ -2293,7 +2293,7 @@  csky_stub_prev_register (const frame_info_ptr &this_frame,
 				       prev_regnum);
 }
 
-static frame_unwind csky_stub_unwind = {
+static const frame_unwind_legacy csky_stub_unwind (
   "csky stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2302,7 +2302,7 @@  static frame_unwind csky_stub_unwind = {
   csky_stub_prev_register,
   NULL,
   csky_stub_unwind_sniffer
-};
+);
 
 /* Implement the this_base, this_locals, and this_args hooks
    for the normal unwinder.  */
diff --git a/gdb/dummy-frame.c b/gdb/dummy-frame.c
index 09513ea4aad..045c2e44872 100644
--- a/gdb/dummy-frame.c
+++ b/gdb/dummy-frame.c
@@ -375,8 +375,7 @@  dummy_frame_this_id (const frame_info_ptr &this_frame,
   (*this_id) = cache->this_id;
 }
 
-const struct frame_unwind dummy_frame_unwind =
-{
+const struct frame_unwind_legacy dummy_frame_unwind (
   "dummy",
   DUMMY_FRAME,
   FRAME_UNWIND_GDB,
@@ -384,8 +383,8 @@  const struct frame_unwind dummy_frame_unwind =
   dummy_frame_this_id,
   dummy_frame_prev_register,
   NULL,
-  dummy_frame_sniffer,
-};
+  dummy_frame_sniffer
+);
 
 /* See dummy-frame.h.  */
 
diff --git a/gdb/dummy-frame.h b/gdb/dummy-frame.h
index 7d963ad9beb..a1341797acd 100644
--- a/gdb/dummy-frame.h
+++ b/gdb/dummy-frame.h
@@ -54,7 +54,7 @@  extern void dummy_frame_discard (frame_id dummy_id, thread_info *thread);
 /* If the PC falls in a dummy frame, return a dummy frame
    unwinder.  */
 
-extern const struct frame_unwind dummy_frame_unwind;
+extern const struct frame_unwind_legacy dummy_frame_unwind;
 
 /* Destructor for dummy_frame.  DATA is supplied by registrant.
    REGISTERS_VALID is 1 for dummy_frame_pop, 0 for dummy_frame_discard.  */
diff --git a/gdb/dwarf2/frame-tailcall.c b/gdb/dwarf2/frame-tailcall.c
index 45ba3a70262..20a98f436aa 100644
--- a/gdb/dwarf2/frame-tailcall.c
+++ b/gdb/dwarf2/frame-tailcall.c
@@ -469,8 +469,7 @@  tailcall_frame_prev_arch (const frame_info_ptr &this_frame,
 /* Virtual tail call frame unwinder if dwarf2_tailcall_sniffer_first finds
    a chain to create.  */
 
-const struct frame_unwind dwarf2_tailcall_frame_unwind =
-{
+const struct frame_unwind_legacy dwarf2_tailcall_frame_unwind (
   "dwarf2 tailcall",
   TAILCALL_FRAME,
   FRAME_UNWIND_DEBUGINFO,
@@ -481,7 +480,7 @@  const struct frame_unwind dwarf2_tailcall_frame_unwind =
   tailcall_frame_sniffer,
   tailcall_frame_dealloc_cache,
   tailcall_frame_prev_arch
-};
+);
 
 void _initialize_tailcall_frame ();
 void
diff --git a/gdb/dwarf2/frame-tailcall.h b/gdb/dwarf2/frame-tailcall.h
index 3f49487ac2a..3569c7dd3e2 100644
--- a/gdb/dwarf2/frame-tailcall.h
+++ b/gdb/dwarf2/frame-tailcall.h
@@ -34,6 +34,6 @@  extern struct value *
   dwarf2_tailcall_prev_register_first (const frame_info_ptr &this_frame,
 				       void **tailcall_cachep, int regnum);
 
-extern const struct frame_unwind dwarf2_tailcall_frame_unwind;
+extern const struct frame_unwind_legacy dwarf2_tailcall_frame_unwind;
 
 #endif /* !DWARF2_FRAME_TAILCALL_H */
diff --git a/gdb/dwarf2/frame.c b/gdb/dwarf2/frame.c
index 7bbe6cab22d..6386ac20899 100644
--- a/gdb/dwarf2/frame.c
+++ b/gdb/dwarf2/frame.c
@@ -1331,16 +1331,15 @@  dwarf2_frame_sniffer (const struct frame_unwind *self,
   if (fde->cie->signal_frame
       || dwarf2_frame_signal_frame_p (get_frame_arch (this_frame),
 				      this_frame))
-    return self->type == SIGTRAMP_FRAME;
+    return self->type () == SIGTRAMP_FRAME;
 
-  if (self->type != NORMAL_FRAME)
+  if (self->type () != NORMAL_FRAME)
     return 0;
 
   return 1;
 }
 
-static const struct frame_unwind dwarf2_frame_unwind =
-{
+static const struct frame_unwind_legacy dwarf2_frame_unwind (
   "dwarf2",
   NORMAL_FRAME,
   FRAME_UNWIND_DEBUGINFO,
@@ -1350,10 +1349,9 @@  static const struct frame_unwind dwarf2_frame_unwind =
   NULL,
   dwarf2_frame_sniffer,
   dwarf2_frame_dealloc_cache
-};
+);
 
-static const struct frame_unwind dwarf2_signal_frame_unwind =
-{
+static const struct frame_unwind_legacy dwarf2_signal_frame_unwind (
   "dwarf2 signal",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_DEBUGINFO,
@@ -1365,7 +1363,7 @@  static const struct frame_unwind dwarf2_signal_frame_unwind =
 
   /* TAILCALL_CACHE can never be in such frame to need dealloc_cache.  */
   NULL
-};
+);
 
 /* Append the DWARF-2 frame unwinders to GDBARCH's list.  */
 
diff --git a/gdb/frame-unwind.c b/gdb/frame-unwind.c
index fa0ea1cba4c..fd3d3b378ab 100644
--- a/gdb/frame-unwind.c
+++ b/gdb/frame-unwind.c
@@ -128,7 +128,7 @@  frame_unwind_try_unwinder (const frame_info_ptr &this_frame, void **this_cache,
 
   try
     {
-      frame_debug_printf ("trying unwinder \"%s\"", unwinder->name);
+      frame_debug_printf ("trying unwinder \"%s\"", unwinder->name ());
       res = unwinder->sniffer (unwinder, this_frame, this_cache);
     }
   catch (const gdb_exception &ex)
@@ -334,6 +334,59 @@  frame_unwind_got_address (const frame_info_ptr &frame, int regnum,
   return reg_val;
 }
 
+/* This method just passes the parameters to the callback pointer.  */
+enum unwind_stop_reason
+frame_unwind_legacy::stop_reason (const frame_info_ptr &this_frame,
+				  void **this_prologue_cache) const
+{
+  return stop_reason_p (this_frame, this_prologue_cache);
+}
+
+/* This method just passes the parameters to the callback pointer.  */
+void
+frame_unwind_legacy::this_id (const frame_info_ptr &this_frame,
+			      void **this_prologue_cache,
+			      struct frame_id *id) const
+{
+  return this_id_p (this_frame, this_prologue_cache, id);
+}
+
+/* This method just passes the parameters to the callback pointer.  */
+struct value *
+frame_unwind_legacy::prev_register (const frame_info_ptr &this_frame,
+				    void **this_prologue_cache,
+				    int regnum) const
+{
+  return prev_register_p (this_frame, this_prologue_cache, regnum);
+}
+
+/* This method just passes the parameters to the callback pointer.  */
+int
+frame_unwind_legacy::sniffer (const struct frame_unwind *self,
+			      const frame_info_ptr &this_frame,
+			      void **this_prologue_cache) const
+{
+  return sniffer_p (self, this_frame, this_prologue_cache);
+}
+
+/* This method just passes the parameters to the callback pointer.  */
+void
+frame_unwind_legacy::dealloc_cache (frame_info *self, void *this_cache) const
+{
+  if (dealloc_cache_p != nullptr)
+    dealloc_cache_p (self, this_cache);
+}
+
+/* This method just passes the parameters to the callback pointer.  */
+struct gdbarch *
+frame_unwind_legacy::prev_arch (const frame_info_ptr &this_frame,
+				void **this_prologue_cache) const
+{
+  if (prev_arch_p == nullptr)
+    error (_("No prev_arch callback installed"));
+  return prev_arch_p (this_frame, this_prologue_cache);
+}
+
 /* Implement "maintenance info frame-unwinders" command.  */
 
 static void
@@ -351,9 +404,9 @@  maintenance_info_frame_unwinders (const char *args, int from_tty)
 
   for (const struct frame_unwind* unwinder: table)
     {
-      const char *name = unwinder->name;
-      const char *type = frame_type_str (unwinder->type);
-      const char *uclass = frame_unwinder_class_str (unwinder->unwinder_class);
+      const char *name = unwinder->name ();
+      const char *type = frame_type_str (unwinder->type ());
+      const char *uclass = frame_unwinder_class_str (unwinder->unwinder_class ());
 
       ui_out_emit_list tuple_emitter (uiout, nullptr);
       uiout->field_string ("name", name);
diff --git a/gdb/frame-unwind.h b/gdb/frame-unwind.h
index deab4f7dbfb..62da34b6ee8 100644
--- a/gdb/frame-unwind.h
+++ b/gdb/frame-unwind.h
@@ -169,25 +169,153 @@  enum frame_unwind_class
   FRAME_UNWIND_ARCH,
 };
 
