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[RFA] read_frame_register_value and big endian arches
- From: Joel Brobecker <brobecker at adacore dot com>
- To: gdb-patches at sourceware dot org
- Cc: Joel Brobecker <brobecker at adacore dot com>
- Date: Sun, 30 Oct 2011 21:03:16 -0400
- Subject: [RFA] read_frame_register_value and big endian arches
- References: <20111026213726.GV19246@adacore.com>
Hello,
I am afraid I introduced a regression on big-endian architectures
(Eg. sparc-solaris, erc32-elf) after my latest patch:
[RFA/RFC] Restore old handling of multi-register variables
http://www.sourceware.org/ml/gdb-patches/2011-10/msg00709.html
It's just an oversight: 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.
For instance, the testcase shows a parameter whose type is
a 2-byte integer. This parameter is passed by register, in
a 4-byte register.
In that case, the new function read_frame_register_value was always
reading from the first bytes of the register, which is wrong for
big-endian architectures.
gdb/ChangeLog:
* findvar.c (read_frame_register_value): Read the correct bytes
from registers on big-endian architectures.
gdb/testsuite/ChangeLog:
* gdb.ada/small_reg_param: New testcase.
Tested on x86_64-linux. Also tested on erc32-elf and sparc-solaris,
but with AdaCore's testsuite (I am still forbidden from running
the testsuite on any of our Solaris machine because it crashes
the system really bad). I also checked the patch against AVR,
and make sure that it does not create any regression there.
Also included is a new testcase which, when run manually, reproduces
the problem on erc32-elf, and probably on sparc-solaris too.
---
gdb/findvar.c | 14 ++++++--
gdb/testsuite/gdb.ada/small_reg_param.exp | 46 +++++++++++++++++++++++++
gdb/testsuite/gdb.ada/small_reg_param/foo.adb | 21 +++++++++++
gdb/testsuite/gdb.ada/small_reg_param/pck.adb | 22 ++++++++++++
gdb/testsuite/gdb.ada/small_reg_param/pck.ads | 22 ++++++++++++
5 files changed, 122 insertions(+), 3 deletions(-)
create mode 100644 gdb/testsuite/gdb.ada/small_reg_param.exp
create mode 100644 gdb/testsuite/gdb.ada/small_reg_param/foo.adb
create mode 100644 gdb/testsuite/gdb.ada/small_reg_param/pck.adb
create mode 100644 gdb/testsuite/gdb.ada/small_reg_param/pck.ads
diff --git a/gdb/findvar.c b/gdb/findvar.c
index 54e7b4a..426b488 100644
--- a/gdb/findvar.c
+++ b/gdb/findvar.c
@@ -641,11 +641,19 @@ read_frame_register_value (struct value *value, struct frame_info *frame)
{
struct value *regval = get_frame_register_value (frame, regnum);
int reg_len = TYPE_LENGTH (value_type (regval));
+ int reg_offset = 0;
+ /* If the register length is larger than the number of bytes
+ remaining to copy, then only copy the appropriate bytes. */
if (offset + reg_len > len)
- reg_len = len - offset;
- value_contents_copy (value, offset, regval, value_offset (regval),
- reg_len);
+ {
+ reg_len = len - offset;
+ if (gdbarch_byte_order (get_frame_arch (frame)) == BFD_ENDIAN_BIG)
+ reg_offset = TYPE_LENGTH (value_type (regval)) - reg_len;
+ }
+
+ value_contents_copy (value, offset, regval,
+ value_offset (regval) + reg_offset, reg_len);
offset += reg_len;
regnum++;
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"
+
diff --git a/gdb/testsuite/gdb.ada/small_reg_param/foo.adb b/gdb/testsuite/gdb.ada/small_reg_param/foo.adb
new file mode 100644
index 0000000..e6b1f53
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/small_reg_param/foo.adb
@@ -0,0 +1,21 @@
+-- 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/>.
+
+with Pck; use Pck;
+
+procedure Foo is
+begin
+ Call_Me (50);
+end Foo;
diff --git a/gdb/testsuite/gdb.ada/small_reg_param/pck.adb b/gdb/testsuite/gdb.ada/small_reg_param/pck.adb
new file mode 100644
index 0000000..55455c7
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/small_reg_param/pck.adb
@@ -0,0 +1,22 @@
+-- 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/>.
+
+package body Pck is
+ Last_Word : Word := 0;
+ procedure Call_Me (W : Word) is
+ begin
+ Last_Word := W;
+ end Call_Me;
+end Pck;
diff --git a/gdb/testsuite/gdb.ada/small_reg_param/pck.ads b/gdb/testsuite/gdb.ada/small_reg_param/pck.ads
new file mode 100644
index 0000000..7ae299a
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/small_reg_param/pck.ads
@@ -0,0 +1,22 @@
+-- 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/>.
+
+package Pck is
+
+ type Word is range 0 .. 16#FFFF#;
+ for Word'size use 16;
+
+ procedure Call_Me (W : Word);
+end Pck;
--
1.7.1