From: Tom de Vries Date: Thu, 27 May 2021 13:22:38 +0000 (+0200) Subject: [gdb/symtab] Fix Dwarf Error: cannot find DIE X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=6dcd1193d978ac48fa566815dd949e264cd6bc37;p=deliverable%2Fbinutils-gdb.git [gdb/symtab] Fix Dwarf Error: cannot find DIE When loading the debug info package libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug from openSUSE Leap 15.2, we run into a dwarf error: ... $ gdb -q -batch libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug Dwarf Error: Cannot not find DIE at 0x18a936e7 \ [from module libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug] ... The DIE @ 0x18a936e7 does in fact exist, and is part of a CU @ 0x18a23e52. No error message is printed when using -readnow. What happens is the following: - a dwarf2_per_cu_data P is created for the CU. - a dwarf2_cu A is created for the same CU. - another dwarf2_cu B is created for the same CU. - the dwarf2_cu B is set in per_objfile->m_dwarf2_cus, such that per_objfile->get_cu (P) returns B. - P->load_all_dies is set to 1. - all dies are read into the A->partial_dies htab - dwarf2_cu A is destroyed. - we try to find the partial_die for the DIE @ 0x18a936e7 in B->partial_dies. We can't find it, but do not try to load all dies, because P->load_all_dies is already set to 1. - an error message is generated. The question is why we're creating dwarf2_cu A and B for the same CU. The dwarf2_cu A is created here: ... (gdb) bt #0 dwarf2_cu::dwarf2_cu (this=0x79a9660, per_cu=0x23c0b30, per_objfile=0x1ad01b0) at dwarf2/cu.c:38 #1 0x0000000000675799 in cutu_reader::cutu_reader (this=0x7fffffffd040, this_cu=0x23c0b30, per_objfile=0x1ad01b0, abbrev_table=0x0, existing_cu=0x0, skip_partial=false) at dwarf2/read.c:6487 #2 0x0000000000676eb3 in process_psymtab_comp_unit (this_cu=0x23c0b30, per_objfile=0x1ad01b0, want_partial_unit=false, pretend_language=language_minimal) at dwarf2/read.c:7028 ... And the dwarf2_cu B is created here: ... (gdb) bt #0 dwarf2_cu::dwarf2_cu (this=0x885e8c0, per_cu=0x23c0b30, per_objfile=0x1ad01b0) at dwarf2/cu.c:38 #1 0x0000000000675799 in cutu_reader::cutu_reader (this=0x7fffffffcc50, this_cu=0x23c0b30, per_objfile=0x1ad01b0, abbrev_table=0x0, existing_cu=0x0, skip_partial=false) at dwarf2/read.c:6487 #2 0x0000000000678118 in load_partial_comp_unit (this_cu=0x23c0b30, per_objfile=0x1ad01b0, existing_cu=0x0) at dwarf2/read.c:7436 #3 0x000000000069721d in find_partial_die (sect_off=(unknown: 0x18a55054), offset_in_dwz=0, cu=0x0) at dwarf2/read.c:19391 #4 0x000000000069755b in partial_die_info::fixup (this=0x9096900, cu=0xa6a85f0) at dwarf2/read.c:19512 #5 0x0000000000697586 in partial_die_info::fixup (this=0x8629bb0, cu=0xa6a85f0) at dwarf2/read.c:19516 #6 0x00000000006787b1 in scan_partial_symbols (first_die=0x8629b40, lowpc=0x7fffffffcf58, highpc=0x7fffffffcf50, set_addrmap=0, cu=0x79a9660) at dwarf2/read.c:7563 #7 0x0000000000678878 in scan_partial_symbols (first_die=0x796ebf0, lowpc=0x7fffffffcf58, highpc=0x7fffffffcf50, set_addrmap=0, cu=0x79a9660) at dwarf2/read.c:7580 #8 0x0000000000676b82 in process_psymtab_comp_unit_reader (reader=0x7fffffffd040, info_ptr=0x7fffc1b3f29b, comp_unit_die=0x6ea90f0, pretend_language=language_minimal) at dwarf2/read.c:6954 #9 0x0000000000676ffd in process_psymtab_comp_unit (this_cu=0x23c0b30, per_objfile=0x1ad01b0, want_partial_unit=false, pretend_language=language_minimal) at dwarf2/read.c:7057 ... So in frame #9, a cutu_reader is created with dwarf2_cu A. Then a fixup takes us to the following CU @ 0x18aa33d6, in frame #5. And a similar fixup in frame #4 takes us back to CU @ 0x18a23e52. At that point, there's no information available that we're already trying to read that CU, and we end up creating another cutu_reader with dwarf2_cu B. It seems that there are two related problems: - creating two dwarf2_cu's is not optimal - the unoptimal case is not handled