-struct frame_unwind
+class frame_unwind
 {
-  const char *name;
+  const char *m_name;
   /* The frame's type.  Should this instead be a collection of
      predicates that test the frame for various attributes?  */
-  enum frame_type type;
+  enum frame_type m_type;
   /* What kind of unwinder is this.  It generally follows from where
      the unwinder was added or where it looks for information to do the
      unwinding.  */
-  enum frame_unwind_class unwinder_class;
+  enum frame_unwind_class m_unwinder_class;
+  const struct frame_data *m_unwind_data;
+public:
+  frame_unwind (const char *name, frame_type type, frame_unwind_class uclass,
+		       const struct frame_data *data)
+    : m_name (name), m_type (type), m_unwinder_class (uclass),
+      m_unwind_data (data)
+    { }
+
+  const char *name () const
+  {
+    return m_name;
+  }
+
+  enum frame_type type () const
+  {
+    return m_type;
+  }
+
+  enum frame_unwind_class unwinder_class () const
+  {
+    return m_unwinder_class;
+  }
+
+  const struct frame_data *unwind_data () const
+  {
+    return m_unwind_data;
+  }
+
+  /* Default stop_reason function.  It reports NO_REASON, unless the
+     frame is the outermost.  */
+  virtual enum unwind_stop_reason stop_reason (const frame_info_ptr &this_frame,
+					       void **this_prologue_cache) const
+  {
+    return default_frame_unwind_stop_reason (this_frame, this_prologue_cache);
+  }
+
+  /* Default frame sniffer.  Will always return that the unwinder
+     is able to unwind the frame.  */
+  virtual int sniffer (const frame_unwind *self,
+		       const frame_info_ptr &this_frame,
+		       void **this_prologue_cache) const
+  {
+    return 1;
+  }
+
+  /* The following methods are here mostly for interface functionality.  They
+     all throw an error when called, as a safe way to check if an unwinder has
+     implemented the desired functionality.  */
+
+  /* Calculate the ID of the given frame using this unwinder.  */
+  virtual void this_id (const frame_info_ptr &this_frame,
+			void **this_prologue_cache,
+			struct frame_id *id) const
+  {
+    error (_("No method this_id implemented for unwinder %s"), m_name);
+  }
+
+  /* Get the value of a register in a previous frame.  */
+  virtual struct value *prev_register (const frame_info_ptr &this_frame,
+				       void **this_prologue_cache,
+				       int regnum) const
+  {
+    error (_("No method prev_register implemented for unwinder %s"), m_name);
+  }
+
+  /* Properly deallocate the cache.  */
+  virtual void dealloc_cache (frame_info *self, void *this_cache) const
+  {
+    error (_("No method dealloc_cache implemented for unwinder %s"), m_name);
+  }
+
+  /* Get the previous architecture.  */
+  virtual struct gdbarch *prev_arch (const frame_info_ptr &this_frame,
+				     void **this_prologue_cache) const
+  {
+    error (_("No method prev_arch implemented for unwinder %s"), m_name);
+  }
+};
+
+/* This is a legacy version of the frame unwinder.  The original struct
+   used function pointers for callbacks, this updated version has a
+   method that just passes the parameters along to the callback
+   pointer.
+   Do not use this class for new unwinders.  Instead, see other classes
+   that inherit from frame_unwind, such as the python unwinder.  */
+class frame_unwind_legacy : public frame_unwind
+{
+private:
   /* Should an attribute indicating the frame's address-in-block go
      here?  */
-  frame_unwind_stop_reason_ftype *stop_reason;
-  frame_this_id_ftype *this_id;
-  frame_prev_register_ftype *prev_register;
-  const struct frame_data *unwind_data;
-  frame_sniffer_ftype *sniffer;
-  frame_dealloc_cache_ftype *dealloc_cache;
-  frame_prev_arch_ftype *prev_arch;
+  frame_unwind_stop_reason_ftype *stop_reason_p;
+  frame_this_id_ftype *this_id_p;
+  frame_prev_register_ftype *prev_register_p;
+  frame_sniffer_ftype *sniffer_p;
+  frame_dealloc_cache_ftype *dealloc_cache_p;
+  frame_prev_arch_ftype *prev_arch_p;
+public:
+  frame_unwind_legacy (const char *n, frame_type t, frame_unwind_class c,
+		       frame_unwind_stop_reason_ftype *sr,
+		       frame_this_id_ftype *ti,
+		       frame_prev_register_ftype *pr,
+		       const struct frame_data *ud,
+		       frame_sniffer_ftype *s,
+		       frame_dealloc_cache_ftype *dc = nullptr,
+		       frame_prev_arch_ftype *pa = nullptr)
+  : frame_unwind (n, t, c, ud), stop_reason_p (sr),
+    this_id_p (ti), prev_register_p (pr), sniffer_p (s),
+    dealloc_cache_p (dc), prev_arch_p (pa) { }
+
+  /* This method just passes the parameters to the callback pointer.  */
+  enum unwind_stop_reason stop_reason (const frame_info_ptr &this_frame,
+					void **this_prologue_cache) const override;
+
+  /* This method just passes the parameters to the callback pointer.  */
+  void this_id (const frame_info_ptr &this_frame, void **this_prologue_cache,
+		 struct frame_id *id) const override;
+
+  /* This method just passes the parameters to the callback pointer.  */
+  struct value *prev_register (const frame_info_ptr &this_frame,
+				void **this_prologue_cache,
+				int regnum) const override;
+
+  /* This method just passes the parameters to the callback pointer.  */
+  int sniffer (const frame_unwind *self,
+		const frame_info_ptr &this_frame,
+		void **this_prologue_cache) const override;
+
+  /* This method just passes the parameters to the callback pointer.
+     It is safe to call this method if no callback is installed, it
+     just turns into a noop.  */
+  void dealloc_cache (frame_info *self, void *this_cache) const override;
+
+  /* This method just passes the parameters to the callback pointer.
+     If this function is called with no installed callback, this method
+     will error out.  Wrap calls in try-catch blocks.  */
+  struct gdbarch *prev_arch (const frame_info_ptr &this_frame,
+			      void **this_prologue_cache) const override;
 };
 
 /* Register a frame unwinder, _prepending_ it to the front of the
diff --git a/gdb/frame.c b/gdb/frame.c
index f042bbb2ec2..b20a8f5668d 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -267,12 +267,10 @@  frame_addr_hash_eq (const void *a, const void *b)
 static void
 frame_info_del (frame_info *frame)
 {
-  if (frame->prologue_cache != nullptr
-      && frame->unwind->dealloc_cache != nullptr)
+  if (frame->prologue_cache != nullptr)
     frame->unwind->dealloc_cache (frame, frame->prologue_cache);
 
-  if (frame->base_cache != nullptr
-      && frame->base->unwind->dealloc_cache != nullptr)
+  if (frame->base_cache != nullptr)
     frame->base->unwind->dealloc_cache (frame, frame->base_cache);
 }
 
@@ -485,12 +483,12 @@  frame_info::to_string () const
   res += string_printf ("{level=%d,", fi->level);
 
   if (fi->unwind != NULL)
-    res += string_printf ("type=%s,", frame_type_str (fi->unwind->type));
+    res += string_printf ("type=%s,", frame_type_str (fi->unwind->type ()));
   else
     res += "type=<unknown>,";
 
   if (fi->unwind != NULL)
-    res += string_printf ("unwinder=\"%s\",", fi->unwind->name);
+    res += string_printf ("unwinder=\"%s\",", fi->unwind->name ());
   else
     res += "unwinder=<unknown>,";
 
@@ -2361,7 +2359,7 @@  get_prev_frame_always_1 (const frame_info_ptr &this_frame)
      This check is valid only if this frame and the next frame are NORMAL.
      See the comment at frame_id_inner for details.  */
   if (get_frame_type (this_frame) == NORMAL_FRAME
-      && this_frame->next->unwind->type == NORMAL_FRAME
+      && this_frame->next->unwind->type () == NORMAL_FRAME
       && frame_id_inner (get_frame_arch (frame_info_ptr (this_frame->next)),
 			 get_frame_id (this_frame),
 			 get_frame_id (frame_info_ptr (this_frame->next))))
@@ -2989,7 +2987,7 @@  get_frame_type (const frame_info_ptr &frame)
     /* Initialize the frame's unwinder because that's what
        provides the frame's type.  */
     frame_unwind_find_by_frame (frame, &frame->prologue_cache);
-  return frame->unwind->type;
+  return frame->unwind->type ();
 }
 
 struct program_space *
@@ -3070,11 +3068,15 @@  frame_unwind_arch (const frame_info_ptr &next_frame)
       if (next_frame->unwind == NULL)
 	frame_unwind_find_by_frame (next_frame, &next_frame->prologue_cache);
 
-      if (next_frame->unwind->prev_arch != NULL)
-	arch = next_frame->unwind->prev_arch (next_frame,
-					      &next_frame->prologue_cache);
-      else
-	arch = get_frame_arch (next_frame);
+      try
+	{
+	  arch = next_frame->unwind->prev_arch (next_frame,
+						&next_frame->prologue_cache);
+	}
+      catch (gdb_exception &e)
+	{
+	  arch = get_frame_arch (next_frame);
+	}
 
       next_frame->prev_arch.arch = arch;
       next_frame->prev_arch.p = true;
diff --git a/gdb/frv-linux-tdep.c b/gdb/frv-linux-tdep.c
index 874e2b02e8d..5251e7bd0c9 100644
--- a/gdb/frv-linux-tdep.c
+++ b/gdb/frv-linux-tdep.c
@@ -331,8 +331,7 @@  frv_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind frv_linux_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy frv_linux_sigtramp_frame_unwind (
   "frv linux sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -341,7 +340,7 @@  static const struct frame_unwind frv_linux_sigtramp_frame_unwind =
   frv_linux_sigtramp_frame_prev_register,
   NULL,
   frv_linux_sigtramp_frame_sniffer
-};
+);
 
 /* The FRV kernel defines ELF_NGREG as 46.  We add 2 in order to include
    the loadmap addresses in the register set.  (See below for more info.)  */
diff --git a/gdb/frv-tdep.c b/gdb/frv-tdep.c
index e443fe22b76..bc18ea126ca 100644
--- a/gdb/frv-tdep.c
+++ b/gdb/frv-tdep.c
@@ -1404,7 +1404,7 @@  frv_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 }
 
-static const struct frame_unwind frv_frame_unwind = {
+static const struct frame_unwind_legacy frv_frame_unwind (
   "frv prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1413,7 +1413,7 @@  static const struct frame_unwind frv_frame_unwind = {
   frv_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 frv_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/ft32-tdep.c b/gdb/ft32-tdep.c
index 42102bdbb66..ec8ea67eabd 100644
--- a/gdb/ft32-tdep.c
+++ b/gdb/ft32-tdep.c
@@ -523,8 +523,7 @@  ft32_frame_prev_register (const frame_info_ptr &this_frame,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind ft32_frame_unwind =
-{
+static const struct frame_unwind_legacy ft32_frame_unwind (
   "ft32 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -533,7 +532,7 @@  static const struct frame_unwind ft32_frame_unwind =
   ft32_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Return the base address of this_frame.  */
 
diff --git a/gdb/h8300-tdep.c b/gdb/h8300-tdep.c
index 017be737796..3a8fc9d1821 100644
--- a/gdb/h8300-tdep.c
+++ b/gdb/h8300-tdep.c
@@ -499,7 +499,7 @@  h8300_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind h8300_frame_unwind = {
+static const struct frame_unwind_legacy h8300_frame_unwind (
   "h8300 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -508,7 +508,7 @@  static const struct frame_unwind h8300_frame_unwind = {
   h8300_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 h8300_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/hppa-linux-tdep.c b/gdb/hppa-linux-tdep.c
index 6cd7de08308..13229bf3e87 100644
--- a/gdb/hppa-linux-tdep.c
+++ b/gdb/hppa-linux-tdep.c
@@ -307,7 +307,7 @@  hppa_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind hppa_linux_sigtramp_frame_unwind = {
+static const struct frame_unwind_legacy hppa_linux_sigtramp_frame_unwind (
   "hppa linux sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -316,7 +316,7 @@  static const struct frame_unwind hppa_linux_sigtramp_frame_unwind = {
   hppa_linux_sigtramp_frame_prev_register,
   NULL,
   hppa_linux_sigtramp_frame_sniffer
-};
+);
 
