[v2] AndesTech NDS32 port

Message ID ca473d29-ceb4-ba5e-1337-d479a5f16d8b@gmail.com
State New, archived
Headers

Commit Message

Yan-Ting Lin May 15, 2016, 9:39 a.m. UTC
  Hi GDB maintainers and reviewers,

Thanks for the review. After reworking, we submit a new patch here.

The main modification includes:
1. Document about NDS32 Features in target description is provided.
2. The code to validate FPU registers in target description is rewritten for better match with document.
3. Some unused elements due to this rewrite are removed.
4. Add missing comments for some functions.
5. Use fp_offset to check if reg FP is set in prologue, so unused var use_frame is removed.
6. The unnecessary call to register_remote_support_xml() is removed.
7. Year in copyright declaration is changed to start from 2013, and that is the year we submitted our first patch.
8. Change to top-level configure.ac/configure is removed. They need to be changed manually to enable gdb building.


Thanks for your time reviewing our patch again.


ChangeLog entries:

gdb/:
2016-05-15  Yan-Ting Lin  <currygt52@gmail.com>

	* Makefile.in: Add NDS32.
	* NEWS: Mention new NDS32 port.
	* configure.tgt: Add NDS32.
	* nds32-tdep.c: New file.
	* nds32-tdep.h: New file.
	* features/Makefile: Add NDS32.
	* features/nds32-core.xml: New file.
	* features/nds32-fpu.xml: New file.
	* features/nds32-system.xml: New file.
	* features/nds32.xml: New file.
	* features/nds32.c: New file (generated).


gdb/testsuite/:
2016-05-15  Yan-Ting Lin  <currygt52@gmail.com>

	* gdb.base/float.exp: Add target check for nds32*-*-*.
	* gdb.xml/tdesc-regs.exp: Set core-regs for nds32*-*-*.


gdb/doc/:
2016-05-15  Yan-Ting Lin  <currygt52@gmail.com>

	* gdb.texinfo (Standard Target Features): Document NDS32 features.
	(NDS32 Features): New Section.
From 41eabdde1a6f183fc0e5c69cfa32fe991117c886 Mon Sep 17 00:00:00 2001
From: Yan-Ting Lin <currygt52@gmail.com>
Date: Sat, 14 May 2016 22:37:56 +0800
Subject: [PATCH] gdb: new AndesTech NDS32 port

---
 gdb/Makefile.in                      |    4 +-
 gdb/NEWS                             |    4 +
 gdb/configure.tgt                    |    5 +
 gdb/doc/gdb.texinfo                  |   23 +
 gdb/features/Makefile                |    1 +
 gdb/features/nds32-core.xml          |   44 +
 gdb/features/nds32-fpu.xml           |   42 +
 gdb/features/nds32-system.xml        |   14 +
 gdb/features/nds32.c                 |   92 ++
 gdb/features/nds32.xml               |   14 +
 gdb/nds32-tdep.c                     | 2194 ++++++++++++++++++++++++++++++++++
 gdb/nds32-tdep.h                     |   56 +
 gdb/testsuite/gdb.base/float.exp     |    9 +
 gdb/testsuite/gdb.xml/tdesc-regs.exp |    3 +
 14 files changed, 2504 insertions(+), 1 deletion(-)
 create mode 100644 gdb/features/nds32-core.xml
 create mode 100644 gdb/features/nds32-fpu.xml
 create mode 100644 gdb/features/nds32-system.xml
 create mode 100644 gdb/features/nds32.c
 create mode 100644 gdb/features/nds32.xml
 create mode 100644 gdb/nds32-tdep.c
 create mode 100644 gdb/nds32-tdep.h
  

Comments

Yao Qi June 1, 2016, 11:28 a.m. UTC | #1
Yan-Ting Lin <currygt52@gmail.com> writes:

> +enum nds32_regnum
> +{
> +  /* General purpose registers.  */
> +  NDS32_R0_REGNUM = 0,
> +  NDS32_R5_REGNUM = 5,
> +  NDS32_TA_REGNUM = 15,		/* Temporary register.  */
> +  NDS32_FP_REGNUM = 28,		/* Frame pointer.  */
> +  NDS32_GP_REGNUM = 29,		/* Global pointer.  */
> +  NDS32_LP_REGNUM = 30,		/* Link pointer.  */
> +  NDS32_SP_REGNUM = 31,		/* Stack pointer.  */
> +
> +  NDS32_PC_REGNUM = 32,		/* Program counter.  */
> +
> +  NDS32_NUM_REGS,
> +
> +  /* Double precision floating-point registers.  */
> +  NDS32_FD0_REGNUM = NDS32_NUM_REGS,
> +};
> +
> +struct gdbarch_tdep
> +{
> +  /* The guessed FPU configuration.  */
> +  int fpu_freg;
> +  /* FSRs are defined as pseudo registers.  */
> +  int use_pseudo_fsrs;
> +  /* Cached regnum of the first FSR (FS0).  */
> +  int fs0_regnum;
> +  /* Cached regnum of the first FDR (FD0).  */
> +  int fd0_regnum;
> +  /* ABI info.  */
> +  int abi;
> +};

We can either use NDS32_FD0_REGNUM or gdbarch_tdep.fd0_regnum, IMO.  If
the register number of fd0 is fixed, we can use NDS32_FD0_REGNUM,
otherwise, we need to use gdbarch_tdep.fd0_regnum.  If so, we can remove
one of them.
  
Yan-Ting Lin June 6, 2016, 3:13 p.m. UTC | #2
> We can either use NDS32_FD0_REGNUM or gdbarch_tdep.fd0_regnum, IMO.  If
> the register number of fd0 is fixed, we can use NDS32_FD0_REGNUM,
> otherwise, we need to use gdbarch_tdep.fd0_regnum.  If so, we can remove
> one of them.
>

Hi Yao,

Thanks for the review.

Currently, the register number of fd0, if present, is always fixed, so
all usage of gdbarch_tdep.fd0_regnum is replaced with
NDS32_FD0_REGNUM.
In addition, after reviewing the flow to initialize gdbarch_tdep, the
allocation and initialization of gdbarch_tdep is put just before the
allocation of gdbarch.

The modified patch is attached, please help to review again.
Thanks a lot.
  
Yao Qi June 7, 2016, 3:34 p.m. UTC | #3
Yan-Ting Lin <currygt52@gmail.com> writes:

> Currently, the register number of fd0, if present, is always fixed, so
> all usage of gdbarch_tdep.fd0_regnum is replaced with
> NDS32_FD0_REGNUM.
> In addition, after reviewing the flow to initialize gdbarch_tdep, the
> allocation and initialization of gdbarch_tdep is put just before the
> allocation of gdbarch.
>
> The modified patch is attached, please help to review again.

Patch except doc and news bits is good to me.  Doc and NEWS bits should
be reviewed by Eli.

If there is no other comments in one week, you can push it in.
  
Eli Zaretskii June 7, 2016, 4:30 p.m. UTC | #4
> From: Yao Qi <qiyaoltc@gmail.com>
> Cc: Yao Qi <qiyaoltc@gmail.com>,  gdb-patches@sourceware.org
> Date: Tue, 07 Jun 2016 16:34:13 +0100
> 
> Doc and NEWS bits should be reviewed by Eli.

They are both OK.  (What about the ChangeLog entries, though?)

Thanks.
  
Yao Qi June 8, 2016, 8:17 a.m. UTC | #5
Eli Zaretskii <eliz@gnu.org> writes:

> They are both OK.  (What about the ChangeLog entries, though?)

The most recent ChangeLog entries are
https://sourceware.org/ml/gdb-patches/2016-05/msg00237.html
  
Pedro Alves June 13, 2016, 2:12 p.m. UTC | #6
On 06/06/2016 04:13 PM, Yan-Ting Lin wrote:

> +@emph{Note:} The first sixteen 64-bit double-precision floating-point
> +registers are overlapped with the thirty-two 32-bit single-precision
> +floating-point registers.  The 32-bit single-precision registers, if
> +not being listed explicitly, will be synthesized from halves of the
> +overlapping 64-bit double-precision registers.  Listing 32-bit
> +single-precision registers explicitly is deprecated, and the
> +support to it could be totally removed some day.

Why do we need to support explicitly-listed 32-bit single-precision
registers at all?

The patch looks good to me otherwise, too.

Thanks,
Pedro Alves
  
Yan-Ting Lin June 15, 2016, 8:44 a.m. UTC | #7
2016-06-13 22:12 GMT+08:00 Pedro Alves <palves@redhat.com>:
>
> Why do we need to support explicitly-listed 32-bit single-precision
> registers at all?

Currently, our porting to OpenOCD explicitly lists single-precision
registers, so the support is left.
After removing this from OpenOCD, this support will be also removed.

Thanks.
  
Pedro Alves June 15, 2016, 10:07 a.m. UTC | #8
On 06/15/2016 09:44 AM, Yan-Ting Lin wrote:
> 2016-06-13 22:12 GMT+08:00 Pedro Alves <palves@redhat.com>:
>>
>> Why do we need to support explicitly-listed 32-bit single-precision
>> registers at all?
> 
> Currently, our porting to OpenOCD explicitly lists single-precision
> registers, so the support is left.
> After removing this from OpenOCD, this support will be also removed.

Thanks for the explanation.  Fine with me then.
  
Yan-Ting Lin June 17, 2016, 8:07 a.m. UTC | #9
Yao Qi 於 2016/6/7 下午 11:34 寫道:
> Patch except doc and news bits is good to me.  Doc and NEWS bits should
> be reviewed by Eli.
> 
> If there is no other comments in one week, you can push it in.
> 

Hi GDB maintainers and reviewers,

I will push our patch in after rebasing it to the latest code.

Here is the ChangeLog entries I will push in.
Thanks again for your help.

ChangeLog entries:

gdb/:
2016-06-17  Yan-Ting Lin  <currygt52@gmail.com>

	* Makefile.in (ALL_TARGET_OBS): Add nds32-tdep.o.
	(HFILES_NO_SRCDIR): Add nds32-tdep.h.
	(ALLDEPFILES): Add nds32-tdep.c.
	* NEWS: Mention new NDS32 port.
	* configure.tgt: Add NDS32.
	* nds32-tdep.c: New file.
	* nds32-tdep.h: New file.
	* features/Makefile (XMLTOC): Add nds32.xml.
	* features/nds32-core.xml: New file.
	* features/nds32-fpu.xml: New file.
	* features/nds32-system.xml: New file.
	* features/nds32.c: New file (generated).
	* features/nds32.xml: New file.

gdb/testsuite/:
2016-06-17  Yan-Ting Lin  <currygt52@gmail.com>

	* gdb.base/float.exp: Add target check for nds32*-*-*.
	* gdb.xml/tdesc-regs.exp: Set core-regs for nds32*-*-*.

gdb/doc/:
2016-06-17  Yan-Ting Lin  <currygt52@gmail.com>

	* gdb.texinfo (Standard Target Features): Document NDS32 features.
	(NDS32 Features): New Section.
  

Patch

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 2af78a5..4026950 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -691,6 +691,7 @@  ALL_TARGET_OBS = \
 	moxie-tdep.o \
 	msp430-tdep.o \
 	mt-tdep.o \
+	nds32-tdep.o \
 	nios2-tdep.o nios2-linux-tdep.o \
 	nto-tdep.o \
 	ppc-linux-tdep.o ppcfbsd-tdep.o ppcnbsd-tdep.o ppcobsd-tdep.o  \
@@ -966,7 +967,7 @@  amd64-darwin-tdep.h charset-list.h \
 config/djgpp/langinfo.h config/djgpp/nl_types.h darwin-nat.h \
 dicos-tdep.h filesystem.h gcore.h gdb_wchar.h hppabsd-tdep.h \
 i386-darwin-tdep.h x86-nat.h linux-record.h moxie-tdep.h nios2-tdep.h \
-ft32-tdep.h \
+ft32-tdep.h nds32-tdep.h \
 osdata.h procfs.h python/py-event.h python/py-events.h python/py-stopevent.h \
 python/python-internal.h python/python.h ravenscar-thread.h record.h \
 record-full.h solib-aix.h \
@@ -1723,6 +1724,7 @@  ALLDEPFILES = \
 	mipsnbsd-nat.c mipsnbsd-tdep.c \
 	mips64obsd-nat.c mips64obsd-tdep.c \
 	msp430-tdep.c \
+	nds32-tdep.c \
 	nios2-tdep.c nios2-linux-tdep.c \
 	nbsd-nat.c nbsd-tdep.c obsd-nat.c obsd-tdep.c \
 	posix-hdep.c common/posix-strerror.c \
diff --git a/gdb/NEWS b/gdb/NEWS
index 7bf1e1a..75e8f12 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -59,6 +59,10 @@  maint info line-table REGEXP
   including JIT compiling fast tracepoint's conditional expression
   bytecode into native code.
 
