diff options
| -rw-r--r-- | gdb/dwarf2/index-write.c | 29 | ||||
| -rw-r--r-- | gdb/testsuite/gdb.gdb/index-file.exp | 115 |
2 files changed, 134 insertions, 10 deletions
diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c index c086779..5960bac 100644 --- a/gdb/dwarf2/index-write.c +++ b/gdb/dwarf2/index-write.c @@ -256,20 +256,29 @@ add_index_entry (struct mapped_symtab *symtab, const char *name, int is_static, gdb_index_symbol_kind kind, offset_type cu_index) { - offset_type cu_index_and_attrs; + symtab_index_entry *slot = &find_slot (symtab, name); + if (slot->name == NULL) + { + /* This is a new element in the hash table. */ + ++symtab->n_elements; - ++symtab->n_elements; - if (4 * symtab->n_elements / 3 >= symtab->data.size ()) - hash_expand (symtab); + /* We might need to grow the hash table. */ + if (4 * symtab->n_elements / 3 >= symtab->data.size ()) + { + hash_expand (symtab); - symtab_index_entry &slot = find_slot (symtab, name); - if (slot.name == NULL) - { - slot.name = name; + /* This element will have a different slot in the new table. */ + slot = &find_slot (symtab, name); + + /* But it should still be a new element in the hash table. */ + gdb_assert (slot->name == nullptr); + } + + slot->name = name; /* index_offset is set later. */ } - cu_index_and_attrs = 0; + offset_type cu_index_and_attrs = 0; DW2_GDB_INDEX_CU_SET_VALUE (cu_index_and_attrs, cu_index); DW2_GDB_INDEX_SYMBOL_STATIC_SET_VALUE (cu_index_and_attrs, is_static); DW2_GDB_INDEX_SYMBOL_KIND_SET_VALUE (cu_index_and_attrs, kind); @@ -281,7 +290,7 @@ add_index_entry (struct mapped_symtab *symtab, const char *name, the last entry pushed), but a symbol could have multiple kinds in one CU. To keep things simple we don't worry about the duplication here and sort and uniquify the list after we've processed all symbols. */ - slot.cu_indices.push_back (cu_index_and_attrs); + slot->cu_indices.push_back (cu_index_and_attrs); } /* See symtab_index_entry. */ diff --git a/gdb/testsuite/gdb.gdb/index-file.exp b/gdb/testsuite/gdb.gdb/index-file.exp new file mode 100644 index 0000000..c6edd28 --- /dev/null +++ b/gdb/testsuite/gdb.gdb/index-file.exp @@ -0,0 +1,115 @@ +# 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/>. + +# Load the GDB executable, and then 'save gdb-index', and make some +# checks of the generated index file. + +load_lib selftest-support.exp + +# Can't save an index with readnow. +require !readnow + +# A multiplier used to ensure slow tasks are less likely to timeout. +set timeout_factor 20 + +set filename [selftest_prepare] +if { $filename eq "" } { + unsupported "${gdb_test_file_name}.exp" + return -1 +} + +with_timeout_factor $timeout_factor { + # Start GDB, load FILENAME. + clean_restart $filename +} + +# Generate an index file. +set dir1 [standard_output_file "index_1"] +remote_exec host "mkdir -p ${dir1}" +with_timeout_factor $timeout_factor { + gdb_test_no_output "save gdb-index $dir1" \ + "create gdb-index file" +} + +# Close GDB. +gdb_exit + +# Validate that the index-file FILENAME has made efficient use of its +# symbol hash table. Calculate the number of symbols in the hash +# table and the total hash table size. The hash table starts with +# 1024 entries, and then doubles each time it is filled to 75%. At +# 75% filled, doubling the size takes it to 37.5% filled. +# +# Thus, the hash table is correctly filled if: +# 1. Its size is 1024 (i.e. it has not yet had its first doubling), or +# 2. Its filled percentage is over 37% +# +# We could check that it is not over filled, but I don't as that's not +# really an issue. But we did once have a bug where the table was +# doubled incorrectly, in which case we'd see a filled percentage of +# around 2% in some cases, which is a huge waste of disk space. +proc check_symbol_table_usage { filename } { + # Open the file in binary mode and read-only mode. + set fp [open $filename rb] + + # Configure the channel to use binary translation. + fconfigure $fp -translation binary + + # Read the first 8 bytes of the file, which contain the header of + # the index section. + set header [read $fp [expr 7 * 4]] + + # Scan the header to get the version, the CU list offset, and the + # types CU list offset. + binary scan $header iiiiii version \ + _ _ _ symbol_table_offset shortcut_offset + + # The length of the symbol hash table (in entries). + set len [expr ($shortcut_offset - $symbol_table_offset) / 8] + + # Now walk the hash table and count how many entries are in use. + set offset $symbol_table_offset + set count 0 + while { $offset < $shortcut_offset } { + seek $fp $offset + set entry [read $fp 8] + binary scan $entry ii name_ptr flags + if { $name_ptr != 0 } { + incr count + } + + incr offset 8 + } + + # Close the file. + close $fp + + # Calculate how full the cache is. + set pct [expr (100 * double($count)) / $len] + + # Write our results out to the gdb.log. + verbose -log "Hash table size: $len" + verbose -log "Hash table entries: $count" + verbose -log "Percentage usage: $pct%" + + # The minimum fill percentage is actually 37.5%, but we give TCL a + # little flexibility in case the FP maths give a result a little + # off. + gdb_assert { $len == 1024 || $pct > 37 } \ + "symbol hash table usage" +} + +set index_filename_base [file tail $filename] +check_symbol_table_usage "$dir1/${index_filename_base}.gdb-index" |