 /* Attempt to find (and return) the global pointer for the given
    function.
diff --git a/gdb/hppa-tdep.c b/gdb/hppa-tdep.c
index 838cc42ec77..deb7e5f7b4e 100644
--- a/gdb/hppa-tdep.c
+++ b/gdb/hppa-tdep.c
@@ -2282,8 +2282,7 @@  hppa_frame_unwind_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind hppa_frame_unwind =
-{
+static const struct frame_unwind_legacy hppa_frame_unwind (
   "hppa unwind table",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2292,7 +2291,7 @@  static const struct frame_unwind hppa_frame_unwind =
   hppa_frame_prev_register,
   NULL,
   hppa_frame_unwind_sniffer
-};
+);
 
 /* This is a generic fallback frame unwinder that kicks in if we fail all
    the other ones.  Normally we would expect the stub and regular unwinder
@@ -2396,8 +2395,7 @@  hppa_fallback_frame_prev_register (const frame_info_ptr &this_frame,
 					  info->saved_regs, regnum);
 }
 
-static const struct frame_unwind hppa_fallback_frame_unwind =
-{
+static const struct frame_unwind_legacy hppa_fallback_frame_unwind (
   "hppa prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2406,7 +2404,7 @@  static const struct frame_unwind hppa_fallback_frame_unwind =
   hppa_fallback_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Stub frames, used for all kinds of call stubs.  */
 struct hppa_stub_unwind_cache
@@ -2479,7 +2477,7 @@  hppa_stub_unwind_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind hppa_stub_frame_unwind = {
+static const struct frame_unwind_legacy hppa_stub_frame_unwind (
   "hppa stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2488,7 +2486,7 @@  static const struct frame_unwind hppa_stub_frame_unwind = {
   hppa_stub_frame_prev_register,
   NULL,
   hppa_stub_unwind_sniffer
-};
+);
 
 CORE_ADDR
 hppa_unwind_pc (struct gdbarch *gdbarch, const frame_info_ptr &next_frame)
diff --git a/gdb/i386-obsd-tdep.c b/gdb/i386-obsd-tdep.c
index e262528506c..1d2bef770bc 100644
--- a/gdb/i386-obsd-tdep.c
+++ b/gdb/i386-obsd-tdep.c
@@ -389,7 +389,7 @@  i386obsd_trapframe_sniffer (const struct frame_unwind *self,
 		   || startswith (name, "Xsoft")));
 }
 
-static const struct frame_unwind i386obsd_trapframe_unwind = {
+static const struct frame_unwind_legacy i386obsd_trapframe_unwind (
   "i386 openbsd trap",
   /* FIXME: kettenis/20051219: This really is more like an interrupt
      frame, but SIGTRAMP_FRAME would print <signal handler called>,
@@ -401,7 +401,7 @@  static const struct frame_unwind i386obsd_trapframe_unwind = {
   i386obsd_trapframe_prev_register,
   NULL,
   i386obsd_trapframe_sniffer
-};
+);
 
 
 static void 
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 57c0253e1de..e98e7caffd8 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -2195,8 +2195,7 @@  i386_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind i386_frame_unwind =
-{
+static const struct frame_unwind_legacy i386_frame_unwind (
   "i386 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2205,7 +2204,7 @@  static const struct frame_unwind i386_frame_unwind =
   i386_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Normal frames, but in a function epilogue.  */
 
@@ -2351,8 +2350,7 @@  i386_epilogue_frame_prev_register (const frame_info_ptr &this_frame,
   return i386_frame_prev_register (this_frame, this_cache, regnum);
 }
 
-static const struct frame_unwind i386_epilogue_override_frame_unwind =
-{
+static const struct frame_unwind_legacy i386_epilogue_override_frame_unwind (
   "i386 epilogue override",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2361,10 +2359,9 @@  static const struct frame_unwind i386_epilogue_override_frame_unwind =
   i386_epilogue_frame_prev_register,
   NULL,
   i386_epilogue_override_frame_sniffer
-};
+);
 
-static const struct frame_unwind i386_epilogue_frame_unwind =
-{
+static const struct frame_unwind_legacy i386_epilogue_frame_unwind (
   "i386 epilogue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2373,7 +2370,7 @@  static const struct frame_unwind i386_epilogue_frame_unwind =
   i386_epilogue_frame_prev_register,
   NULL,
   i386_epilogue_frame_sniffer
-};
+);
 
 
 /* Stack-based trampolines.  */
@@ -2446,8 +2443,7 @@  i386_stack_tramp_frame_sniffer (const struct frame_unwind *self,
     return 0;
 }
 
-static const struct frame_unwind i386_stack_tramp_frame_unwind =
-{
+static const struct frame_unwind_legacy i386_stack_tramp_frame_unwind (
   "i386 stack tramp",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2456,7 +2452,7 @@  static const struct frame_unwind i386_stack_tramp_frame_unwind =
   i386_epilogue_frame_prev_register,
   NULL,
   i386_stack_tramp_frame_sniffer
-};
+);
 
 /* Generate a bytecode expression to get the value of the saved PC.  */
 
@@ -2596,8 +2592,7 @@  i386_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind i386_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy i386_sigtramp_frame_unwind (
   "i386 sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2606,7 +2601,7 @@  static const struct frame_unwind i386_sigtramp_frame_unwind =
   i386_sigtramp_frame_prev_register,
   NULL,
   i386_sigtramp_frame_sniffer
-};
+);
 
 
 static CORE_ADDR
diff --git a/gdb/ia64-tdep.c b/gdb/ia64-tdep.c
index e214d963f5f..f4ff03c2df8 100644
--- a/gdb/ia64-tdep.c
+++ b/gdb/ia64-tdep.c
@@ -2161,8 +2161,7 @@  ia64_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache,
     }
 }
  
-static const struct frame_unwind ia64_frame_unwind =
-{
+static const struct frame_unwind_legacy ia64_frame_unwind (
   "ia64 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2171,7 +2170,7 @@  static const struct frame_unwind ia64_frame_unwind =
   &ia64_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Signal trampolines.  */
 
@@ -2351,8 +2350,7 @@  ia64_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind ia64_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy ia64_sigtramp_frame_unwind (
   "ia64 sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2361,7 +2359,7 @@  static const struct frame_unwind ia64_sigtramp_frame_unwind =
   ia64_sigtramp_frame_prev_register,
   NULL,
   ia64_sigtramp_frame_sniffer
-};
+);
 
 
 
@@ -3012,8 +3010,7 @@  ia64_libunwind_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind ia64_libunwind_frame_unwind =
-{
+static const struct frame_unwind_legacy ia64_libunwind_frame_unwind (
   "ia64 libunwind",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3023,7 +3020,7 @@  static const struct frame_unwind ia64_libunwind_frame_unwind =
   NULL,
   ia64_libunwind_frame_sniffer,
   libunwind_frame_dealloc_cache
-};
+);
 
 static void
 ia64_libunwind_sigtramp_frame_this_id (const frame_info_ptr &this_frame,
@@ -3102,8 +3099,7 @@  ia64_libunwind_sigtramp_frame_sniffer (const struct frame_unwind *self,
     return ia64_sigtramp_frame_sniffer (self, this_frame, this_cache);
 }
 
-static const struct frame_unwind ia64_libunwind_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy ia64_libunwind_sigtramp_frame_unwind (
   "ia64 libunwind sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3112,7 +3108,7 @@  static const struct frame_unwind ia64_libunwind_sigtramp_frame_unwind =
   ia64_libunwind_sigtramp_frame_prev_register,
   NULL,
   ia64_libunwind_sigtramp_frame_sniffer
-};
+);
 
 /* Set of libunwind callback acccessor functions.  */
 unw_accessors_t ia64_unw_accessors =
diff --git a/gdb/inline-frame.c b/gdb/inline-frame.c
index 2da4cad5f9d..b274ab23125 100644
--- a/gdb/inline-frame.c
+++ b/gdb/inline-frame.c
@@ -264,7 +264,7 @@  inline_frame_sniffer (const struct frame_unwind *self,
   return 1;
 }
 
-const struct frame_unwind inline_frame_unwind = {
+const struct frame_unwind_legacy inline_frame_unwind (
   "inline",
   INLINE_FRAME,
   FRAME_UNWIND_GDB,
@@ -273,7 +273,7 @@  const struct frame_unwind inline_frame_unwind = {
   inline_frame_prev_register,
   NULL,
   inline_frame_sniffer
-};
+);
 
 /* Return non-zero if BLOCK, an inlined function block containing PC,
    has a group of contiguous instructions starting at PC (but not
diff --git a/gdb/inline-frame.h b/gdb/inline-frame.h
index bbe617c7c5b..a8bd9b07414 100644
--- a/gdb/inline-frame.h
+++ b/gdb/inline-frame.h
@@ -27,7 +27,7 @@  struct process_stratum_target;
 
 /* The inline frame unwinder.  */
 
-extern const struct frame_unwind inline_frame_unwind;
+extern const struct frame_unwind_legacy inline_frame_unwind;
 
 /* Skip all inlined functions whose call sites are at the current PC.
 
diff --git a/gdb/iq2000-tdep.c b/gdb/iq2000-tdep.c
index ea249060e6b..48e0ab18094 100644
--- a/gdb/iq2000-tdep.c
+++ b/gdb/iq2000-tdep.c
@@ -423,7 +423,7 @@  iq2000_frame_this_id (const frame_info_ptr &this_frame, void **this_cache,
   *this_id = frame_id_build (cache->saved_sp, cache->pc);
 }
 
-static const struct frame_unwind iq2000_frame_unwind = {
+static const struct frame_unwind_legacy iq2000_frame_unwind (
   "iq2000 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -432,7 +432,7 @@  static const struct frame_unwind iq2000_frame_unwind = {
   iq2000_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 iq2000_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/jit.c b/gdb/jit.c
index db1b64d0b0b..efb65167a08 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -1103,8 +1103,7 @@  jit_frame_prev_register (const frame_info_ptr &this_frame, void **cache, int reg
 /* Relay everything back to the unwinder registered by the JIT debug
    info reader.*/
 
-static const struct frame_unwind jit_frame_unwind =
-{
+static const struct frame_unwind_legacy jit_frame_unwind (
   "jit",
   NORMAL_FRAME,
   FRAME_UNWIND_EXTENSION,
@@ -1114,7 +1113,7 @@  static const struct frame_unwind jit_frame_unwind =
   NULL,
   jit_frame_sniffer,
   jit_dealloc_cache
-};
+);
 
