Add basic Webassembly support via Emscripten.

cross/wasm.txt

@@ -0,0 +1,19 @@
+[binaries]
+c = '/home/jpakkane/emsdk/fastcomp/emscripten/emcc'
+cpp = '/home/jpakkane/emsdk/fastcomp/emscripten/em++'
+ar = '/home/jpakkane/emsdk/fastcomp/emscripten/emar'
+
+[properties]
+
+c_args = ['-s', 'WASM=1', '-s', 'EXPORT_ALL=1']
+c_link_args = ['-s','EXPORT_ALL=1']
+cpp_args = ['-s', 'WASM=1', '-s', 'EXPORT_ALL=1']
+cpp_link_args = ['-s', 'EXPORT_ALL=1']
+
+[host_machine]
+
+system = 'emscripten'
+cpu_family = 'wasm32'
+cpu = 'wasm32'
+endian = 'little'
+

docs/markdown/Reference-tables.md

@@ -13,6 +13,7 @@ These are return values of the `get_id` (Compiler family) and
 | clang     | The Clang compiler               | gcc             |
 | clang-cl  | The Clang compiler (MSVC compatible driver) | msvc |
 | dmd       | D lang reference compiler        |                 |
+| emscripten| Emscripten WASM compiler         |                 |
 | flang     | Flang Fortran compiler           |                 |
 | g95       | The G95 Fortran compiler         |                 |
 | gcc       | The GNU Compiler Collection      | gcc             |
@@ -66,6 +67,8 @@ set in the cross file.
 | s390x               | IBM zSystem s390x     |
 | sparc               | 32 bit SPARC          |
 | sparc64             | SPARC v9 processor    |
+| wasm32              | 32 bit Webassembly    |
+| wasm64              | 64 bit Webassembly    |
 | x86                 | 32 bit x86 processor  |
 | x86_64              | 64 bit x86 processor  |
 
@@ -86,6 +89,7 @@ These are provided by the `.system()` method call.
 | cygwin              | The Cygwin environment for Windows |
 | darwin              | Either OSX or iOS |
 | dragonfly           | DragonFly BSD |
+| emscripten          | Emscripten's Javascript environment |
 | freebsd             | FreeBSD and its derivatives |
 | gnu                 | GNU Hurd |
 | haiku               | |

docs/markdown/snippets/wasm.md

@@ -0,0 +1,5 @@
+## Experimental Webassembly support via Emscripten
+
+Meson now supports compiling code to Webassembly using the Emscripten
+compiler. As with most things regarding Webassembly, this support is
+subject to change.

mesonbuild/build.py

@@ -1432,6 +1432,8 @@ class Executable(BuildTarget):
             # Executable for Windows or C#/Mono
             if machine.is_windows() or machine.is_cygwin() or 'cs' in self.compilers:
                 self.suffix = 'exe'
+            elif machine.system.startswith('wasm') or machine.system == 'emscripten':
+                self.suffix = 'js'
             elif ('c' in self.compilers and self.compilers['c'].get_id().startswith('arm') or
                   'cpp' in self.compilers and self.compilers['cpp'].get_id().startswith('arm')):
                 self.suffix = 'axf'

mesonbuild/compilers/__init__.py

@@ -126,6 +126,7 @@ from .c import (
     ClangClCCompiler,
     GnuCCompiler,
     ElbrusCCompiler,
+    EmscriptenCCompiler,
     IntelCCompiler,
     IntelClCCompiler,
     PGICCompiler,
@@ -140,6 +141,7 @@ from .cpp import (
     ClangClCPPCompiler,
     GnuCPPCompiler,
     ElbrusCPPCompiler,
+    EmscriptenCPPCompiler,
     IntelCPPCompiler,
     IntelClCPPCompiler,
     PGICPPCompiler,

mesonbuild/compilers/c.py

@@ -119,6 +119,31 @@ class ClangCCompiler(ClangCompiler, CCompiler):
         return basic
 
 
+class EmscriptenCCompiler(ClangCCompiler):
+    def __init__(self, exelist, version, compiler_type, for_machine: MachineChoice, is_cross, exe_wrapper=None, **kwargs):
+        if not is_cross:
+            raise MesonException('Emscripten compiler can only be used for cross compilation.')
+        ClangCCompiler.__init__(self, exelist, version, compiler_type, for_machine, is_cross, exe_wrapper, **kwargs)
+        self.id = 'emscripten'
+
+    def get_option_link_args(self, options):
+        return []
+
+    def get_linker_always_args(self):
+        return []
+
+    def get_asneeded_args(self):
+        return []
+
+    def get_lundef_args(self):
+        return []
+
+    def build_rpath_args(self, *args, **kwargs):
+        return []
+
+    def get_soname_args(self, *args, **kwargs):
+        raise MesonException('Emscripten does not support shared libraries.')
+
 class ArmclangCCompiler(ArmclangCompiler, CCompiler):
     def __init__(self, exelist, version, compiler_type, for_machine: MachineChoice, is_cross, exe_wrapper=None, **kwargs):
         CCompiler.__init__(self, exelist, version, for_machine, is_cross, exe_wrapper, **kwargs)

mesonbuild/compilers/compilers.py

@@ -1204,6 +1204,7 @@ class CompilerType(enum.Enum):
     CLANG_STANDARD = 10
     CLANG_OSX = 11
     CLANG_MINGW = 12
+    CLANG_EMSCRIPTEN = 13
     # Possibly clang-cl?
 
