From 2e6a9f7959dca5af9a7e6e5cea8c5dccd2e510f0 Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Wed, 27 May 2020 11:14:10 -0400 Subject: [PATCH] Add comp_unit_head to dwarf2_per_cu_data The per_cu_header_read_in function allows obtaining a filled comp_unit_head object for a given dwarf2_per_cu_data object. If a dwarf2_cu object exists for this dwarf2_per_cu_data, then it just returns a pointer to the comp_unit_head from that dwarf2_cu. Otherwise, it reads the header into a temporary buffer provided by the caller, and returns a pointer to that. Since the dwarf2_per_cu_data::cu link is going to be removed (dwarf2_per_cu_data will become objfile-independent while dwarf2_cu stays objfile-dependent), we cannot rely anymore on returning the header from the dwarf2_cu object. The not too complex solution implemented by this patch is to keep a copy of the header in the dwarf2_per_cu_data object, independent from the copy in dwarf2_cu. The new copy is only used in the addr_size, offset_size and ref_addr_size methods of dwarf2_per_cu_data. There's nothing intrinsic to the comp_unit_head object that prevents it to be shared between two dwarf2_cu objects (belonging to different objfiles) representing the same CU. In other words, I think we could eventually get rid of the copy in dwarf2_cu to only keep the one in dwarf2_per_cu_data. It is not trivial, however, so I have decided not to do it for the moment. gdb/ChangeLog: * dwarf2/read.h (struct dwarf2_per_cu_data) : New fields. : New method. * dwarf2/read.c (per_cu_header_read_in): Remove. (dwarf2_per_cu_data::get_header): New. (dwarf2_per_cu_data::addr_size): Update. (dwarf2_per_cu_data::offset_size): Update. (dwarf2_per_cu_data::ref_addr_size): Update. Change-Id: Id7541fca7562843eba110ece21c4df38d45fca23 --- gdb/ChangeLog | 11 ++++++++++ gdb/dwarf2/read.c | 52 ++++++++++++++++------------------------------- gdb/dwarf2/read.h | 19 +++++++++++++++++ 3 files changed, 48 insertions(+), 34 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 13aeada94fd..b85a8aa2dcd 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,14 @@ +2020-05-27 Simon Marchi + + * dwarf2/read.h (struct dwarf2_per_cu_data) : New fields. + : New method. + * dwarf2/read.c (per_cu_header_read_in): Remove. + (dwarf2_per_cu_data::get_header): New. + (dwarf2_per_cu_data::addr_size): Update. + (dwarf2_per_cu_data::offset_size): Update. + (dwarf2_per_cu_data::ref_addr_size): Update. + 2020-05-27 Simon Marchi * dwarf2/read.c (load_cu): Return dwarf2_cu. diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index a27c351e1cc..a6b7f2c6d25 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -23335,26 +23335,23 @@ dwarf2_symbol_mark_computed (const struct attribute *attr, struct symbol *sym, } } -/* Return comp_unit_head for PER_CU, either already available in PER_CU->CU - (CU_HEADERP is unused in such case) or prepare a temporary copy at - CU_HEADERP first. */ +/* See read.h. */ -static const struct comp_unit_head * -per_cu_header_read_in (struct comp_unit_head *cu_headerp, - const struct dwarf2_per_cu_data *per_cu) +const comp_unit_head * +dwarf2_per_cu_data::get_header () const { - const gdb_byte *info_ptr; - - if (per_cu->cu) - return &per_cu->cu->header; + if (!m_header_read_in) + { + const gdb_byte *info_ptr + = this->section->buffer + to_underlying (this->sect_off); - info_ptr = per_cu->section->buffer + to_underlying (per_cu->sect_off); + memset (&m_header, 0, sizeof (m_header)); - memset (cu_headerp, 0, sizeof (*cu_headerp)); - read_comp_unit_head (cu_headerp, info_ptr, per_cu->section, - rcuh_kind::COMPILE); + read_comp_unit_head (&m_header, info_ptr, this->section, + rcuh_kind::COMPILE); + } - return cu_headerp; + return &m_header; } /* See read.h. */ @@ -23362,12 +23359,7 @@ per_cu_header_read_in (struct comp_unit_head *cu_headerp, int dwarf2_per_cu_data::addr_size () const { - struct comp_unit_head cu_header_local; - const struct comp_unit_head *cu_headerp; - - cu_headerp = per_cu_header_read_in (&cu_header_local, this); - - return cu_headerp->addr_size; + return this->get_header ()->addr_size; } /* See read.h. */ @@ -23375,12 +23367,7 @@ dwarf2_per_cu_data::addr_size () const int dwarf2_per_cu_data::offset_size () const { - struct comp_unit_head cu_header_local; - const struct comp_unit_head *cu_headerp; - - cu_headerp = per_cu_header_read_in (&cu_header_local, this); - - return cu_headerp->offset_size; + return this->get_header ()->offset_size; } /* See read.h. */ @@ -23388,15 +23375,12 @@ dwarf2_per_cu_data::offset_size () const int dwarf2_per_cu_data::ref_addr_size () const { - struct comp_unit_head cu_header_local; - const struct comp_unit_head *cu_headerp; - - cu_headerp = per_cu_header_read_in (&cu_header_local, this); + const comp_unit_head *header = this->get_header (); - if (cu_headerp->version == 2) - return cu_headerp->addr_size; + if (header->version == 2) + return header->addr_size; else - return cu_headerp->offset_size; + return header->offset_size; } /* See read.h. */ diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h index 3500b0e7ba9..b75be312217 100644 --- a/gdb/dwarf2/read.h +++ b/gdb/dwarf2/read.h @@ -22,6 +22,7 @@ #include #include +#include "dwarf2/comp-unit.h" #include "dwarf2/index-cache.h" #include "dwarf2/section.h" #include "filename-seen-cache.h" @@ -468,6 +469,21 @@ struct dwarf2_per_cu_data /* Backlink to the owner of this. */ dwarf2_per_bfd *per_bfd; + /* DWARF header of this CU. Note that dwarf2_cu reads its own version of the + header, which may differ from this one, since it may pass rcuh_kind::TYPE + to read_comp_unit_head, whereas for dwarf2_per_cu_data we always pass + rcuh_kind::COMPILE. + + Don't access this field directly, use the get_header method instead. It + should be private, but we can't make it private at the moment. */ + mutable comp_unit_head m_header; + + /* True if HEADER has been read in. + + Don't access this field directly. It should be private, but we can't make + it private at the moment. */ + mutable bool m_header_read_in; + /* When dwarf2_per_bfd::using_index is true, the 'quick' field is active. Otherwise, the 'psymtab' field is active. */ union @@ -537,6 +553,9 @@ struct dwarf2_per_cu_data imported_symtabs = nullptr; } + /* Get the header of this per_cu, reading it if necessary. */ + const comp_unit_head *get_header () const; + /* Return the address size given in the compilation unit header for this CU. */ int addr_size () const; -- 2.30.2