meson: Pass objects and dependencies to declare_dependency()

We used to request declare_dependency() to link_whole static libraries.
If a static library is a thin archive, GNU ld keeps all object files
referenced by the archive open, and sometimes exceeds the open file limit.

Another problem with link_whole is that suboptimal handling of nested
dependencies.

link_whole by itself does not propagate dependencies. In particular,
gnutls, a dependency of crypto, is not propagated to its users, and we
currently workaround the issue by declaring gnutls as a dependency for
each crypto user.  On the other hand, if you write something like

  libfoo = static_library('foo', 'foo.c', dependencies: gnutls)
  foo = declare_dependency(link_whole: libfoo)

  libbar = static_library('bar', 'bar.c', dependencies: foo)
  bar = declare_dependency(link_whole: libbar, dependencies: foo)
  executable('prog', sources: files('prog.c'), dependencies: [foo, bar])

hoping to propagate the gnutls dependency into bar.c, you'll see a
linking failure for "prog", because the foo.c.o object file is included in
libbar.a and therefore it is linked twice into "prog": once from libfoo.a
and once from libbar.a.  Here Meson does not see the duplication, it
just asks the linker to link all of libfoo.a and libbar.a into "prog".

Instead of using link_whole, extract objects included in static libraries
and pass them to declare_dependency(); and then the dependencies can be
added as well so that they are propagated, because object files on the
linker command line are always deduplicated.

This requires Meson 1.1.0 or later.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-ID: <20240524-objects-v1-1-07cbbe96166b@daynix.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/docs/devel/build-system.rst b/docs/devel/build-system.rst
index f4fd76117df3c3d0c716373fe74a54fb58dc0a7a..39a1934c63fca53314af566ca6612a16154e8564 100644 (file)
--- a/docs/devel/build-system.rst
+++ b/docs/devel/build-system.rst
@@ -238,7 +238,8 @@ Subsystem sourcesets:
                                 name_suffix: 'fa',
                                 build_by_default: false)
 
-    chardev = declare_dependency(link_whole: libchardev)
+    chardev = declare_dependency(objects: libchardev.extract_all_objects(recursive: false),
+                                 dependencies: chardev_ss.dependencies())
 
   As of Meson 0.55.1, the special ``.fa`` suffix should be used for everything
   that is used with ``link_whole``, to ensure that the link flags are placed

diff --git a/gdbstub/meson.build b/gdbstub/meson.build
index da5721d8452b00742da50f74be78ce1615ced8d1..c56b54eae7ef25e9108b8d9e2cb619adf1360321 100644 (file)
--- a/gdbstub/meson.build
+++ b/gdbstub/meson.build
@@ -28,9 +28,9 @@ libgdb_system = static_library('gdb_system',
                                 name_suffix: 'fa',
                                 build_by_default: false)
 
-gdb_user = declare_dependency(link_whole: libgdb_user)
+gdb_user = declare_dependency(objects: libgdb_user.extract_all_objects(recursive: false))
 user_ss.add(gdb_user)
-gdb_system = declare_dependency(link_whole: libgdb_system)
+gdb_system = declare_dependency(objects: libgdb_system.extract_all_objects(recursive: false))
 system_ss.add(gdb_system)
 
 common_ss.add(files('syscalls.c'))

diff --git a/meson.build b/meson.build
index df9a64302f050e9e4dbdc6df7a96e7e0d4c7cd42..0c314ae5701b1e1ec21bce19ffaa08f56d56fa7b 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -1,4 +1,4 @@
-project('qemu', ['c'], meson_version: '>=0.63.0',
+project('qemu', ['c'], meson_version: '>=1.1.0',
         default_options: ['warning_level=1', 'c_std=gnu11', 'cpp_std=gnu++11', 'b_colorout=auto',
                           'b_staticpic=false', 'stdsplit=false', 'optimization=2', 'b_pie=true'],
         version: files('VERSION'))
@@ -3461,7 +3461,7 @@ endif
 
 if enable_modules
   libmodulecommon = static_library('module-common', files('module-common.c') + genh, pic: true, c_args: '-DBUILD_DSO')
-  modulecommon = declare_dependency(link_whole: libmodulecommon, compile_args: '-DBUILD_DSO')
+  modulecommon = declare_dependency(objects: libmodulecommon.extract_all_objects(recursive: false), compile_args: '-DBUILD_DSO')
 endif
 
