From a34439de42266b9d88de869460be9b5dc1c7fb20 Mon Sep 17 00:00:00 2001
From: vms <michail.vms@gmail.com>
Date: Fri, 25 Oct 2019 01:56:04 +0300
Subject: [PATCH] optimize memory.grow 0 (#443)

---
 wasmtime-runtime/src/memory.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/wasmtime-runtime/src/memory.rs b/wasmtime-runtime/src/memory.rs
index 121cbc34a2..fca4b384be 100644
--- a/wasmtime-runtime/src/memory.rs
+++ b/wasmtime-runtime/src/memory.rs
@@ -80,6 +80,11 @@ impl LinearMemory {
     /// Returns `None` if memory can't be grown by the specified amount
     /// of wasm pages.
     pub fn grow(&mut self, delta: u32) -> Option<u32> {
+        // Optimization of memory.grow 0 calls.
+        if delta == 0 {
+            return Some(self.current);
+        }
+
         let new_pages = match self.current.checked_add(delta) {
             Some(new_pages) => new_pages,
             // Linear memory size overflow.