gdb: Store an x86_xsave_layout in i386_gdbarch_tdep.

This structure is fetched from the current target in i386_gdbarch_init
via a new "fetch_x86_xsave_layout" target method.

Approved-By: Simon Marchi <simon.marchi@efficios.com>

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);
+  for (arches = gdbarch_list_lookup_by_info (arches, &info);
-  if (arches != NULL)
+       arches != NULL;
-    return arches->gdbarch;
+       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);
 

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;
 

gdb/target-debug.h

@@ -242,4 +242,24 @@ 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 */

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
@@ -4535,3 +4537,28 @@ debug_target::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector
   gdb_puts ("\n", gdb_stdlog);
   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;
+}

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)
 {

gdb/target.h

@@ -86,6 +86,7 @@ typedef const gdb_byte const_gdb_byte;
 #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.  */
 
@@ -1325,6 +1326,10 @@ 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
@@ -2305,6 +2310,8 @@ 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);