 
 /* This is the information that is stored at jit_gdbarch_data for each
diff --git a/gdb/lm32-tdep.c b/gdb/lm32-tdep.c
index 7fbf403dd28..02bd1a8762a 100644
--- a/gdb/lm32-tdep.c
+++ b/gdb/lm32-tdep.c
@@ -446,7 +446,7 @@  lm32_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 }
 
-static const struct frame_unwind lm32_frame_unwind = {
+static const struct frame_unwind_legacy lm32_frame_unwind (
   "lm32 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -455,7 +455,7 @@  static const struct frame_unwind lm32_frame_unwind = {
   lm32_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 lm32_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/loongarch-tdep.c b/gdb/loongarch-tdep.c
index c86a2f9ea9c..5b2293911ea 100644
--- a/gdb/loongarch-tdep.c
+++ b/gdb/loongarch-tdep.c
@@ -449,7 +449,7 @@  loongarch_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_register (info, this_frame, regnum);
 }
 
-static const struct frame_unwind loongarch_frame_unwind = {
+static const struct frame_unwind_legacy loongarch_frame_unwind (
   "loongarch prologue",
   /*.type	   =*/NORMAL_FRAME,
   /*.unwinder_class=*/FRAME_UNWIND_ARCH,
@@ -459,8 +459,8 @@  static const struct frame_unwind loongarch_frame_unwind = {
   /*.unwind_data   =*/nullptr,
   /*.sniffer	   =*/default_frame_sniffer,
   /*.dealloc_cache =*/nullptr,
-  /*.prev_arch	   =*/nullptr,
-};
+  /*.prev_arch	   =*/nullptr
+);
 
 /* Write the contents of buffer VAL into the general-purpose argument
    register defined by GAR in REGCACHE.  GAR indicates the available
diff --git a/gdb/m32c-tdep.c b/gdb/m32c-tdep.c
index 0f74cf1458e..fca328eda73 100644
--- a/gdb/m32c-tdep.c
+++ b/gdb/m32c-tdep.c
@@ -1954,7 +1954,7 @@  m32c_prev_register (const frame_info_ptr &this_frame,
 }
 
 
-static const struct frame_unwind m32c_unwind = {
+static const struct frame_unwind_legacy m32c_unwind (
   "m32c prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1963,7 +1963,7 @@  static const struct frame_unwind m32c_unwind = {
   m32c_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 
 /* Inferior calls.  */
diff --git a/gdb/m32r-linux-tdep.c b/gdb/m32r-linux-tdep.c
index ae8e364d794..01e47ed67ec 100644
--- a/gdb/m32r-linux-tdep.c
+++ b/gdb/m32r-linux-tdep.c
@@ -300,7 +300,7 @@  m32r_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind m32r_linux_sigtramp_frame_unwind = {
+static const struct frame_unwind_legacy m32r_linux_sigtramp_frame_unwind (
   "m32r linux sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -309,7 +309,7 @@  static const struct frame_unwind m32r_linux_sigtramp_frame_unwind = {
   m32r_linux_sigtramp_frame_prev_register,
   NULL,
   m32r_linux_sigtramp_frame_sniffer
-};
+);
 
 /* Mapping between the registers in `struct pt_regs'
    format and GDB's register array layout.  */
diff --git a/gdb/m32r-tdep.c b/gdb/m32r-tdep.c
index 1743884ba3c..c58c82e3fa6 100644
--- a/gdb/m32r-tdep.c
+++ b/gdb/m32r-tdep.c
@@ -830,7 +830,7 @@  m32r_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 }
 
-static const struct frame_unwind m32r_frame_unwind = {
+static const struct frame_unwind_legacy m32r_frame_unwind (
   "m32r prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -839,7 +839,7 @@  static const struct frame_unwind m32r_frame_unwind = {
   m32r_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 m32r_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/m68hc11-tdep.c b/gdb/m68hc11-tdep.c
index 44a032157af..7c00061bd09 100644
--- a/gdb/m68hc11-tdep.c
+++ b/gdb/m68hc11-tdep.c
@@ -935,7 +935,7 @@  m68hc11_frame_prev_register (const frame_info_ptr &this_frame,
   return value;
 }
 
-static const struct frame_unwind m68hc11_frame_unwind = {
+static const struct frame_unwind_legacy m68hc11_frame_unwind (
   "m68hc11 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -944,7 +944,7 @@  static const struct frame_unwind m68hc11_frame_unwind = {
   m68hc11_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 m68hc11_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/m68k-linux-tdep.c b/gdb/m68k-linux-tdep.c
index e1d2f51522a..5b3ad72074b 100644
--- a/gdb/m68k-linux-tdep.c
+++ b/gdb/m68k-linux-tdep.c
@@ -313,8 +313,7 @@  m68k_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return m68k_linux_pc_in_sigtramp (this_frame);
 }
 
-static const struct frame_unwind m68k_linux_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy m68k_linux_sigtramp_frame_unwind (
   "m68k linux sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -323,7 +322,7 @@  static const struct frame_unwind m68k_linux_sigtramp_frame_unwind =
   m68k_linux_sigtramp_frame_prev_register,
   NULL,
   m68k_linux_sigtramp_frame_sniffer
-};
+);
 
 /* Register maps for supply/collect regset functions.  */
 
diff --git a/gdb/m68k-tdep.c b/gdb/m68k-tdep.c
index 0fcd340eee7..a051e514245 100644
--- a/gdb/m68k-tdep.c
+++ b/gdb/m68k-tdep.c
@@ -1006,8 +1006,7 @@  m68k_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind m68k_frame_unwind =
-{
+static const struct frame_unwind_legacy m68k_frame_unwind (
   "m68k prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1016,7 +1015,7 @@  static const struct frame_unwind m68k_frame_unwind =
   m68k_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 m68k_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/mep-tdep.c b/gdb/mep-tdep.c
index 004a9f44dca..1648f3fee85 100644
--- a/gdb/mep-tdep.c
+++ b/gdb/mep-tdep.c
@@ -2060,7 +2060,7 @@  mep_frame_prev_register (const frame_info_ptr &this_frame,
 }
 
 
-static const struct frame_unwind mep_frame_unwind = {
+static const struct frame_unwind_legacy mep_frame_unwind (
   "mep prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2069,7 +2069,7 @@  static const struct frame_unwind mep_frame_unwind = {
   mep_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 
 /* Return values.  */
diff --git a/gdb/microblaze-tdep.c b/gdb/microblaze-tdep.c
index 8d53d193dd4..05fedf6c9d6 100644
--- a/gdb/microblaze-tdep.c
+++ b/gdb/microblaze-tdep.c
@@ -477,8 +477,7 @@  microblaze_frame_prev_register (const frame_info_ptr &this_frame,
 
 }
 
-static const struct frame_unwind microblaze_frame_unwind =
-{
+static const struct frame_unwind_legacy microblaze_frame_unwind (
   "microblaze prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -487,7 +486,7 @@  static const struct frame_unwind microblaze_frame_unwind =
   microblaze_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 microblaze_frame_base_address (const frame_info_ptr &next_frame,
diff --git a/gdb/mips-sde-tdep.c b/gdb/mips-sde-tdep.c
index 18cb9485639..783e6fd35ab 100644
--- a/gdb/mips-sde-tdep.c
+++ b/gdb/mips-sde-tdep.c
@@ -160,8 +160,7 @@  mips_sde_frame_sniffer (const struct frame_unwind *self,
 
 /* Data structure for the SDE frame unwinder.  */
 
-static const struct frame_unwind mips_sde_frame_unwind =
-{
+static const struct frame_unwind_legacy mips_sde_frame_unwind (
   "mips sde sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -170,7 +169,7 @@  static const struct frame_unwind mips_sde_frame_unwind =
   mips_sde_frame_prev_register,
   NULL,
   mips_sde_frame_sniffer
-};
+);
 
 /* Implement the this_base, this_locals, and this_args hooks
    for the normal unwinder.  */
diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index 92630f329d8..b33df4e3461 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -2928,8 +2928,7 @@  mips_insn16_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind mips_insn16_frame_unwind =
-{
+static const struct frame_unwind_legacy mips_insn16_frame_unwind (
   "mips insn16 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2938,7 +2937,7 @@  static const struct frame_unwind mips_insn16_frame_unwind =
   mips_insn16_frame_prev_register,
   NULL,
   mips_insn16_frame_sniffer
-};
+);
 
 static CORE_ADDR
 mips_insn16_frame_base_address (const frame_info_ptr &this_frame,
@@ -3365,8 +3364,7 @@  mips_micro_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind mips_micro_frame_unwind =
-{
+static const struct frame_unwind_legacy mips_micro_frame_unwind (
   "mips micro prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3375,7 +3373,7 @@  static const struct frame_unwind mips_micro_frame_unwind =
   mips_micro_frame_prev_register,
   NULL,
   mips_micro_frame_sniffer
-};
+);
 
 static CORE_ADDR
 mips_micro_frame_base_address (const frame_info_ptr &this_frame,
@@ -3745,8 +3743,7 @@  mips_insn32_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind mips_insn32_frame_unwind =
-{
+static const struct frame_unwind_legacy mips_insn32_frame_unwind (
   "mips insn32 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3755,7 +3752,7 @@  static const struct frame_unwind mips_insn32_frame_unwind =
   mips_insn32_frame_prev_register,
   NULL,
   mips_insn32_frame_sniffer
-};
+);
 
 static CORE_ADDR
 mips_insn32_frame_base_address (const frame_info_ptr &this_frame,
@@ -3863,8 +3860,7 @@  mips_stub_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind mips_stub_frame_unwind =
-{
+static const struct frame_unwind_legacy mips_stub_frame_unwind (
   "mips stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3873,7 +3869,7 @@  static const struct frame_unwind mips_stub_frame_unwind =
   mips_stub_frame_prev_register,
   NULL,
   mips_stub_frame_sniffer
-};
+);
 
 static CORE_ADDR
 mips_stub_frame_base_address (const frame_info_ptr &this_frame,
diff --git a/gdb/mn10300-tdep.c b/gdb/mn10300-tdep.c
index 63fc62c734f..19dd3b2bac0 100644
--- a/gdb/mn10300-tdep.c
+++ b/gdb/mn10300-tdep.c
@@ -1126,7 +1126,7 @@  mn10300_frame_prev_register (const frame_info_ptr &this_frame,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind mn10300_frame_unwind = {
+static const struct frame_unwind_legacy mn10300_frame_unwind (
   "mn10300 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1135,7 +1135,7 @@  static const struct frame_unwind mn10300_frame_unwind = {
   mn10300_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static void
 mn10300_frame_unwind_init (struct gdbarch *gdbarch)
diff --git a/gdb/moxie-tdep.c b/gdb/moxie-tdep.c
index d4684a0d3c3..22c74d28920 100644
--- a/gdb/moxie-tdep.c
+++ b/gdb/moxie-tdep.c
@@ -584,7 +584,7 @@  moxie_frame_prev_register (const frame_info_ptr &this_frame,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind moxie_frame_unwind = {
+static const struct frame_unwind_legacy moxie_frame_unwind (
   "moxie prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -593,7 +593,7 @@  static const struct frame_unwind moxie_frame_unwind = {
   moxie_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Return the base address of this_frame.  */
 
