gdb: LoongArch: Add initial target description support

This commit adds initial target description support for LoongArch.

Signed-off-by: Zhensong Liu <liuzhensong@loongson.cn>
Signed-off-by: Qing zhang <zhangqing@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>

7 files changed, 353 insertions, 0 deletions

diff --git a/gdb/arch/loongarch.c b/gdb/arch/loongarch.c
new file mode 100644
index 0000000..934f6e4
--- /dev/null
+++ b/gdb/arch/loongarch.c
@@ -0,0 +1,88 @@
+/* Copyright (C) 2022 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 "gdbsupport/common-defs.h"
+#include "loongarch.h"
+#include <stdlib.h>
+#include <unordered_map>
+
+/* Target description features.  */
+
+#include "../features/loongarch/base32.c"
+#include "../features/loongarch/base64.c"
+
+static target_desc_up
+loongarch_create_target_description (const struct loongarch_gdbarch_features features)
+{
+  /* Now we should create a new target description.  */
+  target_desc_up tdesc = allocate_target_description ();
+
+  std::string arch_name = "loongarch";
+
+  if (features.xlen == 4)
+    arch_name.append ("32");
+  else if (features.xlen == 8)
+    arch_name.append ("64");
+
+  set_tdesc_architecture (tdesc.get (), arch_name.c_str ());
+
+  long regnum = 0;
+
+  /* For now we only support creating 32-bit or 64-bit x-registers.  */
+  if (features.xlen == 4)
+    regnum = create_feature_loongarch_base32 (tdesc.get (), regnum);
+  else if (features.xlen == 8)
+    regnum = create_feature_loongarch_base64 (tdesc.get (), regnum);
+
+  return tdesc;
+}
+
+/* Wrapper used by std::unordered_map to generate hash for feature set.  */
+struct loongarch_gdbarch_features_hasher
+{
+  std::size_t
+  operator() (const loongarch_gdbarch_features &features) const noexcept
+  {
+    return features.hash ();
+  }
+};
+
+/* Cache of previously seen target descriptions, indexed by the feature set
+   that created them.  */
+static std::unordered_map<loongarch_gdbarch_features,
+			  const target_desc_up,
+			  loongarch_gdbarch_features_hasher> loongarch_tdesc_cache;
+
+const target_desc *
+loongarch_lookup_target_description (const struct loongarch_gdbarch_features features)
+{
+  /* Lookup in the cache.  If we find it then return the pointer out of
+     the target_desc_up (which is a unique_ptr).  This is safe as the
+     loongarch_tdesc_cache will exist until GDB exits.  */
+  const auto it = loongarch_tdesc_cache.find (features);
+  if (it != loongarch_tdesc_cache.end ())
+    return it->second.get ();
+
+  target_desc_up tdesc (loongarch_create_target_description (features));
+
+  /* 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 ();
+  loongarch_tdesc_cache.emplace (features, std::move (tdesc));
+  return ptr;
+}
diff --git a/gdb/arch/loongarch.h b/gdb/arch/loongarch.h
new file mode 100644
index 0000000..9e10df9
--- /dev/null
+++ b/gdb/arch/loongarch.h
@@ -0,0 +1,73 @@
+/* Common target-dependent functionality for LoongArch
+
+   Copyright (C) 2022 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/>.  */
+
+#ifndef ARCH_LOONGARCH_H
+#define ARCH_LOONGARCH_H
+
+#include "gdbsupport/tdesc.h"
+
+/* The set of LoongArch architectural features that we track that impact how
+   we configure the actual gdbarch instance.  We hold one of these in the
+   gdbarch_tdep structure, and use it to distinguish between different
+   LoongArch gdbarch instances.