+* New targets
+
+Andes NDS32			nds32*-*-elf
+
 *** Changes in GDB 7.11
 
 * GDB now supports debugging kernel-based threads on FreeBSD.
diff --git a/gdb/configure.tgt b/gdb/configure.tgt
index cd8e05d..7f1aac3 100644
--- a/gdb/configure.tgt
+++ b/gdb/configure.tgt
@@ -394,6 +394,11 @@  mt-*-*)
 	gdb_target_obs="mt-tdep.o"
 	;;
 
+nds32*-*-elf)
+	# Target: AndesTech NDS32 core
+	gdb_target_obs="nds32-tdep.o"
+	;;
+
 nios2*-*-linux*)
 	# Target: Altera Nios II running Linux
 	gdb_target_obs="nios2-tdep.o nios2-linux-tdep.o solib-svr4.o \
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index f74c41c..b045ec9 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -40701,6 +40701,7 @@  registers using the capitalization used in the description.
 * MicroBlaze Features::
 * MIPS Features::
 * M68K Features::
+* NDS32 Features::
 * Nios II Features::
 * PowerPC Features::
 * S/390 and System z Features::
@@ -40909,6 +40910,28 @@  This feature is optional.  If present, it should contain registers
 @samp{fpiaddr}.
 @end table
 