correctly This patch addresses the last problem, by moving the load_all_dies flag from dwarf2_per_cu_data to dwarf2_cu, such that it is paired with the partial_dies field, which ensures that the two can be kept in sync. Tested on x86_64-linux. gdb/ChangeLog: 2021-05-27 Tom de Vries PR symtab/27898 * dwarf2/cu.c (dwarf2_cu::dwarf2_cu): Add load_all_dies init. * dwarf2/cu.h (dwarf2_cu): Add load_all_dies field. * dwarf2/read.c (load_partial_dies, find_partial_die): Update. * dwarf2/read.h (dwarf2_per_cu_data::dwarf2_per_cu_data): Remove load_all_dies init. (dwarf2_per_cu_data): Remove load_all_dies field. --- diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 39f444e1f7..3154a8d0ed 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,13 @@ +2021-05-27 Tom de Vries + + PR symtab/27898 + * dwarf2/cu.c (dwarf2_cu::dwarf2_cu): Add load_all_dies init. + * dwarf2/cu.h (dwarf2_cu): Add load_all_dies field. + * dwarf2/read.c (load_partial_dies, find_partial_die): Update. + * dwarf2/read.h (dwarf2_per_cu_data::dwarf2_per_cu_data): Remove + load_all_dies init. + (dwarf2_per_cu_data): Remove load_all_dies field. + 2021-05-26 Simon Marchi * regcache.c (reg_buffer::reg_buffer): Default-initialize diff --git a/gdb/dwarf2/cu.c b/gdb/dwarf2/cu.c index 2451df4f5b..1031ed3aa0 100644 --- a/gdb/dwarf2/cu.c +++ b/gdb/dwarf2/cu.c @@ -35,7 +35,8 @@ dwarf2_cu::dwarf2_cu (dwarf2_per_cu_data *per_cu, producer_is_icc (false), producer_is_icc_lt_14 (false), producer_is_codewarrior (false), - processing_has_namespace_info (false) + processing_has_namespace_info (false), + load_all_dies (false) { } diff --git a/gdb/dwarf2/cu.h b/gdb/dwarf2/cu.h index ff56ec5527..b4a5b08d5a 100644 --- a/gdb/dwarf2/cu.h +++ b/gdb/dwarf2/cu.h @@ -264,6 +264,12 @@ public: bool processing_has_namespace_info : 1; + /* This flag will be set when reading partial DIEs if we need to load + absolutely all DIEs for this compilation unit, instead of just the ones + we think are interesting. It gets set if we look for a DIE in the + hash table and don't find it. */ + bool load_all_dies : 1; + struct partial_die_info *find_partial_die (sect_offset sect_off); /* If this CU was inherited by another CU (via specification, diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index d3b5b89c1c..3f496347cc 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -18817,7 +18817,7 @@ load_partial_dies (const struct die_reader_specs *reader, last_die = NULL; gdb_assert (cu->per_cu != NULL); - if (cu->per_cu->load_all_dies) + if (cu->load_all_dies) load_all = 1; cu->partial_dies @@ -19385,9 +19385,9 @@ find_partial_die (sect_offset sect_off, int offset_in_dwz, struct dwarf2_cu *cu) /* If we didn't find it, and not all dies have been loaded, load them all and try again. */ - if (pd == NULL && cu->per_cu->load_all_dies == 0) + if (pd == NULL && cu->load_all_dies == 0) { - cu->per_cu->load_all_dies = 1; + cu->load_all_dies = 1; /* This is nasty. When we reread the DIEs, somewhere up the call chain THIS_CU->cu may already be in use. So we can't just free it and diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h index 6af1f44bd4..0bb3da5a34 100644 --- a/gdb/dwarf2/read.h +++ b/gdb/dwarf2/read.h @@ -421,7 +421,6 @@ struct dwarf2_per_cu_data { dwarf2_per_cu_data () : queued (false), - load_all_dies (false), is_debug_types (false), is_dwz (false), reading_dwo_directly (false), @@ -447,12 +446,6 @@ struct dwarf2_per_cu_data any of the current compilation units are processed. */ unsigned int queued : 1; - /* This flag will be set when reading partial DIEs if we need to load - absolutely all DIEs for this compilation unit, instead of just the ones - we think are interesting. It gets set if we look for a DIE in the - hash table and don't find it. */ - unsigned int load_all_dies : 1; - /* Non-zero if this CU is from .debug_types. Struct dwarf2_per_cu_data is contained in struct signatured_type iff this is non-zero. */