Refactor stub pthread library and enable unconditionally.

This commit changes the layout of the stub pthread library to match
that of libc-top-half: splits it into (mostly) one file per function,
and ensures the same API is exposed from both libraries, adding stub
functions as necessary.

This commit also removes `-lwasi-emulated-pthread` as well as
`-D_WASI_EMULATED_PTHREAD` and enables this functionality
unconditionally, seeing as this is necessary for building libc++ with
threading enabled.

It adds a flag `-D_WASI_STRICT_PTHREAD` that causes thread creation
functions (`pthread_create`, `pthread_detach`, `pthread_join`) to
be defined as a macro causing a compile error, which can be used to
locate the parts of a codebase requiring changes for the single thread
model.

Specifically, after this commit, the two targets `wasm32-wasip1` and
`wasm32-wasip1-threads` differ as follows (cleaned up for clarity):

    --- expected/wasm32-wasip1/defined-symbols.txt
    +++ expected/wasm32-wasip1-threads/defined-symbols.txt
    +flockfile
    +ftrylockfile
    +funlockfile
    +sem_destroy
    +sem_getvalue
    +sem_init
    +sem_post
    +sem_timedwait
    +sem_trywait
    +sem_wait
    +thrd_detach
    +wasi_thread_start

    --- expected/wasm32-wasip1/predefined-macros.txt
    +++ expected/wasm32-wasip1-threads/predefined-macros.txt
    +#define _REENTRANT 1
    +#define SEM_NSEMS_MAX 256
    +#define SEM_VALUE_MAX 0x7fffffff
    +#define __wasm_atomics__ 1
    +#define __wasm_bulk_memory__ 1

Author: whitequark

Makefile

@@ -71,7 +71,7 @@ DLMALLOC_SOURCES = $(DLMALLOC_SRC_DIR)/dlmalloc.c
 DLMALLOC_INC = $(DLMALLOC_DIR)/include
 EMMALLOC_DIR = emmalloc
 EMMALLOC_SOURCES = $(EMMALLOC_DIR)/emmalloc.c
-STUB_PTHREADS_DIR = stub-pthreads
+THREAD_STUB_DIR = thread-stub
 LIBC_BOTTOM_HALF_DIR = libc-bottom-half
 LIBC_BOTTOM_HALF_CLOUDLIBC_SRC = $(LIBC_BOTTOM_HALF_DIR)/cloudlibc/src
 LIBC_BOTTOM_HALF_CLOUDLIBC_SRC_INC = $(LIBC_BOTTOM_HALF_CLOUDLIBC_SRC)/include
@@ -138,8 +138,6 @@ LIBWASI_EMULATED_SIGNAL_SOURCES = \
 LIBWASI_EMULATED_SIGNAL_MUSL_SOURCES = \
     $(LIBC_TOP_HALF_MUSL_SRC_DIR)/signal/psignal.c \
     $(LIBC_TOP_HALF_MUSL_SRC_DIR)/string/strsignal.c
-LIBWASI_EMULATED_PTHREAD_SOURCES = \
-    $(STUB_PTHREADS_DIR)/stub-pthreads-emulated.c
 LIBDL_SOURCES = $(LIBC_TOP_HALF_MUSL_SRC_DIR)/misc/dl.c
 LIBSETJMP_SOURCES = $(LIBC_TOP_HALF_MUSL_SRC_DIR)/setjmp/wasm32/rt.c
 LIBC_BOTTOM_HALF_CRT_SOURCES = $(wildcard $(LIBC_BOTTOM_HALF_DIR)/crt/*.c)
@@ -373,12 +371,38 @@ endif
 ifeq ($(THREAD_MODEL), single)
 # pthreads stubs for single-threaded environment
 LIBC_TOP_HALF_MUSL_SOURCES += \
-    $(STUB_PTHREADS_DIR)/barrier.c \
-    $(STUB_PTHREADS_DIR)/condvar.c \
-    $(STUB_PTHREADS_DIR)/mutex.c \
-    $(STUB_PTHREADS_DIR)/rwlock.c \
-    $(STUB_PTHREADS_DIR)/spinlock.c \
-    $(STUB_PTHREADS_DIR)/stub-pthreads-good.c
+    $(addprefix $(THREAD_STUB_DIR)/, \
+        pthread_barrier_destroy.c \
+        pthread_barrier_init.c \
+        pthread_barrier_wait.c \
+        pthread_cond_broadcast.c \
+        pthread_cond_destroy.c \
+        pthread_cond_init.c \
+        pthread_cond_signal.c \
+        pthread_cond_timedwait.c \
+        pthread_cond_wait.c \
+        pthread_create.c \
+        pthread_detach.c \
+        pthread_getattr_np.c \
+        pthread_join.c \
+        pthread_mutex_consistent.c \
+        pthread_mutex_getprioceiling.c \
+        pthread_mutex_lock.c \
+        pthread_mutex_timedlock.c \
+        pthread_mutex_trylock.c \
+        pthread_mutex_unlock.c \
+        pthread_once.c \
+        pthread_rwlock_rdlock.c \
+        pthread_rwlock_timedrdlock.c \
+        pthread_rwlock_timedwrlock.c \
+        pthread_rwlock_tryrdlock.c \
+        pthread_rwlock_trywrlock.c \
+        pthread_rwlock_unlock.c \
+        pthread_rwlock_wrlock.c \
+        pthread_spin_lock.c \
+        pthread_spin_trylock.c \
+        pthread_spin_unlock.c \
+    )
 endif
 