+@node NDS32 Features
+@subsection NDS32 Features
+@cindex target descriptions, NDS32 features
+
+The @samp{org.gnu.gdb.nds32.core} feature is required for NDS32
+targets.  It should contain at least registers @samp{r0} through
+@samp{r10}, @samp{r15}, @samp{fp}, @samp{gp}, @samp{lp}, @samp{sp},
+and @samp{pc}.
+
+The @samp{org.gnu.gdb.nds32.fpu} feature is optional.  If present,
+it should contain 64-bit double-precision floating-point registers
+@samp{fd0} through @emph{fdN}, which should be @samp{fd3}, @samp{fd7},
+@samp{fd15}, or @samp{fd31} based on the FPU configuration implemented.
+
+@emph{Note:} The first sixteen 64-bit double-precision floating-point
+registers are overlapped with the thirty-two 32-bit single-precision
+floating-point registers.  The 32-bit single-precision registers, if
+not being listed explicitly, will be synthesized from halves of the
+overlapping 64-bit double-precision registers.  Listing 32-bit
+single-precision registers explicitly is deprecated, and the
+support to it could be totally removed some day.
+
 @node Nios II Features
 @subsection Nios II Features
 @cindex target descriptions, Nios II features
diff --git a/gdb/features/Makefile b/gdb/features/Makefile
index e5c5154..809c811 100644
--- a/gdb/features/Makefile
+++ b/gdb/features/Makefile
@@ -189,6 +189,7 @@  XMLTOC = \
 	mips-linux.xml \
 	mips64-dsp-linux.xml \
 	mips64-linux.xml \
+	nds32.xml \
 	nios2-linux.xml \
 	nios2.xml \
 	rs6000/powerpc-32.xml \
diff --git a/gdb/features/nds32-core.xml b/gdb/features/nds32-core.xml
new file mode 100644
index 0000000..9ea1640
--- /dev/null
+++ b/gdb/features/nds32-core.xml
@@ -0,0 +1,44 @@ 
+<?xml version="1.0"?>
+<!-- Copyright (C) 2013-2016 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.nds32.core">
+  <reg name="r0" bitsize="32" regnum="0"/>
+  <reg name="r1" bitsize="32"/>
+  <reg name="r2" bitsize="32"/>
+  <reg name="r3" bitsize="32"/>
+  <reg name="r4" bitsize="32"/>
+  <reg name="r5" bitsize="32"/>
+  <reg name="r6" bitsize="32"/>
+  <reg name="r7" bitsize="32"/>
+  <reg name="r8" bitsize="32"/>
+  <reg name="r9" bitsize="32"/>
+  <reg name="r10" bitsize="32"/>
+  <reg name="r11" bitsize="32"/>
+  <reg name="r12" bitsize="32"/>
+  <reg name="r13" bitsize="32"/>
+  <reg name="r14" bitsize="32"/>
+  <reg name="r15" bitsize="32"/>
+  <reg name="r16" bitsize="32"/>
+  <reg name="r17" bitsize="32"/>
+  <reg name="r18" bitsize="32"/>
+  <reg name="r19" bitsize="32"/>
+  <reg name="r20" bitsize="32"/>
+  <reg name="r21" bitsize="32"/>
+  <reg name="r22" bitsize="32"/>
+  <reg name="r23" bitsize="32"/>
+  <reg name="r24" bitsize="32"/>
+  <reg name="r25" bitsize="32"/>
+  <reg name="r26" bitsize="32"/>
+  <reg name="r27" bitsize="32"/>
+  <reg name="fp" bitsize="32" type="data_ptr"/>
+  <reg name="gp" bitsize="32" type="data_ptr"/>
+  <reg name="lp" bitsize="32" type="code_ptr"/>
+  <reg name="sp" bitsize="32" type="data_ptr"/>
+
+  <reg name="pc" bitsize="32" type="code_ptr"/>
+</feature>
diff --git a/gdb/features/nds32-fpu.xml b/gdb/features/nds32-fpu.xml
new file mode 100644
index 0000000..b01a4c0
--- /dev/null
+++ b/gdb/features/nds32-fpu.xml
@@ -0,0 +1,42 @@ 
+<?xml version="1.0"?>
+<!-- Copyright (C) 2013-2016 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.nds32.fpu">
+  <reg name="fd0" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd1" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd2" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd3" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd4" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd5" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd6" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd7" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd8" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd9" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd10" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd11" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd12" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd13" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd14" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd15" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd16" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd17" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd18" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd19" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd20" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd21" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd22" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd23" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd24" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd25" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd26" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd27" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd28" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd29" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd30" bitsize="64" type="ieee_double" group="float"/>
+  <reg name="fd31" bitsize="64" type="ieee_double" group="float"/>
+</feature>
diff --git a/gdb/features/nds32-system.xml b/gdb/features/nds32-system.xml
new file mode 100644
index 0000000..c2ea8ac
--- /dev/null
+++ b/gdb/features/nds32-system.xml
@@ -0,0 +1,14 @@ 
+<?xml version="1.0"?>
+<!-- Copyright (C) 2013-2016 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.nds32.system">
+  <reg name="ir0" bitsize="32"/>
+
+  <reg name="itb" bitsize="32"/>
+  <reg name="ifc_lp" bitsize="32"/>
+</feature>
diff --git a/gdb/features/nds32.c b/gdb/features/nds32.c
new file mode 100644
index 0000000..21f63f5
--- /dev/null
+++ b/gdb/features/nds32.c
@@ -0,0 +1,92 @@ 
+/* THIS FILE IS GENERATED.  -*- buffer-read-only: t -*- vi:set ro:
+  Original: nds32.xml */
+
+#include "defs.h"
+#include "osabi.h"
+#include "target-descriptions.h"
+
+struct target_desc *tdesc_nds32;
+static void
+initialize_tdesc_nds32 (void)
+{
+  struct target_desc *result = allocate_target_description ();
+  struct tdesc_feature *feature;
+
+  set_tdesc_architecture (result, bfd_scan_arch ("n1h"));
+
+  feature = tdesc_create_feature (result, "org.gnu.gdb.nds32.core");
+  tdesc_create_reg (feature, "r0", 0, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r1", 1, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r2", 2, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r3", 3, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r4", 4, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r5", 5, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r6", 6, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r7", 7, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r8", 8, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r9", 9, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r10", 10, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r11", 11, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r12", 12, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r13", 13, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r14", 14, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r15", 15, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r16", 16, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r17", 17, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r18", 18, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r19", 19, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r20", 20, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r21", 21, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r22", 22, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r23", 23, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r24", 24, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r25", 25, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r26", 26, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r27", 27, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "fp", 28, 1, NULL, 32, "data_ptr");
+  tdesc_create_reg (feature, "gp", 29, 1, NULL, 32, "data_ptr");
+  tdesc_create_reg (feature, "lp", 30, 1, NULL, 32, "code_ptr");
+  tdesc_create_reg (feature, "sp", 31, 1, NULL, 32, "data_ptr");
+  tdesc_create_reg (feature, "pc", 32, 1, NULL, 32, "code_ptr");
+
+  feature = tdesc_create_feature (result, "org.gnu.gdb.nds32.fpu");
+  tdesc_create_reg (feature, "fd0", 33, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd1", 34, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd2", 35, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd3", 36, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd4", 37, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd5", 38, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd6", 39, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd7", 40, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd8", 41, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd9", 42, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd10", 43, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd11", 44, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd12", 45, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd13", 46, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd14", 47, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd15", 48, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd16", 49, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd17", 50, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd18", 51, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd19", 52, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd20", 53, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd21", 54, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd22", 55, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd23", 56, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd24", 57, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd25", 58, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd26", 59, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd27", 60, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd28", 61, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd29", 62, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd30", 63, 1, "float", 64, "ieee_double");
+  tdesc_create_reg (feature, "fd31", 64, 1, "float", 64, "ieee_double");
+
+  feature = tdesc_create_feature (result, "org.gnu.gdb.nds32.system");
+  tdesc_create_reg (feature, "ir0", 65, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "itb", 66, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "ifc_lp", 67, 1, NULL, 32, "int");
+
+  tdesc_nds32 = result;
+}
diff --git a/gdb/features/nds32.xml b/gdb/features/nds32.xml
new file mode 100644
index 0000000..4819317
--- /dev/null
+++ b/gdb/features/nds32.xml
@@ -0,0 +1,14 @@ 
+<?xml version="1.0"?>
+<!-- Copyright (C) 2013-2016 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 target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>nds32</architecture>
+  <xi:include href="nds32-core.xml"/>
+  <xi:include href="nds32-fpu.xml"/>
+  <xi:include href="nds32-system.xml"/>
+</target>
diff --git a/gdb/nds32-tdep.c b/gdb/nds32-tdep.c
new file mode 100644
index 0000000..48dda27
--- /dev/null
+++ b/gdb/nds32-tdep.c
@@ -0,0 +1,2194 @@ 
+/* Target-dependent code for the NDS32 architecture, for GDB.
+
+   Copyright (C) 2013-2016 Free Software Foundation, Inc.
+   Contributed by Andes Technology Corporation.
+
+   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 "defs.h"
+#include "frame.h"
+#include "frame-unwind.h"
+#include "frame-base.h"
+#include "symtab.h"
+#include "gdbtypes.h"
+#include "gdbcore.h"
+#include "value.h"
+#include "reggroups.h"
+#include "inferior.h"
+#include "osabi.h"
+#include "arch-utils.h"
+#include "regcache.h"
+#include "dis-asm.h"
+#include "user-regs.h"
+#include "elf-bfd.h"
+#include "dwarf2-frame.h"
+#include "remote.h"
+#include "target-descriptions.h"
+
+#include "nds32-tdep.h"
+#include "elf/nds32.h"
+#include "opcode/nds32.h"
+#include "features/nds32.c"
+
+/* Simple macros for instruction analysis.  */
+#define CHOP_BITS(insn, n)	(insn & ~__MASK (n))
+#define N32_LSMW_ENABLE4(insn)	(((insn) >> 6) & 0xf)
+#define N32_SMW_ADM \
+	N32_TYPE4 (LSMW, 0, 0, 0, 1, (N32_LSMW_ADM << 2) | N32_LSMW_LSMW)
+#define N32_LMW_BIM \
+	N32_TYPE4 (LSMW, 0, 0, 0, 0, (N32_LSMW_BIM << 2) | N32_LSMW_LSMW)
+#define N32_FLDI_SP \
+	N32_TYPE2 (LDC, 0, REG_SP, 0)
+
+extern void _initialize_nds32_tdep (void);
+
+/* Use an invalid address value as 'not available' marker.  */
+enum { REG_UNAVAIL = (CORE_ADDR) -1 };
+
+/* Use an impossible value as invalid offset.  */
+enum { INVALID_OFFSET = (CORE_ADDR) -1 };