+
+   The information in here ideally comes from the target description,
+   however, if the target doesn't provide a target description then we will
+   create a default target description by first populating one of these
+   based on what we know about the binary being executed, and using that to
+   drive default target description creation.  */
+
+struct loongarch_gdbarch_features
+{
+  /* The size of the x-registers in bytes.  This is either 4 (loongarch32)
+     or 8 (loongarch64).  No other value is valid.  Initialise to the invalid
+     0 value so we can spot if one of these is used uninitialised.  */
+  int xlen = 0;
+
+  /* Equality operator.  */
+  bool operator== (const struct loongarch_gdbarch_features &rhs) const
+  {
+    return (xlen == rhs.xlen);
+  }
+
+  /* Inequality operator.  */
+  bool operator!= (const struct loongarch_gdbarch_features &rhs) const
+  {
+    return !((*this) == rhs);
+  }
+
+  /* Used by std::unordered_map to hash feature sets.  */
+  std::size_t hash () const noexcept
+  {
+    std::size_t val = (xlen & 0x1f) << 5;
+    return val;
+  }
+};
+
+/* Lookup an already existing target description matching FEATURES, or
+   create a new target description if this is the first time we have seen
+   FEATURES.  For the same FEATURES the same target_desc is always
+   returned.  This is important when trying to lookup gdbarch objects as
+   GDBARCH_LIST_LOOKUP_BY_INFO performs a pointer comparison on target
+   descriptions to find candidate gdbarch objects.  */
+
+const target_desc *loongarch_lookup_target_description
+	(const struct loongarch_gdbarch_features features);
+
+#endif /* ARCH_LOONGARCH_H  */
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 8e7fb2d..1f85913 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -46293,6 +46293,7 @@ registers using the capitalization used in the description.
 * ARC Features::
 * ARM Features::
 * i386 Features::
+* LoongArch Features::
 * MicroBlaze Features::
 * MIPS Features::
 * M68K Features::
@@ -46521,6 +46522,15 @@ The @samp{org.gnu.gdb.i386.pkeys} feature is optional.  It should
 describe a single register, @samp{pkru}.  It is a 32-bit register
 valid for i386 and amd64.
 
+@node LoongArch Features
+@subsection LoongArch Features
+@cindex target descriptions, LoongArch Features
+
+The @samp{org.gnu.gdb.loongarch.base} feature is required for LoongArch
+targets.  It should contain the registers @samp{r0} through @samp{r31},
+@samp{pc}, and @samp{badv}.  Either the architectural names (@samp{r0},
+@samp{r1}, etc) can be used, or the ABI names (@samp{zero}, @samp{ra}, etc).
+
 @node MicroBlaze Features
 @subsection MicroBlaze Features
 @cindex target descriptions, MicroBlaze features
diff --git a/gdb/features/loongarch/base32.c b/gdb/features/loongarch/base32.c
new file mode 100644
index 0000000..7105c15
--- /dev/null
+++ b/gdb/features/loongarch/base32.c
@@ -0,0 +1,47 @@
+/* THIS FILE IS GENERATED.  -*- buffer-read-only: t -*- vi:set ro:
+  Original: base32.xml */
+
+#include "gdbsupport/tdesc.h"
+
+static int
+create_feature_loongarch_base32 (struct target_desc *result, long regnum)
+{
+  struct tdesc_feature *feature;
+
+  feature = tdesc_create_feature (result, "org.gnu.gdb.loongarch.base");
+  tdesc_create_reg (feature, "r0", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r1", regnum++, 1, "general", 32, "code_ptr");
+  tdesc_create_reg (feature, "r2", regnum++, 1, "general", 32, "data_ptr");
+  tdesc_create_reg (feature, "r3", regnum++, 1, "general", 32, "data_ptr");
+  tdesc_create_reg (feature, "r4", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r5", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r6", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r7", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r8", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r9", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r10", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r11", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r12", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r13", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r14", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r15", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r16", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r17", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r18", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r19", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r20", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r21", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r22", regnum++, 1, "general", 32, "data_ptr");
