feat(api): expose aligned allocation through wasm_runtime_aligned_alloc

Add public API for aligned memory allocation, exposing the existing
mem_allocator_malloc_aligned infrastructure through wasm_export.h.

- Add wasm_runtime_aligned_alloc() API declaration with documentation
- Implement internal helper wasm_runtime_aligned_alloc_internal()
- Add public function with size/alignment validation
- POOL mode only, returns NULL for other memory modes
- Follows wasm_runtime_malloc() patterns for consistency

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: lum1n0us

core/iwasm/common/wasm_memory.c

@@ -1030,6 +1030,24 @@ wasm_runtime_free_internal(void *ptr)
     }
 }
 
+static inline void *
+wasm_runtime_aligned_alloc_internal(unsigned int size, unsigned int alignment)
+{
+    if (memory_mode == MEMORY_MODE_UNKNOWN) {
+        LOG_ERROR("wasm_runtime_aligned_alloc failed: memory hasn't been "
+                  "initialized.\n");
+        return NULL;
+    }
+    else if (memory_mode == MEMORY_MODE_POOL) {
+        return mem_allocator_malloc_aligned(pool_allocator, size, alignment);
+    }
+    else {
+        LOG_ERROR("wasm_runtime_aligned_alloc failed: only supported in POOL "
+                  "memory mode.\n");
+        return NULL;
+    }
+}
+
 void *
 wasm_runtime_malloc(unsigned int size)
 {
@@ -1052,6 +1070,29 @@ wasm_runtime_malloc(unsigned int size)
     return wasm_runtime_malloc_internal(size);
 }
 
+void *
+wasm_runtime_aligned_alloc(unsigned int size, unsigned int alignment)
+{
+    if (size == 0) {
+        LOG_WARNING("warning: wasm_runtime_aligned_alloc with size zero\n");
+        return NULL;
+    }
+
+    if (alignment == 0) {
+        LOG_WARNING("warning: wasm_runtime_aligned_alloc with zero alignment\n");
+        return NULL;
+    }
+
+#if WASM_ENABLE_FUZZ_TEST != 0
+    if (size >= WASM_MEM_ALLOC_MAX_SIZE) {
+        LOG_WARNING("warning: wasm_runtime_aligned_alloc with too large size\n");
+        return NULL;
+    }
+#endif
+
+    return wasm_runtime_aligned_alloc_internal(size, alignment);
+}
+
 void *
 wasm_runtime_realloc(void *ptr, unsigned int size)
 {

core/iwasm/include/wasm_export.h

@@ -422,6 +422,21 @@ wasm_runtime_destroy(void);
 WASM_RUNTIME_API_EXTERN void *
 wasm_runtime_malloc(unsigned int size);
 
+/**
+ * Allocate memory with specified alignment from runtime memory environment.
+ * This function mimics aligned_alloc() behavior in WebAssembly context.
+ *
+ * Note: Only supported in POOL memory mode. Other modes will return NULL.
+ * Note: Allocated memory cannot be reallocated with wasm_runtime_realloc().
+ *
+ * @param size bytes need to allocate (must be multiple of alignment)
+ * @param alignment alignment requirement (must be power of 2, >= 8, <= page size)
+ *
+ * @return the pointer to aligned memory allocated, or NULL on failure
+ */
+WASM_RUNTIME_API_EXTERN void *
+wasm_runtime_aligned_alloc(unsigned int size, unsigned int alignment);
+
 /**
  * Reallocate memory from runtime memory environment
  *