+
+/* Instruction groups for NDS32 epilogue analysis.  */
+enum
+{
+  /* Instructions used everywhere, not only in epilogue.  */
+  INSN_NORMAL,
+  /* Instructions used to reset sp for local vars, arguments, etc.  */
+  INSN_RESET_SP,
+  /* Instructions used to recover saved regs and to recover padding.  */
+  INSN_RECOVER,
+  /* Instructions used to return to the caller.  */
+  INSN_RETURN,
+  /* Instructions used to recover saved regs and to return to the caller.  */
+  INSN_RECOVER_RETURN,
+};
+
+static const char *const nds32_register_names[] =
+{
+  /* 32 GPRs.  */
+  "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
+  "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
+  "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
+  "r24", "r25", "r26", "r27", "fp", "gp", "lp", "sp",
+  /* PC.  */
+  "pc",
+};
+
+static const char *const nds32_fdr_register_names[] =
+{
+  "fd0", "fd1", "fd2", "fd3", "fd4", "fd5", "fd6", "fd7",
+  "fd8", "fd9", "fd10", "fd11", "fd12", "fd13", "fd14", "fd15",
+  "fd16", "fd17", "fd18", "fd19", "fd20", "fd21", "fd22", "fd23",
+  "fd24", "fd25", "fd26", "fd27", "fd28", "fd29", "fd30", "fd31"
+};
+
+static const char *const nds32_fsr_register_names[] =
+{
+  "fs0", "fs1", "fs2", "fs3", "fs4", "fs5", "fs6", "fs7",
+  "fs8", "fs9", "fs10", "fs11", "fs12", "fs13", "fs14", "fs15",
+  "fs16", "fs17", "fs18", "fs19", "fs20", "fs21", "fs22", "fs23",
+  "fs24", "fs25", "fs26", "fs27", "fs28", "fs29", "fs30", "fs31"
+};
+
+/* The number of registers for four FPU configuration options.  */
+const int num_fdr_map[] = { 4, 8, 16, 32 };
+const int num_fsr_map[] = { 8, 16, 32, 32 };
+
+/* Aliases for registers.  */
+static const struct
+{
+  const char *name;
+  const char *alias;
+} nds32_register_aliases[] =
+{
+  {"r15", "ta"},
+  {"r26", "p0"},
+  {"r27", "p1"},
+  {"fp", "r28"},
+  {"gp", "r29"},
+  {"lp", "r30"},
+  {"sp", "r31"},
+
+  {"cr0", "cpu_ver"},
+  {"cr1", "icm_cfg"},
+  {"cr2", "dcm_cfg"},
+  {"cr3", "mmu_cfg"},
+  {"cr4", "msc_cfg"},
+  {"cr5", "core_id"},
+  {"cr6", "fucop_exist"},
+  {"cr7", "msc_cfg2"},
+
+  {"ir0", "psw"},
+  {"ir1", "ipsw"},
+  {"ir2", "p_psw"},
+  {"ir3", "ivb"},
+  {"ir4", "eva"},
+  {"ir5", "p_eva"},
+  {"ir6", "itype"},
+  {"ir7", "p_itype"},
+  {"ir8", "merr"},
+  {"ir9", "ipc"},
+  {"ir10", "p_ipc"},
+  {"ir11", "oipc"},
+  {"ir12", "p_p0"},
+  {"ir13", "p_p1"},
+  {"ir14", "int_mask"},
+  {"ir15", "int_pend"},
+  {"ir16", "sp_usr"},
+  {"ir17", "sp_priv"},
+  {"ir18", "int_pri"},
+  {"ir19", "int_ctrl"},
+  {"ir20", "sp_usr1"},
+  {"ir21", "sp_priv1"},
+  {"ir22", "sp_usr2"},
+  {"ir23", "sp_priv2"},
+  {"ir24", "sp_usr3"},
+  {"ir25", "sp_priv3"},
+  {"ir26", "int_mask2"},
+  {"ir27", "int_pend2"},
+  {"ir28", "int_pri2"},
+  {"ir29", "int_trigger"},
+
+  {"mr0", "mmu_ctl"},
+  {"mr1", "l1_pptb"},
+  {"mr2", "tlb_vpn"},
+  {"mr3", "tlb_data"},
+  {"mr4", "tlb_misc"},
+  {"mr5", "vlpt_idx"},
+  {"mr6", "ilmb"},
+  {"mr7", "dlmb"},
+  {"mr8", "cache_ctl"},
+  {"mr9", "hsmp_saddr"},
+  {"mr10", "hsmp_eaddr"},
+  {"mr11", "bg_region"},
+
+  {"dr0", "bpc0"},
+  {"dr1", "bpc1"},
+  {"dr2", "bpc2"},
+  {"dr3", "bpc3"},
+  {"dr4", "bpc4"},
+  {"dr5", "bpc5"},
+  {"dr6", "bpc6"},
+  {"dr7", "bpc7"},
+  {"dr8", "bpa0"},
+  {"dr9", "bpa1"},
+  {"dr10", "bpa2"},
+  {"dr11", "bpa3"},
+  {"dr12", "bpa4"},
+  {"dr13", "bpa5"},
+  {"dr14", "bpa6"},
+  {"dr15", "bpa7"},
+  {"dr16", "bpam0"},
+  {"dr17", "bpam1"},
+  {"dr18", "bpam2"},
+  {"dr19", "bpam3"},
+  {"dr20", "bpam4"},
+  {"dr21", "bpam5"},
+  {"dr22", "bpam6"},
+  {"dr23", "bpam7"},
+  {"dr24", "bpv0"},
+  {"dr25", "bpv1"},
+  {"dr26", "bpv2"},
+  {"dr27", "bpv3"},
+  {"dr28", "bpv4"},
+  {"dr29", "bpv5"},
+  {"dr30", "bpv6"},
+  {"dr31", "bpv7"},
+  {"dr32", "bpcid0"},
+  {"dr33", "bpcid1"},
+  {"dr34", "bpcid2"},
+  {"dr35", "bpcid3"},
+  {"dr36", "bpcid4"},
+  {"dr37", "bpcid5"},
+  {"dr38", "bpcid6"},
+  {"dr39", "bpcid7"},
+  {"dr40", "edm_cfg"},
+  {"dr41", "edmsw"},
+  {"dr42", "edm_ctl"},
+  {"dr43", "edm_dtr"},
+  {"dr44", "bpmtc"},
+  {"dr45", "dimbr"},
+  {"dr46", "tecr0"},
+  {"dr47", "tecr1"},
+
+  {"hspr0", "hsp_ctl"},
+  {"hspr1", "sp_bound"},
+  {"hspr2", "sp_bound_priv"},
+
+  {"pfr0", "pfmc0"},
+  {"pfr1", "pfmc1"},
+  {"pfr2", "pfmc2"},
+  {"pfr3", "pfm_ctl"},
+  {"pfr4", "pft_ctl"},
+
+  {"dmar0", "dma_cfg"},
+  {"dmar1", "dma_gcsw"},
+  {"dmar2", "dma_chnsel"},
+  {"dmar3", "dma_act"},
+  {"dmar4", "dma_setup"},
+  {"dmar5", "dma_isaddr"},
+  {"dmar6", "dma_esaddr"},
+  {"dmar7", "dma_tcnt"},
+  {"dmar8", "dma_status"},
+  {"dmar9", "dma_2dset"},
+  {"dmar10", "dma_2dsctl"},
+  {"dmar11", "dma_rcnt"},
+  {"dmar12", "dma_hstatus"},
+
+  {"racr0", "prusr_acc_ctl"},
+  {"fucpr", "fucop_ctl"},
+
+  {"idr0", "sdz_ctl"},
+  {"idr1", "misc_ctl"},
+  {"idr2", "ecc_misc"},
+
+  {"secur0", "sfcr"},
+  {"secur1", "sign"},
+  {"secur2", "isign"},
+  {"secur3", "p_isign"},
+};
+
+/* Value of a register alias.  BATON is the regnum of the corresponding
+   register.  */
+
+static struct value *
+value_of_nds32_reg (struct frame_info *frame, const void *baton)
+{
+  return value_of_register ((int) (intptr_t) baton, frame);
+}
+
+/* Implement the "frame_align" gdbarch method.  */
+
+static CORE_ADDR
+nds32_frame_align (struct gdbarch *gdbarch, CORE_ADDR sp)
+{
+  /* 8-byte aligned.  */
+  return align_down (sp, 8);
+}
+
+/* Implement the "breakpoint_from_pc" gdbarch method.
+
+   Use the program counter to determine the contents and size of a
+   breakpoint instruction.  Return a pointer to a string of bytes that
+   encode a breakpoint instruction, store the length of the string in
+   *LENPTR and optionally adjust *PCPTR to point to the correct memory
+   location for inserting the breakpoint.  */
+
+static const gdb_byte *
+nds32_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr,
+			  int *lenptr)
+{
+  /* The same insn machine code is used for little-endian and big-endian.  */
+  static const gdb_byte break_insn[] = { 0xEA, 0x00 };
+
+  *lenptr = sizeof (break_insn);
+  return break_insn;
+}
+
+/* Implement the "dwarf2_reg_to_regnum" gdbarch method.  */
+
+static int
+nds32_dwarf2_reg_to_regnum (struct gdbarch *gdbarch, int num)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  const int FSR = 38;
+  const int FDR = FSR + 32;
+
+  if (num >= 0 && num < 32)
+    {
+      /* General-purpose registers (R0 - R31).  */
+      return num;
+    }
+  else if (num >= FSR && num < FSR + 32)
+    {
+      /* Single precision floating-point registers (FS0 - FS31).  */
+      return num - FSR + tdep->fs0_regnum;
+    }
+  else if (num >= FDR && num < FDR + 32)
+    {
+      /* Double precision floating-point registers (FD0 - FD31).  */
+      return num - FDR + tdep->fd0_regnum;
+    }
+
+  /* No match, return a inaccessible register number.  */
+  return -1;
+}
+
+/* NDS32 register groups.  */
+static struct reggroup *nds32_cr_reggroup;
+static struct reggroup *nds32_ir_reggroup;
+static struct reggroup *nds32_mr_reggroup;
+static struct reggroup *nds32_dr_reggroup;
+static struct reggroup *nds32_pfr_reggroup;
+static struct reggroup *nds32_hspr_reggroup;
+static struct reggroup *nds32_dmar_reggroup;
+static struct reggroup *nds32_racr_reggroup;
+static struct reggroup *nds32_idr_reggroup;
+static struct reggroup *nds32_secur_reggroup;
+
+static void
+nds32_init_reggroups (void)
+{
+  nds32_cr_reggroup = reggroup_new ("cr", USER_REGGROUP);
+  nds32_ir_reggroup = reggroup_new ("ir", USER_REGGROUP);
+  nds32_mr_reggroup = reggroup_new ("mr", USER_REGGROUP);
+  nds32_dr_reggroup = reggroup_new ("dr", USER_REGGROUP);
+  nds32_pfr_reggroup = reggroup_new ("pfr", USER_REGGROUP);
+  nds32_hspr_reggroup = reggroup_new ("hspr", USER_REGGROUP);
+  nds32_dmar_reggroup = reggroup_new ("dmar", USER_REGGROUP);
+  nds32_racr_reggroup = reggroup_new ("racr", USER_REGGROUP);
+  nds32_idr_reggroup = reggroup_new ("idr", USER_REGGROUP);
+  nds32_secur_reggroup = reggroup_new ("secur", USER_REGGROUP);
+}
+
+static void
+nds32_add_reggroups (struct gdbarch *gdbarch)
+{
+  /* Add pre-defined register groups.  */
+  reggroup_add (gdbarch, general_reggroup);
+  reggroup_add (gdbarch, float_reggroup);
+  reggroup_add (gdbarch, system_reggroup);
+  reggroup_add (gdbarch, all_reggroup);
+  reggroup_add (gdbarch, save_reggroup);
+  reggroup_add (gdbarch, restore_reggroup);
+
+  /* Add NDS32 register groups.  */
+  reggroup_add (gdbarch, nds32_cr_reggroup);
+  reggroup_add (gdbarch, nds32_ir_reggroup);
+  reggroup_add (gdbarch, nds32_mr_reggroup);
+  reggroup_add (gdbarch, nds32_dr_reggroup);
+  reggroup_add (gdbarch, nds32_pfr_reggroup);
+  reggroup_add (gdbarch, nds32_hspr_reggroup);
+  reggroup_add (gdbarch, nds32_dmar_reggroup);
+  reggroup_add (gdbarch, nds32_racr_reggroup);
+  reggroup_add (gdbarch, nds32_idr_reggroup);
+  reggroup_add (gdbarch, nds32_secur_reggroup);
+}
+
+/* Implement the "register_reggroup_p" gdbarch method.  */
+
+static int
+nds32_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
+			   struct reggroup *reggroup)
+{
+  const char *reg_name;
+  const char *group_name;
+  int ret;
+
+  if (reggroup == all_reggroup)
+    return 1;
+
+  /* General reggroup contains only GPRs and PC.  */
+  if (reggroup == general_reggroup)
+    return regnum <= NDS32_PC_REGNUM;
+
+  if (reggroup == float_reggroup || reggroup == save_reggroup
+      || reggroup == restore_reggroup)
+    {
+      ret = tdesc_register_in_reggroup_p (gdbarch, regnum, reggroup);
+      if (ret != -1)
+	return ret;
+
+      return default_register_reggroup_p (gdbarch, regnum, reggroup);
+    }
+
+  if (reggroup == system_reggroup)
+    return (regnum > NDS32_PC_REGNUM)
+	    && !nds32_register_reggroup_p (gdbarch, regnum, float_reggroup);
+
+  /* The NDS32 reggroup contains registers whose name is prefixed
+     by reggroup name.  */
+  reg_name = gdbarch_register_name (gdbarch, regnum);
+  group_name = reggroup_name (reggroup);
+  return !strncmp (reg_name, group_name, strlen (group_name));
+}
+
+/* Implement the "pseudo_register_type" tdesc_arch_data method.  */
+
+static struct type *
+nds32_pseudo_register_type (struct gdbarch *gdbarch, int regnum)
+{
+  regnum -= gdbarch_num_regs (gdbarch);
+
+  /* Currently, only FSRs could be defined as pseudo registers.  */
+  if (regnum < gdbarch_num_pseudo_regs (gdbarch))
+    return arch_float_type (gdbarch, -1, "builtin_type_ieee_single",
+			    floatformats_ieee_single);
+
+  warning (_("Unknown nds32 pseudo register %d."), regnum);
+  return NULL;
+}
+
+/* Implement the "pseudo_register_name" tdesc_arch_data method.  */
+
+static const char *
+nds32_pseudo_register_name (struct gdbarch *gdbarch, int regnum)
+{
+  regnum -= gdbarch_num_regs (gdbarch);
+
+  /* Currently, only FSRs could be defined as pseudo registers.  */
+  if (regnum < gdbarch_num_pseudo_regs (gdbarch))
+    return nds32_fsr_register_names[regnum];
+
+  warning (_("Unknown nds32 pseudo register %d."), regnum);
+  return NULL;
+}
+
+/* Implement the "pseudo_register_read" gdbarch method.  */
+
+static enum register_status
+nds32_pseudo_register_read (struct gdbarch *gdbarch,
+			    struct regcache *regcache, int regnum,
+			    gdb_byte *buf)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  gdb_byte reg_buf[8];
+  int offset, fdr_regnum;
+  enum register_status status = REG_UNKNOWN;
+
+  /* Sanity check.  */
+  if (tdep->fpu_freg == -1 || tdep->use_pseudo_fsrs == 0)
+    return status;
+
+  regnum -= gdbarch_num_regs (gdbarch);
+
+  /* Currently, only FSRs could be defined as pseudo registers.  */
+  if (regnum < gdbarch_num_pseudo_regs (gdbarch))
+    {
+      /* fs0 is always the most significant half of fd0.  */
+      if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
+	offset = (regnum & 1) ? 4 : 0;
+      else
+	offset = (regnum & 1) ? 0 : 4;
+
+      fdr_regnum = tdep->fd0_regnum + (regnum >> 1);
+      status = regcache_raw_read (regcache, fdr_regnum, reg_buf);
+      if (status == REG_VALID)
+	memcpy (buf, reg_buf + offset, 4);
+    }
+
+  return status;
+}
+
+/* Implement the "pseudo_register_write" gdbarch method.  */
+
+static void
+nds32_pseudo_register_write (struct gdbarch *gdbarch,
+			     struct regcache *regcache, int regnum,
+			     const gdb_byte *buf)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  gdb_byte reg_buf[8];
+  int offset, fdr_regnum;
+
+  /* Sanity check.  */
+  if (tdep->fpu_freg == -1 || tdep->use_pseudo_fsrs == 0)
+    return;
+
+  regnum -= gdbarch_num_regs (gdbarch);
+
+  /* Currently, only FSRs could be defined as pseudo registers.  */
+  if (regnum < gdbarch_num_pseudo_regs (gdbarch))
+    {
+      /* fs0 is always the most significant half of fd0.  */