diff --git a/gdb/msp430-tdep.c b/gdb/msp430-tdep.c
index 765b15b87e7..ce82a0cee34 100644
--- a/gdb/msp430-tdep.c
+++ b/gdb/msp430-tdep.c
@@ -541,7 +541,7 @@  msp430_prev_register (const frame_info_ptr &this_frame,
     return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind msp430_unwind = {
+static const struct frame_unwind_legacy msp430_unwind (
   "msp430 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -550,7 +550,7 @@  static const struct frame_unwind msp430_unwind = {
   msp430_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Implement the "dwarf2_reg_to_regnum" gdbarch method.  */
 
diff --git a/gdb/nds32-tdep.c b/gdb/nds32-tdep.c
index 6fd5c3c7a28..6aca27ee96a 100644
--- a/gdb/nds32-tdep.c
+++ b/gdb/nds32-tdep.c
@@ -987,8 +987,7 @@  nds32_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind nds32_frame_unwind =
-{
+static const struct frame_unwind_legacy nds32_frame_unwind (
   "nds32 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -996,8 +995,8 @@  static const struct frame_unwind nds32_frame_unwind =
   nds32_frame_this_id,
   nds32_frame_prev_register,
   NULL,
-  default_frame_sniffer,
-};
+  default_frame_sniffer
+);
 
 /* Return the frame base address of *THIS_FRAME.  */
 
@@ -1372,8 +1371,7 @@  nds32_epilogue_frame_prev_register (const frame_info_ptr &this_frame,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind nds32_epilogue_frame_unwind =
-{
+static const struct frame_unwind_legacy nds32_epilogue_frame_unwind (
   "nds32 epilogue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1382,7 +1380,7 @@  static const struct frame_unwind nds32_epilogue_frame_unwind =
   nds32_epilogue_frame_prev_register,
   NULL,
   nds32_epilogue_frame_sniffer
-};
+);
 
 
 /* Floating type and struct type that has only one floating type member
diff --git a/gdb/nios2-tdep.c b/gdb/nios2-tdep.c
index 179c3d72a49..709b86742e3 100644
--- a/gdb/nios2-tdep.c
+++ b/gdb/nios2-tdep.c
@@ -1976,8 +1976,7 @@  nios2_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
 /* Data structures for the normal prologue-analysis-based
    unwinder.  */
 
-static const struct frame_unwind nios2_frame_unwind =
-{
+static const struct frame_unwind_legacy nios2_frame_unwind (
   "nios2 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1986,7 +1985,7 @@  static const struct frame_unwind nios2_frame_unwind =
   nios2_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static const struct frame_base nios2_frame_base =
 {
@@ -2078,8 +2077,7 @@  nios2_stub_frame_sniffer (const struct frame_unwind *self,
 
 /* Define the data structures for the stub unwinder.  */
 
-static const struct frame_unwind nios2_stub_frame_unwind =
-{
+static const struct frame_unwind_legacy nios2_stub_frame_unwind (
   "nios2 stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2088,7 +2086,7 @@  static const struct frame_unwind nios2_stub_frame_unwind =
   nios2_stub_frame_prev_register,
   NULL,
   nios2_stub_frame_sniffer
-};
+);
 
 
 
diff --git a/gdb/or1k-tdep.c b/gdb/or1k-tdep.c
index b1d7911de98..e36e4ce9dd1 100644
--- a/gdb/or1k-tdep.c
+++ b/gdb/or1k-tdep.c
@@ -1124,7 +1124,7 @@  or1k_frame_prev_register (const frame_info_ptr &this_frame,
 
 /* Data structures for the normal prologue-analysis-based unwinder.  */
 
-static const struct frame_unwind or1k_frame_unwind = {
+static const struct frame_unwind_legacy or1k_frame_unwind (
   "or1k prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1133,8 +1133,8 @@  static const struct frame_unwind or1k_frame_unwind = {
   or1k_frame_prev_register,
   NULL,
   default_frame_sniffer,
-  NULL,
-};
+  NULL
+);
 
 /* Architecture initialization for OpenRISC 1000.  */
 
diff --git a/gdb/ppc-fbsd-tdep.c b/gdb/ppc-fbsd-tdep.c
index f7f99660e29..d8c76f77fd8 100644
--- a/gdb/ppc-fbsd-tdep.c
+++ b/gdb/ppc-fbsd-tdep.c
@@ -261,7 +261,7 @@  ppcfbsd_sigtramp_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_register (cache, this_frame, regnum);
 }
 
-static const struct frame_unwind ppcfbsd_sigtramp_frame_unwind = {
+static const struct frame_unwind_legacy ppcfbsd_sigtramp_frame_unwind (
   "ppc freebsd sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -270,7 +270,7 @@  static const struct frame_unwind ppcfbsd_sigtramp_frame_unwind = {
   ppcfbsd_sigtramp_frame_prev_register,
   NULL,
   ppcfbsd_sigtramp_frame_sniffer
-};
+);
 
 static enum return_value_convention
 ppcfbsd_return_value (struct gdbarch *gdbarch, struct value *function,
diff --git a/gdb/ppc-obsd-tdep.c b/gdb/ppc-obsd-tdep.c
index f7e642ee05c..68edd54dd96 100644
--- a/gdb/ppc-obsd-tdep.c
+++ b/gdb/ppc-obsd-tdep.c
@@ -230,7 +230,7 @@  ppcobsd_sigtramp_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_register (cache, this_frame, regnum);
 }
 
-static const struct frame_unwind ppcobsd_sigtramp_frame_unwind = {
+static const struct frame_unwind_legacy ppcobsd_sigtramp_frame_unwind (
   "ppc openbsd sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -239,7 +239,7 @@  static const struct frame_unwind ppcobsd_sigtramp_frame_unwind = {
   ppcobsd_sigtramp_frame_prev_register,
   NULL,
   ppcobsd_sigtramp_frame_sniffer
-};
+);
 
 
 static void
diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c
index 668835e0444..91c9fbf2274 100644
--- a/gdb/python/py-unwind.c
+++ b/gdb/python/py-unwind.c
@@ -806,7 +806,7 @@  pyuw_sniffer (const struct frame_unwind *self, const frame_info_ptr &this_frame,
 {
   PYUW_SCOPED_DEBUG_ENTER_EXIT;
 
-  struct gdbarch *gdbarch = (struct gdbarch *) (self->unwind_data);
+  struct gdbarch *gdbarch = (struct gdbarch *) (self->unwind_data ());
   cached_frame_info *cached_frame;
 
   gdbpy_enter enter_py (gdbarch);
@@ -947,6 +947,41 @@  struct pyuw_gdbarch_data_type
 
 static const registry<gdbarch>::key<pyuw_gdbarch_data_type> pyuw_gdbarch_data;
 
+/* Class for frame unwinders registered by the Python architecture callback.  */
+class frame_unwind_python : public frame_unwind
+{
+public:
+  frame_unwind_python (const struct frame_data *newarch)
+    : frame_unwind ("python", NORMAL_FRAME, FRAME_UNWIND_EXTENSION, newarch)
+  { }
+
+  /* No need to override stop_reason, we want the default.  */
+
+  int sniffer (const frame_unwind *self, const frame_info_ptr &this_frame,
+		void **this_prologue_cache) const override
+  {
+    return pyuw_sniffer (self, this_frame, this_prologue_cache);
+  }
+
+  void this_id (const frame_info_ptr &this_frame, void **this_prologue_cache,
+		struct frame_id *id) const override
+  {
+    pyuw_this_id (this_frame, this_prologue_cache, id);
+  }
+
+  struct value *prev_register (const frame_info_ptr &this_frame,
+			       void **this_prologue_cache,
+			       int regnum) const override
+  {
+      return pyuw_prev_register (this_frame, this_prologue_cache, regnum);
+  }
+
+  void dealloc_cache (frame_info *self, void *this_cache) const override
+  {
+      pyuw_dealloc_cache (self, this_cache);
+  }
+};
+
 /* New inferior architecture callback: register the Python unwinders
    intermediary.  */
 
@@ -960,17 +995,9 @@  pyuw_on_new_gdbarch (gdbarch *newarch)
   if (!data->unwinder_registered)
     {
       struct frame_unwind *unwinder
-	  = GDBARCH_OBSTACK_ZALLOC (newarch, struct frame_unwind);
-
-      unwinder->name = "python";
-      unwinder->type = NORMAL_FRAME;
-      unwinder->unwinder_class = FRAME_UNWIND_EXTENSION;
-      unwinder->stop_reason = default_frame_unwind_stop_reason;
-      unwinder->this_id = pyuw_this_id;
-      unwinder->prev_register = pyuw_prev_register;
-      unwinder->unwind_data = (const struct frame_data *) newarch;
-      unwinder->sniffer = pyuw_sniffer;
-      unwinder->dealloc_cache = pyuw_dealloc_cache;
+	  = obstack_new<frame_unwind_python>
+	    (gdbarch_obstack (newarch), (const struct frame_data *) newarch);
+
       frame_unwind_prepend_unwinder (newarch, unwinder);
       data->unwinder_registered = 1;
     }
diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 2bf3e214446..c069850d4bd 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -1893,8 +1893,7 @@  record_btrace_frame_dealloc_cache (frame_info *self, void *this_cache)
    Therefore this unwinder reports any possibly unwound registers as
    <unavailable>.  */
 
-const struct frame_unwind record_btrace_frame_unwind =
-{
+const struct frame_unwind_legacy record_btrace_frame_unwind (
   "record-btrace",
   NORMAL_FRAME,
   FRAME_UNWIND_GDB,
@@ -1904,10 +1903,9 @@  const struct frame_unwind record_btrace_frame_unwind =
   NULL,
   record_btrace_frame_sniffer,
   record_btrace_frame_dealloc_cache
-};
+);
 
-const struct frame_unwind record_btrace_tailcall_frame_unwind =
-{
+const struct frame_unwind_legacy record_btrace_tailcall_frame_unwind (
   "record-btrace tailcall",
   TAILCALL_FRAME,
   FRAME_UNWIND_GDB,
@@ -1917,7 +1915,7 @@  const struct frame_unwind record_btrace_tailcall_frame_unwind =
   NULL,
   record_btrace_tailcall_frame_sniffer,
   record_btrace_frame_dealloc_cache
-};
+);
 
 /* Implement the get_unwinder method.  */
 
diff --git a/gdb/record.h b/gdb/record.h
index f44b3952943..44918ef4242 100644
--- a/gdb/record.h
+++ b/gdb/record.h
@@ -36,8 +36,8 @@  extern struct cmd_list_element *show_record_cmdlist;
 extern struct cmd_list_element *info_record_cmdlist;
 
