[patch] Fix DW_OP_stack_value for big endian

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

Hi,

there is a clear bug with DW_OP_stack_value (DWARF_VALUE_STACK) for 32-bit
types on 64-bit s390x where DW_OP_lit5 gets evaluated as 0.

I am not completely sure with the DWARF standard understanding for
DW_OP_implicit_value (DWARF_VALUE_LITERAL) but I think it also should be fixed
(if such DWARF is valid at all).

I also believe gdbarch_byte_order (and not gdbarch_bits_big_endian) should be
used in this case.

This is a pre-requisite for the entryval patchset on big-endian arches.

No regressions on {x86_64,x86_64-m32,i686}-fedora16-linux-gnu.
Tested on {x86_64,x86_64-m32}-fedora16-linux-gnu,
{s390x,s390x-m31}-rhel62-linux-gnu.

I will check it in if no comments appear.


Thanks,
Jan


gdb/
2011-08-05  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* dwarf2loc.c (dwarf2_evaluate_loc_desc_full) <DWARF_VALUE_STACK>
	(dwarf2_evaluate_loc_desc_full) <DWARF_VALUE_LITERAL>: New variable
	objfile_gdbarch.  Fix BFD_ENDIAN_BIG case.

gdb/testsuite/
2011-08-05  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.dwarf2/dw2-op-stack-value.S: New file.
	* gdb.dwarf2/dw2-op-stack-value.exp: New file.

--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -1232,7 +1232,13 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 	    retval = allocate_value (type);
 	    contents = value_contents_raw (retval);
 	    if (n > TYPE_LENGTH (type))
-	      n = TYPE_LENGTH (type);
+	      {
+		struct gdbarch *objfile_gdbarch = get_objfile_arch (objfile);
+
+		if (gdbarch_byte_order (objfile_gdbarch) == BFD_ENDIAN_BIG)
+		  val_bytes += n - TYPE_LENGTH (type);
+		n = TYPE_LENGTH (type);
+	      }
 	    memcpy (contents, val_bytes, n);
 	  }
 	  break;
@@ -1254,7 +1260,13 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 	    n -= byte_offset;
 
