Commit Graph

8 Commits

Author SHA1 Message Date
Pavel Labath 2f0881160c [DebugInfo] Reduce debug_str_offsets section size
Summary:
The accelerator tables use the debug_str section to store their strings.
However, they do not support the indirect method of access that is
available for the debug_info section (DW_FORM_strx et al.).

Currently our code is assuming that all strings can/will be referenced
indirectly, and puts all of them into the debug_str_offsets section.
This is generally true for regular (unsplit) dwarf, but in the DWO case,
most of the strings in the debug_str section will only be used from the
accelerator tables. Therefore the contents of the debug_str_offsets
section will be largely unused and bloating the main executable.

This patch rectifies this by teaching the DwarfStringPool to
differentiate between strings accessed directly and indirectly. When a
user inserts a string into the pool it has to declare whether that
string will be referenced directly or not. If at least one user requsts
indirect access, that string will be assigned an index ID and put into
debug_str_offsets table. Otherwise, the offset table is skipped.

This approach reduces the overall binary size (when compiled with
-gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is
shrunk by 99%).

Reviewers: probinson, dblaikie, JDevlieghere

Subscribers: aprantl, mgrang, llvm-commits

Differential Revision: https://reviews.llvm.org/D49493

llvm-svn: 339122
2018-08-07 09:54:52 +00:00
Jonas Devlieghere c0fb4b6b88 [dsymutil] Move abstractions into separate files (NFC)
This patch splits off some abstractions used by dsymutil's dwarf linker
and moves them into separate header and implementation files. This
almost halves the number of LOC in DwarfLinker.cpp and makes it a lot
easier to understand what functionality lives where.

Differential revision: https://reviews.llvm.org/D48647

llvm-svn: 335749
2018-06-27 16:13:40 +00:00
Jonas Devlieghere caf26f23af [dsymutil] Move string pool into its own implementatino file. NFC.
The DwarfLinker implementation is already relatively large with over 4k
LOC. This commit moves the implementation of NonRelocatableStringpool
into a separate cpp file.

llvm-svn: 326425
2018-03-01 10:05:54 +00:00
Jonas Devlieghere fa5c1b11cc [dsymutil] Fix typos and formatting. NFC.
Some over-due gardening: this fixes a bunch of typos and makes the
formatting consistent with LLVM's style guide.

llvm-svn: 325768
2018-02-22 11:32:51 +00:00
Jonas Devlieghere e7d3d907b5 [dsymutil] Make NonRelocatableStringPool a wrapper around DwarfStringPoolEntry. NFC
This is needed in order to use our StringPool entries in the Apple
accelerator tables.

As this is NFC we rely on the existing tests for correctness.

llvm-svn: 323339
2018-01-24 16:16:43 +00:00
Eugene Zelenko 0ad18f888e [dsymutil, llvm-objcopy] Fix some Clang-tidy modernize and Include What You Use warnings; other minor fixes (NFC).
llvm-svn: 317123
2017-11-01 21:16:06 +00:00
Benjamin Kramer 391be792f2 One more batch of self-containing headers.
llvm-svn: 258974
2016-01-27 19:29:56 +00:00
Frederic Riss 30711fbbf7 [dsymutil] Split NonRelocatableStringPool into its own file. NFC.
llvm-svn: 246009
2015-08-26 05:09:52 +00:00