arc: Pass proper CPU value to the disassembler

There was a problem with generation of the disassembler options for ARC in GDB,
because a BFD architecture name was used as a CPU name, but they have different
meaning even if some architectures have same name as respective CPUs.  Target
description specifies a BFD architecture, which is different from ARC CPU, as
accepted by the disassembler (and most other ARC tools), because CPU values are
much more fine grained - there can be multiple CPU values per single BFD
architecture.  As a result this code should translate architecture to some CPU
value.  Since there is no info on exact CPU configuration, it is best to use
the most feature-rich CPU, so that the disassembler will recognize all
instructions available to the specified architecture.

gdb/ChangeLog
yyyy-mm-dd  Anton Kolesov  <Anton.Kolesov@synopsys.com>

	* arc-tdep.c (arc_gdbarch_init): Pass proper cpu value to disassembler.
	* arc-tdep.h (arc_arch_is_em): New function.
	(arc_arch_is_hs): Likewise.

gdb/testsuite/ChangeLog
yyyy-mm-dd  Anton Kolesov  <Anton.Kolesov@synopsys.com>

	* gdb.arch/arc-tdesc-cpu.exp: New file.
	* gdb.arch/arc-tdesc-cpu.xml: Likewise.

2 files changed, 101 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.arch/arc-tdesc-cpu.exp b/gdb/testsuite/gdb.arch/arc-tdesc-cpu.exp
new file mode 100644
index 0000000..f1c009d
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/arc-tdesc-cpu.exp
@@ -0,0 +1,48 @@
+# Copyright 2017 Free Software Foundation, Inc.
+
+# 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/>.
+
+if {[gdb_skip_xml_test]} {
+    unsupported "arc-tdesc-cpu.exp"
+    return -1
+}
+
+gdb_start
+
+# Test whether it is OK to have `arc:HS` in the target description
+# architecture.  `HS` is a valid BFD architecture name, however the
+# disassembler doesn't accept it as a CPU name.  This test checks that GDB
+# doesn't pass architecture from the target description directly to the
+# disassembler and instead uses one of the valid CPU names.
+
+set filename $srcdir/$subdir/arc-tdesc-cpu.xml
+
+set cmd "set tdesc filename $filename"
+gdb_test $cmd
+
+# An error message is emitted by the disassembler, therefore it is not shown
+# unless the disassembler is actually invoked.  Address "0" is not invalid,
+# but that doesn't matter for this test case, because it is only the
+# disassembler error message that is interesting.
+set cmd "x /i 0"
+set msg "setting HS architecture"
+gdb_test_multiple $cmd $msg {
+    -re "Unrecognised disassembler CPU option: HS.*$gdb_prompt" {
+	fail $msg
+    }
+    -re "^$cmd\r\n\\s*$hex:\\s+Cannot access memory at address $hex\r\n$gdb_prompt"
+    {
+	pass $msg
+    }
+}
diff --git a/gdb/testsuite/gdb.arch/arc-tdesc-cpu.xml b/gdb/testsuite/gdb.arch/arc-tdesc-cpu.xml
new file mode 100644
index 0000000..fe158ae
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/arc-tdesc-cpu.xml
@@ -0,0 +1,53 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2017 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>arc:HS</architecture>
+
+  <feature name="org.gnu.gdb.arc.core.v2">
+    <reg name="r0"  bitsize="32"/>
+    <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="gp"  bitsize="32"/>
+    <reg name="fp"  bitsize="32"/>
+    <reg name="sp"  bitsize="32"/>
+    <reg name="ilink" bitsize="32"/>
+    <reg name="r30"   bitsize="32"/>
+    <reg name="blink" bitsize="32"/>
+    <reg name="lp_count" bitsize="32"/>
+    <reg name="pcl" bitsize="32"/>
+  </feature>
+
+  <feature name="org.gnu.gdb.arc.aux-minimal">
+    <reg name="pc"       bitsize="32"/>
+    <reg name="status32" bitsize="32"/>
+  </feature>
+</target>