 	    if (n > TYPE_LENGTH (type))
-	      n = TYPE_LENGTH (type);
+	      {
+		struct gdbarch *objfile_gdbarch = get_objfile_arch (objfile);
+
+		if (gdbarch_byte_order (objfile_gdbarch) == BFD_ENDIAN_BIG)
+		  ldata += n - TYPE_LENGTH (type);
+		n = TYPE_LENGTH (type);
+	      }
 	    memcpy (contents, ldata, n);
 	  }
 	  break;
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.S
@@ -0,0 +1,132 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   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/>.  */
+
+	.section .data
+aa551234:	.byte	0xaa, 0x55, 0x12, 0x34
+
+	.section .debug_info
+.Lcu1_begin:
+	/* CU header */
+	.4byte	.Lcu1_end - .Lcu1_start		/* Length of Compilation Unit */
+.Lcu1_start:
+	.2byte	2				/* DWARF Version */
+	.4byte	.Labbrev1_begin			/* Offset into abbrev section */
+	.byte	4				/* Pointer size */
+
+	/* CU die */
+	.uleb128 1				/* Abbrev: DW_TAG_compile_unit */
+	.ascii	"file1.txt\0"			/* DW_AT_name */
+	.ascii	"GNU C 3.3.3\0"			/* DW_AT_producer */
+	.byte	2				/* DW_LANG_C (C) */
+
+.L2byte_type:
+	.uleb128	2			/* Abbrev: DW_TAG_base_type */
+	.ascii		"2byte\0"		/* DW_AT_name */
+	.byte		2			/* DW_AT_byte_size */
+	.byte		7			/* DW_AT_encoding: DW_ATE_unsigned */
+
+.L4byte_type:
+	.uleb128	2			/* Abbrev: DW_TAG_base_type */
+	.ascii		"4byte\0"		/* DW_AT_name */
+	.byte		4			/* DW_AT_byte_size */
+	.byte		7			/* DW_AT_encoding: DW_ATE_unsigned */
+
+.L8byte_type:
+	.uleb128	2			/* Abbrev: DW_TAG_base_type */
+	.ascii		"8byte\0"		/* DW_AT_name */
+	.byte		4			/* DW_AT_byte_size */
+	.byte		7			/* DW_AT_encoding: DW_ATE_unsigned */
+
+	.uleb128	3			/* Abbrev: DW_TAG_variable */
+	.ascii		"stack2\0"		/* DW_AT_name */
+	.4byte		.L2byte_type-.Lcu1_begin	/* DW_AT_type */
+	.byte		2f - 1f			/* DW_AT_location */
+1:	.byte		0x31			/*   DW_OP_lit1 */
+	.byte		0x9f			/*   DW_OP_stack_value */
+2:
+
+	.uleb128	3			/* Abbrev: DW_TAG_variable */
+	.ascii		"stack8\0"		/* DW_AT_name */
+	.4byte		.L8byte_type-.Lcu1_begin	/* DW_AT_type */
+	.byte		2f - 1f			/* DW_AT_location */
+1:	.byte		0x31			/*   DW_OP_lit1 */
+	.byte		0x9f			/*   DW_OP_stack_value */
+2:
+
+	.uleb128	3			/* Abbrev: DW_TAG_variable */
+	.ascii		"implicit4to2\0"	/* DW_AT_name */
+	.4byte		.L2byte_type-.Lcu1_begin	/* DW_AT_type */
+	.byte		3f - 1f			/* DW_AT_location */
+1:	.byte		0x9e			/*   DW_OP_implicit_value */
+	.uleb128	3f - 2f
+2:	.byte		0x11, 0x22, 0x33, 0x44
+3:
+
+	.uleb128	3			/* Abbrev: DW_TAG_variable */
+	.ascii		"implicit4to4\0"	/* DW_AT_name */
+	.4byte		.L4byte_type-.Lcu1_begin	/* DW_AT_type */
+	.byte		3f - 1f			/* DW_AT_location */
+1:	.byte		0x9e			/*   DW_OP_implicit_value */
+	.uleb128	3f - 2f
+2:	.byte		0x11, 0x22, 0x33, 0x44
+3:
+
+	.byte		0			/* End of children of CU */
+
+.Lcu1_end:
+
+/* Abbrev table */
+	.section .debug_abbrev
+.Labbrev1_begin:
+	.uleb128	1			/* Abbrev code */
+	.uleb128	0x11			/* DW_TAG_compile_unit */
+	.byte		1			/* has_children */
+	.uleb128	0x3			/* DW_AT_name */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0x25			/* DW_AT_producer */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0x13			/* DW_AT_language */
+	.uleb128	0xb			/* DW_FORM_data1 */
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
+
+	.uleb128	2			/* Abbrev code */
+	.uleb128	0x24			/* DW_TAG_base_type */
+	.byte		0			/* has_children */
+	.uleb128	0x3			/* DW_AT_name */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0xb			/* DW_AT_byte_size */
+	.uleb128	0xb			/* DW_FORM_data1 */
+	.uleb128	0x3e			/* DW_AT_encoding */
+	.uleb128	0xb			/* DW_FORM_data1 */
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
+
+	.uleb128	3			/* Abbrev code */
+	.uleb128	0x34			/* DW_TAG_variable */
+	.byte		0			/* has_children */
+	.uleb128	0x3			/* DW_AT_name */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0x49			/* DW_AT_type */
+	.uleb128	0x13			/* DW_FORM_ref4 */
+	.uleb128	0x2			/* DW_AT_location */
+	.uleb128	0xa			/* DW_FORM_block1 */
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
+
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp
@@ -0,0 +1,52 @@
+# 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 dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0   
+}
+
+set testfile "dw2-op-stack-value"
+set srcfile ${testfile}.S
+set executable ${testfile}.x
+
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${objdir}/${subdir}/${executable}" object {nodebug}] != "" } {
+    return -1
+}
+
+clean_restart $executable
+
+gdb_test "p/x stack2" " = 0x1"
+gdb_test "p/x stack8" " = 0x1"
+
+set test "x/wx &aa551234"
+gdb_test_multiple $test $test {
+    -re ":\[ \t\]*0x341255aa\r\n$gdb_prompt $" {
+	# little endian
+	pass $test
+	gdb_test "p/x implicit4to2" " = 0x2211"
+	gdb_test "p/x implicit4to4" " = 0x44332211"
+    }
+    -re ":\[ \t\]*0xaa551234\r\n$gdb_prompt $" {
+	# big endian
+	pass $test
+	gdb_test "p/x implicit4to2" " = 0x3344"
+	gdb_test "p/x implicit4to4" " = 0x11223344"
+    }
+    -re ":\[ \t\]*0x\[0-9a-f\]{8}\r\n$gdb_prompt $" {
+	unsupported $test
+    }
+}