read_frame_register_value and big endian arches

The read_frame_register_value function as it was implemented introduced
a regression on big-endian targets. The problem appears when trying to
get the value of an entity stored inside a register, and when the size
of the entity is smaller than the size of the register. In that case,
we were always reading the first N bytes of the register, which is wrong
for big-endian architectures, where we need to read the last N bytes of
the register.

gdb/ChangeLog:

        * findvar.c (read_frame_register_value): Read correct bytes from
        register on big-endian architectures.

gdb/testsuite/ChangeLog:

        * gdb.ada/small_reg_param: New testcase.

1 files changed, 46 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.ada/small_reg_param.exp b/gdb/testsuite/gdb.ada/small_reg_param.exp
new file mode 100644
index 0000000..00b066b
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/small_reg_param.exp
@@ -0,0 +1,46 @@
+# Copyright 2011 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/>.
+
+load_lib "ada.exp"
+
+set testdir "small_reg_param"
+set testfile "${testdir}/foo"
+set srcfile ${srcdir}/${subdir}/${testfile}.adb
+set binfile ${objdir}/${subdir}/${testfile}
+
+file mkdir ${objdir}/${subdir}/${testdir}
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug optimize=-O1]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+if ![runto main] then {
+  perror "Couldn't run ${testfile}"
+  return
+} 
+
+gdb_breakpoint "call_me"
+
+# Continue until we hit the breakpoint inside `Call_Me'.  We verify
+# that the parameter value is correct.
+gdb_test "continue" \
+    "Breakpoint .*, pck\\.call_me \\(w=50\\) at .*/pck.adb:.*" \
+    "continue to call_me"
+
+# And just to make sure, we also verify that the parameter value
+# is correct when we print it manually.
+gdb_test "print w" " = 50"
+