 MUSL_PRINTSCAN_SOURCES = \
@@ -505,7 +529,6 @@ LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS = $(call objs,$(LIBWASI_EMULATED_PROCESS_CL
 LIBWASI_EMULATED_GETPID_OBJS = $(call objs,$(LIBWASI_EMULATED_GETPID_SOURCES))
 LIBWASI_EMULATED_SIGNAL_OBJS = $(call objs,$(LIBWASI_EMULATED_SIGNAL_SOURCES))
 LIBWASI_EMULATED_SIGNAL_MUSL_OBJS = $(call objs,$(LIBWASI_EMULATED_SIGNAL_MUSL_SOURCES))
-LIBWASI_EMULATED_PTHREAD_OBJS = $(call objs,$(LIBWASI_EMULATED_PTHREAD_SOURCES))
 LIBDL_OBJS = $(call objs,$(LIBDL_SOURCES))
 LIBSETJMP_OBJS = $(call objs,$(LIBSETJMP_SOURCES))
 LIBC_BOTTOM_HALF_CRT_OBJS = $(call objs,$(LIBC_BOTTOM_HALF_CRT_SOURCES))
@@ -529,7 +552,6 @@ LIBWASI_EMULATED_PROCESS_CLOCKS_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULA
 LIBWASI_EMULATED_GETPID_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_GETPID_OBJS))
 LIBWASI_EMULATED_SIGNAL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_SIGNAL_OBJS))
 LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS))
-LIBWASI_EMULATED_PTHREAD_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_PTHREAD_OBJS))
 LIBDL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBDL_OBJS))
 LIBSETJMP_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBSETJMP_OBJS))
 BULK_MEMORY_SO_OBJS = $(patsubst %.o,%.pic.o,$(BULK_MEMORY_OBJS))
@@ -546,7 +568,6 @@ PIC_OBJS = \
 	$(LIBWASI_EMULATED_GETPID_SO_OBJS) \
 	$(LIBWASI_EMULATED_SIGNAL_SO_OBJS) \
 	$(LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS) \
-	$(LIBWASI_EMULATED_PTHREAD_SO_OBJS) \
 	$(LIBDL_SO_OBJS) \
 	$(LIBSETJMP_SO_OBJS) \
 	$(BULK_MEMORY_SO_OBJS) \
@@ -646,8 +667,6 @@ $(OBJDIR)/libwasi-emulated-getpid.so.a: $(LIBWASI_EMULATED_GETPID_SO_OBJS)
 
 $(OBJDIR)/libwasi-emulated-signal.so.a: $(LIBWASI_EMULATED_SIGNAL_SO_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS)
 