 /* Unwinders for some record targets.  */
-extern const struct frame_unwind record_btrace_frame_unwind;
-extern const struct frame_unwind record_btrace_tailcall_frame_unwind;
+extern const struct frame_unwind_legacy record_btrace_frame_unwind;
+extern const struct frame_unwind_legacy record_btrace_tailcall_frame_unwind;
 
 /* A list of different recording methods.  */
 enum record_method
diff --git a/gdb/riscv-tdep.c b/gdb/riscv-tdep.c
index 860a895bc06..b9391d0845b 100644
--- a/gdb/riscv-tdep.c
+++ b/gdb/riscv-tdep.c
@@ -3899,8 +3899,7 @@  riscv_frame_prev_register (const frame_info_ptr &this_frame,
    are the fallback unwinder (DWARF unwinder is used first), we use the
    default frame sniffer, which always accepts the frame.  */
 
-static const struct frame_unwind riscv_frame_unwind =
-{
+static const struct frame_unwind_legacy riscv_frame_unwind (
   /*.name          =*/ "riscv prologue",
   /*.type          =*/ NORMAL_FRAME,
   /*.unwinder_class=*/FRAME_UNWIND_ARCH,
@@ -3910,8 +3909,8 @@  static const struct frame_unwind riscv_frame_unwind =
   /*.unwind_data   =*/ NULL,
   /*.sniffer       =*/ default_frame_sniffer,
   /*.dealloc_cache =*/ NULL,
-  /*.prev_arch     =*/ NULL,
-};
+  /*.prev_arch     =*/ NULL
+);
 
 /* Extract a set of required target features out of ABFD.  If ABFD is
    nullptr then a RISCV_GDBARCH_FEATURES is returned in its default state.  */
diff --git a/gdb/rl78-tdep.c b/gdb/rl78-tdep.c
index 4af93c37df1..62098d9f85a 100644
--- a/gdb/rl78-tdep.c
+++ b/gdb/rl78-tdep.c
@@ -1182,8 +1182,7 @@  rl78_prev_register (const frame_info_ptr &this_frame,
     return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind rl78_unwind =
-{
+static const struct frame_unwind_legacy rl78_unwind (
   "rl78 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1192,7 +1191,7 @@  static const struct frame_unwind rl78_unwind =
   rl78_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Implement the "dwarf_reg_to_regnum" gdbarch method.  */
 
diff --git a/gdb/rs6000-aix-tdep.c b/gdb/rs6000-aix-tdep.c
index ea44765c7fa..4cf539507ac 100644
--- a/gdb/rs6000-aix-tdep.c
+++ b/gdb/rs6000-aix-tdep.c
@@ -327,7 +327,7 @@  aix_sighandle_frame_sniffer (const struct frame_unwind *self,
 
 /* AIX signal handler frame unwinder */
 
-static const struct frame_unwind aix_sighandle_frame_unwind = {
+static const struct frame_unwind_legacy aix_sighandle_frame_unwind (
   "rs6000 aix sighandle",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -336,7 +336,7 @@  static const struct frame_unwind aix_sighandle_frame_unwind = {
   aix_sighandle_frame_prev_register,
   NULL,
   aix_sighandle_frame_sniffer
-};
+);
 
 /* Core file support.  */
 
diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c
index 5d1fde07145..c4f015de4b3 100644
--- a/gdb/rs6000-tdep.c
+++ b/gdb/rs6000-tdep.c
@@ -3837,8 +3837,7 @@  rs6000_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
 }
 
-static const struct frame_unwind rs6000_frame_unwind =
-{
+static const struct frame_unwind_legacy rs6000_frame_unwind (
   "rs6000 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3847,7 +3846,7 @@  static const struct frame_unwind rs6000_frame_unwind =
   rs6000_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Allocate and initialize a frame cache for an epilogue frame.
    SP is restored and prev-PC is stored in LR.  */
@@ -3979,8 +3978,7 @@  rs6000_epilogue_frame_sniffer (const struct frame_unwind *self,
 /* Frame unwinder for epilogue frame.  This is required for reverse step-over
    a function without debug information.  */
 
-static const struct frame_unwind rs6000_epilogue_frame_unwind =
-{
+static const struct frame_unwind_legacy rs6000_epilogue_frame_unwind (
   "rs6000 epilogue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -3988,7 +3986,7 @@  static const struct frame_unwind rs6000_epilogue_frame_unwind =
   rs6000_epilogue_frame_this_id, rs6000_epilogue_frame_prev_register,
   NULL,
   rs6000_epilogue_frame_sniffer
-};
+);
 
 
 static CORE_ADDR
diff --git a/gdb/rx-tdep.c b/gdb/rx-tdep.c
index b35d477204e..ebdb324945d 100644
--- a/gdb/rx-tdep.c
+++ b/gdb/rx-tdep.c
@@ -630,7 +630,7 @@  rx_exception_sniffer (const struct frame_unwind *self,
 /* Data structure for normal code using instruction-based prologue
    analyzer.  */
 
-static const struct frame_unwind rx_frame_unwind = {
+static const struct frame_unwind_legacy rx_frame_unwind (
   "rx prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -639,12 +639,12 @@  static const struct frame_unwind rx_frame_unwind = {
   rx_frame_prev_register,
   NULL,
   rx_frame_sniffer
-};
+);
 
 /* Data structure for exception code using instruction-based prologue
    analyzer.  */
 
-static const struct frame_unwind rx_exception_unwind = {
+static const struct frame_unwind_legacy rx_exception_unwind (
   "rx exception",
   /* SIGTRAMP_FRAME could be used here, but backtraces are less informative.  */
   NORMAL_FRAME,
@@ -654,7 +654,7 @@  static const struct frame_unwind rx_exception_unwind = {
   rx_frame_prev_register,
   NULL,
   rx_exception_sniffer
-};
+);
 
 /* Implement the "push_dummy_call" gdbarch method.  */
 static CORE_ADDR
diff --git a/gdb/s12z-tdep.c b/gdb/s12z-tdep.c
index bb0c8bef327..6a377709eff 100644
--- a/gdb/s12z-tdep.c
+++ b/gdb/s12z-tdep.c
@@ -441,7 +441,7 @@  s12z_frame_prev_register (const frame_info_ptr &this_frame,
 }
 
 /* Data structures for the normal prologue-analysis-based unwinder.  */
-static const struct frame_unwind s12z_frame_unwind = {
+static const struct frame_unwind_legacy s12z_frame_unwind (
   "s12z prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -450,8 +450,8 @@  static const struct frame_unwind s12z_frame_unwind = {
   s12z_frame_prev_register,
   NULL,
   default_frame_sniffer,
-  NULL,
-};
+  NULL
+);
 
 
 constexpr gdb_byte s12z_break_insn[] = {0x00};
diff --git a/gdb/s390-linux-tdep.c b/gdb/s390-linux-tdep.c
index 556fad64926..96d6d446219 100644
--- a/gdb/s390-linux-tdep.c
+++ b/gdb/s390-linux-tdep.c
@@ -541,7 +541,7 @@  s390_sigtramp_frame_sniffer (const struct frame_unwind *self,
 
 /* S390 sigtramp frame unwinder.  */
 
-static const struct frame_unwind s390_sigtramp_frame_unwind = {
+static const struct frame_unwind_legacy s390_sigtramp_frame_unwind (
   "s390 linux sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -550,7 +550,7 @@  static const struct frame_unwind s390_sigtramp_frame_unwind = {
   s390_sigtramp_frame_prev_register,
   NULL,
   s390_sigtramp_frame_sniffer
-};
+);
 
 /* Syscall handling.  */
 
diff --git a/gdb/s390-tdep.c b/gdb/s390-tdep.c
index 065c52e6442..4d429ba0301 100644
--- a/gdb/s390-tdep.c
+++ b/gdb/s390-tdep.c
@@ -2645,7 +2645,7 @@  s390_frame_prev_register (const frame_info_ptr &this_frame,
 
 /* Default S390 frame unwinder.  */
 
-static const struct frame_unwind s390_frame_unwind = {
+static const struct frame_unwind_legacy s390_frame_unwind (
   "s390 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2654,7 +2654,7 @@  static const struct frame_unwind s390_frame_unwind = {
   s390_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 /* Code stubs and their stack frames.  For things like PLTs and NULL
    function calls (where there is no true frame and the return address
@@ -2740,7 +2740,7 @@  s390_stub_frame_sniffer (const struct frame_unwind *self,
 
 /* S390 stub frame unwinder.  */
 
-static const struct frame_unwind s390_stub_frame_unwind = {
+static const struct frame_unwind_legacy s390_stub_frame_unwind (
   "s390 stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2749,7 +2749,7 @@  static const struct frame_unwind s390_stub_frame_unwind = {
   s390_stub_frame_prev_register,
   NULL,
   s390_stub_frame_sniffer
-};
+);
 
 /* Frame base handling.  */
 
diff --git a/gdb/sentinel-frame.c b/gdb/sentinel-frame.c
index 9fe4036dbbe..c809259920d 100644
--- a/gdb/sentinel-frame.c
+++ b/gdb/sentinel-frame.c
@@ -78,8 +78,7 @@  sentinel_frame_prev_arch (const frame_info_ptr &this_frame,
   return cache->regcache->arch ();
 }
 
-const struct frame_unwind sentinel_frame_unwind =
-{
+const struct frame_unwind_legacy sentinel_frame_unwind (
   "sentinel",
   SENTINEL_FRAME,
   FRAME_UNWIND_GDB,
@@ -89,5 +88,5 @@  const struct frame_unwind sentinel_frame_unwind =
   NULL,
   NULL,
   NULL,
-  sentinel_frame_prev_arch,
-};
+  sentinel_frame_prev_arch
+);
diff --git a/gdb/sentinel-frame.h b/gdb/sentinel-frame.h
index 1a37ff1f49a..4b498f18940 100644
--- a/gdb/sentinel-frame.h
+++ b/gdb/sentinel-frame.h
@@ -34,6 +34,6 @@  extern void *sentinel_frame_cache (struct regcache *regcache);
 
 /* At present there is only one type of sentinel frame.  */
 
-extern const struct frame_unwind sentinel_frame_unwind;
+extern const struct frame_unwind_legacy sentinel_frame_unwind;
 
 #endif /* !defined (SENTINEL_FRAME_H)  */
diff --git a/gdb/sh-tdep.c b/gdb/sh-tdep.c
index 8491adbb5c1..d3cb50fe352 100644
--- a/gdb/sh-tdep.c
+++ b/gdb/sh-tdep.c
@@ -1928,7 +1928,7 @@  sh_frame_this_id (const frame_info_ptr &this_frame, void **this_cache,
   *this_id = frame_id_build (cache->saved_sp, cache->pc);
 }
 