 qom_ss = qom_ss.apply({})
@@ -3469,14 +3469,15 @@ libqom = static_library('qom', qom_ss.sources() + genh,
                         dependencies: [qom_ss.dependencies()],
                         name_suffix: 'fa',
                         build_by_default: false)
-qom = declare_dependency(link_whole: libqom)
+qom = declare_dependency(objects: libqom.extract_all_objects(recursive: false),
+                         dependencies: qom_ss.dependencies())
 
 event_loop_base = files('event-loop-base.c')
 event_loop_base = static_library('event-loop-base',
                                  sources: event_loop_base + genh,
                                  name_suffix: 'fa',
                                  build_by_default: false)
-event_loop_base = declare_dependency(link_whole: event_loop_base,
+event_loop_base = declare_dependency(objects: event_loop_base.extract_all_objects(recursive: false),
                                      dependencies: [qom])
 
 stub_ss = stub_ss.apply({})
@@ -3621,7 +3622,8 @@ foreach d, list : modules
       endif
       emulator_modules += shared_module(sl.name(),
                     name_prefix: '',
-                    link_whole: sl,
+                    objects: sl.extract_all_objects(recursive: false),
+                    dependencies: module_ss.dependencies(),
                     install: true,
                     install_dir: qemu_moddir)
       if module_ss.sources() != []
@@ -3669,7 +3671,8 @@ foreach d, list : target_modules
             system_mods += sl
             emulator_modules += shared_module(sl.name(),
                     name_prefix: '',
-                    link_whole: sl,
+                    objects: sl.extract_all_objects(recursive: false),
+                    dependencies: target_module_ss.dependencies(),
                     install: true,
                     install_dir: qemu_moddir)
             # FIXME: Should use sl.extract_all_objects(recursive: true) too.
@@ -3728,8 +3731,8 @@ libauthz = static_library('authz', authz_ss.sources() + genh,
                           name_suffix: 'fa',
                           build_by_default: false)
 
-authz = declare_dependency(link_whole: libauthz,
-                           dependencies: qom)
+authz = declare_dependency(objects: libauthz.extract_all_objects(recursive: false),
+                           dependencies: [authz_ss.dependencies(), qom])
 
 crypto_ss = crypto_ss.apply({})
 libcrypto = static_library('crypto', crypto_ss.sources() + genh,
@@ -3737,8 +3740,8 @@ libcrypto = static_library('crypto', crypto_ss.sources() + genh,
                            name_suffix: 'fa',
                            build_by_default: false)
 
-crypto = declare_dependency(link_whole: libcrypto,
-                            dependencies: [authz, qom])
+crypto = declare_dependency(objects: libcrypto.extract_all_objects(recursive: false),
+                            dependencies: [crypto_ss.dependencies(), authz, qom])
 
 io_ss = io_ss.apply({})
 libio = static_library('io', io_ss.sources() + genh,
@@ -3747,12 +3750,13 @@ libio = static_library('io', io_ss.sources() + genh,
                        name_suffix: 'fa',
                        build_by_default: false)
 
-io = declare_dependency(link_whole: libio, dependencies: [crypto, qom])
+io = declare_dependency(objects: libio.extract_all_objects(recursive: false),
+                        dependencies: [io_ss.dependencies(), crypto, qom])
 
 libmigration = static_library('migration', sources: migration_files + genh,
                               name_suffix: 'fa',
                               build_by_default: false)
-migration = declare_dependency(link_with: libmigration,
+migration = declare_dependency(objects: libmigration.extract_all_objects(recursive: false),
                                dependencies: [qom, io])
 system_ss.add(migration)
 
@@ -3762,8 +3766,8 @@ libblock = static_library('block', block_ss.sources() + genh,
                           name_suffix: 'fa',
                           build_by_default: false)
 
-block = declare_dependency(link_whole: [libblock],
-                           dependencies: [crypto, io])
+block = declare_dependency(objects: libblock.extract_all_objects(recursive: false),
+                           dependencies: [block_ss.dependencies(), crypto, io])
 
 blockdev_ss = blockdev_ss.apply({})
 libblockdev = static_library('blockdev', blockdev_ss.sources() + genh,
@@ -3771,8 +3775,8 @@ libblockdev = static_library('blockdev', blockdev_ss.sources() + genh,
                              name_suffix: 'fa',
                              build_by_default: false)
 
