[v6,02/15] gdb: Store an x86_xsave_layout in i386_gdbarch_tdep.

diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index a97e11647b9..d5423681802 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -8504,10 +8504,21 @@  i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   int bnd0_regnum;
   int num_bnd_cooked;
 
+  x86_xsave_layout xsave_layout = target_fetch_x86_xsave_layout ();
+
   /* If there is already a candidate, use it.  */
-  arches = gdbarch_list_lookup_by_info (arches, &info);
-  if (arches != NULL)
-    return arches->gdbarch;
+  for (arches = gdbarch_list_lookup_by_info (arches, &info);
+       arches != NULL;
+       arches = gdbarch_list_lookup_by_info (arches->next, &info))
+    {
+      /* Check that the XSAVE layout of ARCHES matches the layout for
+	 the current target.  */
+      i386_gdbarch_tdep *other_tdep
+	= gdbarch_tdep<i386_gdbarch_tdep> (arches->gdbarch);
+
+      if (other_tdep->xsave_layout == xsave_layout)
+	return arches->gdbarch;
+    }
 
   /* Allocate space for the new architecture.  Assume i386 for now.  */
   gdbarch *gdbarch
@@ -8762,6 +8773,7 @@  i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
       gdbarch_free (gdbarch);
       return NULL;
     }
+  tdep->xsave_layout = xsave_layout;
 
   num_bnd_cooked = (tdep->bnd0r_regnum > 0 ? I387_NUM_BND_REGS : 0);
 
diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
index bf52020ab67..34dc53db8d9 100644
--- a/gdb/i386-tdep.h
+++ b/gdb/i386-tdep.h
@@ -23,6 +23,7 @@ 
 #include "gdbarch.h"
 #include "infrun.h"
 #include "expression.h"
+#include "gdbsupport/x86-xstate.h"
 
 class frame_info_ptr;
 struct gdbarch;
@@ -145,6 +146,9 @@  struct i386_gdbarch_tdep : gdbarch_tdep_base
   /* Offset of XCR0 in XSAVE extended state.  */
   int xsave_xcr0_offset = 0;
 
+  /* Layout of the XSAVE area extended region.  */
+  x86_xsave_layout xsave_layout;
+
   /* Register names.  */
   const char * const *register_names = nullptr;
 
diff --git a/gdb/target-debug.h b/gdb/target-debug.h
index acb01d47e7c..6b8983104ea 100644
--- a/gdb/target-debug.h
+++ b/gdb/target-debug.h
@@ -236,4 +236,24 @@  target_debug_print_gdb_byte_vector_r (gdb::byte_vector &vector)
 {
   target_debug_print_const_gdb_byte_vector_r (vector);
 }
+
+static void
+target_debug_print_x86_xsave_layout (const x86_xsave_layout &layout)
+{
+  gdb_puts ("{", gdb_stdlog);
+  gdb_printf (gdb_stdlog, " sizeof_xsave=%d", layout.sizeof_xsave);
+#define POFFS(region)							\
+  if (layout.region##_offset != 0)					\
+    gdb_printf (gdb_stdlog, ", %s_offset=%d", #region,			\
+		layout.region##_offset)
+  POFFS(avx);
+  POFFS(bndregs);
+  POFFS(bndcfg);
+  POFFS(k);
+  POFFS(zmm_h);
+  POFFS(zmm);
+  POFFS(pkru);
+#undef POFFS
+  gdb_puts (" }", gdb_stdlog);
+}
 #endif /* TARGET_DEBUG_H */
diff --git a/gdb/target-delegates.c b/gdb/target-delegates.c
index 57b66ce87b1..1d1f8c60f4e 100644
--- a/gdb/target-delegates.c
+++ b/gdb/target-delegates.c
@@ -196,6 +196,7 @@  struct dummy_target : public target_ops
   bool supports_memory_tagging () override;
   bool fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3) override;
   bool store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3) override;
+  x86_xsave_layout fetch_x86_xsave_layout () override;
 };
 
 struct debug_target : public target_ops
@@ -370,6 +371,7 @@  struct debug_target : public target_ops
   bool supports_memory_tagging () override;
   bool fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3) override;
   bool store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3) override;
+  x86_xsave_layout fetch_x86_xsave_layout () override;
 };
 
 void
@@ -4536,3 +4538,28 @@  debug_target::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector
   return result;
 }
 
+x86_xsave_layout
+target_ops::fetch_x86_xsave_layout ()
+{
+  return this->beneath ()->fetch_x86_xsave_layout ();
+}
+
+x86_xsave_layout
+dummy_target::fetch_x86_xsave_layout ()
+{
+  return x86_xsave_layout ();
+}
+
+x86_xsave_layout
+debug_target::fetch_x86_xsave_layout ()
+{
+  x86_xsave_layout result;
+  gdb_printf (gdb_stdlog, "-> %s->fetch_x86_xsave_layout (...)\n", this->beneath ()->shortname ());
+  result = this->beneath ()->fetch_x86_xsave_layout ();
+  gdb_printf (gdb_stdlog, "<- %s->fetch_x86_xsave_layout (", this->beneath ()->shortname ());
+  gdb_puts (") = ", gdb_stdlog);
+  target_debug_print_x86_xsave_layout (result);
+  gdb_puts ("\n", gdb_stdlog);
+  return result;
+}
+
diff --git a/gdb/target.c b/gdb/target.c
index 16f43d072cd..f650e5ccb51 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -832,6 +832,12 @@  target_store_memtags (CORE_ADDR address, size_t len,
   return current_inferior ()->top_target ()->store_memtags (address, len, tags, type);
 }
 
+x86_xsave_layout
+target_fetch_x86_xsave_layout ()
+{
+  return current_inferior ()->top_target ()->fetch_x86_xsave_layout ();
+}
+
 void
 target_log_command (const char *p)
 {
diff --git a/gdb/target.h b/gdb/target.h
index 6ae400e2cc2..9325b111c5b 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -82,6 +82,7 @@  struct inferior;
 #include "disasm-flags.h"
 #include "tracepoint.h"
 #include "gdbsupport/fileio.h"
+#include "gdbsupport/x86-xstate.h"
 
 #include "gdbsupport/break-common.h" /* For enum target_hw_bp_type.  */
 
@@ -1321,6 +1322,10 @@  struct target_ops
     virtual bool store_memtags (CORE_ADDR address, size_t len,
 				const gdb::byte_vector &tags, int type)
       TARGET_DEFAULT_NORETURN (tcomplain ());
+
+    /* Return the x86 XSAVE extended state area layout.  */
+    virtual x86_xsave_layout fetch_x86_xsave_layout ()
+      TARGET_DEFAULT_RETURN (x86_xsave_layout ());
   };
 
 /* Deleter for std::unique_ptr.  See comments in
@@ -2301,6 +2306,8 @@  extern bool target_fetch_memtags (CORE_ADDR address, size_t len,
 extern bool target_store_memtags (CORE_ADDR address, size_t len,
 				  const gdb::byte_vector &tags, int type);
 
+extern x86_xsave_layout target_fetch_x86_xsave_layout ();
+
 /* Command logging facility.  */
 
 extern void target_log_command (const char *p);