+  tdesc_create_reg (feature, "r23", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r24", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r25", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r26", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r27", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r28", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r29", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r30", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "r31", regnum++, 1, "general", 32, "uint32");
+  tdesc_create_reg (feature, "pc", regnum++, 1, "general", 32, "code_ptr");
+  tdesc_create_reg (feature, "badv", regnum++, 1, "general", 32, "code_ptr");
+  return regnum;
+}
diff --git a/gdb/features/loongarch/base32.xml b/gdb/features/loongarch/base32.xml
new file mode 100644
index 0000000..5b00f8a
--- /dev/null
+++ b/gdb/features/loongarch/base32.xml
@@ -0,0 +1,44 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2022 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.loongarch.base">
+  <reg name="r0" bitsize="32" type="uint32" group="general"/>
+  <reg name="r1" bitsize="32" type="code_ptr" group="general"/>
+  <reg name="r2" bitsize="32" type="data_ptr" group="general"/>
+  <reg name="r3" bitsize="32" type="data_ptr" group="general"/>
+  <reg name="r4" bitsize="32" type="uint32" group="general"/>
+  <reg name="r5" bitsize="32" type="uint32" group="general"/>
+  <reg name="r6" bitsize="32" type="uint32" group="general"/>
+  <reg name="r7" bitsize="32" type="uint32" group="general"/>
+  <reg name="r8" bitsize="32" type="uint32" group="general"/>
+  <reg name="r9" bitsize="32" type="uint32" group="general"/>
+  <reg name="r10" bitsize="32" type="uint32" group="general"/>
+  <reg name="r11" bitsize="32" type="uint32" group="general"/>
+  <reg name="r12" bitsize="32" type="uint32" group="general"/>
+  <reg name="r13" bitsize="32" type="uint32" group="general"/>
+  <reg name="r14" bitsize="32" type="uint32" group="general"/>
+  <reg name="r15" bitsize="32" type="uint32" group="general"/>
+  <reg name="r16" bitsize="32" type="uint32" group="general"/>
+  <reg name="r17" bitsize="32" type="uint32" group="general"/>
+  <reg name="r18" bitsize="32" type="uint32" group="general"/>
+  <reg name="r19" bitsize="32" type="uint32" group="general"/>
+  <reg name="r20" bitsize="32" type="uint32" group="general"/>
+  <reg name="r21" bitsize="32" type="uint32" group="general"/>
+  <reg name="r22" bitsize="32" type="data_ptr" group="general"/>
+  <reg name="r23" bitsize="32" type="uint32" group="general"/>
+  <reg name="r24" bitsize="32" type="uint32" group="general"/>
+  <reg name="r25" bitsize="32" type="uint32" group="general"/>
+  <reg name="r26" bitsize="32" type="uint32" group="general"/>
+  <reg name="r27" bitsize="32" type="uint32" group="general"/>
+  <reg name="r28" bitsize="32" type="uint32" group="general"/>
+  <reg name="r29" bitsize="32" type="uint32" group="general"/>
+  <reg name="r30" bitsize="32" type="uint32" group="general"/>
+  <reg name="r31" bitsize="32" type="uint32" group="general"/>
+  <reg name="pc" bitsize="32" type="code_ptr" group="general"/>
+  <reg name="badv" bitsize="32" type="code_ptr" group="general"/>
+</feature>
diff --git a/gdb/features/loongarch/base64.c b/gdb/features/loongarch/base64.c
new file mode 100644
index 0000000..63eee02
--- /dev/null
+++ b/gdb/features/loongarch/base64.c
@@ -0,0 +1,47 @@
+/* THIS FILE IS GENERATED.  -*- buffer-read-only: t -*- vi:set ro:
+  Original: base64.xml */
+
+#include "gdbsupport/tdesc.h"
+
+static int
+create_feature_loongarch_base64 (struct target_desc *result, long regnum)
+{
+  struct tdesc_feature *feature;
+
+  feature = tdesc_create_feature (result, "org.gnu.gdb.loongarch.base");
+  tdesc_create_reg (feature, "r0", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r1", regnum++, 1, "general", 64, "code_ptr");
+  tdesc_create_reg (feature, "r2", regnum++, 1, "general", 64, "data_ptr");
+  tdesc_create_reg (feature, "r3", regnum++, 1, "general", 64, "data_ptr");
