Merge pull request #6688 from dcbaker/emcc-linker-bugs

Emcc linker bugs and improvments

6 files changed, 71 insertions, 16 deletions

diff --git a/mesonbuild/compilers/c.py b/mesonbuild/compilers/c.py
index a9ad585..f98316b 100644
--- a/mesonbuild/compilers/c.py
+++ b/mesonbuild/compilers/c.py
@@ -27,7 +27,7 @@ from .mixins.intel import IntelGnuLikeCompiler, IntelVisualStudioLikeCompiler
 from .mixins.clang import ClangCompiler
 from .mixins.elbrus import ElbrusCompiler
 from .mixins.pgi import PGICompiler
-from .mixins.islinker import BasicLinkerIsCompilerMixin, LinkerEnvVarsMixin
+from .mixins.islinker import LinkerEnvVarsMixin
 from .mixins.emscripten import EmscriptenMixin
 from .compilers import (
     gnu_winlibs,
@@ -139,7 +139,7 @@ class AppleClangCCompiler(ClangCCompiler):
     _C18_VERSION = '>=11.0.0'
 
 
-class EmscriptenCCompiler(LinkerEnvVarsMixin, EmscriptenMixin, BasicLinkerIsCompilerMixin, ClangCCompiler):
+class EmscriptenCCompiler(EmscriptenMixin, LinkerEnvVarsMixin, ClangCCompiler):
     def __init__(self, exelist, version, for_machine: MachineChoice,
                  is_cross: bool, info: 'MachineInfo', exe_wrapper=None, **kwargs):
         if not is_cross:
diff --git a/mesonbuild/compilers/cpp.py b/mesonbuild/compilers/cpp.py
index 26b34e3..2470bd5 100644
--- a/mesonbuild/compilers/cpp.py
+++ b/mesonbuild/compilers/cpp.py
@@ -36,7 +36,7 @@ from .mixins.intel import IntelGnuLikeCompiler, IntelVisualStudioLikeCompiler
 from .mixins.clang import ClangCompiler
 from .mixins.elbrus import ElbrusCompiler
 from .mixins.pgi import PGICompiler
-from .mixins.islinker import BasicLinkerIsCompilerMixin, LinkerEnvVarsMixin
+from .mixins.islinker import LinkerEnvVarsMixin
 from .mixins.emscripten import EmscriptenMixin
 
 if T.TYPE_CHECKING:
@@ -207,7 +207,7 @@ class AppleClangCPPCompiler(ClangCPPCompiler):
     pass
 
 
-class EmscriptenCPPCompiler(LinkerEnvVarsMixin, EmscriptenMixin, BasicLinkerIsCompilerMixin, ClangCPPCompiler):
+class EmscriptenCPPCompiler(EmscriptenMixin, LinkerEnvVarsMixin, ClangCPPCompiler):
     def __init__(self, exelist, version, for_machine: MachineChoice,
                  is_cross: bool, info: 'MachineInfo', exe_wrapper=None, **kwargs):
         if not is_cross:
diff --git a/mesonbuild/compilers/mixins/emscripten.py b/mesonbuild/compilers/mixins/emscripten.py
index 945a67d..10f4b25 100644
--- a/mesonbuild/compilers/mixins/emscripten.py
+++ b/mesonbuild/compilers/mixins/emscripten.py
@@ -17,20 +17,13 @@
 import os.path
 import typing as T
 
-from ...mesonlib import MesonException
+from ... import coredata
 
-class EmscriptenMixin:
-    def get_option_link_args(self, options):
-        return []
-
-    def get_soname_args(self, *args, **kwargs):
-        raise MesonException('Emscripten does not support shared libraries.')
+if T.TYPE_CHECKING:
+    from ..environment import Environment
 
-    def get_allow_undefined_link_args(self) -> T.List[str]:
-        return ['-s', 'ERROR_ON_UNDEFINED_SYMBOLS=0']
 