-$(OBJDIR)/libwasi-emulated-pthread.so.a: $(LIBWASI_EMULATED_PTHREAD_SO_OBJS)
-
 $(OBJDIR)/libdl.so.a: $(LIBDL_SO_OBJS)
 
 $(OBJDIR)/libsetjmp.so.a: $(LIBSETJMP_SO_OBJS)
@@ -666,8 +685,6 @@ $(SYSROOT_LIB)/libwasi-emulated-getpid.a: $(LIBWASI_EMULATED_GETPID_OBJS)
 
 $(SYSROOT_LIB)/libwasi-emulated-signal.a: $(LIBWASI_EMULATED_SIGNAL_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS)
 
-$(SYSROOT_LIB)/libwasi-emulated-pthread.a: $(LIBWASI_EMULATED_PTHREAD_OBJS)
-
 $(SYSROOT_LIB)/libdl.a: $(LIBDL_OBJS)
 
 $(SYSROOT_LIB)/libsetjmp.a: $(LIBSETJMP_OBJS)
@@ -770,12 +787,6 @@ $(FTS_OBJS) $(FTS_SO_OBJS): CFLAGS += \
 $(LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS) $(LIBWASI_EMULATED_PROCESS_CLOCKS_SO_OBJS): CFLAGS += \
     -I$(LIBC_BOTTOM_HALF_CLOUDLIBC_SRC)
 
-$(LIBWASI_EMULATED_PTHREAD_OBJS) $(LIBWASI_EMULATED_PTHREAD_SO_OBJS): CFLAGS += \
-    -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/include \
-    -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/internal \
-    -I$(LIBC_TOP_HALF_MUSL_DIR)/arch/wasm32 \
-    -D_WASI_EMULATED_PTHREAD
-
 # emmalloc uses a lot of pointer type-punning, which is UB under strict aliasing,
 # and this was found to have real miscompilations in wasi-libc#421.
 $(EMMALLOC_OBJS): CFLAGS += \
@@ -816,7 +827,6 @@ LIBC_SO = \
 	$(SYSROOT_LIB)/libwasi-emulated-process-clocks.so \
 	$(SYSROOT_LIB)/libwasi-emulated-getpid.so \
 	$(SYSROOT_LIB)/libwasi-emulated-signal.so \
-	$(SYSROOT_LIB)/libwasi-emulated-pthread.so \
 	$(SYSROOT_LIB)/libdl.so
 ifeq ($(BUILD_LIBSETJMP),yes)
 LIBC_SO += \
@@ -835,10 +845,6 @@ STATIC_LIBS = \
     $(SYSROOT_LIB)/libwasi-emulated-getpid.a \
     $(SYSROOT_LIB)/libwasi-emulated-signal.a \
     $(SYSROOT_LIB)/libdl.a
-ifneq ($(THREAD_MODEL), posix)
-    STATIC_LIBS += \
-        $(SYSROOT_LIB)/libwasi-emulated-pthread.a
-endif
 ifeq ($(BUILD_LIBSETJMP),yes)
 STATIC_LIBS += \
 	$(SYSROOT_LIB)/libsetjmp.a

expected/wasm32-wasip1/defined-symbols.txt

@@ -182,15 +182,14 @@ __progname
 __progname_full
 __pthread_cond_timedwait
 __pthread_create
-__pthread_detach
 __pthread_join
 __pthread_key_create
 __pthread_key_delete
-__pthread_mutex_consistent
 __pthread_mutex_lock
 __pthread_mutex_timedlock
 __pthread_mutex_trylock
 __pthread_mutex_unlock
+__pthread_once
 __pthread_rwlock_rdlock
 __pthread_rwlock_timedrdlock
 __pthread_rwlock_timedwrlock
@@ -991,13 +990,14 @@ pthread_condattr_setpshared
 pthread_create
 pthread_detach
 pthread_equal
-pthread_exit
+pthread_getattr_np
 pthread_getspecific
 pthread_join
 pthread_key_create
 pthread_key_delete
 pthread_mutex_consistent
 pthread_mutex_destroy
+pthread_mutex_getprioceiling
 pthread_mutex_init
 pthread_mutex_lock
 pthread_mutex_timedlock