diff options
Diffstat (limited to 'gdb-rhbz-2232086-generate-dwarf-5-index-consistently.patch')
| -rw-r--r-- | gdb-rhbz-2232086-generate-dwarf-5-index-consistently.patch | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/gdb-rhbz-2232086-generate-dwarf-5-index-consistently.patch b/gdb-rhbz-2232086-generate-dwarf-5-index-consistently.patch new file mode 100644 index 0000000..e9b0b9e --- /dev/null +++ b/gdb-rhbz-2232086-generate-dwarf-5-index-consistently.patch @@ -0,0 +1,101 @@ +From FEDORA_PATCHES Mon Sep 17 00:00:00 2001 +From: Andrew Burgess <aburgess@redhat.com> +Date: Mon, 27 Nov 2023 13:19:39 +0000 +Subject: gdb-rhbz-2232086-generate-dwarf-5-index-consistently.patch + +;; Back-port upstream commit 3644f41dc80 as part of a fix for +;; non-deterministic gdb-index generation (RH BZ 2232086). + +gdb: generate dwarf-5 index identically as worker-thread count changes + +Similar to the previous commit, this commit ensures that the dwarf-5 +index files are generated identically as the number of worker-threads +changes. + +Building the dwarf-5 index makes use of a closed hash table, the +bucket_hash local within debug_names::build(). Entries are added to +bucket_hash from m_name_to_value_set, which, in turn, is populated +by calls to debug_names::insert() in write_debug_names. The insert +calls are ordered based on the entries within the cooked_index, and +the ordering within cooked_index depends on the number of worker +threads that GDB is using. + +My proposal is to sort each chain within the bucket_hash closed hash +table prior to using this to build the dwarf-5 index. + +The buckets within bucket_hash will always have the same ordering (for +a given GDB build with a given executable), and by sorting the chains +within each bucket, we can be sure that GDB will see each entry in a +deterministic order. + +I've extended the index creation test to cover this case. + +Approved-By: Tom Tromey <tom@tromey.com> + +diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c +--- a/gdb/dwarf2/index-write.c ++++ b/gdb/dwarf2/index-write.c +@@ -452,6 +452,11 @@ class c_str_view + return strcmp (m_cstr, other.m_cstr) == 0; + } + ++ bool operator< (const c_str_view &other) const ++ { ++ return strcmp (m_cstr, other.m_cstr) < 0; ++ } ++ + /* Return the underlying C string. Note, the returned string is + only a reference with lifetime of this object. */ + const char *c_str () const +@@ -771,10 +776,18 @@ class debug_names + } + for (size_t bucket_ix = 0; bucket_ix < bucket_hash.size (); ++bucket_ix) + { +- const std::forward_list<hash_it_pair> &hashitlist +- = bucket_hash[bucket_ix]; ++ std::forward_list<hash_it_pair> &hashitlist = bucket_hash[bucket_ix]; + if (hashitlist.empty ()) + continue; ++ ++ /* Sort the items within each bucket. This ensures that the ++ generated index files will be the same no matter the order in ++ which symbols were added into the index. */ ++ hashitlist.sort ([] (const hash_it_pair &a, const hash_it_pair &b) ++ { ++ return a.it->first < b.it->first; ++ }); ++ + uint32_t &bucket_slot = m_bucket_table[bucket_ix]; + /* The hashes array is indexed starting at 1. */ + store_unsigned_integer (reinterpret_cast<gdb_byte *> (&bucket_slot), +diff --git a/gdb/testsuite/gdb.gdb/index-file.exp b/gdb/testsuite/gdb.gdb/index-file.exp +--- a/gdb/testsuite/gdb.gdb/index-file.exp ++++ b/gdb/testsuite/gdb.gdb/index-file.exp +@@ -47,6 +47,9 @@ remote_exec host "mkdir -p ${dir1}" + with_timeout_factor $timeout_factor { + gdb_test_no_output "save gdb-index $dir1" \ + "create gdb-index file" ++ ++ gdb_test_no_output "save gdb-index -dwarf-5 $dir1" \ ++ "create dwarf-index files" + } + + # Close GDB. +@@ -143,13 +146,16 @@ if { $worker_threads > 1 } { + with_timeout_factor $timeout_factor { + gdb_test_no_output "save gdb-index $dir2" \ + "create second gdb-index file" ++ ++ gdb_test_no_output "save gdb-index -dwarf-5 $dir2" \ ++ "create second dwarf-index files" + } + + # Close GDB. + gdb_exit + + # Now check that the index files are identical. +- foreach suffix { gdb-index } { ++ foreach suffix { gdb-index debug_names debug_str } { + set result \ + [remote_exec host \ + "cmp -s \"$dir1/${index_filename_base}.${suffix}\" \"$dir2/${index_filename_base}.${suffix}\""] |