+      if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
+	offset = (regnum & 1) ? 4 : 0;
+      else
+	offset = (regnum & 1) ? 0 : 4;
+
+      fdr_regnum = tdep->fd0_regnum + (regnum >> 1);
+      regcache_raw_read (regcache, fdr_regnum, reg_buf);
+      memcpy (reg_buf + offset, buf, 4);
+      regcache_raw_write (regcache, fdr_regnum, reg_buf);
+    }
+}
+
+/* Helper function for NDS32 ABI.  Return true if FPRs can be used
+   to pass function arguments and return value.  */
+
+static int
+nds32_abi_use_fpr (int abi)
+{
+  return abi == E_NDS_ABI_V2FP_PLUS;
+}
+
+/* Helper function for NDS32 ABI.  Return true if GPRs and stack
+   can be used together to pass an argument.  */
+
+static int
+nds32_abi_split (int abi)
+{
+  return abi == E_NDS_ABI_AABI;
+}
+
+#define NDS32_NUM_SAVED_REGS (NDS32_LP_REGNUM + 1)
+
+struct nds32_frame_cache
+{
+  /* The previous frame's inner most stack address.  Used as this
+     frame ID's stack_addr.  */
+  CORE_ADDR prev_sp;
+
+  /* The frame's base, optionally used by the high-level debug info.  */
+  CORE_ADDR base;
+
+  /* During prologue analysis, keep how far the SP and FP have been offset
+     from the start of the stack frame (as defined by the previous frame's
+     stack pointer).
+     During epilogue analysis, keep how far the SP has been offset from the
+     current stack pointer.  */
+  CORE_ADDR sp_offset;
+  CORE_ADDR fp_offset;
+
+  /* The address of the first instruction in this function.  */
+  CORE_ADDR pc;
+
+  /* Saved registers.  */
+  CORE_ADDR saved_regs[NDS32_NUM_SAVED_REGS];
+};
+
+/* Allocate and initialize a frame cache.  */
+
+static struct nds32_frame_cache *
+nds32_alloc_frame_cache (void)
+{
+  struct nds32_frame_cache *cache;
+  int i;
+
+  cache = FRAME_OBSTACK_ZALLOC (struct nds32_frame_cache);
+
+  /* Initialize fp_offset to check if FP is set in prologue.  */
+  cache->fp_offset = INVALID_OFFSET;
+
+  /* Saved registers.  We initialize these to -1 since zero is a valid
+     offset.  */
+  for (i = 0; i < NDS32_NUM_SAVED_REGS; i++)
+    cache->saved_regs[i] = REG_UNAVAIL;
+
+  return cache;
+}
+
+/* Helper function for instructions used to push multiple words.  */
+
+static void
+nds32_push_multiple_words (struct nds32_frame_cache *cache, int rb, int re,
+			   int enable4)
+{
+  CORE_ADDR sp_offset = cache->sp_offset;
+  int i;
+
+  /* Check LP, GP, FP in enable4.  */
+  for (i = 1; i <= 3; i++)
+    {
+      if ((enable4 >> i) & 0x1)
+	{
+	  sp_offset += 4;
+	  cache->saved_regs[NDS32_SP_REGNUM - i] = sp_offset;
+	}
+    }
+
+  /* Skip case where re == rb == sp.  */
+  if ((rb < REG_FP) && (re < REG_FP))
+    {
+      for (i = re; i >= rb; i--)
+	{
+	  sp_offset += 4;
+	  cache->saved_regs[i] = sp_offset;
+	}
+    }
+
+  /* For sp, update the offset.  */
+  cache->sp_offset = sp_offset;
+}
+
+/* Analyze the instructions within the given address range.  If CACHE
+   is non-NULL, fill it in.  Return the first address beyond the given
+   address range.  If CACHE is NULL, return the first address not
+   recognized as a prologue instruction.  */
+
+static CORE_ADDR
+nds32_analyze_prologue (struct gdbarch *gdbarch, CORE_ADDR pc,
+			CORE_ADDR limit_pc, struct nds32_frame_cache *cache)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  int abi_use_fpr = nds32_abi_use_fpr (tdep->abi);
+  /* Current scanning status.  */
+  int in_prologue_bb = 0;
+  int val_ta = 0;
+  uint32_t insn, insn_len;
+
+  for (; pc < limit_pc; pc += insn_len)
+    {
+      insn = read_memory_unsigned_integer (pc, 4, BFD_ENDIAN_BIG);
+
+      if ((insn & 0x80000000) == 0)
+	{
+	  /* 32-bit instruction */
+	  insn_len = 4;
+
+	  if (CHOP_BITS (insn, 15) == N32_TYPE2 (ADDI, REG_SP, REG_SP, 0))
+	    {
+	      /* addi $sp, $sp, imm15s */
+	      int imm15s = N32_IMM15S (insn);
+
+	      if (imm15s < 0)
+		{
+		  if (cache != NULL)
+		    cache->sp_offset += -imm15s;
+
+		  in_prologue_bb = 1;
+		  continue;
+		}
+	    }
+	  else if (CHOP_BITS (insn, 15) == N32_TYPE2 (ADDI, REG_FP, REG_SP, 0))
+	    {
+	      /* addi $fp, $sp, imm15s */
+	      int imm15s = N32_IMM15S (insn);
+
+	      if (imm15s > 0)
+		{
+		  if (cache != NULL)
+		    cache->fp_offset = cache->sp_offset - imm15s;
+
+		  in_prologue_bb = 1;
+		  continue;
+		}
+	    }
+	  else if ((insn & ~(__MASK (19) << 6)) == N32_SMW_ADM
+		   && N32_RA5 (insn) == REG_SP)
+	    {
+	      /* smw.adm Rb, [$sp], Re, enable4 */
+	      if (cache != NULL)
+		nds32_push_multiple_words (cache, N32_RT5 (insn),
+					   N32_RB5 (insn),
+					   N32_LSMW_ENABLE4 (insn));
+	      in_prologue_bb = 1;
+	      continue;
+	    }
+	  else if (insn == N32_ALU1 (ADD, REG_SP, REG_SP, REG_TA)
+		   || insn == N32_ALU1 (ADD, REG_SP, REG_TA, REG_SP))
+	    {
+	      /* add $sp, $sp, $ta */
+	      /* add $sp, $ta, $sp */
+	      if (val_ta < 0)
+		{
+		  if (cache != NULL)
+		    cache->sp_offset += -val_ta;
+
+		  in_prologue_bb = 1;
+		  continue;
+		}
+	    }
+	  else if (CHOP_BITS (insn, 20) == N32_TYPE1 (MOVI, REG_TA, 0))
+	    {
+	      /* movi $ta, imm20s */
+	      if (cache != NULL)
+		val_ta = N32_IMM20S (insn);
+
+	      continue;
+	    }
+	  else if (CHOP_BITS (insn, 20) == N32_TYPE1 (SETHI, REG_TA, 0))
+	    {
+	      /* sethi $ta, imm20u */
+	      if (cache != NULL)
+		val_ta = N32_IMM20U (insn) << 12;
+
+	      continue;
+	    }
+	  else if (CHOP_BITS (insn, 15) == N32_TYPE2 (ORI, REG_TA, REG_TA, 0))
+	    {
+	      /* ori $ta, $ta, imm15u */
+	      if (cache != NULL)
+		val_ta |= N32_IMM15U (insn);
+
+	      continue;
+	    }
+	  else if (CHOP_BITS (insn, 15) == N32_TYPE2 (ADDI, REG_TA, REG_TA, 0))
+	    {
+	      /* addi $ta, $ta, imm15s */
+	      if (cache != NULL)
+		val_ta += N32_IMM15S (insn);
+
+	      continue;
+	    }
+	  if (insn == N32_ALU1 (ADD, REG_GP, REG_TA, REG_GP)
+	      || insn == N32_ALU1 (ADD, REG_GP, REG_GP, REG_TA))
+	    {
+	      /* add $gp, $ta, $gp */
+	      /* add $gp, $gp, $ta */
+	      in_prologue_bb = 1;
+	      continue;
+	    }
+	  else if (CHOP_BITS (insn, 20) == N32_TYPE1 (MOVI, REG_GP, 0))
+	    {
+	      /* movi $gp, imm20s */
+	      in_prologue_bb = 1;
+	      continue;
+	    }
+	  else if (CHOP_BITS (insn, 20) == N32_TYPE1 (SETHI, REG_GP, 0))
+	    {
+	      /* sethi $gp, imm20u */
+	      in_prologue_bb = 1;
+	      continue;
+	    }
+	  else if (CHOP_BITS (insn, 15) == N32_TYPE2 (ORI, REG_GP, REG_GP, 0))
+	    {
+	      /* ori $gp, $gp, imm15u */
+	      in_prologue_bb = 1;
+	      continue;
+	    }
+	  else
+	    {
+	      /* Jump/Branch insns never appear in prologue basic block.
+		 The loop can be escaped early when these insns are met.  */
+	      if (in_prologue_bb == 1)
+		{
+		  int op = N32_OP6 (insn);
+
+		  if (op == N32_OP6_JI
+		      || op == N32_OP6_JREG
+		      || op == N32_OP6_BR1
+		      || op == N32_OP6_BR2
+		      || op == N32_OP6_BR3)
+		    break;
+		}
+	    }
+
+	  if (abi_use_fpr && N32_OP6 (insn) == N32_OP6_SDC
+	      && __GF (insn, 12, 3) == 0)
+	    {
+	      /* For FPU insns, CP (bit [13:14]) should be CP0,  and only
+		 normal form (bit [12] == 0) is used.  */
+
+	      /* fsdi FDt, [$sp + (imm12s << 2)] */
+	      if (N32_RA5 (insn) == REG_SP)
+		continue;
+	    }
+
+	  /* The optimizer might shove anything into the prologue, if
+	     we build up cache (cache != NULL) from analyzing prologue,
+	     we just skip what we don't recognize and analyze further to
+	     make cache as complete as possible.  However, if we skip
+	     prologue, we'll stop immediately on unrecognized
+	     instruction.  */
+	  if (cache == NULL)
+	    break;
+	}
+      else
+	{
+	  /* 16-bit instruction */
+	  insn_len = 2;
+
+	  insn >>= 16;
+
+	  if (CHOP_BITS (insn, 10) == N16_TYPE10 (ADDI10S, 0))
+	    {
+	      /* addi10s.sp */
+	      int imm10s = N16_IMM10S (insn);
+
+	      if (imm10s < 0)
+		{
+		  if (cache != NULL)
+		    cache->sp_offset += -imm10s;
+
+		  in_prologue_bb = 1;
+		  continue;
+		}
+	    }
+	  else if (__GF (insn, 7, 8) == N16_T25_PUSH25)
+	    {
+	      /* push25 */
+	      if (cache != NULL)
+		{
+		  int imm8u = (insn & 0x1f) << 3;
+		  int re = (insn >> 5) & 0x3;
+		  const int reg_map[] = { 6, 8, 10, 14 };
+
+		  /* Operation 1 -- smw.adm R6, [$sp], Re, #0xe */
+		  nds32_push_multiple_words (cache, 6, reg_map[re], 0xe);
+
+		  /* Operation 2 -- sp = sp - (imm5u << 3) */
+		  cache->sp_offset += imm8u;
+		}
+
+	      in_prologue_bb = 1;
+	      continue;
+	    }
+	  else if (insn == N16_TYPE5 (ADD5PC, REG_GP))
+	    {
+	      /* add5.pc $gp */
+	      in_prologue_bb = 1;
+	      continue;
+	    }
+	  else if (CHOP_BITS (insn, 5) == N16_TYPE55 (MOVI55, REG_GP, 0))
+	    {
+	      /* movi55 $gp, imm5s */
+	      in_prologue_bb = 1;
+	      continue;
+	    }
+	  else
+	    {
+	      /* Jump/Branch insns never appear in prologue basic block.
+		 The loop can be escaped early when these insns are met.  */
+	      if (in_prologue_bb == 1)
+		{
+		  uint32_t insn5 = CHOP_BITS (insn, 5);
+		  uint32_t insn8 = CHOP_BITS (insn, 8);
+		  uint32_t insn38 = CHOP_BITS (insn, 11);
+
+		  if (insn5 == N16_TYPE5 (JR5, 0)
+		      || insn5 == N16_TYPE5 (JRAL5, 0)
+		      || insn5 == N16_TYPE5 (RET5, 0)
+		      || insn8 == N16_TYPE8 (J8, 0)
+		      || insn8 == N16_TYPE8 (BEQZS8, 0)
+		      || insn8 == N16_TYPE8 (BNEZS8, 0)
+		      || insn38 == N16_TYPE38 (BEQZ38, 0, 0)
+		      || insn38 == N16_TYPE38 (BNEZ38, 0, 0)
+		      || insn38 == N16_TYPE38 (BEQS38, 0, 0)
+		      || insn38 == N16_TYPE38 (BNES38, 0, 0))
+		    break;
+		}
+	    }
+
+	  /* The optimizer might shove anything into the prologue, if
+	     we build up cache (cache != NULL) from analyzing prologue,
+	     we just skip what we don't recognize and analyze further to
+	     make cache as complete as possible.  However, if we skip
+	     prologue, we'll stop immediately on unrecognized
+	     instruction.  */
+	  if (cache == NULL)
+	    break;
+	}
+    }
+
+  return pc;
+}
+
+/* Implement the "skip_prologue" gdbarch method.
+
+   Find the end of function prologue.  */
+
+static CORE_ADDR
+nds32_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  CORE_ADDR func_addr, limit_pc;
+
+  /* See if we can determine the end of the prologue via the symbol table.
+     If so, then return either PC, or the PC after the prologue, whichever
+     is greater.  */
+  if (find_pc_partial_function (pc, NULL, &func_addr, NULL))
+    {
+      CORE_ADDR post_prologue_pc
+	= skip_prologue_using_sal (gdbarch, func_addr);
+      if (post_prologue_pc != 0)
+	return max (pc, post_prologue_pc);
+    }
+
+  /* Can't determine prologue from the symbol table, need to examine
+     instructions.  */
+
+  /* Find an upper limit on the function prologue using the debug
+     information.  If the debug information could not be used to provide
+     that bound, then use an arbitrary large number as the upper bound.  */
+  limit_pc = skip_prologue_using_sal (gdbarch, pc);
+  if (limit_pc == 0)
+    limit_pc = pc + 128;	/* Magic.  */
+
+  /* Find the end of prologue.  */
+  return nds32_analyze_prologue (gdbarch, pc, limit_pc, NULL);
+}
+
+/* Allocate and fill in *THIS_CACHE with information about the prologue of
+   *THIS_FRAME.  Do not do this if *THIS_CACHE was already allocated.  Return
+   a pointer to the current nds32_frame_cache in *THIS_CACHE.  */
+
+static struct nds32_frame_cache *
+nds32_frame_cache (struct frame_info *this_frame, void **this_cache)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  struct nds32_frame_cache *cache;
+  CORE_ADDR current_pc;
+  ULONGEST prev_sp;
+  ULONGEST this_base;
+  int i;
+
+  if (*this_cache)
+    return (struct nds32_frame_cache *) *this_cache;
+
+  cache = nds32_alloc_frame_cache ();
+  *this_cache = cache;
+
+  cache->pc = get_frame_func (this_frame);
+  current_pc = get_frame_pc (this_frame);
+  nds32_analyze_prologue (gdbarch, cache->pc, current_pc, cache);
+
+  /* Compute the previous frame's stack pointer (which is also the
+     frame's ID's stack address), and this frame's base pointer.  */
+  if (cache->fp_offset != INVALID_OFFSET)
+    {
+      /* FP is set in prologue, so it can be used to calculate other info.  */
+      this_base = get_frame_register_unsigned (this_frame, NDS32_FP_REGNUM);
+      prev_sp = this_base + cache->fp_offset;
+    }
+  else
+    {
+      this_base = get_frame_register_unsigned (this_frame, NDS32_SP_REGNUM);
+      prev_sp = this_base + cache->sp_offset;
+    }
+
+  cache->prev_sp = prev_sp;
+  cache->base = this_base;
+
+  /* Adjust all the saved registers such that they contain addresses
+     instead of offsets.  */
+  for (i = 0; i < NDS32_NUM_SAVED_REGS; i++)
+    if (cache->saved_regs[i] != REG_UNAVAIL)