+  tdesc_create_reg (feature, "r4", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r5", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r6", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r7", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r8", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r9", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r10", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r11", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r12", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r13", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r14", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r15", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r16", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r17", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r18", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r19", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r20", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r21", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r22", regnum++, 1, "general", 64, "data_ptr");
+  tdesc_create_reg (feature, "r23", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r24", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r25", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r26", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r27", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r28", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r29", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r30", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "r31", regnum++, 1, "general", 64, "uint64");
+  tdesc_create_reg (feature, "pc", regnum++, 1, "general", 64, "code_ptr");
+  tdesc_create_reg (feature, "badv", regnum++, 1, "general", 64, "code_ptr");
+  return regnum;
+}
diff --git a/gdb/features/loongarch/base64.xml b/gdb/features/loongarch/base64.xml
new file mode 100644
index 0000000..bef91e5
--- /dev/null
+++ b/gdb/features/loongarch/base64.xml
@@ -0,0 +1,44 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2022 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.loongarch.base">
+  <reg name="r0" bitsize="64" type="uint64" group="general"/>
+  <reg name="r1" bitsize="64" type="code_ptr" group="general"/>
+  <reg name="r2" bitsize="64" type="data_ptr" group="general"/>
+  <reg name="r3" bitsize="64" type="data_ptr" group="general"/>
+  <reg name="r4" bitsize="64" type="uint64" group="general"/>
+  <reg name="r5" bitsize="64" type="uint64" group="general"/>
+  <reg name="r6" bitsize="64" type="uint64" group="general"/>
+  <reg name="r7" bitsize="64" type="uint64" group="general"/>
+  <reg name="r8" bitsize="64" type="uint64" group="general"/>
+  <reg name="r9" bitsize="64" type="uint64" group="general"/>
+  <reg name="r10" bitsize="64" type="uint64" group="general"/>
+  <reg name="r11" bitsize="64" type="uint64" group="general"/>
+  <reg name="r12" bitsize="64" type="uint64" group="general"/>
+  <reg name="r13" bitsize="64" type="uint64" group="general"/>
+  <reg name="r14" bitsize="64" type="uint64" group="general"/>
+  <reg name="r15" bitsize="64" type="uint64" group="general"/>
+  <reg name="r16" bitsize="64" type="uint64" group="general"/>
+  <reg name="r17" bitsize="64" type="uint64" group="general"/>
+  <reg name="r18" bitsize="64" type="uint64" group="general"/>
+  <reg name="r19" bitsize="64" type="uint64" group="general"/>
+  <reg name="r20" bitsize="64" type="uint64" group="general"/>
+  <reg name="r21" bitsize="64" type="uint64" group="general"/>
+  <reg name="r22" bitsize="64" type="data_ptr" group="general"/>
+  <reg name="r23" bitsize="64" type="uint64" group="general"/>
+  <reg name="r24" bitsize="64" type="uint64" group="general"/>
+  <reg name="r25" bitsize="64" type="uint64" group="general"/>
+  <reg name="r26" bitsize="64" type="uint64" group="general"/>
+  <reg name="r27" bitsize="64" type="uint64" group="general"/>
+  <reg name="r28" bitsize="64" type="uint64" group="general"/>
+  <reg name="r29" bitsize="64" type="uint64" group="general"/>
+  <reg name="r30" bitsize="64" type="uint64" group="general"/>
+  <reg name="r31" bitsize="64" type="uint64" group="general"/>
+  <reg name="pc" bitsize="64" type="code_ptr" group="general"/>
+  <reg name="badv" bitsize="64" type="code_ptr" group="general"/>
+</feature>