-blockdev = declare_dependency(link_whole: [libblockdev],
-                              dependencies: [block, event_loop_base])
+blockdev = declare_dependency(objects: libblockdev.extract_all_objects(recursive: false),
+                              dependencies: [blockdev_ss.dependencies(), block, event_loop_base])
 
 qmp_ss = qmp_ss.apply({})
 libqmp = static_library('qmp', qmp_ss.sources() + genh,
@@ -3780,20 +3784,22 @@ libqmp = static_library('qmp', qmp_ss.sources() + genh,
                         name_suffix: 'fa',
                         build_by_default: false)
 
-qmp = declare_dependency(link_whole: [libqmp])
+qmp = declare_dependency(objects: libqmp.extract_all_objects(recursive: false),
+                         dependencies: qmp_ss.dependencies())
 
 libchardev = static_library('chardev', chardev_ss.sources() + genh,
                             name_suffix: 'fa',
                             dependencies: chardev_ss.dependencies(),
                             build_by_default: false)
 
-chardev = declare_dependency(link_whole: libchardev)
+chardev = declare_dependency(objects: libchardev.extract_all_objects(recursive: false),
+                             dependencies: chardev_ss.dependencies())
 
 hwcore_ss = hwcore_ss.apply({})
 libhwcore = static_library('hwcore', sources: hwcore_ss.sources() + genh,
                            name_suffix: 'fa',
                            build_by_default: false)
-hwcore = declare_dependency(link_whole: libhwcore)
+hwcore = declare_dependency(objects: libhwcore.extract_all_objects(recursive: false))
 common_ss.add(hwcore)
 
 ###########

diff --git a/pythondeps.toml b/pythondeps.toml
index 9c16602d303c54533ecb5c47762b23aa2d645937..6aba0c9daaa97c67037f090f7f476a866e9b4a99 100644 (file)
--- a/pythondeps.toml
+++ b/pythondeps.toml
@@ -19,7 +19,7 @@
 
 [meson]
 # The install key should match the version in python/wheels/
-meson = { accepted = ">=0.63.0", installed = "1.2.3", canary = "meson" }
+meson = { accepted = ">=1.1.0", installed = "1.2.3", canary = "meson" }
 
 [docs]
 # Please keep the installed versions in sync with docs/requirements.txt

diff --git a/tcg/meson.build b/tcg/meson.build
index ffbe754d8b3256f19b3878bfdf03a453fddda802..165e773abbefe8c423132b4270a7ef998c644f4c 100644 (file)
--- a/tcg/meson.build
+++ b/tcg/meson.build
@@ -36,7 +36,8 @@ libtcg_user = static_library('tcg_user',
                              c_args: '-DCONFIG_USER_ONLY',
                              build_by_default: false)
 
-tcg_user = declare_dependency(link_with: libtcg_user)
+tcg_user = declare_dependency(objects: libtcg_user.extract_all_objects(recursive: false),
+                              dependencies: tcg_ss.dependencies())
 user_ss.add(tcg_user)
 
 libtcg_system = static_library('tcg_system',
@@ -46,5 +47,6 @@ libtcg_system = static_library('tcg_system',
                                 c_args: '-DCONFIG_SOFTMMU',
                                 build_by_default: false)
 
-tcg_system = declare_dependency(link_with: libtcg_system)
+tcg_system = declare_dependency(objects: libtcg_system.extract_all_objects(recursive: false),
+                                dependencies: tcg_ss.dependencies())
 system_ss.add(tcg_system)

diff --git a/tests/qtest/libqos/meson.build b/tests/qtest/libqos/meson.build
index 558eb4c24be1dfa1c0aa8286d3f733546e41de0b..05fe57a4b978ae96ca0c8f641b9a3e804ebae67d 100644 (file)
--- a/tests/qtest/libqos/meson.build
+++ b/tests/qtest/libqos/meson.build
@@ -72,4 +72,4 @@ libqos = static_library('qos', libqos_srcs + genh,
                         name_suffix: 'fa',
                         build_by_default: false)
 
-qos = declare_dependency(link_whole: libqos)
+qos = declare_dependency(objects: libqos.extract_all_objects(recursive: false))