+      cache->saved_regs[i] = cache->prev_sp - cache->saved_regs[i];
+
+  return cache;
+}
+
+/* Implement the "this_id" frame_unwind method.
+
+   Our frame ID for a normal frame is the current function's starting
+   PC and the caller's SP when we were called.  */
+
+static void
+nds32_frame_this_id (struct frame_info *this_frame,
+		     void **this_cache, struct frame_id *this_id)
+{
+  struct nds32_frame_cache *cache = nds32_frame_cache (this_frame, this_cache);
+
+  /* This marks the outermost frame.  */
+  if (cache->prev_sp == 0)
+    return;
+
+  *this_id = frame_id_build (cache->prev_sp, cache->pc);
+}
+
+/* Implement the "prev_register" frame_unwind method.  */
+
+static struct value *
+nds32_frame_prev_register (struct frame_info *this_frame, void **this_cache,
+			   int regnum)
+{
+  struct nds32_frame_cache *cache = nds32_frame_cache (this_frame, this_cache);
+
+  if (regnum == NDS32_SP_REGNUM)
+    return frame_unwind_got_constant (this_frame, regnum, cache->prev_sp);
+
+  /* The PC of the previous frame is stored in the LP register of
+     the current frame.  */
+  if (regnum == NDS32_PC_REGNUM)
+    regnum = NDS32_LP_REGNUM;
+
+  if (regnum < NDS32_NUM_SAVED_REGS && cache->saved_regs[regnum] != REG_UNAVAIL)
+    return frame_unwind_got_memory (this_frame, regnum,
+				    cache->saved_regs[regnum]);
+
+  return frame_unwind_got_register (this_frame, regnum, regnum);
+}
+
+static const struct frame_unwind nds32_frame_unwind =
+{
+  NORMAL_FRAME,
+  default_frame_unwind_stop_reason,
+  nds32_frame_this_id,
+  nds32_frame_prev_register,
+  NULL,
+  default_frame_sniffer,
+};
+
+/* Return the frame base address of *THIS_FRAME.  */
+
+static CORE_ADDR
+nds32_frame_base_address (struct frame_info *this_frame, void **this_cache)
+{
+  struct nds32_frame_cache *cache = nds32_frame_cache (this_frame, this_cache);
+
+  return cache->base;
+}
+
+static const struct frame_base nds32_frame_base =
+{
+  &nds32_frame_unwind,
+  nds32_frame_base_address,
+  nds32_frame_base_address,
+  nds32_frame_base_address
+};
+
+/* Helper function for instructions used to pop multiple words.  */
+
+static void
+nds32_pop_multiple_words (struct nds32_frame_cache *cache, int rb, int re,
+			  int enable4)
+{
+  CORE_ADDR sp_offset = cache->sp_offset;
+  int i;
+
+  /* Skip case where re == rb == sp.  */
+  if ((rb < REG_FP) && (re < REG_FP))
+    {
+      for (i = rb; i <= re; i++)
+	{
+	  cache->saved_regs[i] = sp_offset;
+	  sp_offset += 4;
+	}
+    }
+
+  /* Check FP, GP, LP in enable4.  */
+  for (i = 3; i >= 1; i--)
+    {
+      if ((enable4 >> i) & 0x1)
+	{
+	  cache->saved_regs[NDS32_SP_REGNUM - i] = sp_offset;
+	  sp_offset += 4;
+	}
+    }
+
+  /* For sp, update the offset.  */
+  cache->sp_offset = sp_offset;
+}
+
+/* The instruction sequences in NDS32 epilogue are
+
+   INSN_RESET_SP  (optional)
+		  (If exists, this must be the first instruction in epilogue
+		   and the stack has not been destroyed.).
+   INSN_RECOVER  (optional).
+   INSN_RETURN/INSN_RECOVER_RETURN  (required).  */
+
+/* Helper function for analyzing the given 32-bit INSN.  If CACHE is non-NULL,
+   the necessary information will be recorded.  */
+
+static inline int
+nds32_analyze_epilogue_insn32 (int abi_use_fpr, uint32_t insn,
+			       struct nds32_frame_cache *cache)
+{
+  if (CHOP_BITS (insn, 15) == N32_TYPE2 (ADDI, REG_SP, REG_SP, 0)
+      && N32_IMM15S (insn) > 0)
+    /* addi $sp, $sp, imm15s */
+    return INSN_RESET_SP;
+  else if (CHOP_BITS (insn, 15) == N32_TYPE2 (ADDI, REG_SP, REG_FP, 0)
+	   && N32_IMM15S (insn) < 0)
+    /* addi $sp, $fp, imm15s */
+    return INSN_RESET_SP;
+  else if ((insn & ~(__MASK (19) << 6)) == N32_LMW_BIM
+	   && N32_RA5 (insn) == REG_SP)
+    {
+      /* lmw.bim Rb, [$sp], Re, enable4 */
+      if (cache != NULL)
+	nds32_pop_multiple_words (cache, N32_RT5 (insn),
+				  N32_RB5 (insn), N32_LSMW_ENABLE4 (insn));
+
+      return INSN_RECOVER;
+    }
+  else if (insn == N32_JREG (JR, 0, REG_LP, 0, 1))
+    /* ret $lp */
+    return INSN_RETURN;
+  else if (insn == N32_ALU1 (ADD, REG_SP, REG_SP, REG_TA)
+	   || insn == N32_ALU1 (ADD, REG_SP, REG_TA, REG_SP))
+    /* add $sp, $sp, $ta */
+    /* add $sp, $ta, $sp */
+    return INSN_RESET_SP;
+  else if (abi_use_fpr
+	   && (insn & ~(__MASK (5) << 20 | __MASK (13))) == N32_FLDI_SP)
+    {
+      if (__GF (insn, 12, 1) == 0)
+	/* fldi FDt, [$sp + (imm12s << 2)] */
+	return INSN_RECOVER;
+      else
+	{
+	  /* fldi.bi FDt, [$sp], (imm12s << 2) */
+	  int offset = N32_IMM12S (insn) << 2;
+
+	  if (offset == 8 || offset == 12)
+	    {
+	      if (cache != NULL)
+		cache->sp_offset += offset;
+
+	      return INSN_RECOVER;
+	    }
+	}
+    }
+
+  return INSN_NORMAL;
+}
+
+/* Helper function for analyzing the given 16-bit INSN.  If CACHE is non-NULL,
+   the necessary information will be recorded.  */
+
+static inline int
+nds32_analyze_epilogue_insn16 (uint32_t insn, struct nds32_frame_cache *cache)
+{
+  if (insn == N16_TYPE5 (RET5, REG_LP))
+    /* ret5 $lp */
+    return INSN_RETURN;
+  else if (CHOP_BITS (insn, 10) == N16_TYPE10 (ADDI10S, 0))
+    {
+      /* addi10s.sp */
+      int imm10s = N16_IMM10S (insn);
+
+      if (imm10s > 0)
+	{
+	  if (cache != NULL)
+	    cache->sp_offset += imm10s;
+
+	  return INSN_RECOVER;
+	}
+    }
+  else if (__GF (insn, 7, 8) == N16_T25_POP25)
+    {
+      /* pop25 */
+      if (cache != NULL)
+	{
+	  int imm8u = (insn & 0x1f) << 3;
+	  int re = (insn >> 5) & 0x3;
+	  const int reg_map[] = { 6, 8, 10, 14 };
+
+	  /* Operation 1 -- sp = sp + (imm5u << 3) */
+	  cache->sp_offset += imm8u;
+
+	  /* Operation 2 -- lmw.bim R6, [$sp], Re, #0xe */
+	  nds32_pop_multiple_words (cache, 6, reg_map[re], 0xe);
+	}
+
+      /* Operation 3 -- ret $lp */
+      return INSN_RECOVER_RETURN;
+    }
+
+  return INSN_NORMAL;
+}
+
+/* Analyze a reasonable amount of instructions from the given PC to find
+   the instruction used to return to the caller.  Return 1 if the 'return'
+   instruction could be found, 0 otherwise.
+
+   If CACHE is non-NULL, fill it in.  */
+
+static int
+nds32_analyze_epilogue (struct gdbarch *gdbarch, CORE_ADDR pc,
+			struct nds32_frame_cache *cache)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  int abi_use_fpr = nds32_abi_use_fpr (tdep->abi);
+  CORE_ADDR limit_pc;
+  uint32_t insn, insn_len;
+  int insn_type = INSN_NORMAL;
+
+  if (abi_use_fpr)
+    limit_pc = pc + 48;
+  else
+    limit_pc = pc + 16;
+
+  for (; pc < limit_pc; pc += insn_len)
+    {
+      insn = read_memory_unsigned_integer (pc, 4, BFD_ENDIAN_BIG);
+
+      if ((insn & 0x80000000) == 0)
+	{
+	  /* 32-bit instruction */
+	  insn_len = 4;
+
+	  insn_type = nds32_analyze_epilogue_insn32 (abi_use_fpr, insn, cache);
+	  if (insn_type == INSN_RETURN)
+	    return 1;
+	  else if (insn_type == INSN_RECOVER)
+	    continue;
+	}
+      else
+	{
+	  /* 16-bit instruction */
+	  insn_len = 2;
+
+	  insn >>= 16;
+	  insn_type = nds32_analyze_epilogue_insn16 (insn, cache);
+	  if (insn_type == INSN_RETURN || insn_type == INSN_RECOVER_RETURN)
+	    return 1;
+	  else if (insn_type == INSN_RECOVER)
+	    continue;
+	}
+
+      /* Stop the scan if this is an unexpected instruction.  */
+      break;
+    }
+
+  return 0;
+}
+
+/* Implement the "stack_frame_destroyed_p" gdbarch method.  */
+
+static int
+nds32_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  int abi_use_fpr = nds32_abi_use_fpr (tdep->abi);
+  int insn_type = INSN_NORMAL;
+  int ret_found = 0;
+  uint32_t insn;
+
+  insn = read_memory_unsigned_integer (addr, 4, BFD_ENDIAN_BIG);
+
+  if ((insn & 0x80000000) == 0)
+    {
+      /* 32-bit instruction */
+
+      insn_type = nds32_analyze_epilogue_insn32 (abi_use_fpr, insn, NULL);
+    }
+  else
+    {
+      /* 16-bit instruction */
+
+      insn >>= 16;
+      insn_type = nds32_analyze_epilogue_insn16 (insn, NULL);
+    }
+
+  if (insn_type == INSN_NORMAL || insn_type == INSN_RESET_SP)
+    return 0;
+
+  /* Search the required 'return' instruction within the following reasonable
+     instructions.  */
+  ret_found = nds32_analyze_epilogue (gdbarch, addr, NULL);
+  if (ret_found == 0)
+    return 0;
+
+  /* Scan backwards to make sure that the last instruction has adjusted
+     stack.  Both a 16-bit and a 32-bit instruction will be tried.  This is
+     just a heuristic, so the false positives will be acceptable.  */
+  insn = read_memory_unsigned_integer (addr - 2, 4, BFD_ENDIAN_BIG);
+
+  /* Only 16-bit instructions are possible at addr - 2.  */
+  if ((insn & 0x80000000) != 0)
+    {
+      /* This may be a 16-bit instruction or part of a 32-bit instruction.  */
+
+      insn_type = nds32_analyze_epilogue_insn16 (insn >> 16, NULL);
+      if (insn_type == INSN_RECOVER)
+	return 1;
+    }
+
+  insn = read_memory_unsigned_integer (addr - 4, 4, BFD_ENDIAN_BIG);
+
+  /* If this is a 16-bit instruction at addr - 4, then there must be another
+     16-bit instruction at addr - 2, so only 32-bit instructions need to
+     be analyzed here.  */
+  if ((insn & 0x80000000) == 0)
+    {
+      /* This may be a 32-bit instruction or part of a 32-bit instruction.  */
+
+      insn_type = nds32_analyze_epilogue_insn32 (abi_use_fpr, insn, NULL);
+      if (insn_type == INSN_RECOVER || insn_type == INSN_RESET_SP)
+	return 1;
+    }
+
+  return 0;
+}
+
+/* Implement the "sniffer" frame_unwind method.  */
+
+static int
+nds32_epilogue_frame_sniffer (const struct frame_unwind *self,
+			      struct frame_info *this_frame, void **this_cache)
+{
+  if (frame_relative_level (this_frame) == 0)
+    return nds32_stack_frame_destroyed_p (get_frame_arch (this_frame),
+					  get_frame_pc (this_frame));
+  else
+    return 0;
+}
+
+/* Allocate and fill in *THIS_CACHE with information needed to unwind
+   *THIS_FRAME within epilogue.  Do not do this if *THIS_CACHE was already
+   allocated.  Return a pointer to the current nds32_frame_cache in
+   *THIS_CACHE.  */
+
+static struct nds32_frame_cache *
+nds32_epilogue_frame_cache (struct frame_info *this_frame, void **this_cache)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  struct nds32_frame_cache *cache;
+  CORE_ADDR current_pc, current_sp;
+  int i;
+
+  if (*this_cache)
+    return (struct nds32_frame_cache *) *this_cache;
+
+  cache = nds32_alloc_frame_cache ();
+  *this_cache = cache;
+
+  cache->pc = get_frame_func (this_frame);
+  current_pc = get_frame_pc (this_frame);
+  nds32_analyze_epilogue (gdbarch, current_pc, cache);
+
+  current_sp = get_frame_register_unsigned (this_frame, NDS32_SP_REGNUM);
+  cache->prev_sp = current_sp + cache->sp_offset;
+
+  /* Adjust all the saved registers such that they contain addresses
+     instead of offsets.  */
+  for (i = 0; i < NDS32_NUM_SAVED_REGS; i++)
+    if (cache->saved_regs[i] != REG_UNAVAIL)
+      cache->saved_regs[i] = current_sp + cache->saved_regs[i];
+
+  return cache;
+}
+
+/* Implement the "this_id" frame_unwind method.  */
+
+static void
+nds32_epilogue_frame_this_id (struct frame_info *this_frame,
+			      void **this_cache, struct frame_id *this_id)
+{
+  struct nds32_frame_cache *cache
+    = nds32_epilogue_frame_cache (this_frame, this_cache);
+
+  /* This marks the outermost frame.  */
+  if (cache->prev_sp == 0)
+    return;
+
+  *this_id = frame_id_build (cache->prev_sp, cache->pc);
+}
+
+/* Implement the "prev_register" frame_unwind method.  */
+
+static struct value *
+nds32_epilogue_frame_prev_register (struct frame_info *this_frame,
+				    void **this_cache, int regnum)
+{
+  struct nds32_frame_cache *cache
+    = nds32_epilogue_frame_cache (this_frame, this_cache);
+
+  if (regnum == NDS32_SP_REGNUM)
+    return frame_unwind_got_constant (this_frame, regnum, cache->prev_sp);
+
+  /* The PC of the previous frame is stored in the LP register of
+     the current frame.  */
+  if (regnum == NDS32_PC_REGNUM)
+    regnum = NDS32_LP_REGNUM;
+
+  if (regnum < NDS32_NUM_SAVED_REGS && cache->saved_regs[regnum] != REG_UNAVAIL)
+    return frame_unwind_got_memory (this_frame, regnum,
+				    cache->saved_regs[regnum]);
+
+  return frame_unwind_got_register (this_frame, regnum, regnum);
+}
+
+static const struct frame_unwind nds32_epilogue_frame_unwind =
+{
+  NORMAL_FRAME,
+  default_frame_unwind_stop_reason,
+  nds32_epilogue_frame_this_id,
+  nds32_epilogue_frame_prev_register,
+  NULL,
+  nds32_epilogue_frame_sniffer
+};
+
+/* Implement the "dummy_id" gdbarch method.  */
+
+static struct frame_id
+nds32_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  CORE_ADDR sp = get_frame_register_unsigned (this_frame, NDS32_SP_REGNUM);
+
+  return frame_id_build (sp, get_frame_pc (this_frame));
+}
