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windows: Use TLS context/dispatch with shared-glapi 

However they have to be called via _glapi_get_dispatch/context. This
would be safe to do on any platform, but the extra indirection is only
necessary on Windows since TLS vars can't be exported from a DLL.

Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13634>
This commit is contained in:
Jesse Natalie 2021-11-02 11:38:02 -07:00 committed by Marge Bot
parent 58aad3f403
commit c47fd3dc00
2 changed files with 42 additions and 32 deletions
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69
meson.build
View File

@ -508,44 +508,49 @@ foreach platform : _platforms
pre_args += '-DHAVE_@0@_PLATFORM'.format(platform.to_upper())
endforeach
use_elf_tls = false
if not with_platform_windows or not with_shared_glapi
pre_args += '-DUSE_ELF_TLS'
use_elf_tls = true
use_elf_tls = true
pre_args += '-DUSE_ELF_TLS'
if with_platform_android and get_option('platform-sdk-version') >= 29
# By default the NDK compiler, at least, emits emutls references instead of
# ELF TLS, even when building targeting newer API levels. Make it actually do
# ELF TLS instead.
c_args += '-fno-emulated-tls'
cpp_args += '-fno-emulated-tls'
if with_platform_android and get_option('platform-sdk-version') >= 29
# By default the NDK compiler, at least, emits emutls references instead of
# ELF TLS, even when building targeting newer API levels. Make it actually do
# ELF TLS instead.
c_args += '-fno-emulated-tls'
cpp_args += '-fno-emulated-tls'
endif
# -mtls-dialect=gnu2 speeds up non-initial-exec TLS significantly but requires
# full toolchain (including libc) support.
have_mtls_dialect = false
foreach c_arg : get_option('c_args')
if c_arg.startswith('-mtls-dialect=')
have_mtls_dialect = true
break
endif
# -mtls-dialect=gnu2 speeds up non-initial-exec TLS significantly but requires
# full toolchain (including libc) support.
have_mtls_dialect = false
foreach c_arg : get_option('c_args')
if c_arg.startswith('-mtls-dialect=')
have_mtls_dialect = true
break
endif
endforeach
if not have_mtls_dialect
# need .run to check libc support. meson aborts when calling .run when
# cross-compiling, but because this is just an optimization we can skip it
if meson.is_cross_build()
warning('cannot auto-detect -mtls-dialect when cross-compiling, using compiler default')
else
# -fpic to force dynamic tls, otherwise TLS relaxation defeats check
gnu2_test = cc.run('int __thread x; int main() { return x; }', args: ['-mtls-dialect=gnu2', '-fpic'], name: '-mtls-dialect=gnu2')
if gnu2_test.returncode() == 0
c_args += '-mtls-dialect=gnu2'
cpp_args += '-mtls-dialect=gnu2'
endif
endforeach
if not have_mtls_dialect
# need .run to check libc support. meson aborts when calling .run when
# cross-compiling, but because this is just an optimization we can skip it
if meson.is_cross_build()
warning('cannot auto-detect -mtls-dialect when cross-compiling, using compiler default')
else
# -fpic to force dynamic tls, otherwise TLS relaxation defeats check
gnu2_test = cc.run('int __thread x; int main() { return x; }', args: ['-mtls-dialect=gnu2', '-fpic'], name: '-mtls-dialect=gnu2')
if gnu2_test.returncode() == 0
c_args += '-mtls-dialect=gnu2'
cpp_args += '-mtls-dialect=gnu2'
endif
endif
endif
if with_platform_windows and with_shared_glapi
# Windows doesn't support DLL exports/imports being TLS variables. When using shared
# glapi, libglapi.dll hosts the TLS, but other DLLs need to use them. Instead of falling
# all the way back to using globals and manual per-thread data, keep using TLS but just
# put accesses to it behind a function so the variable doesn't need to be exported.
pre_args += '-DUSE_TLS_BEHIND_FUNCTIONS'
endif
if with_glx != 'disabled'
if not (with_platform_x11 and with_any_opengl)
error('Cannot build GLX support without X11 platform support and at least one OpenGL API')

5
src/mapi/glapi/glapi.h
View File

@ -91,8 +91,13 @@ _GLAPI_EXPORT extern __THREAD_INITIAL_EXEC void * _glapi_tls_Context;
_GLAPI_EXPORT extern const struct _glapi_table *_glapi_Dispatch;
_GLAPI_EXPORT extern const void *_glapi_Context;
#if defined (USE_TLS_BEHIND_FUNCTIONS)
# define GET_DISPATCH() _glapi_get_dispatch()
# define GET_CURRENT_CONTEXT(C) struct gl_context *C = (struct gl_context *) _glapi_get_context()
#else
# define GET_DISPATCH() _glapi_tls_Dispatch
# define GET_CURRENT_CONTEXT(C) struct gl_context *C = (struct gl_context *) _glapi_tls_Context
#endif
#else