[PATCH] gdb/disassembly: Update to handle non-statement addresses
Andrew Burgess
andrew.burgess@embecosm.com
Thu Jul 23 10:19:17 GMT 2020
Thanks for all the reviews.
Below is the final version of the patch that I pushed.
- Fixed the typos pointed out,
- No longer compiling the test at -O1,
- Make use of MACRO_AT_func to generate DWARF.
- Test /s and /m disassembly.
Thanks,
Andrew
---
commit 78344df7b5d7d7fcf6aa7945b8c4b56bcc9388ce
Author: Andrew Burgess <andrew.burgess@embecosm.com>
Date: Tue Jul 21 11:21:50 2020 +0100
gdb/disassembly: Update to handle non-statement addresses
After the introduction of support for non-statement addresses in the
line table, the output for 'disassemble /m' can be broken in some
cases.
With the /m format disassembly GDB associates a set of addresses with
each line, these addresses are then sorted and printed for each line.
When the non-statement support was added GDB was incorrectly told to
ignore non-statement instructions, and not add these to the result
table. This means that these instructions are completely missing from
the output.
This commit removes the code that caused non-statement lines to be
ignored.
A result of this change is that GDB will now potentially include new
line numbers in the 'disassemble /m' output, lines that previously
were only in the line table as non-statement lines will now appear in
the disassembly output. This feels like an improvement though.
gdb/ChangeLog:
* disasm.c (do_mixed_source_and_assembly_deprecated): Don't
exclude non-statement entries.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/dw2-disasm-over-non-stmt.exp: New file.
diff --git a/gdb/disasm.c b/gdb/disasm.c
index 143ba2f59b9..e45c8400689 100644
--- a/gdb/disasm.c
+++ b/gdb/disasm.c
@@ -376,12 +376,6 @@ do_mixed_source_and_assembly_deprecated
if (le[i].line == le[i + 1].line && le[i].pc == le[i + 1].pc)
continue; /* Ignore duplicates. */
- /* Ignore non-statement line table entries. This means we print the
- source line at the place where GDB would insert a breakpoint for
- that line, which seems more intuitive. */
- if (le[i].is_stmt == 0)
- continue;
-
/* Skip any end-of-function markers. */
if (le[i].line == 0)
continue;
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-disasm-over-non-stmt.exp b/gdb/testsuite/gdb.dwarf2/dw2-disasm-over-non-stmt.exp
new file mode 100644
index 00000000000..6df275f1b11
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-disasm-over-non-stmt.exp
@@ -0,0 +1,206 @@
+# Copyright 2020 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/>.
+
+# Create an example function that contains both addresses marked as
+# statements and addresses marked as non-statements, and then
+# disassemble the function.
+#
+# Of particular interest is how 'disassemble /m' handles the
+# non-statement addresses, we want to ensure that these addresses are
+# included in the disassembly output. For completeness we test both
+# 'disassemble /m' and 'disassemble /s'.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+ return 0
+}
+
+# The .c files use __attribute__.
+if [get_compiler_info] {
+ return -1
+}
+if !$gcc_compiled {
+ return 0
+}
+
+# Reuse many of the test source files from dw2-inline-header-1.exp.