+
+/* Implement the "unwind_pc" gdbarch method.  */
+
+static CORE_ADDR
+nds32_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+  return frame_unwind_register_unsigned (next_frame, NDS32_PC_REGNUM);
+}
+
+/* Implement the "unwind_sp" gdbarch method.  */
+
+static CORE_ADDR
+nds32_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+  return frame_unwind_register_unsigned (next_frame, NDS32_SP_REGNUM);
+}
+
+/* Floating type and struct type that has only one floating type member
+   can pass value using FPU registers (when FPU ABI is used).  */
+
+static int
+nds32_check_calling_use_fpr (struct type *type)
+{
+  struct type *t;
+  enum type_code typecode;
+
+  t = type;
+  while (1)
+    {
+      t = check_typedef (t);
+      typecode = TYPE_CODE (t);
+      if (typecode != TYPE_CODE_STRUCT)
+	break;
+      else if (TYPE_NFIELDS (t) != 1)
+	return 0;
+      else
+	t = TYPE_FIELD_TYPE (t, 0);
+    }
+
+  return typecode == TYPE_CODE_FLT;
+}
+
+/* Return the alignment (in bytes) of the given type.  */
+
+static int
+nds32_type_align (struct type *type)
+{
+  int n;
+  int align;
+  int falign;
+
+  type = check_typedef (type);
+  switch (TYPE_CODE (type))
+    {
+    default:
+      /* Should never happen.  */
+      internal_error (__FILE__, __LINE__, _("unknown type alignment"));
+      return 4;
+
+    case TYPE_CODE_PTR:
+    case TYPE_CODE_ENUM:
+    case TYPE_CODE_INT:
+    case TYPE_CODE_FLT:
+    case TYPE_CODE_SET:
+    case TYPE_CODE_RANGE:
+    case TYPE_CODE_REF:
+    case TYPE_CODE_CHAR:
+    case TYPE_CODE_BOOL:
+      return TYPE_LENGTH (type);
+
+    case TYPE_CODE_ARRAY:
+    case TYPE_CODE_COMPLEX:
+      return nds32_type_align (TYPE_TARGET_TYPE (type));
+
+    case TYPE_CODE_STRUCT:
+    case TYPE_CODE_UNION:
+      align = 1;
+      for (n = 0; n < TYPE_NFIELDS (type); n++)
+	{
+	  falign = nds32_type_align (TYPE_FIELD_TYPE (type, n));
+	  if (falign > align)
+	    align = falign;
+	}
+      return align;
+    }
+}
+
+/* Implement the "push_dummy_call" gdbarch method.  */
+
+static CORE_ADDR
+nds32_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
+		       struct regcache *regcache, CORE_ADDR bp_addr,
+		       int nargs, struct value **args, CORE_ADDR sp,
+		       int struct_return, CORE_ADDR struct_addr)
+{
+  const int REND = 6;		/* End for register offset.  */
+  int goff = 0;			/* Current gpr offset for argument.  */
+  int foff = 0;			/* Current fpr offset for argument.  */
+  int soff = 0;			/* Current stack offset for argument.  */
+  int i;
+  ULONGEST regval;
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  struct type *func_type = value_type (function);
+  int abi_use_fpr = nds32_abi_use_fpr (tdep->abi);
+  int abi_split = nds32_abi_split (tdep->abi);
+
+  /* Set the return address.  For the NDS32, the return breakpoint is
+     always at BP_ADDR.  */
+  regcache_cooked_write_unsigned (regcache, NDS32_LP_REGNUM, bp_addr);
+
+  /* If STRUCT_RETURN is true, then the struct return address (in
+     STRUCT_ADDR) will consume the first argument-passing register.
+     Both adjust the register count and store that value.  */
+  if (struct_return)
+    {
+      regcache_cooked_write_unsigned (regcache, NDS32_R0_REGNUM, struct_addr);
+      goff++;
+    }
+
+  /* Now make sure there's space on the stack */
+  for (i = 0; i < nargs; i++)
+    {
+      struct type *type = value_type (args[i]);
+      int align = nds32_type_align (type);
+
+      /* If align is zero, it may be an empty struct.
+	 Just ignore the argument of empty struct.  */
+      if (align == 0)
+	continue;
+
+      sp -= TYPE_LENGTH (type);
+      sp = align_down (sp, align);
+    }
+
+  /* Stack must be 8-byte aligned.  */
+  sp = align_down (sp, 8);
+
+  soff = 0;
+  for (i = 0; i < nargs; i++)
+    {
+      const gdb_byte *val;
+      int align, len;
+      struct type *type;
+      int calling_use_fpr;
+      int use_fpr = 0;
+
+      type = value_type (args[i]);
+      calling_use_fpr = nds32_check_calling_use_fpr (type);
+      len = TYPE_LENGTH (type);
+      align = nds32_type_align (type);
+      val = value_contents (args[i]);
+
+      /* The size of a composite type larger than 4 bytes will be rounded
+	 up to the nearest multiple of 4.  */
+      if (len > 4)
+	len = align_up (len, 4);
+
+      /* Variadic functions are handled differently between AABI and ABI2FP+.
+
+	 For AABI, the caller pushes arguments in registers, callee stores
+	 unnamed arguments in stack, and then va_arg fetch arguments in stack.
+	 Therefore, we don't have to handle variadic functions specially.
+
+	 For ABI2FP+, the caller pushes only named arguments in registers
+	 and pushes all unnamed arguments in stack.  */
+
+      if (abi_use_fpr && TYPE_VARARGS (func_type)
+	  && i >= TYPE_NFIELDS (func_type))
+	goto use_stack;
+
+      /* Try to use FPRs to pass arguments only when
+	 1. The program is built using toolchain with FPU support.
+	 2. The type of this argument can use FPR to pass value.  */
+      use_fpr = abi_use_fpr && calling_use_fpr;
+
+      if (use_fpr)
+	{
+	  /* Adjust alignment.  */
+	  if ((align >> 2) > 0)
+	    foff = align_up (foff, align >> 2);
+
+	  if (foff < REND)
+	    {
+	      int fs0_regnum = tdep->fs0_regnum;
+	      int fd0_regnum = tdep->fd0_regnum;
+
+	      if (fs0_regnum == -1)
+		goto error_no_fpr;
+
+	      switch (len)
+		{
+		case 4:
+		  regcache_cooked_write (regcache, fs0_regnum + foff, val);
+		  foff++;
+		  break;
+		case 8:
+		  regcache_cooked_write (regcache, fd0_regnum + foff / 2, val);
+		  foff += 2;
+		  break;
+		default:
+		  /* Long double?  */
+		  internal_error (__FILE__, __LINE__,
+				  "Do not know how to handle %d-byte double.\n",
+				  len);
+		  break;
+		}
+	      continue;
+	    }
+	}
+      else
+	{
+	  /*
+	     When passing arguments using GPRs,
+
+	     * A composite type not larger than 4 bytes is passed in $rN.
+	       The format is as if the value is loaded with load instruction
+	       of corresponding size (e.g., LB, LH, LW).
+
+	       For example,
+
+		       r0
+		       31      0
+	       LITTLE: [x x b a]
+		  BIG: [x x a b]
+
+	     * Otherwise, a composite type is passed in consecutive registers.
+	       The size is rounded up to the nearest multiple of 4.
+	       The successive registers hold the parts of the argument as if
+	       were loaded using lmw instructions.
+
+	       For example,
+
+		       r0	 r1
+		       31      0 31      0
+	       LITTLE: [d c b a] [x x x e]
+		  BIG: [a b c d] [e x x x]
+	   */
+
+	  /* Adjust alignment.  */
+	  if ((align >> 2) > 0)
+	    goff = align_up (goff, align >> 2);
+
+	  if (len <= (REND - goff) * 4)
+	    {
+	      /* This argument can be passed wholly via GPRs.  */
+	      while (len > 0)
+		{
+		  regval = extract_unsigned_integer (val, (len > 4) ? 4 : len,
+						     byte_order);
+		  regcache_cooked_write_unsigned (regcache,
+						  NDS32_R0_REGNUM + goff,
+						  regval);
+		  len -= 4;
+		  val += 4;
+		  goff++;
+		}
+	      continue;
+	    }
+	  else if (abi_split)
+	    {
+	      /* Some parts of this argument can be passed via GPRs.  */
+	      while (goff < REND)
+		{
+		  regval = extract_unsigned_integer (val, (len > 4) ? 4 : len,
+						     byte_order);
+		  regcache_cooked_write_unsigned (regcache,
+						  NDS32_R0_REGNUM + goff,
+						  regval);
+		  len -= 4;
+		  val += 4;
+		  goff++;
+		}
+	    }
+	}
+
+use_stack:
+      /*
+	 When pushing (split parts of) an argument into stack,
+
+	 * A composite type not larger than 4 bytes is copied to different
+	   base address.
+	   In little-endian, the first byte of this argument is aligned
+	   at the low address of the next free word.
+	   In big-endian, the last byte of this argument is aligned
+	   at the high address of the next free word.
+
+	   For example,
+
+	   sp [ - ]  [ c ] hi
+	      [ c ]  [ b ]
+	      [ b ]  [ a ]
+	      [ a ]  [ - ] lo
+	     LITTLE   BIG
+       */
+
+      /* Adjust alignment.  */
+      soff = align_up (soff, align);
+
+      while (len > 0)
+	{
+	  int rlen = (len > 4) ? 4 : len;
+
+	  if (byte_order == BFD_ENDIAN_BIG)
+	    write_memory (sp + soff + 4 - rlen, val, rlen);
+	  else
+	    write_memory (sp + soff, val, rlen);
+
+	  len -= 4;
+	  val += 4;
+	  soff += 4;
+	}
+    }
+
+  /* Finally, update the SP register.  */
+  regcache_cooked_write_unsigned (regcache, NDS32_SP_REGNUM, sp);
+
+  return sp;
+
+error_no_fpr:
+  /* If use_fpr, but no floating-point register exists,
+     then it is an error.  */
+  error (_("Fail to call. FPU registers are required."));
+}
+
+/* Read, for architecture GDBARCH, a function return value of TYPE
+   from REGCACHE, and copy that into VALBUF.  */
+
+static void
+nds32_extract_return_value (struct gdbarch *gdbarch, struct type *type,
+			    struct regcache *regcache, gdb_byte *valbuf)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  int abi_use_fpr = nds32_abi_use_fpr (tdep->abi);
+  int calling_use_fpr;
+  int len;
+
+  calling_use_fpr = nds32_check_calling_use_fpr (type);
+  len = TYPE_LENGTH (type);
+
+  if (abi_use_fpr && calling_use_fpr)
+    {
+      if (len == 4)
+	regcache_cooked_read (regcache, tdep->fs0_regnum, valbuf);
+      else if (len == 8)
+	regcache_cooked_read (regcache, tdep->fd0_regnum, valbuf);
+      else
+	internal_error (__FILE__, __LINE__,
+			_("Cannot extract return value of %d bytes "
+			  "long floating-point."), len);
+    }
+  else
+    {
+      /*
+	 When returning result,
+
+	 * A composite type not larger than 4 bytes is returned in $r0.
+	   The format is as if the result is loaded with load instruction
+	   of corresponding size (e.g., LB, LH, LW).
+
+	   For example,
+
+		   r0
+		   31      0
+	   LITTLE: [x x b a]
+	      BIG: [x x a b]
+
+	 * Otherwise, a composite type not larger than 8 bytes is returned
+	   in $r0 and $r1.
+	   In little-endian, the first word is loaded in $r0.
+	   In big-endian, the last word is loaded in $r1.
+
+	   For example,
+
+		   r0	     r1
+		   31      0 31      0
+	   LITTLE: [d c b a] [x x x e]
+	      BIG: [x x x a] [b c d e]
+       */
+
+      ULONGEST tmp;
+
+      if (len < 4)
+	{
+	  /* By using store_unsigned_integer we avoid having to do
+	     anything special for small big-endian values.  */
+	  regcache_cooked_read_unsigned (regcache, NDS32_R0_REGNUM, &tmp);
+	  store_unsigned_integer (valbuf, len, byte_order, tmp);
+	}
+      else if (len == 4)
+	{
+	  regcache_cooked_read (regcache, NDS32_R0_REGNUM, valbuf);
+	}
+      else if (len < 8)
+	{
+	  int len1, len2;
+
+	  len1 = byte_order == BFD_ENDIAN_BIG ? len - 4 : 4;
+	  len2 = len - len1;
+
+	  regcache_cooked_read_unsigned (regcache, NDS32_R0_REGNUM, &tmp);
+	  store_unsigned_integer (valbuf, len1, byte_order, tmp);
+
+	  regcache_cooked_read_unsigned (regcache, NDS32_R0_REGNUM + 1, &tmp);
+	  store_unsigned_integer (valbuf + len1, len2, byte_order, tmp);
+	}
+      else
+	{
+	  regcache_cooked_read (regcache, NDS32_R0_REGNUM, valbuf);
+	  regcache_cooked_read (regcache, NDS32_R0_REGNUM + 1, valbuf + 4);
+	}
+    }
+}
+
+/* Write, for architecture GDBARCH, a function return value of TYPE
+   from VALBUF into REGCACHE.  */
+
+static void
+nds32_store_return_value (struct gdbarch *gdbarch, struct type *type,
+			  struct regcache *regcache, const gdb_byte *valbuf)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  int abi_use_fpr = nds32_abi_use_fpr (tdep->abi);
+  int calling_use_fpr;
+  int len;
+
+  calling_use_fpr = nds32_check_calling_use_fpr (type);
+  len = TYPE_LENGTH (type);
+
+  if (abi_use_fpr && calling_use_fpr)
+    {
+      if (len == 4)
+	regcache_cooked_write (regcache, tdep->fs0_regnum, valbuf);
+      else if (len == 8)
+	regcache_cooked_write (regcache, tdep->fd0_regnum, valbuf);
+      else
+	internal_error (__FILE__, __LINE__,
+			_("Cannot store return value of %d bytes "
+			  "long floating-point."), len);
+    }
+  else
+    {
+      ULONGEST regval;
+
+      if (len < 4)
+	{
+	  regval = extract_unsigned_integer (valbuf, len, byte_order);
+	  regcache_cooked_write_unsigned (regcache, NDS32_R0_REGNUM, regval);
+	}
+      else if (len == 4)
+	{
+	  regcache_cooked_write (regcache, NDS32_R0_REGNUM, valbuf);
+	}
+      else if (len < 8)
+	{
+	  int len1, len2;
+
+	  len1 = byte_order == BFD_ENDIAN_BIG ? len - 4 : 4;
+	  len2 = len - len1;
+
+	  regval = extract_unsigned_integer (valbuf, len1, byte_order);
+	  regcache_cooked_write_unsigned (regcache, NDS32_R0_REGNUM, regval);
+
+	  regval = extract_unsigned_integer (valbuf + len1, len2, byte_order);
+	  regcache_cooked_write_unsigned (regcache, NDS32_R0_REGNUM + 1,
+					  regval);
+	}
+      else
+	{
