Wasm shared heap about wasm-micro-runtime

[lum1n0us]

Would u mind giving us, the community, a quick introduction about:

• What's shared heap?
• What kind of questions does shared heap try to answer?
• Is there any other options? And why we choose shared heap?

[wenyongh]

@WenLY1 Many people may not know the background and the design details of the shared heap, I submitted issue #3546 to try to illustrate that, suggest you to post tasks in that issue to track and discuss instead.

[WenLY1]

If wasm shared heap is enable, should the boundary check keep enabled ? In the following code, if bounds checks is disabled, should we return the offset directly or judge whether the addr is in shared heap?
In function wasm_runtime_addr_native_to_app

    if (bounds_checks) {
        if (memory_inst->memory_data <= addr && addr < memory_inst->memory_data_end) {
            ret = (uint64)(addr - memory_inst->memory_data);
            SHARED_MEMORY_UNLOCK(memory_inst);
            return ret;
        }
    }
    /* If bounds checks is disabled, return the offset directly */
    else if (addr != NULL) {
        ret = (uint64)(addr - memory_inst->memory_data);
        SHARED_MEMORY_UNLOCK(memory_inst);
        return ret;
    }