Merge pull request #91 from turbolent/improve-shared-memory

examples/pthreads/Makefile

@@ -0,0 +1,16 @@
+LDFLAGS += -lm -L../../wasi -lw2c2wasi -L../../futex -lw2c2futex
+CFLAGS += -O0 -g -DWASM_THREADS_PTHREADS
+W2C2 ?= ../../w2c2/w2c2
+
+pthreads: pthreads.o main.o
+	$(CC) $(CFLAGS) $^ -o pthreads $(LDFLAGS)
+
+%.c: src/%.wasm
+	$(W2C2) -g $< $@
+
+%.o: %.c
+	$(CC) -I../../w2c2 -c $(CFLAGS) $< -o $@
+
+.PHONY: clean
+clean:
+	rm -f *.o pthreads pthreads.h

examples/pthreads/main.c

@@ -0,0 +1,58 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "w2c2_base.h"
+#include "../../wasi/wasi.h"
+#include "pthreads.h"
+
+void
+trap(
+    Trap trap
+) {
+    fprintf(stderr, "TRAP: %s\n", trapDescription(trap));
+    abort();
+}
+
+
+wasmMemory*
+wasiMemory(
+    void* instance
+) {
+    return pthreads_memory((pthreadsInstance*)instance);
+}
+
+extern char** environ;
+
+wasmMemory* mem = NULL;
+
+void* resolveImport(const char* moduleName, const char* importName) {
+    if (strcmp(moduleName, "env") == 0 && strcmp(importName, "memory") == 0) {
+        return mem;
+    }
+    return NULL;
+}
+
+int main(int argc, char** argv) {
+    pthreadsInstance instance;
+
+    mem = WASM_MEMORY_ALLOCATE_SHARED(10, 20);
+
+    pthreadsInstantiate(&instance, resolveImport);
+
+    if (!wasiInit(argc, argv, environ)) {
+        fprintf(stderr, "failed to initialize WASI\n");
+        return 1;
+    }
+
+    if (!wasiFileDescriptorAdd(-1, "/", NULL)) {
+        fprintf(stderr, "failed to add preopen\n");
+        return 1;
+    }
+
+
+    pthreads__start(&instance);
+
+    pthreadsFreeInstance(&instance);
+
+    return 0;
+}

examples/pthreads/src/Makefile

@@ -0,0 +1,8 @@
+CC = ${WASI_SDK_PATH}/bin/clang
+
+pthreads.wasm: main.c
+	$(CC) --target=wasm32-wasi-threads --sysroot ${WASI_SDK_PATH}/share/wasi-sysroot -O0 -g -pthread -Wl,--import-memory,--export-memory,--max-memory=67108864 -o $@ $<
+
+.PHONY:
+clean:
+	rm pthreads.wasm

examples/pthreads/src/main.c

@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <pthread.h>
+
+#define NUM_THREADS 4
+#define NUM_ITER 10
+
+int g_count = 0;
+
+static void* thread(void *arg) {
+    printf("Entering thread\n");
+
+    for (int i = 0; i < NUM_ITER; i++) {
+        printf(
+            "Incremented counter: %d\n",
+            __atomic_add_fetch(&g_count, 1, __ATOMIC_SEQ_CST)
+        );
+    }
+
+    printf("Leaving thread\n");
+
+    return NULL;
+}
+
+int main(int argc, char **argv) {
+    pthread_t tids[NUM_THREADS];
+
+    printf("Starting threads\n");
+
+    for (int i = 0; i < NUM_THREADS; i++) {
+        if (pthread_create(&tids[i], NULL, thread, NULL) != 0) {
+            printf("Thread creation failed\n");
+        }
+    }
+
+    printf("Joining threads\n");
+
+    for (int i = 0; i < NUM_THREADS; i++) {
+        if (pthread_join(tids[i], NULL) != 0) {
+            printf("Thread join failed\n");
+        }
+    }
+
+    printf(
+        "Value of counter after update: %d (expected=%d)\n",
+        g_count,
+        NUM_THREADS * NUM_ITER
+    );
+    if (g_count != NUM_THREADS * NUM_ITER) {
+        __builtin_trap();
+    }
+
+    return 0;
+}

examples/threads/Makefile

@@ -9,7 +9,7 @@ else
 endif
 
 threads: threads.o main.o
-	$(CC) $^ -o threads $(LDFLAGS)
+	$(CC) $(CFLAGS) $^ -o threads $(LDFLAGS)
 
 %.c: src/%.wasm
 	$(W2C2) -g $< $@

futex/futex_test.c

@@ -56,7 +56,7 @@ testFutex(void) {
     TestThreadArg arg3;
     TestThreadArg arg4;
 
-    mem = wasmMemoryAllocateShared(1, 1);
+    mem = wasmMemoryAllocate(1, 1, true);
 