     ICC_STANDARD = 20

mesonbuild/compilers/cpp.py

@@ -131,7 +131,7 @@ class CPPCompiler(CLikeCompiler, Compiler):
         }
 
         # Currently, remapping is only supported for Clang, Elbrus and GCC
-        assert(self.id in frozenset(['clang', 'lcc', 'gcc']))
+        assert(self.id in frozenset(['clang', 'lcc', 'gcc', 'emscripten']))
 
         if cpp_std not in CPP_FALLBACKS:
             # 'c++03' and 'c++98' don't have fallback types
@@ -183,6 +183,39 @@ class ClangCPPCompiler(ClangCompiler, CPPCompiler):
         return ['-lstdc++']
 
 
+class EmscriptenCPPCompiler(ClangCPPCompiler):
+    def __init__(self, exelist, version, compiler_type, for_machine: MachineChoice, is_cross, exe_wrapper=None, **kwargs):
+        if not is_cross:
+            raise MesonException('Emscripten compiler can only be used for cross compilation.')
+        ClangCPPCompiler.__init__(self, exelist, version, compiler_type, for_machine, is_cross, exe_wrapper, **kwargs)
+        self.id = 'emscripten'
+
+    def get_option_compile_args(self, options):
+        args = []
+        std = options['cpp_std']
+        if std.value != 'none':
+            args.append(self._find_best_cpp_std(std.value))
+        return args
+
+    def get_option_link_args(self, options):
+        return []
+
+    def get_linker_always_args(self):
+        return []
+
+    def get_asneeded_args(self):
+        return []
+
+    def get_lundef_args(self):
+        return []
+
+    def build_rpath_args(self, *args, **kwargs):
+        return []
+
+    def get_soname_args(self, *args, **kwargs):
+        raise MesonException('Emscripten does not support shared libraries.')
+
+
 class ArmclangCPPCompiler(ArmclangCompiler, CPPCompiler):
     def __init__(self, exelist, version, compiler_type, for_machine: MachineChoice, is_cross, exe_wrapper=None, **kwargs):
         CPPCompiler.__init__(self, exelist, version, for_machine, is_cross, exe_wrapper, **kwargs)

mesonbuild/envconfig.py

@@ -53,6 +53,8 @@ known_cpu_families = (
     's390x',
     'sparc',
     'sparc64',
+    'wasm32',
+    'wasm64',
     'x86',
     'x86_64'
 )
@@ -66,6 +68,7 @@ CPU_FAMILES_64_BIT = [
     'ppc64',
     'riscv64',
     'sparc64',
+    'wasm64',
     'x86_64',
 ]
 

mesonbuild/environment.py

@@ -60,6 +60,8 @@ from .compilers import (
     ElbrusCCompiler,
     ElbrusCPPCompiler,
     ElbrusFortranCompiler,
+    EmscriptenCCompiler,
+    EmscriptenCPPCompiler,
     IntelCCompiler,
     IntelCPPCompiler,
     IntelClCCompiler,
@@ -707,6 +709,11 @@ class Environment:
                     cls = GnuCCompiler if lang == 'c' else GnuCPPCompiler
                 return cls(ccache + compiler, version, compiler_type, for_machine, is_cross, exe_wrap, defines, full_version=full_version)
 
+            if 'Emscripten' in out:
+                cls = EmscriptenCCompiler if lang == 'c' else EmscriptenCPPCompiler
+                compiler_type = CompilerType.CLANG_EMSCRIPTEN
+                return cls(ccache + compiler, version, compiler_type, for_machine, is_cross, exe_wrap, full_version=full_version)
+
             if 'armclang' in out:
                 # The compiler version is not present in the first line of output,
                 # instead it is present in second line, startswith 'Component:'.

mesonbuild/minstall.py

@@ -465,6 +465,13 @@ class Installer:
                     pdb_outname = os.path.splitext(outname)[0] + '.pdb'
                     self.do_copyfile(pdb_filename, pdb_outname)
                     set_mode(pdb_outname, install_mode, d.install_umask)
+                if fname.endswith('.js'):
+                    # Emscripten outputs js files and optionally a wasm file.
+                    # If one was generated, install it as well.
+                    wasm_source = os.path.splitext(fname)[0] + '.wasm'
+                    if os.path.exists(wasm_source):
+                        wasm_output = os.path.splitext(outname)[0] + '.wasm'
+                        self.do_copyfile(wasm_source, wasm_output)
             elif os.path.isdir(fname):
                 fname = os.path.join(d.build_dir, fname.rstrip('/'))
                 outname = os.path.join(outdir, os.path.basename(fname))

test cases/wasm/1 basic/hello.cpp

@@ -0,0 +1,7 @@
+#include<iostream>
+
+int main() {
+  std::cout << "Hello World" << std::endl;
+  return 0;
+}
+

test cases/wasm/1 basic/hello.html

@@ -0,0 +1,8 @@
+<html>
+  <head>
+    <meta charset="utf-8">
+  </head>
+  <body>
+    <script src="hello.js"></script>
+  </body>
+</html>

test cases/wasm/1 basic/meson.build

@@ -0,0 +1,3 @@
+project('emcctest', 'cpp')
+
+executable('hello', 'hello.cpp')