Commit graph

10 commits

Author SHA1 Message Date
Daniel Bertalan
c0cf6e3744 CMake: Set -fvisibility-inlines-hidden on ELF platforms
The C++ semantics of `inline` dictate that such functions might be
defined in multiple translation units. As with all other functions, they
must have the same address in all TUs. Because of this, the compiler
emits `inline` functions as weak symbols, which the dynamic linker can
then resolve to the same address everywhere.

This rule is responsible for a significant overhead at startup, as such
lookups happen by name. Namely, 86'000 of the 114'000 by-name symbol
lookups when loading LibWeb can be attributed to this. Most of these
are only ever defined in a single object, making this even more
pointless.

As nothing in our code relies on either ELF symbol interposition rules
or function address equality, we can use the -fvisibility-inlines-hidden
escape hatch, which causes this rule to be disregarded. As the symbols
are now hidden, no load-time symbol lookup is needed. This flag is used
without issues in other large C++ codebases like Chromium and LLVM.

Some relevant light reading, suggested by Nico:
- https://ridiculousfish.com/blog/posts/i-didnt-order-that-so-why-is-it-on-my-bill-episode-1.html
- https://www.cs.dartmouth.edu/~sergey/cs258/ABI/UlrichDrepper-How-To-Write-Shared-Libraries.pdf
- https://blog.llvm.org/2018/11/30-faster-windows-builds-with-clang-cl_14.html
- https://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Dialect-Options.html#index-fvisibility-inlines-hidden
2023-08-12 05:14:20 +02:00
implicitfield
941d68ac2d Toolchain+Ports: Update LLVM to 16.0.6 2023-06-27 12:40:38 +02:00
MacDue
7f3b98093e Meta: Enable DWARF 5 debug information
For our use case DWARF 5 seems to work fine now (see previous commit)
2023-05-14 09:21:08 +02:00
Nico Weber
8f988b7bae Meta: Move more common flags to common_compile_options.cmake
For the most part no behavior change, except that we now pass
-Wno-implicit-const-int-float-conversion and -Wno-literal-suffix
only to clang and gcc each in both lagom and serenity builds,
while we previously passed them to both in lagom builds (and
passed them to one each in serenity builds). The former is
a clang flag, the latter a gcc flag, but since we also use
-Wno-unknown-warning-option it doesn't really matter.
2023-04-18 10:05:49 +02:00
Nico Weber
4aaefeb1d5 Meta: Move some flags to common_compile_options.cmake
No behavior change.
2023-04-17 00:52:21 +02:00
Timon Kruiper
dfc6555fec CMake: Add -mstrict-align flag to compile options for aarch64 build
The aarch64 processor is set up to trap on unaligned memory accesses, so
to enforce that the compiler correctly generates aligned accesses, the
-mstrict-align flag is needed. We also need the -Wno-cast-align as there
are some files in AK that don't build without the flag.
2023-02-15 22:53:19 +01:00
Tim Schumacher
ef7f343e95 CMake: Set DWARF version before the debug information level
Setting the DWARF version after having selected which level of debug
information to generate apparently undoes some settings again.

Doing the reverse apparently keeps both the version and the debug level
setting, resulting in a significantly smaller disk image size.
2023-02-02 16:31:09 +01:00
Liav A
fb0dee5a54 Meta: Force compilation with DWARF revision 4
We currently don't support DWARF revision 5 and LLVM/Clang might create
such debug info into our binaries in x86_64, which will lead to a crash
in CrashReporter that is unable to parse that information correctly.
2022-12-28 11:53:41 +01:00
Tim Schumacher
678db534ff LibC: Properly implement stack protectors
The shared parts are now firmly compiled into LibC instead of being
defined as a static library and then being copied over manually.
The non-shared ("local") parts are kept as a static library that is
linked into each binary on demand.

This finally allows us to support linking with the -fstack-protector
flag, which now replaces the `ssp` target being linked into each binary
accidentally via CMake.
2022-11-01 14:49:09 +00:00
Linus Groh
ee721978f6 Meta: Move compiler flags into standalone CMake files
This way we can have all of them in a single place, similar to how we
structure options added via the serenity_option() macro.
2022-05-14 17:53:06 +02:00