Re: [PATCH][gdb/symtab] Handle DW_AT_ranges with DW_FORM_sec_off in partial DIE

[Bernd Edlinger <bernd.edlinger@hotmail.de>]

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On 1/25/21 1:24 PM, Tom de Vries wrote:
> Hi,
> 
> While looking into a failure in gdb.go/package.exp with gcc-11, I noticed that
> gdb shows some complaints when loading the executable (also with gcc-10, where
> the test-case passes):
> ...
> $ gdb -batch -iex "set complaints 100" package.10 -ex start
> During symbol reading: Attribute value is not a constant (DW_FORM_sec_offset)
> Temporary breakpoint 1 at 0x402ae6: file gdb.go/package1.go, line 8.
> During symbol reading: Attribute value is not a constant (DW_FORM_sec_offset)
> During symbol reading: Invalid .debug_rnglists data (no base address)
> ...
> 
> Fix this by using as_unsigned () to read DW_AT_ranges in the partial DIE
> reader, similar to how that is done in dwarf2_get_pc_bounds.
> 
> Tested on x86_64-linux.
> 
> Any comments?
> 

Oh, interesting.

This is exactly what I have posted here:

https://sourceware.org/pipermail/gdb-patches/2021-January/174660.html

but my test case shows the regression in the partial symbols.



Maybe you can take my test case and merge it to your patch?


Thanks
Bernd.

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From 338f196f9cb4da8b85e42f435424f1c6dc396b36 Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Sat, 28 Nov 2020 17:29:18 +0100
Subject: [PATCH] Fix partial symbols

The DW_AT_ranges attribute is of type DW_FORM_sec_offset
or DW_FORM_rnglistx.

But the function attribute attribute::constant_value () does only
handle DW_FORM_sdata, DW_FORM_implicit_const, DW_FORM_udata
DW_FORM_data1, DW_FORM_data2, DW_FORM_data4, DW_FORM_data8
and returns the default value for anything else.

Therefore the wrong range is parsed.

Fixes: 529908cbd0a ("Remove DW_UNSND")

gdb:
2021-01-03  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* dwarf2/read.c (partial_die_info::read): Fix DW_AT_ranges.

gdb/testsuite:
2021-01-03  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* gdb.cp/step-and-next-psymtab.exp: New test.
	* gdb.cp/step-and-next-psymtab.cc: New test.
---
 gdb/dwarf2/read.c                              |  2 +-
 gdb/testsuite/gdb.cp/step-and-next-psymtab.cc  | 27 ++++++++++++++++++++
 gdb/testsuite/gdb.cp/step-and-next-psymtab.exp | 34 ++++++++++++++++++++++++++
 3 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 gdb/testsuite/gdb.cp/step-and-next-psymtab.cc
 create mode 100644 gdb/testsuite/gdb.cp/step-and-next-psymtab.exp

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 309ff83..5191d69 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -19810,7 +19810,7 @@ struct type *
 	    /* It would be nice to reuse dwarf2_get_pc_bounds here,
 	       but that requires a full DIE, so instead we just
 	       reimplement it.  */
-	    unsigned int ranges_offset = (attr.constant_value (0)
+	    unsigned int ranges_offset = (attr.as_unsigned ()
 					  + (need_ranges_base
 					     ? cu->ranges_base
 					     : 0));
diff --git a/gdb/testsuite/gdb.cp/step-and-next-psymtab.cc b/gdb/testsuite/gdb.cp/step-and-next-psymtab.cc
new file mode 100644
index 0000000..1bb724b
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/step-and-next-psymtab.cc
@@ -0,0 +1,27 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2021 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/>.  */
+
+#include "step-and-next-inline.h"
+
+int
+get_alias_set1 (tree *t)
+{
+  if (t != NULL
+      && TREE_TYPE (t).z != 1)
+    return 0;
+  return 1;
+}
diff --git a/gdb/testsuite/gdb.cp/step-and-next-psymtab.exp b/gdb/testsuite/gdb.cp/step-and-next-psymtab.exp
new file mode 100644
index 0000000..2268f16
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/step-and-next-psymtab.exp
@@ -0,0 +1,34 @@
+# Copyright 2021 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/>.
+
+standard_testfile step-and-next-inline.cc .cc
+
+if [get_compiler_info "c++"] {
+    unsupported "couldn't find a valid c++ compiler"
+    return -1
+}
+
+set options {c++ debug nowarnings optimize=-O2}
+# avoid DW_TAG_compile_unit with low_pc != 0 (gcc-8 and earlier)
+lappend options additional_flags=-ffunction-sections
+
+set sources [list $srcfile $srcfile2]
+
+if { [prepare_for_testing "failed to prepare" $testfile $sources $options] } {
+    return -1
+}
+
+# there are 4 tree_check instances not 3
+gdb_test "b tree_check" ".*Breakpoint .* \\(4 locations\\).*" "test1"
-- 
1.9.1