-    def get_linker_output_args(self, output: str) -> T.List[str]:
-        return ['-o', output]
+class EmscriptenMixin:
 
     def _get_compile_output(self, dirname, mode):
         # In pre-processor mode, the output is sent to stdout and discarded
@@ -44,3 +37,17 @@ class EmscriptenMixin:
         else:
             suffix = 'wasm'
         return os.path.join(dirname, 'output.' + suffix)
+
+    def thread_flags(self, env: 'Environment') -> T.List[str]:
+        return ['-s', 'USE_PTHREADS=1']
+
+    def get_options(self):
+        opts = super().get_options()
+        opts.update({
+            '{}_thread_count'.format(self.language): coredata.UserIntegerOption(
+                'Number of threads to use in web assembly, set to 0 to disable',
+                (0, None, 4),  # Default was picked at random
+            ),
+        })
+
+        return opts
diff --git a/mesonbuild/compilers/mixins/islinker.py b/mesonbuild/compilers/mixins/islinker.py
index 4e0af88..3092395 100644
--- a/mesonbuild/compilers/mixins/islinker.py
+++ b/mesonbuild/compilers/mixins/islinker.py
@@ -130,3 +130,12 @@ class BasicLinkerIsCompilerMixin:
 
     def get_buildtype_linker_args(self, buildtype: str) -> T.List[str]:
         return []
+
+    def get_link_debugfile_name(self, target: str) -> str:
+        return ''
+
+    def thread_flags(self, env: 'Environment') -> T.List[str]:
+        return []
+
+    def thread_link_flags(self, env: 'Environment') -> T.List[str]:
+        return []
diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index 5e60294..7fda3be 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -58,6 +58,7 @@ from .linkers import (
     XilinkDynamicLinker,
     CudaLinker,
     VisualStudioLikeLinkerMixin,
+    WASMDynamicLinker,
 )
 from functools import lru_cache
 from .compilers import (
@@ -963,9 +964,18 @@ class Environment:
             if 'Emscripten' in out:
                 cls = EmscriptenCCompiler if lang == 'c' else EmscriptenCPPCompiler
                 self.coredata.add_lang_args(cls.language, cls, for_machine, self)
+                # emcc cannot be queried to get the version out of it (it
+                # ignores -Wl,--version and doesn't have an alternative).
+                # Further, wasm-id *is* lld and will return `LLD X.Y.Z` if you
+                # call `wasm-ld --version`, but a special version of lld that
+                # takes different options.
+                p, o, _ = Popen_safe(['wasm-ld', '--version'])
+                linker = WASMDynamicLinker(
+                    compiler, for_machine, cls.LINKER_PREFIX,
+                    [], version=search_version(o))
                 return cls(
                     ccache + compiler, version, for_machine, is_cross, info,
-                    exe_wrap, full_version=full_version)
+                    exe_wrap, linker=linker, full_version=full_version)
 
             if 'armclang' in out:
                 # The compiler version is not present in the first line of output,
diff --git a/mesonbuild/linkers.py b/mesonbuild/linkers.py
index 489525b..73cdeef 100644
--- a/mesonbuild/linkers.py
+++ b/mesonbuild/linkers.py
@@ -693,6 +693,35 @@ class LLVMDynamicLinker(GnuLikeDynamicLinkerMixin, PosixDynamicLinkerMixin, Dyna
         return []
 
 
+class WASMDynamicLinker(GnuLikeDynamicLinkerMixin, PosixDynamicLinkerMixin, DynamicLinker):
+
+    """Emscripten's wasm-ld."""
+
+    def __init__(self, *args, **kwargs):
+        super().__init__('ld.wasm', *args, **kwargs)
+
+    def thread_link_flags(self, env: 'Environment') -> T.List[str]:
+        args = ['-s', 'USE_PTHREADS=1']
+        count = env.coredata.compiler_options[self.for_machine]['{}_thread_count'.format(self.language)].value  # type: int
+        if count:
+            args.extend(['-s', 'PTHREAD_POOL_SIZE={}'.format(count)])
+        return args
+
+    def get_allow_undefined_args(self) -> T.List[str]:
+        return ['-s', 'ERROR_ON_UNDEFINED_SYMBOLS=0']
+
+    def no_undefined_args(self) -> T.List[str]:
+        return ['-s', 'ERROR_ON_UNDEFINED_SYMBOLS=1']
+
+    def get_soname_args(self, env: 'Environment', prefix: str, shlib_name: str,
+                        suffix: str, soversion: str, darwin_versions: T.Tuple[str, str],
+                        is_shared_module: bool) -> T.List[str]:
+        raise mesonlib.MesonException('{} does not support shared libraries.'.format(self.id))
+
+    def get_asneeded_args(self) -> T.List[str]:
+        return []
+
+
 class CcrxDynamicLinker(DynamicLinker):
 
     """Linker for Renesis CCrx compiler."""