Merge branch 'tls-config-options' into 'master'

Add test coverage for TLS/TSD combinations

See merge request glvnd/libglvnd!251

.gitlab-ci.yml

@@ -84,7 +84,13 @@ build-x86_64-tsd-meson:
   extends:
     - .build-check-meson
   variables:
-    CONFIGURE_OPTIONS: -Dtls=disabled
+    CONFIGURE_OPTIONS: -Dtls=false
+
+build-x86_64-tsd-tls-meson:
+  extends:
+    - .build-check-meson
+  variables:
+    CONFIGURE_OPTIONS: -Ddispatch-tls=false
 
 build-i386-tsd:
   extends:
@@ -96,7 +102,13 @@ build-i386-tsd-meson:
   extends:
     - .build-check-meson
   variables:
-    CONFIGURE_OPTIONS: -Dtls=disabled --cross-file .gitlab-ci/i686-linux-gnu
+    CONFIGURE_OPTIONS: -Dtls=false --cross-file .gitlab-ci/i686-linux-gnu
+
+build-i386-tsd-tls-meson:
+  extends:
+    - .build-check-meson
+  variables:
+    CONFIGURE_OPTIONS: -Ddispatch-tls=false --cross-file .gitlab-ci/i686-linux-gnu
 
 build-pure-c-tls:
   extends:
@@ -120,4 +132,4 @@ build-pure-c-tld-meson:
   extends:
     - .build-check-meson
   variables:
-    CONFIGURE_OPTIONS: -Dasm=disabled -Dtls=disabled
+    CONFIGURE_OPTIONS: -Dasm=disabled -Dtls=false

meson.build

@@ -110,14 +110,17 @@ if cc.compiles('typeof(int *);', name : 'typeof')
 endif
 
 with_tls = get_option('tls')
-if with_tls.auto()
+if with_tls
+  # Use a __thread variable if possible, even if we can't use the TLS assembly
+  # stubs, because it's still faster than calling pthread_getspecific.
   have_tls = cc.compiles(
     '__thread int foo;',
     name : '__thread',
   )
 else
-  have_tls = with_tls.enabled()
+  have_tls = false
 endif
+message('Using TLS variable for dispatch table: @0@'.format(have_tls))
 
 if have_tls
   add_project_arguments('-DGLDISPATCH_USE_TLS', language : ['c'])
@@ -129,7 +132,15 @@ if use_asm
   # FreeBSD and glibc). on other platforms we use TSD stubs to allow calling
   # extension functions unknown at compile time.
   # https://gitlab.freedesktop.org/glvnd/libglvnd/-/merge_requests/249
-  thread_type = have_tls and (host_machine.system() == 'freebsd' or cc.has_header_symbol('features.h', '__GLIBC__')) ? 'tls' : 'tsd'
+  thread_type = 'tsd'
+  if get_option('dispatch-tls')
+    if have_tls
+      if host_machine.system() == 'freebsd' or cc.has_header_symbol('features.h', '__GLIBC__')
+        thread_type = 'tls'
+      endif
+    endif
+  endif
+
   if host_machine.cpu_family().startswith('x86')
     gl_dispatch_type = '@0@_@1@'.format(
       host_machine.cpu_family(),

meson_options.txt

@@ -56,8 +56,15 @@ option(
 )
 option(
   'tls',
-  type : 'feature',
-  description : 'Use Thread Local Storage.'
+  type : 'boolean',
+  value : true,
+  description : 'Use Thread Local Storage (if supported).'
+)
+option(
+  'dispatch-tls',
+  type : 'boolean',
+  value : true,
+  description : 'Use TLS-based stubs in libGLdispatch (if supported).'
 )
 option(
   'dispatch-page-size',