File gdb-symtab-work-around-gas-pr28629.patch of Package gdb
From 1b878333913343630472f89b4bc42f51b1619308 Mon Sep 17 00:00:00 2001
From: Tom de Vries <tdevries@suse.de>
Date: Wed, 1 Nov 2023 00:33:12 +0100
Subject: [PATCH 1/2] [gdb/symtab] Work around gas PR28629
When running test-case gdb.tui/tui-layout-asm-short-prog.exp on AlmaLinux 9.2
ppc64le, I run into:
...
FAIL: gdb.tui/tui-layout-asm-short-prog.exp: check asm box contents
...
The problem is that we get:
...
7 [ No Assembly Available ]
...
because tui_get_begin_asm_address doesn't succeed.
In more detail, tui_get_begin_asm_address calls:
...
find_line_pc (sal.symtab, sal.line, &addr);
...
with:
...
(gdb) p *sal.symtab
$5 = {next = 0x130393c0, m_compunit = 0x130392f0, m_linetable = 0x0,
filename = "tui-layout-asm-short-prog.S",
filename_for_id = "$gdb/build/gdb/testsuite/tui-layout-asm-short-prog.S",
m_language = language_asm, fullname = 0x0}
(gdb) p sal.line
$6 = 1
...
The problem is the filename_for_id which is the source file prefixed with the
compilation dir rather than the source dir.
This is due to faulty debug info generated by gas, PR28629:
...
<1a> DW_AT_name : tui-layout-asm-short-prog.S
<1e> DW_AT_comp_dir : $gdb/build/gdb/testsuite
<22> DW_AT_producer : GNU AS 2.35.2
...
The DW_AT_name is relative, and it's relative to the DW_AT_comp_dir entry,
making the effective name $gdb/build/gdb/testsuite/tui-layout-asm-short-prog.S.
The bug is fixed starting version 2.38, where we get instead:
...
<1a> DW_AT_name :
$gdb/src/gdb/testsuite/gdb.tui/tui-layout-asm-short-prog.S
<1e> DW_AT_comp_dir : $gdb/build/gdb/testsuite
<22> DW_AT_producer : GNU AS 2.38
...
Work around the faulty debug info by constructing the filename_for_id using
the second directory from the directory table in the .debug_line header:
...
The Directory Table (offset 0x22, lines 2, columns 1):
Entry Name
0 $gdb/build/gdb/testsuite
1 $gdb/src/gdb/testsuite/gdb.tui
...
Note that the used gas contains a backport of commit 3417bfca676 ("GAS:
DWARF-5: Ensure that the 0'th entry in the directory table contains the
current working directory."), because directory 0 is correct. With the
unpatched 2.35.2 release the directory 0 entry is incorrect: it's a copy of
entry 1.
Add a dwarf assembly test-case that reflects the debug info as generated by
unpatched gas 2.35.2.
Tested on x86_64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
---
gdb/dwarf2/cu.c | 1 +
gdb/dwarf2/cu.h | 1 +
gdb/dwarf2/read.c | 37 +++++++-
.../gdb.dwarf2/dw2-gas-workaround.exp | 92 +++++++++++++++++++
4 files changed, 130 insertions(+), 1 deletion(-)
create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-gas-workaround.exp
diff --git a/gdb/dwarf2/cu.c b/gdb/dwarf2/cu.c
index a908ec908cd..f9b05dfc709 100644
--- a/gdb/dwarf2/cu.c
+++ b/gdb/dwarf2/cu.c
@@ -40,6 +40,7 @@ dwarf2_cu::dwarf2_cu (dwarf2_per_cu_data *per_cu,
producer_is_icc_lt_14 (false),
producer_is_codewarrior (false),
producer_is_clang (false),
+ producer_is_gas_lt_2_38 (false),
producer_is_gas_2_39 (false),
processing_has_namespace_info (false),
load_all_dies (false)
diff --git a/gdb/dwarf2/cu.h b/gdb/dwarf2/cu.h
index 6c611710503..ef8db480e3f 100644
--- a/gdb/dwarf2/cu.h
+++ b/gdb/dwarf2/cu.h
@@ -265,6 +265,7 @@ struct dwarf2_cu
bool producer_is_icc_lt_14 : 1;
bool producer_is_codewarrior : 1;
bool producer_is_clang : 1;
+ bool producer_is_gas_lt_2_38 : 1;
bool producer_is_gas_2_39 : 1;
/* When true, the file that we're processing is known to have
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index fc4667b782f..50fa302b43a 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -147,6 +147,8 @@ static int dwarf2_locexpr_block_index;
static int dwarf2_loclist_block_index;
static int ada_block_index;
+static bool producer_is_gas_lt_2_38 (struct dwarf2_cu *cu);
+