-static const struct frame_unwind sh_frame_unwind = {
+static const struct frame_unwind_legacy sh_frame_unwind (
   "sh prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1937,7 +1937,7 @@  static const struct frame_unwind sh_frame_unwind = {
   sh_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 sh_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
@@ -1995,8 +1995,7 @@  sh_stub_unwind_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind sh_stub_unwind =
-{
+static const struct frame_unwind_legacy sh_stub_unwind (
   "sh stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -2005,7 +2004,7 @@  static const struct frame_unwind sh_stub_unwind =
   sh_frame_prev_register,
   NULL,
   sh_stub_unwind_sniffer
-};
+);
 
 /* Implement the stack_frame_destroyed_p gdbarch method.
 
diff --git a/gdb/sparc-netbsd-tdep.c b/gdb/sparc-netbsd-tdep.c
index 5b3dd067375..bc058dcbf63 100644
--- a/gdb/sparc-netbsd-tdep.c
+++ b/gdb/sparc-netbsd-tdep.c
@@ -248,8 +248,7 @@  sparc32nbsd_sigcontext_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind sparc32nbsd_sigcontext_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc32nbsd_sigcontext_frame_unwind (
   "sparc32 netbsd sigcontext",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -258,7 +257,7 @@  static const struct frame_unwind sparc32nbsd_sigcontext_frame_unwind =
   sparc32nbsd_sigcontext_frame_prev_register,
   NULL,
   sparc32nbsd_sigcontext_frame_sniffer
-};
+);
 
 /* Return the address of a system call's alternative return
    address.  */
diff --git a/gdb/sparc-obsd-tdep.c b/gdb/sparc-obsd-tdep.c
index 5d42e4e6515..fe6a73909ae 100644
--- a/gdb/sparc-obsd-tdep.c
+++ b/gdb/sparc-obsd-tdep.c
@@ -133,8 +133,7 @@  sparc32obsd_sigtramp_frame_sniffer (const struct frame_unwind *self,
 
   return 0;
 }
-static const struct frame_unwind sparc32obsd_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc32obsd_sigtramp_frame_unwind (
   "sparc32 openbsd sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -143,7 +142,7 @@  static const struct frame_unwind sparc32obsd_sigtramp_frame_unwind =
   sparc32obsd_sigtramp_frame_prev_register,
   NULL,
   sparc32obsd_sigtramp_frame_sniffer
-};
+);
 
 
 
diff --git a/gdb/sparc-sol2-tdep.c b/gdb/sparc-sol2-tdep.c
index bb9c8a549b1..b6ac8011b7b 100644
--- a/gdb/sparc-sol2-tdep.c
+++ b/gdb/sparc-sol2-tdep.c
@@ -179,8 +179,7 @@  sparc32_sol2_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return sol2_sigtramp_p (this_frame);
 }
 
-static const struct frame_unwind sparc32_sol2_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc32_sol2_sigtramp_frame_unwind (
   "sparc32 solaris sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -189,7 +188,7 @@  static const struct frame_unwind sparc32_sol2_sigtramp_frame_unwind =
   sparc32_sol2_sigtramp_frame_prev_register,
   NULL,
   sparc32_sol2_sigtramp_frame_sniffer
-};
+);
 
 
 
diff --git a/gdb/sparc-tdep.c b/gdb/sparc-tdep.c
index a40570d6894..e951e0b57a1 100644
--- a/gdb/sparc-tdep.c
+++ b/gdb/sparc-tdep.c
@@ -1345,8 +1345,7 @@  sparc32_frame_prev_register (const frame_info_ptr &this_frame,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind sparc32_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc32_frame_unwind (
   "sparc32 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1355,7 +1354,7 @@  static const struct frame_unwind sparc32_frame_unwind =
   sparc32_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 
 static CORE_ADDR
diff --git a/gdb/sparc64-fbsd-tdep.c b/gdb/sparc64-fbsd-tdep.c
index 1d4c075a961..6630a9b51b0 100644
--- a/gdb/sparc64-fbsd-tdep.c
+++ b/gdb/sparc64-fbsd-tdep.c
@@ -196,8 +196,7 @@  sparc64fbsd_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind sparc64fbsd_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc64fbsd_sigtramp_frame_unwind (
   "sparc64 freebsd sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -206,7 +205,7 @@  static const struct frame_unwind sparc64fbsd_sigtramp_frame_unwind =
   sparc64fbsd_sigtramp_frame_prev_register,
   NULL,
   sparc64fbsd_sigtramp_frame_sniffer
-};
+);
 
 
 static const struct regset sparc64fbsd_gregset =
diff --git a/gdb/sparc64-netbsd-tdep.c b/gdb/sparc64-netbsd-tdep.c
index 82eb99f57c1..53c49fe1130 100644
--- a/gdb/sparc64-netbsd-tdep.c
+++ b/gdb/sparc64-netbsd-tdep.c
@@ -222,8 +222,7 @@  sparc64nbsd_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind sparc64nbsd_sigcontext_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc64nbsd_sigcontext_frame_unwind (
   "sparc64 netbsd sigcontext",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -232,7 +231,7 @@  static const struct frame_unwind sparc64nbsd_sigcontext_frame_unwind =
   sparc64nbsd_sigcontext_frame_prev_register,
   NULL,
   sparc64nbsd_sigtramp_frame_sniffer
-};
+);
 
 
 static const struct regset sparc64nbsd_gregset =
diff --git a/gdb/sparc64-obsd-tdep.c b/gdb/sparc64-obsd-tdep.c
index ad69476dac4..92c7f311a0d 100644
--- a/gdb/sparc64-obsd-tdep.c
+++ b/gdb/sparc64-obsd-tdep.c
@@ -219,8 +219,7 @@  sparc64obsd_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind sparc64obsd_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc64obsd_frame_unwind (
   "sparc64 openbsd sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -229,7 +228,7 @@  static const struct frame_unwind sparc64obsd_frame_unwind =
   sparc64obsd_frame_prev_register,
   NULL,
   sparc64obsd_sigtramp_frame_sniffer
-};
+);
 
 /* Kernel debugging support.  */
 
@@ -304,8 +303,7 @@  sparc64obsd_trapframe_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind sparc64obsd_trapframe_unwind =
-{
+static const struct frame_unwind_legacy sparc64obsd_trapframe_unwind (
   "sparc64 openbsd trap",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -314,7 +312,7 @@  static const struct frame_unwind sparc64obsd_trapframe_unwind =
   sparc64obsd_trapframe_prev_register,
   NULL,
   sparc64obsd_trapframe_sniffer
-};
+);
 
 
 /* Threads support.  */
diff --git a/gdb/sparc64-sol2-tdep.c b/gdb/sparc64-sol2-tdep.c
index e8d09e2516e..cadbf49788c 100644
--- a/gdb/sparc64-sol2-tdep.c
+++ b/gdb/sparc64-sol2-tdep.c
@@ -182,8 +182,7 @@  sparc64_sol2_sigtramp_frame_sniffer (const struct frame_unwind *self,
   return sol2_sigtramp_p (this_frame);
 }
 
-static const struct frame_unwind sparc64_sol2_sigtramp_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc64_sol2_sigtramp_frame_unwind (
   "sparc64 solaris sigtramp",
   SIGTRAMP_FRAME,
   FRAME_UNWIND_ARCH,
@@ -192,7 +191,7 @@  static const struct frame_unwind sparc64_sol2_sigtramp_frame_unwind =
   sparc64_sol2_sigtramp_frame_prev_register,
   NULL,
   sparc64_sol2_sigtramp_frame_sniffer
-};
+);
 
 
 
diff --git a/gdb/sparc64-tdep.c b/gdb/sparc64-tdep.c
index 30ee241c5b6..43427ad1aba 100644
--- a/gdb/sparc64-tdep.c
+++ b/gdb/sparc64-tdep.c
@@ -1133,8 +1133,7 @@  sparc64_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static const struct frame_unwind sparc64_frame_unwind =
-{
+static const struct frame_unwind_legacy sparc64_frame_unwind (
   "sparc64 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1143,7 +1142,7 @@  static const struct frame_unwind sparc64_frame_unwind =
   sparc64_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 
 static CORE_ADDR
diff --git a/gdb/tic6x-tdep.c b/gdb/tic6x-tdep.c
index bc0465b4635..00192caf386 100644
--- a/gdb/tic6x-tdep.c
+++ b/gdb/tic6x-tdep.c
@@ -451,8 +451,7 @@  tic6x_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
   return info->base;
 }
 
-static const struct frame_unwind tic6x_frame_unwind =
-{
+static const struct frame_unwind_legacy tic6x_frame_unwind (
   "tic6x prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -461,7 +460,7 @@  static const struct frame_unwind tic6x_frame_unwind =
   tic6x_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static const struct frame_base tic6x_frame_base =
 {
@@ -515,8 +514,7 @@  tic6x_stub_unwind_sniffer (const struct frame_unwind *self,
   return 0;
 }
 
-static const struct frame_unwind tic6x_stub_unwind =
-{
+static const struct frame_unwind_legacy tic6x_stub_unwind (
   "tic6x stub",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -525,7 +523,7 @@  static const struct frame_unwind tic6x_stub_unwind =
   tic6x_frame_prev_register,
   NULL,
   tic6x_stub_unwind_sniffer
-};
+);
 
 /* Return the instruction on address PC.  */
 
diff --git a/gdb/tilegx-tdep.c b/gdb/tilegx-tdep.c
index fc1c01c7ea4..18cb722b4a8 100644
--- a/gdb/tilegx-tdep.c
+++ b/gdb/tilegx-tdep.c
@@ -899,7 +899,7 @@  tilegx_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
   return cache->base;
 }
 
-static const struct frame_unwind tilegx_frame_unwind = {
+static const struct frame_unwind_legacy tilegx_frame_unwind (
   "tilegx prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -909,7 +909,7 @@  static const struct frame_unwind tilegx_frame_unwind = {
   NULL,                        /* const struct frame_data *unwind_data  */
   default_frame_sniffer,       /* frame_sniffer_ftype *sniffer  */
   NULL                         /* frame_prev_pc_ftype *prev_pc  */
-};
+);
 
 static const struct frame_base tilegx_frame_base = {
   &tilegx_frame_unwind,
diff --git a/gdb/tramp-frame.c b/gdb/tramp-frame.c
index 2fcc3814e59..7fee4d5c71d 100644
--- a/gdb/tramp-frame.c
+++ b/gdb/tramp-frame.c
@@ -123,7 +123,7 @@  tramp_frame_sniffer (const struct frame_unwind *self,
 		     const frame_info_ptr &this_frame,
 		     void **this_cache)
 {
-  const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
+  const struct tramp_frame *tramp = self->unwind_data ()->tramp_frame;
   CORE_ADDR pc = get_frame_pc (this_frame);
   CORE_ADDR func;
   struct tramp_frame_cache *tramp_cache;
@@ -142,6 +142,46 @@  tramp_frame_sniffer (const struct frame_unwind *self,
   return 1;
 }
 