+standard_testfile dw2-inline-header-lbls.c dw2-inline-header.S \
+ dw2-inline-header.c
+
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+ global srcdir subdir srcfile srcfile3
+ declare_labels lines_label
+
+ get_func_info main
+
+ cu {} {
+ compile_unit {
+ {producer "gcc" }
+ {language @DW_LANG_C}
+ {name ${srcfile3}}
+ {low_pc 0 addr}
+ {stmt_list ${lines_label} DW_FORM_sec_offset}
+ } {
+ subprogram {
+ {external 1 flag}
+ {MACRO_AT_func {main}}
+ }
+ }
+ }
+
+ lines {version 2 default_is_stmt 1} lines_label {
+ include_dir "${srcdir}/${subdir}"
+ file_name "$srcfile3" 1
+
+ program {
+ {DW_LNE_set_address $main_start}
+ {DW_LNS_advance_line 15}
+ {DW_LNS_copy}
+
+ {DW_LNE_set_address line_label_2}
+ {DW_LNS_negate_stmt}
+ {DW_LNS_copy}
+
+ {DW_LNE_set_address line_label_3}
+ {DW_LNS_advance_line 1}
+ {DW_LNS_copy}
+
+ {DW_LNE_set_address line_label_4}
+ {DW_LNS_negate_stmt}
+ {DW_LNS_copy}
+
+ {DW_LNE_set_address line_label_5}
+ {DW_LNS_negate_stmt}
+ {DW_LNS_copy}
+
+ {DW_LNE_set_address line_label_6}
+ {DW_LNS_advance_line 1}
+ {DW_LNS_negate_stmt}
+ {DW_LNS_copy}
+
+ {DW_LNE_set_address $main_end}
+ {DW_LNS_copy}
+ {DW_LNE_end_sequence}
+ }
+ }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+ [list $srcfile $asm_file] {nodebug} ] } {
+ return -1
+}
+
+if ![runto_main] {
+ return -1
+}
+
+# Global lines array, maps lines numbers to the list of addresses
+# associated with that line in the debug output.
+array set lines {}
+
+# Look in the global LINES array and check that the disassembly for
+# line LINENUM includes the address of LABEL.
+proc check_disassembly_results { linenum label } {
+ global lines
+
+ set address [get_hexadecimal_valueof "&${label}" "__unknown__"]
+ set testname "check_disassembly_results $linenum $label"
+ if {![info exists lines($linenum)]} {
+ fail "$testname (no disassembly for $linenum)"
+ return
+ }
+
+ # Use a loop to compare the addresses as the addresses extracted
+ # from the disassembly output can be padded with zeros, while the
+ # address of the label will not be padded.
+ set addrs $lines($linenum)
+ foreach a $addrs {
+ if { $a == $address } {
+ pass $testname
+ return
+ }
+ }
+ fail $testname
+}
+
+foreach_with_prefix opt { m s } {
+ # Disassemble 'main' and split up the disassembly output. We
+ # build an associative array, for each line number store the list
+ # of addresses that were part of its disassembly output.
+ #
+ # LINENUM is the line we are currently collecting the disassembly
+ # addresses for, and ADDRS is the list of addresses collected for
+ # this line.
+ set linenum -1
+ set addrs {}
+
+ # Clear the global associative array used to hold the results.
+ unset lines
+ array set lines {}
+
+ gdb_test_multiple "disassemble /${opt} main" "" {
+ -re "Dump of assembler code for function main:\r\n" {
+ exp_continue
+ }
+
+ -re "^\[^\r\n\]+${srcfile3}:" {
+ exp_continue
+ }
+
+ -re "^(\\d+)\\s+\[^\r\n\]+\r\n" {
+ if { $linenum != -1 } {
+ set lines($linenum) $addrs
+ set addrs {}
+ }
+ set linenum $expect_out(1,string)
+ exp_continue
+ }
+
+ -re "^(?:=>)?\\s*($hex)\\s*\[^\r\n\]+\r\n" {
+ set address $expect_out(1,string)
+ lappend addrs $address
+ exp_continue
+ }
+
+ -re "^\\s*\r\n" {
+ exp_continue
+ }
+
+ -re "^End of assembler dump\\.\r\n" {
+ if { $linenum != -1 } {
+ set lines($linenum) $addrs
+ set linenum -1
+ set addrs {}
+ }
+ exp_continue
+ }
+
+ -re "^$gdb_prompt $" {
+ # All done.
+ }
+ }
+
+ # Now check that each label we expect to be associated with each line
+ # shows up in the disassembly output.
+ check_disassembly_results 16 "line_label_1"
+ check_disassembly_results 16 "line_label_2"
+ check_disassembly_results 17 "line_label_3"
+ check_disassembly_results 17 "line_label_4"
+ check_disassembly_results 17 "line_label_5"
+ check_disassembly_results 18 "line_label_6"
+}
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