[WebAssembly] WASI support for libcxx

This adds explicit support for the WASI platform to libcxx.

WASI libc uses some components from musl, however it's not fully compatible
with musl, so we're planning to stop using _LIBCPP_HAS_MUSL_LIBC and
customize for WASI libc specifically.

Differential Revision: https://reviews.llvm.org/D61336

Reviewers: sbc100, ldionne


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@359703 91177308-0d34-0410-b5e6-96231b3b80d8

include/__config

@@ -307,7 +307,7 @@
    // random data even when using sandboxing mechanisms such as chroots,
    // Capsicum, etc.
 #  define _LIBCPP_USING_ARC4_RANDOM
-#elif defined(__Fuchsia__)
+#elif defined(__Fuchsia__) || defined(__wasi__)
 #  define _LIBCPP_USING_GETENTROPY
 #elif defined(__native_client__)
    // NaCl's sandbox (which PNaCl also runs in) doesn't allow filesystem access,
@@ -341,7 +341,7 @@
 #  if defined(__FreeBSD__)
 #    define _LIBCPP_HAS_QUICK_EXIT
 #    define _LIBCPP_HAS_C11_FEATURES
-#  elif defined(__Fuchsia__)
+#  elif defined(__Fuchsia__) || defined(__wasi__)
 #    define _LIBCPP_HAS_QUICK_EXIT
 #    define _LIBCPP_HAS_TIMESPEC_GET
 #    define _LIBCPP_HAS_C11_FEATURES
@@ -1133,6 +1133,7 @@ _LIBCPP_FUNC_VIS extern "C" void __sanitizer_annotate_contiguous_container(
     !defined(_LIBCPP_HAS_THREAD_API_EXTERNAL)
 #  if defined(__FreeBSD__) || \
       defined(__Fuchsia__) || \
+      defined(__wasi__) || \
       defined(__NetBSD__) || \
       defined(__linux__) || \
       defined(__GNU__) || \
@@ -1179,7 +1180,7 @@ _LIBCPP_FUNC_VIS extern "C" void __sanitizer_annotate_contiguous_container(
 #endif
 
 #if defined(__BIONIC__) || defined(__CloudABI__) ||                            \
-    defined(__Fuchsia__) || defined(_LIBCPP_HAS_MUSL_LIBC)
+    defined(__Fuchsia__) || defined(__wasi__) || defined(_LIBCPP_HAS_MUSL_LIBC)
 #define _LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE
 #endif
 

include/__locale

@@ -35,6 +35,9 @@
 # include <xlocale.h>
 #elif defined(__Fuchsia__)
 # include <support/fuchsia/xlocale.h>
+#elif defined(__wasi__)
+// WASI libc uses musl's locales support.
+# include <support/musl/xlocale.h>
 #elif defined(_LIBCPP_HAS_MUSL_LIBC)
 # include <support/musl/xlocale.h>
 #endif

src/include/config_elast.h

@@ -23,6 +23,8 @@
 #define _LIBCPP_ELAST __ELASTERROR
 #elif defined(__Fuchsia__)
 // No _LIBCPP_ELAST needed on Fuchsia
+#elif defined(__wasi__)
+// No _LIBCPP_ELAST needed on WASI
 #elif defined(__linux__) || defined(_LIBCPP_HAS_MUSL_LIBC)
 #define _LIBCPP_ELAST 4095
 #elif defined(__APPLE__)

src/thread.cpp

@@ -23,9 +23,9 @@
 # endif
 #endif // defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 
-#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__)) || defined(__CloudABI__) || defined(__Fuchsia__)
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__)) || defined(__CloudABI__) || defined(__Fuchsia__) || defined(__wasi__)
 # include <unistd.h>
-#endif // defined(__unix__) || (defined(__APPLE__) && defined(__MACH__)) || defined(__CloudABI__) || defined(__Fuchsia__)
+#endif // defined(__unix__) || (defined(__APPLE__) && defined(__MACH__)) || defined(__CloudABI__) || defined(__Fuchsia__) || defined(__wasi__)
 
 #if defined(__NetBSD__)
 #pragma weak pthread_create // Do not create libpthread dependency

test/support/test_macros.h

@@ -148,7 +148,7 @@
 //  Specifically, FreeBSD does NOT have timespec_get, even though they have all
 //  the rest of C11 - this is PR#38495
 #    define TEST_HAS_C11_FEATURES
-#  elif defined(__Fuchsia__)
+#  elif defined(__Fuchsia__) || defined(__wasi__)
 #    define TEST_HAS_C11_FEATURES
 #    define TEST_HAS_TIMESPEC_GET
 #  elif defined(__linux__)