+class frame_unwind_trampoline : public frame_unwind
+{
+private:
+  frame_prev_arch_ftype *prev_arch_p;
+public:
+  frame_unwind_trampoline (enum frame_type t, const struct frame_data *d,
+			   frame_prev_arch_ftype *pa)
+    : frame_unwind ("trampoline", t, FRAME_UNWIND_GDB, d), prev_arch_p (pa)
+  { }
+
+  int sniffer(const frame_unwind *self, const frame_info_ptr &this_frame,
+	      void **this_prologue_cache) const override
+  {
+    return tramp_frame_sniffer (self, this_frame, this_prologue_cache);
+  }
+  void this_id (const frame_info_ptr &this_frame, void **this_prologue_cache,
+		struct frame_id *id) const override
+  {
+    tramp_frame_this_id (this_frame, this_prologue_cache, id);
+  }
+  struct value *prev_register (const frame_info_ptr &this_frame,
+			       void **this_prologue_cache,
+			       int regnum) const override
+  {
+    return tramp_frame_prev_register (this_frame, this_prologue_cache, regnum);
+  }
+
+  struct gdbarch *prev_arch (const frame_info_ptr &this_frame,
+			     void **this_prologue_cache) const override
+  {
+    return prev_arch_p (this_frame, this_prologue_cache);
+  }
+
+  /* FIXME: This should have a proper algorithm to deallocate the cache,
+     otherwise memory is leaked.  This method is empty here just so the
+     migration to c++ classes doesn't add regressions.  */
+  void dealloc_cache (frame_info *self, void *this_cache) const override
+  { }
+};
+
 void
 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 			      const struct tramp_frame *tramp_frame)
@@ -160,16 +200,11 @@  tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 
   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
-  unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
-
   data->tramp_frame = tramp_frame;
-  unwinder->type = tramp_frame->frame_type;
-  unwinder->unwind_data = data;
-  unwinder->unwinder_class = FRAME_UNWIND_GDB;
-  unwinder->sniffer = tramp_frame_sniffer;
-  unwinder->stop_reason = default_frame_unwind_stop_reason;
-  unwinder->this_id = tramp_frame_this_id;
-  unwinder->prev_register = tramp_frame_prev_register;
-  unwinder->prev_arch = tramp_frame->prev_arch;
+
+  unwinder = obstack_new <frame_unwind_trampoline> (gdbarch_obstack (gdbarch),
+						    tramp_frame->frame_type,
+						    data,
+						    tramp_frame->prev_arch);
   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 }
diff --git a/gdb/v850-tdep.c b/gdb/v850-tdep.c
index f875a351ac7..733e1985fa8 100644
--- a/gdb/v850-tdep.c
+++ b/gdb/v850-tdep.c
@@ -1319,7 +1319,7 @@  v850_frame_this_id (const frame_info_ptr &this_frame, void **this_cache,
   *this_id = frame_id_build (cache->saved_regs[E_SP_REGNUM].addr (), cache->pc);
 }
 
-static const struct frame_unwind v850_frame_unwind = {
+static const struct frame_unwind_legacy v850_frame_unwind (
   "v850 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1328,7 +1328,7 @@  static const struct frame_unwind v850_frame_unwind = {
   v850_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 v850_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/vax-tdep.c b/gdb/vax-tdep.c
index 460a6058d0a..fea24fcf599 100644
--- a/gdb/vax-tdep.c
+++ b/gdb/vax-tdep.c
@@ -385,8 +385,7 @@  vax_frame_prev_register (const frame_info_ptr &this_frame,
   return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
 }
 
-static const struct frame_unwind vax_frame_unwind =
-{
+static const struct frame_unwind_legacy vax_frame_unwind (
   "vax prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -395,7 +394,7 @@  static const struct frame_unwind vax_frame_unwind =
   vax_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 
 static CORE_ADDR
diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c
index f9585adf8fa..07b1e9b1e2c 100644
--- a/gdb/windows-tdep.c
+++ b/gdb/windows-tdep.c
@@ -1320,10 +1320,9 @@  cygwin_sigwrapper_frame_cache (frame_info_ptr this_frame, void **this_cache)
   return cache;
 }
 
-static struct value *
-cygwin_sigwrapper_frame_prev_register (const frame_info_ptr &this_frame,
-				       void **this_cache,
-				       int regnum)
+struct value *
+cygwin_sigwrapper_frame_unwind::prev_register
+    (const frame_info_ptr &this_frame, void **this_cache, int regnum) const
 {
   struct gdbarch *gdbarch = get_frame_arch (this_frame);
   struct cygwin_sigwrapper_frame_cache *cache
@@ -1339,18 +1338,18 @@  cygwin_sigwrapper_frame_prev_register (const frame_info_ptr &this_frame,
   return frame_unwind_got_register (this_frame, regnum, regnum);
 }
 
-static void
-cygwin_sigwrapper_frame_this_id (const frame_info_ptr &this_frame,
-				 void **this_cache,
-				 struct frame_id *this_id)
+void
+cygwin_sigwrapper_frame_unwind::this_id (const frame_info_ptr &this_frame,
+					 void **this_cache,
+					 struct frame_id *this_id) const
 {
   *this_id = frame_id_build_unavailable_stack (get_frame_func (this_frame));
 }
 
-static int
-cygwin_sigwrapper_frame_sniffer (const struct frame_unwind *self_,
-				 const frame_info_ptr &this_frame,
-				 void **this_cache)
+int
+cygwin_sigwrapper_frame_unwind::sniffer (const struct frame_unwind *self_,
+					 const frame_info_ptr &this_frame,
+					 void **this_cache) const
 {
   const auto *self = (const struct cygwin_sigwrapper_frame_unwind *) self_;
   struct gdbarch *gdbarch = get_frame_arch (this_frame);
@@ -1395,13 +1394,7 @@  cygwin_sigwrapper_frame_sniffer (const struct frame_unwind *self_,
 
 cygwin_sigwrapper_frame_unwind::cygwin_sigwrapper_frame_unwind
   (gdb::array_view<const gdb::array_view<const gdb_byte>> patterns_list)
-    : frame_unwind (),
-      patterns_list (patterns_list)
+    : frame_unwind ("cygwin sigwrapper", NORMAL_FRAME, FRAME_UNWIND_GDB,
+		    nullptr), patterns_list (patterns_list)
 {
-  name = "cygwin sigwrapper";
-  type = NORMAL_FRAME;
-  stop_reason = default_frame_unwind_stop_reason;
-  this_id = cygwin_sigwrapper_frame_this_id;
-  prev_register = cygwin_sigwrapper_frame_prev_register;
-  sniffer = cygwin_sigwrapper_frame_sniffer;
 }
diff --git a/gdb/windows-tdep.h b/gdb/windows-tdep.h
index f122f7aaa61..bdab0962ede 100644
--- a/gdb/windows-tdep.h
+++ b/gdb/windows-tdep.h
@@ -60,8 +60,9 @@  extern bool is_linked_with_cygwin_dll (bfd *abfd);
 /* Cygwin sigwapper unwinder.  Unwinds signal frames over
    sigbe/sigdelayed.  */
 
-struct cygwin_sigwrapper_frame_unwind : public frame_unwind
+class cygwin_sigwrapper_frame_unwind : public frame_unwind
 {
+public:
   explicit cygwin_sigwrapper_frame_unwind
     (gdb::array_view<const gdb::array_view<const gdb_byte>> patterns_list);
 
@@ -73,6 +74,19 @@  struct cygwin_sigwrapper_frame_unwind : public frame_unwind
      If any pattern in the list matches, then the frame is assumed to
      be a sigwrapper frame.  */
   gdb::array_view<const gdb::array_view<const gdb_byte>> patterns_list;
+
+  /* Calculate the frame ID of a cygwin wrapper.  */
+  void this_id (const frame_info_ptr &this_frame, void **this_prologue_cache,
+		struct frame_id *id) const override;
+
+  /* Sniff the frame to tell if this unwinder should be used.  */
+  int sniffer (const frame_unwind *self, const frame_info_ptr &this_frame,
+	       void **this_prologue_cache) const override;
+
+  /* Calculate the value of a given register in the previous frame.  */
+  struct value *prev_register (const frame_info_ptr &this_frame,
+			       void **this_cache,
+			       int regnum) const override;
 };
 
 #endif
diff --git a/gdb/xstormy16-tdep.c b/gdb/xstormy16-tdep.c
index 73fa6ed9c0d..750c94a5701 100644
--- a/gdb/xstormy16-tdep.c
+++ b/gdb/xstormy16-tdep.c
@@ -727,7 +727,7 @@  xstormy16_frame_base_address (const frame_info_ptr &this_frame, void **this_cach
   return cache->base;
 }
 
-static const struct frame_unwind xstormy16_frame_unwind = {
+static const struct frame_unwind_legacy xstormy16_frame_unwind (
   "xstormy16 prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -736,7 +736,7 @@  static const struct frame_unwind xstormy16_frame_unwind = {
   xstormy16_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static const struct frame_base xstormy16_frame_base = {
   &xstormy16_frame_unwind,
diff --git a/gdb/xtensa-tdep.c b/gdb/xtensa-tdep.c
index a0801466c42..1425b6029f3 100644
--- a/gdb/xtensa-tdep.c
+++ b/gdb/xtensa-tdep.c
@@ -1495,9 +1495,7 @@  xtensa_frame_prev_register (const frame_info_ptr &this_frame,
 }
 
 
-static const struct frame_unwind
-xtensa_unwind =
-{
+static const struct frame_unwind_legacy xtensa_unwind (
   "xtensa prologue",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1506,7 +1504,7 @@  xtensa_unwind =
   xtensa_frame_prev_register,
   NULL,
   default_frame_sniffer
-};
+);
 
 static CORE_ADDR
 xtensa_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
diff --git a/gdb/z80-tdep.c b/gdb/z80-tdep.c
index ea78a01cbfc..7b3d7f6b6b5 100644
--- a/gdb/z80-tdep.c
+++ b/gdb/z80-tdep.c
@@ -1062,9 +1062,7 @@  z80_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr)
   return 0;
 }
 
-static const struct frame_unwind
-z80_frame_unwind =
-{
+static const struct frame_unwind_legacy z80_frame_unwind (
   "z80",
   NORMAL_FRAME,
   FRAME_UNWIND_ARCH,
@@ -1075,7 +1073,7 @@  z80_frame_unwind =
   default_frame_sniffer
   /*dealloc_cache*/
   /*prev_arch*/
-};
+);
 
 /* Initialize the gdbarch struct for the Z80 arch */
 static struct gdbarch *