From b1136560e772dd4c74f1fbb41f6ba840b92fb9d6 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Wed, 1 Nov 2023 00:33:12 +0100 Subject: [PATCH 2/2] [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 --- gdb/dwarf2/cu.c | 1 + gdb/dwarf2/cu.h | 1 + gdb/dwarf2/read.c | 37 +++++++- .../gdb.dwarf2/dw2-gas-workaround.exp | 94 +++++++++++++++++++ 4 files changed, 132 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 42fd4f4441b..6b5d956649f 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 710aeb5b237..9b1e8775ff4 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 472684a5817..2339cceb829 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -146,6 +146,8 @@ static int dwarf2_loclist_index; static int dwarf2_locexpr_block_index; static int dwarf2_loclist_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 @@ -9663,6 +9665,27 @@ 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); @@ -13377,7 +13400,10 @@ 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 @@ -13413,6 +13439,15 @@ 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..416778f51b7 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dw2-gas-workaround.exp @@ -0,0 +1,94 @@ +# 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 . + +# 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. +if { ![dwarf2_support] } { + return -1 +} + +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 + } +} -- 2.35.3