+	  regcache_cooked_write (regcache, NDS32_R0_REGNUM, valbuf);
+	  regcache_cooked_write (regcache, NDS32_R0_REGNUM + 1, valbuf + 4);
+	}
+    }
+}
+
+/* Implement the "return_value" gdbarch method.
+
+   Determine, for architecture GDBARCH, how a return value of TYPE
+   should be returned.  If it is supposed to be returned in registers,
+   and READBUF is non-zero, read the appropriate value from REGCACHE,
+   and copy it into READBUF.  If WRITEBUF is non-zero, write the value
+   from WRITEBUF into REGCACHE.  */
+
+static enum return_value_convention
+nds32_return_value (struct gdbarch *gdbarch, struct value *func_type,
+		    struct type *type, struct regcache *regcache,
+		    gdb_byte *readbuf, const gdb_byte *writebuf)
+{
+  if (TYPE_LENGTH (type) > 8)
+    {
+      return RETURN_VALUE_STRUCT_CONVENTION;
+    }
+  else
+    {
+      if (readbuf != NULL)
+	nds32_extract_return_value (gdbarch, type, regcache, readbuf);
+      if (writebuf != NULL)
+	nds32_store_return_value (gdbarch, type, regcache, writebuf);
+
+      return RETURN_VALUE_REGISTER_CONVENTION;
+    }
+}
+
+/* Implement the "get_longjmp_target" gdbarch method.  */
+
+static int
+nds32_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
+{
+  gdb_byte buf[4];
+  CORE_ADDR jb_addr;
+  struct gdbarch *gdbarch = get_frame_arch (frame);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+
+  jb_addr = get_frame_register_unsigned (frame, NDS32_R0_REGNUM);
+
+  if (target_read_memory (jb_addr + 11 * 4, buf, 4))
+    return 0;
+
+  *pc = extract_unsigned_integer (buf, 4, byte_order);
+  return 1;
+}
+
+/* Validate the given TDESC, and fixed-number some registers in it.
+   Return 0 if the given TDESC does not contain the required feature
+   or not contain required registers.  */
+
+static int
+nds32_validate_tdesc_p (const struct target_desc *tdesc,
+			struct tdesc_arch_data *tdesc_data,
+			struct gdbarch_tdep *tdep)
+{
+  const struct tdesc_feature *feature;
+  int i, valid_p;
+
+  feature = tdesc_find_feature (tdesc, "org.gnu.gdb.nds32.core");
+  if (feature == NULL)
+    return 0;
+
+  valid_p = 1;
+  /* Validate and fixed-number R0-R10.  */
+  for (i = NDS32_R0_REGNUM; i <= NDS32_R0_REGNUM + 10; i++)
+    valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
+					nds32_register_names[i]);
+
+  /* Validate R15.  */
+  valid_p &= tdesc_unnumbered_register (feature,
+					nds32_register_names[NDS32_TA_REGNUM]);
+
+  /* Validate and fixed-number FP, GP, LP, SP, PC.  */
+  for (i = NDS32_FP_REGNUM; i <= NDS32_PC_REGNUM; i++)
+    valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
+					nds32_register_names[i]);
+
+  if (!valid_p)
+    return 0;
+
+  /* Fixed-number R11-R27.  */
+  for (i = NDS32_R0_REGNUM + 11; i <= NDS32_R0_REGNUM + 27; i++)
+    tdesc_numbered_register (feature, tdesc_data, i, nds32_register_names[i]);
+
+  tdep->fpu_freg = -1;
+  feature = tdesc_find_feature (tdesc, "org.gnu.gdb.nds32.fpu");
+  if (feature != NULL)
+    {
+      int num_fdr_regs, num_fsr_regs, fs0_regnum, num_listed_fsr;
+      int freg = -1;
+
+      /* Guess FPU configuration via listed registers.  */
+      if (tdesc_unnumbered_register (feature, "fd31"))
+	freg = 3;
+      else if (tdesc_unnumbered_register (feature, "fd15"))
+	freg = 2;
+      else if (tdesc_unnumbered_register (feature, "fd7"))
+	freg = 1;
+      else if (tdesc_unnumbered_register (feature, "fd3"))
+	freg = 0;
+
+      if (freg == -1)
+	/* Required FDR is not found.  */
+	return 0;
+
+      /* Record guessed FPU configuration.  */
+      tdep->fpu_freg = freg;
+
+      /* Validate and fixed-number required FDRs.  */
+      num_fdr_regs = num_fdr_map[freg];
+      for (i = 0; i < num_fdr_regs; i++)
+	valid_p &= tdesc_numbered_register (feature, tdesc_data,
+					    NDS32_FD0_REGNUM + i,
+					    nds32_fdr_register_names[i]);
+      if (!valid_p)
+	return 0;
+
+      /* Count the number of listed FSRs, and fixed-number them if present.  */
+      num_fsr_regs = num_fsr_map[freg];
+      fs0_regnum = NDS32_FD0_REGNUM + num_fdr_regs;
+      num_listed_fsr = 0;
+      for (i = 0; i < num_fsr_regs; i++)
+	num_listed_fsr += tdesc_numbered_register (feature, tdesc_data,
+						   fs0_regnum + i,
+						   nds32_fsr_register_names[i]);
+
+      if (num_listed_fsr == 0)
+	/* No required FSRs are listed explicitly,  make them pseudo registers
+	   of FDRs.  */
+	tdep->use_pseudo_fsrs = 1;
+      else if (num_listed_fsr == num_fsr_regs)
+	/* All required FSRs are listed explicitly.  */
+	tdep->use_pseudo_fsrs = 0;
+      else
+	/* Some required FSRs are missing.  */
+	return 0;
+    }
+
+  return 1;
+}
+
+/* Initialize the current architecture based on INFO.  If possible,
+   re-use an architecture from ARCHES, which is a list of
+   architectures already created during this debugging session.
+
+   Called e.g. at program startup, when reading a core file, and when
+   reading a binary file.  */
+
+static struct gdbarch *
+nds32_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
+{
+  struct gdbarch *gdbarch;
+  struct gdbarch_tdep *tdep;
+  struct gdbarch_list *best_arch;
+  struct tdesc_arch_data *tdesc_data = NULL;
+  const struct target_desc *tdesc = info.target_desc;
+  int i, num_regs, maxregs;
+
+  tdep = XCNEW (struct gdbarch_tdep);
+
+  /* Extract the elf_flags if available.  */
+  tdep->abi = E_NDS_ABI_AABI;
+  if (info.abfd && bfd_get_flavour (info.abfd) == bfd_target_elf_flavour)
+    {
+      int eflags = elf_elfheader (info.abfd)->e_flags;
+      tdep->abi = eflags & EF_NDS_ABI;
+    }
+
+  /* If there is already a candidate, use it.  */
+  for (best_arch = gdbarch_list_lookup_by_info (arches, &info);
+       best_arch != NULL;
+       best_arch = gdbarch_list_lookup_by_info (best_arch->next, &info))
+    {
+      struct gdbarch_tdep *idep = gdbarch_tdep (best_arch->gdbarch);
+
+      if (idep->abi != tdep->abi)
+	continue;
+
+      /* Found a match.  */
+      break;
+    }
+
+  if (best_arch != NULL)
+    {
+      xfree (tdep);
+      return best_arch->gdbarch;
+    }
+
+  if (!tdesc_has_registers (tdesc))
+    tdesc = tdesc_nds32;
+
+  tdesc_data = tdesc_data_alloc ();
+
+  if (!nds32_validate_tdesc_p (tdesc, tdesc_data, tdep))
+    {
+      tdesc_data_cleanup (tdesc_data);
+      xfree (tdep);
+      return NULL;
+    }
+
+  /* Allocate space for the new architecture.  */
+  gdbarch = gdbarch_alloc (&info, tdep);
+
+  if (tdep->fpu_freg == -1)
+    num_regs = NDS32_NUM_REGS;
+  else if (tdep->use_pseudo_fsrs == 1)
+    {
+      set_gdbarch_pseudo_register_read (gdbarch, nds32_pseudo_register_read);
+      set_gdbarch_pseudo_register_write (gdbarch, nds32_pseudo_register_write);
+      set_tdesc_pseudo_register_name (gdbarch, nds32_pseudo_register_name);
+      set_tdesc_pseudo_register_type (gdbarch, nds32_pseudo_register_type);
+      set_gdbarch_num_pseudo_regs (gdbarch, num_fsr_map[tdep->fpu_freg]);
+
+      num_regs = NDS32_FD0_REGNUM + num_fdr_map[tdep->fpu_freg];
+    }
+  else
+    num_regs = NDS32_FD0_REGNUM + num_fdr_map[tdep->fpu_freg]
+	       + num_fsr_map[tdep->fpu_freg];
+
+  set_gdbarch_num_regs (gdbarch, num_regs);
+  tdesc_use_registers (gdbarch, tdesc, tdesc_data);
+
+  /* Cache the register number of fs0 and fd0.  */
+  tdep->fs0_regnum = -1;
+  tdep->fd0_regnum = -1;
+  if (tdep->fpu_freg != -1)
+    {
+      tdep->fs0_regnum = user_reg_map_name_to_regnum (gdbarch, "fs0", -1);
+      tdep->fd0_regnum = user_reg_map_name_to_regnum (gdbarch, "fd0", -1);
+    }
+
+  /* Add NDS32 register aliases.  To avoid search in user register name space,
+     user_reg_map_name_to_regnum is not used.  */
+  maxregs = (gdbarch_num_regs (gdbarch) + gdbarch_num_pseudo_regs (gdbarch));
+  for (i = 0; i < ARRAY_SIZE (nds32_register_aliases); i++)
+    {
+      int regnum, j;
+
+      regnum = -1;
+      /* Search register name space.  */
+      for (j = 0; j < maxregs; j++)
+	{
+	  const char *regname = gdbarch_register_name (gdbarch, j);
+
+	  if (regname != NULL
+	      && strcmp (regname, nds32_register_aliases[i].name) == 0)
+	    {
+	      regnum = j;
+	      break;
+	    }
+	}
+
+      /* Try next alias entry if the given name can not be found in register
+	 name space.  */
+      if (regnum == -1)
+	continue;
+
+      user_reg_add (gdbarch, nds32_register_aliases[i].alias,
+		    value_of_nds32_reg, (const void *) (intptr_t) regnum);
+    }
+
+  nds32_add_reggroups (gdbarch);
+
+  /* Hook in ABI-specific overrides, if they have been registered.  */
+  info.tdep_info = (void *) tdesc_data;
+  gdbarch_init_osabi (info, gdbarch);
+
+  /* Override tdesc_register callbacks for system registers.  */
+  set_gdbarch_register_reggroup_p (gdbarch, nds32_register_reggroup_p);
+
+  set_gdbarch_sp_regnum (gdbarch, NDS32_SP_REGNUM);
+  set_gdbarch_pc_regnum (gdbarch, NDS32_PC_REGNUM);
+  set_gdbarch_unwind_sp (gdbarch, nds32_unwind_sp);
+  set_gdbarch_unwind_pc (gdbarch, nds32_unwind_pc);
+  set_gdbarch_stack_frame_destroyed_p (gdbarch, nds32_stack_frame_destroyed_p);
+  set_gdbarch_dwarf2_reg_to_regnum (gdbarch, nds32_dwarf2_reg_to_regnum);
+
+  set_gdbarch_push_dummy_call (gdbarch, nds32_push_dummy_call);
+  set_gdbarch_return_value (gdbarch, nds32_return_value);
+  set_gdbarch_dummy_id (gdbarch, nds32_dummy_id);
+
+  set_gdbarch_skip_prologue (gdbarch, nds32_skip_prologue);
+  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
+  set_gdbarch_breakpoint_from_pc (gdbarch, nds32_breakpoint_from_pc);
+
+  set_gdbarch_frame_align (gdbarch, nds32_frame_align);
+  frame_base_set_default (gdbarch, &nds32_frame_base);
+
+  set_gdbarch_print_insn (gdbarch, print_insn_nds32);
+
+  /* Handle longjmp.  */
+  set_gdbarch_get_longjmp_target (gdbarch, nds32_get_longjmp_target);
+
+  /* The order of appending is the order it check frame.  */
+  dwarf2_append_unwinders (gdbarch);
+  frame_unwind_append_unwinder (gdbarch, &nds32_epilogue_frame_unwind);
+  frame_unwind_append_unwinder (gdbarch, &nds32_frame_unwind);
+
+  return gdbarch;
+}
+
+void
+_initialize_nds32_tdep (void)
+{
+  /* Initialize gdbarch.  */
+  register_gdbarch_init (bfd_arch_nds32, nds32_gdbarch_init);
+
+  initialize_tdesc_nds32 ();
+  nds32_init_reggroups ();
+}
diff --git a/gdb/nds32-tdep.h b/gdb/nds32-tdep.h
new file mode 100644
index 0000000..1cabc33
--- /dev/null
+++ b/gdb/nds32-tdep.h
@@ -0,0 +1,56 @@ 
+/* Target-dependent code for the NDS32 architecture, for GDB.
+
+   Copyright (C) 2013-2016 Free Software Foundation, Inc.
+   Contributed by Andes Technology Corporation.
+
+   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 NDS32_TDEP_H
+#define NDS32_TDEP_H
+
+enum nds32_regnum
+{
+  /* General purpose registers.  */
+  NDS32_R0_REGNUM = 0,
+  NDS32_R5_REGNUM = 5,
+  NDS32_TA_REGNUM = 15,		/* Temporary register.  */
+  NDS32_FP_REGNUM = 28,		/* Frame pointer.  */
+  NDS32_GP_REGNUM = 29,		/* Global pointer.  */
+  NDS32_LP_REGNUM = 30,		/* Link pointer.  */
+  NDS32_SP_REGNUM = 31,		/* Stack pointer.  */
+
+  NDS32_PC_REGNUM = 32,		/* Program counter.  */
+
+  NDS32_NUM_REGS,
+
+  /* Double precision floating-point registers.  */
+  NDS32_FD0_REGNUM = NDS32_NUM_REGS,
+};
+
+struct gdbarch_tdep
+{
+  /* The guessed FPU configuration.  */
+  int fpu_freg;
+  /* FSRs are defined as pseudo registers.  */
+  int use_pseudo_fsrs;
+  /* Cached regnum of the first FSR (FS0).  */
+  int fs0_regnum;
+  /* Cached regnum of the first FDR (FD0).  */
+  int fd0_regnum;
+  /* ABI info.  */
+  int abi;
+};
+#endif /* NDS32_TDEP_H */
diff --git a/gdb/testsuite/gdb.base/float.exp b/gdb/testsuite/gdb.base/float.exp
index 939f07f..bc3e230 100644
--- a/gdb/testsuite/gdb.base/float.exp
+++ b/gdb/testsuite/gdb.base/float.exp
@@ -76,6 +76,15 @@  if { [is_aarch64_target] } then {
 	      pass "info float (with FPU)"
 	  }
     }
+} elseif [istarget "nds32*-*-*"] then {
+    gdb_test_multiple "info float" "info_float" {
+        -re "fd0.*fd3.*$gdb_prompt $" {
+            pass "info float (with FPU)"
+	}
+        -re "No floating.point info available for this processor.*" {
+            pass "info float (without FPU)"
+	}
+    }
 } elseif [istarget "powerpc*-*-*"] then {
     gdb_test_multiple "info float" "info_float" {
         -re "f0.*f1.*f31.*fpscr.*$gdb_prompt $" {
diff --git a/gdb/testsuite/gdb.xml/tdesc-regs.exp b/gdb/testsuite/gdb.xml/tdesc-regs.exp
index 48204cd..c197e28 100644
--- a/gdb/testsuite/gdb.xml/tdesc-regs.exp
+++ b/gdb/testsuite/gdb.xml/tdesc-regs.exp
@@ -39,6 +39,9 @@  switch -glob -- [istarget] {
     "mips*-*-*" {
 	set core-regs {mips-cpu.xml mips-cp0.xml mips-fpu.xml mips-dsp.xml}
     }
+    "nds32*-*-*" {
+	set core-regs {nds32-core.xml}
+    }
     "nios2-*-*" {
 	set core-regs {nios2-cpu.xml}
     }