gdb.trace: Add a testcase for tdesc in tfile.

This tests whether $ymm15 can be correctly collected and printed from
tfile.  It covers:

- storing tdesc in tfile (without that, $ymm15 doesn't exist)
- ax_pseudo_register_collect for x86 (without that, $ymm15 cannot be
  collected)
- register order in tfile_fetch_registers (without that, $ymm15h is
  fetched from wrong position)
- off-by-one in tfile_fetch_registers (without that, $ymm15h is
  incorrectly considered to be out of bounds)
- using proper tdesc in encoding tracepoint actions (without that,
  internal error happens due to $ymm15h being considered unavailable)

gdb/testsuite/ChangeLog:

	* gdb.trace/tfile-avx.c: New test.
	* gdb.trace/tfile-avx.exp: New test.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2016-02-11  Marcin Kościelnicki  <koriakin@0x04.net>
+
+	* gdb.trace/tfile-avx.c: New test.
+	* gdb.trace/tfile-avx.exp: New test.
+
 2016-02-09  Keith Seitz  <keiths@redhat.com>
 
 	PR breakpoints/19546

gdb/testsuite/gdb.trace/tfile-avx.c

@@ -0,0 +1,51 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 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/>.  */
+
+/*
+ * Test program for reading target description from tfile: collects AVX
+ * registers on x86_64.
+ */
+
+#include <immintrin.h>
+
+void
+dummy (void)
+{
+}
+
+static void
+end (void)
+{
+}
+
+int
+main (void)
+{
+  register __v8si a asm("ymm15") = {
+    0x12340001,
+    0x12340002,
+    0x12340003,
+    0x12340004,
+    0x12340005,
+    0x12340006,
+    0x12340007,
+    0x12340008,
+  };
+  asm volatile ("traceme: call dummy" : : "x" (a));
+  end ();
+  return 0;
+}

gdb/testsuite/gdb.trace/tfile-avx.exp

@@ -0,0 +1,73 @@
+# Copyright 2016 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 { ! [is_amd64_regs_target] } {
+    verbose "Skipping tfile AVX test (target is not x86_64)."
+    return
+}
+
+load_lib "trace-support.exp"
+
+standard_testfile
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile \
+     [list debug additional_flags=-mavx]]} {
+    return -1
+}
+
+if ![runto_main] {
+    fail "Can't run to main to check for trace support"
+    return -1
+}
+
+if ![gdb_target_supports_trace] {
+    unsupported "target does not support trace"
+    return -1
+}
+
+gdb_test_multiple "print \$ymm15" "check for AVX support" {
+    -re " = void.*$gdb_prompt $" {
+	verbose "Skipping tfile AVX test (target doesn't support AVX)."
+	return
+    }
+    -re " = \\{.*}.*$gdb_prompt $" {
+	# All is well.
+    }
+}
+
+gdb_test "trace traceme" ".*"
+
+gdb_trace_setactions "set actions for tracepoint" "" \
+	"collect \$ymm15" "^$"
+
+gdb_breakpoint "end"
+
+gdb_test_no_output "tstart"
+
+gdb_test "continue" ".*Breakpoint $decimal, end .*"
+
+set tracefile [standard_output_file ${testfile}]
+
+# Save trace frames to tfile.
+gdb_test "tsave ${tracefile}.tf" \
+    "Trace data saved to file '${tracefile}.tf'.*" \
+    "save tfile trace file"
+
+# Change target to tfile.
+gdb_test "target tfile ${tracefile}.tf" "" "change to tfile target" \
+  "A program is being debugged already.  Kill it. .y or n. $" "y"
+
+gdb_test "tfind 0" "Found trace frame 0, tracepoint .*"
+
+gdb_test "print/x \$ymm15.v8_int32" " = \\{0x12340001, .*, 0x12340008}"