     /* Three threads will wait on waitAddress1,
      * one thread will wait on waitAddress2. */

tests/main.c

@@ -117,7 +117,7 @@ void printOK(const char* description) {
 }
 
 static void initTest() {
-    spectest_memory = wasmMemoryAllocate(1, 2);
+    spectest_memory = wasmMemoryAllocate(1, 2, false);
     spectest_shared_memory = WASM_MEMORY_ALLOCATE_SHARED(1, 2);
     wasmTableAllocate(&spectest_table, 10, 20);
 }

w2c2/c.c

@@ -5378,7 +5378,7 @@ wasmCWriteInitMemories(
                         fputs(indentation, file);
                     }
                     wasmCWriteFileMemoryUse(file, module, moduleMemoryIndex, NULL, true);
-                    fprintf(file, " = wasmMemoryAllocate(%u, %u);\n", memory.min, memory.max);
+                    fprintf(file, " = wasmMemoryAllocate(%u, %u, false);\n", memory.min, memory.max);
                 }
             }
         }

w2c2/w2c2_base.h

@@ -673,9 +673,10 @@ W2C2_INLINE
 wasmMemory*
 wasmMemoryAllocate(
     const U32 initialPages,
-    const U32 maxPages
+    const U32 maxPages,
+    const bool shared
 ) {
-    const U32 size = initialPages * WASM_PAGE_SIZE;
+    const U32 size = (shared ? maxPages : initialPages) * WASM_PAGE_SIZE;
     wasmMemory* memory = (wasmMemory*)calloc(1, sizeof(wasmMemory));
     if (!memory) {
         abort();
@@ -684,34 +685,24 @@ wasmMemoryAllocate(
     memory->size = size;
     memory->pages = initialPages;
     memory->maxPages = maxPages;
-    memory->shared = false;
+    memory->shared = shared;
     memory->futex = NULL;
     memory->futexFree = NULL;
-    return memory;
-}
-
-static
-W2C2_INLINE
-wasmMemory*
-wasmMemoryAllocateShared(
-    const U32 initialPages,
-    const U32 maxPages
-) {
-    wasmMemory* memory = wasmMemoryAllocate(initialPages, maxPages);
-    memory->shared = true;
+    if (shared) {
 #ifdef WASM_MUTEX_TYPE
-    if (!WASM_MUTEX_INIT(&memory->mutex)) {
-        abort();
-    }
+        if (!WASM_MUTEX_INIT(&memory->mutex)) {
+            abort();
+        }
 #else
-    abort();
+        abort();
 #endif
+    }
     return memory;
 }
 
 #ifdef WASM_MUTEX_TYPE
 #define WASM_MEMORY_ALLOCATE_SHARED(initialPages, maxPages) \
-    wasmMemoryAllocateShared(initialPages, maxPages)
+    wasmMemoryAllocate(initialPages, maxPages, true)
 #else
 #define WASM_MEMORY_ALLOCATE_SHARED(initialPages, maxPages) \
     (_Pragma ("GCC error \"Shared memory not supported. Please define a threads implementation to use (WASM_THREADS_*)\"") NULL)
@@ -748,6 +739,8 @@ wasmMemoryGrow(
     wasmMemory* memory,
     const U32 delta
 ) {
+    bool doRealloc = true;
+
     const U32 oldPages = memory->pages;
     const U32 newPages = memory->pages + delta;
 
@@ -759,19 +752,39 @@ wasmMemoryGrow(
         return (U32) -1;
     }
 
+    if (memory->shared) {
+        doRealloc = false;
+#ifdef WASM_MUTEX_TYPE
+        WASM_MUTEX_LOCK(&memory->mutex);
+#else
+        abort();
+#endif
+    }
+
     {
-        const U32 oldSize = oldPages * WASM_PAGE_SIZE;
         const U32 newSize = newPages * WASM_PAGE_SIZE;
-        const U32 deltaSize = delta * WASM_PAGE_SIZE;
-        U8* newData = (U8*)realloc(memory->data, newSize);
-        if (newData == NULL) {
-            return (U32) -1;
+        if (doRealloc) {
+            const U32 oldSize = oldPages * WASM_PAGE_SIZE;
+            const U32 deltaSize = delta * WASM_PAGE_SIZE;
+            U8* newData = (U8*)realloc(memory->data, newSize);
+            if (newData == NULL) {
+                return (U32) -1;
+            }
+
+            memset(newData + oldSize, 0, deltaSize);
+            memory->data = newData;
         }
 
-        memset(newData + oldSize, 0, deltaSize);
         memory->pages = newPages;
         memory->size = newSize;
-        memory->data = newData;
+    }
+
+    if (memory->shared) {
+#ifdef WASM_MUTEX_TYPE
+        WASM_MUTEX_UNLOCK(&memory->mutex);
+#else
+        abort();
+#endif
     }
 
     return oldPages;