/* Size of .debug_loclists section header for 32-bit DWARF format. */
#define LOCLIST_HEADER_SIZE32 12
@@ -7665,6 +7667,27 @@ read_file_scope (struct die_info *die, struct dwarf2_cu *cu)
file_and_directory &fnd = find_file_and_directory (die, cu);
+ /* GAS supports generating dwarf-5 info starting version 2.35. Versions
+ 2.35-2.37 generate an incorrect CU name attribute: it's relative,
+ implicitly prefixing it with the compilation dir. Work around this by
+ prefixing it with the source dir instead. */
+ if (cu->header.version == 5 && !IS_ABSOLUTE_PATH (fnd.get_name ())
+ && producer_is_gas_lt_2_38 (cu))
+ {
+ attr = dwarf2_attr (die, DW_AT_stmt_list, cu);
+ if (attr != nullptr && attr->form_is_unsigned ())
+ {
+ sect_offset line_offset = (sect_offset) attr->as_unsigned ();
+ line_header_up lh = dwarf_decode_line_header (line_offset, cu,
+ fnd.get_comp_dir ());
+ if (lh->version == 5 && lh->is_valid_file_index (1))
+ {
+ std::string dir = lh->include_dir_at (1);
+ fnd.set_comp_dir (std::move (dir));
+ }
+ }
+ }
+
cu->start_compunit_symtab (fnd.get_name (), fnd.intern_comp_dir (objfile),
lowpc);
@@ -11427,7 +11450,10 @@ check_producer (struct dwarf2_cu *cu)
else if (producer_is_clang (cu->producer, &major, &minor))
cu->producer_is_clang = true;
else if (producer_is_gas (cu->producer, &major, &minor))
- cu->producer_is_gas_2_39 = major == 2 && minor == 39;
+ {
+ cu->producer_is_gas_lt_2_38 = major < 2 || (major == 2 && minor < 38);
+ cu->producer_is_gas_2_39 = major == 2 && minor == 39;
+ }
else
{
/* For other non-GCC compilers, expect their behavior is DWARF version
@@ -11463,6 +11489,15 @@ producer_is_codewarrior (struct dwarf2_cu *cu)
return cu->producer_is_codewarrior;
}
+static bool
+producer_is_gas_lt_2_38 (struct dwarf2_cu *cu)
+{
+ if (!cu->checked_producer)
+ check_producer (cu);
+
+ return cu->producer_is_gas_lt_2_38;
+}
+
static bool
producer_is_gas_2_39 (struct dwarf2_cu *cu)
{
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-gas-workaround.exp b/gdb/testsuite/gdb.dwarf2/dw2-gas-workaround.exp
new file mode 100644
index 00000000000..ca2b10f23b3
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-gas-workaround.exp
@@ -0,0 +1,92 @@
+# Copyright 2023 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 line number information in various configurations.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+require dwarf2_support
+
+standard_testfile dw2-lines.c -dw2.S
+
+with_shared_gdb {
+ set func_info_vars [get_func_info bar]
+}
+
+# Helper function.
+proc line_for { l } {
+ global srcfile
+ set line [gdb_get_line_number "$l:" $srcfile]
+ return [expr $line + 1]
+}
+
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+ declare_labels Llines
+ global srcdir subdir srcfile objdir
+ global func_info_vars
+ foreach var $func_info_vars {
+ global $var
+ }
+
+ cu { version 5 } {
+ compile_unit {
+ {language @DW_LANG_Mips_Assembler}
+ {name $srcfile}
+ {comp_dir $objdir}
+ {stmt_list $Llines DW_FORM_sec_offset}
+ {producer "GNU AS 2.35.2"}
+ } {
+ subprogram {
+ {external 1 flag}
+ {name bar}
+ {low_pc $bar_start addr}
+ {high_pc "$bar_start + $bar_len" addr}
+ }
+ }
+ }
+
+ lines [list version 5] Llines {
+ set diridx1 [include_dir "${srcdir}/${subdir}"]
+ set diridx2 [include_dir "${srcdir}/${subdir}"]
+ file_name "$srcfile" $diridx1
+ file_name "$srcfile" $diridx2
+
+ program {
+ DW_LNE_set_address bar_label
+ line [line_for bar_label]
+ DW_LNS_copy
+
+ DW_LNE_set_address bar_label_2
+ DW_LNE_end_sequence
+ }
+ }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+ [list $srcfile $asm_file] {nodebug}] } {
+ return -1
+}
+
+gdb_test_no_output "set debug symtab-create 1"
+gdb_test_multiple "ptype bar" "" {
+ -re -wrap "$objdir.*" {
+ fail $gdb_test_name
+ }
+ -re -wrap "" {
+ pass $gdb_test_name
+ }
+}
base-commit: d9951c3c9ea2e542d071710e9706ed505046fe36
--
2.35.3
