1 files changed, 66 insertions, 0 deletions
diff --git a/gdb/arch/amd64-linux-tdesc.c b/gdb/arch/amd64-linux-tdesc.c
new file mode 100644
index 0000000..e9c4a99
--- /dev/null
+++ b/gdb/arch/amd64-linux-tdesc.c
@@ -0,0 +1,66 @@
+/* Target description related code for GNU/Linux x86-64.
+
+   Copyright (C) 2024 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "arch/x86-linux-tdesc.h"
+#include "arch/amd64-linux-tdesc.h"
+#include "arch/amd64.h"
+#include "arch/x86-linux-tdesc-features.h"
+
+
+/* See arch/amd64-linux-tdesc.h.  */
+
+const struct target_desc *
+amd64_linux_read_description (uint64_t xcr0, bool is_x32)
+{
+  /* The type used for the amd64 and x32 target description caches.  */
+  using tdesc_cache_type = std::unordered_map<uint64_t, const target_desc_up>;
+
+  /* Caches for the previously seen amd64 and x32 target descriptions,
+     indexed by the xcr0 value that created the target description.  These
+     need to be static within this function to ensure they are initialised
+     before first use.  */
+  static tdesc_cache_type amd64_tdesc_cache, x32_tdesc_cache;
+
+  tdesc_cache_type &tdesc_cache = is_x32 ? x32_tdesc_cache : amd64_tdesc_cache;
+
+  /* Only some bits are checked when creating a tdesc, but the XCR0 value
+     contains other feature bits that are not relevant for tdesc creation.
+     When indexing into the TDESC_CACHE we need to use a consistent xcr0
+     value otherwise we might fail to find an existing tdesc which has the
+     same set of relevant bits set.  */
+  xcr0 &= is_x32
+    ? x86_linux_x32_xcr0_feature_mask ()
+    : x86_linux_amd64_xcr0_feature_mask ();
+
+  const auto it = tdesc_cache.find (xcr0);
+  if (it != tdesc_cache.end ())
+    return it->second.get ();
+
+  /* Create the previously unseen target description.  */
+  target_desc_up tdesc (amd64_create_target_description (xcr0, is_x32,
+							 true, true));
+  x86_linux_post_init_tdesc (tdesc.get (), true);
+
+  /* Add to the cache, and return a pointer borrowed from the
+     target_desc_up.  This is safe as the cache (and the pointers contained
+     within it) are not deleted until GDB exits.  */
+  target_desc *ptr = tdesc.get ();
+  tdesc_cache.emplace (xcr0, std::move (tdesc));
+  return ptr;
+}