[wasm] Implement GrowMemory in the wasm interpreter

src/wasm/wasm-interpreter.cc

Index: src/wasm/wasm-interpreter.cc
diff --git a/src/wasm/wasm-interpreter.cc b/src/wasm/wasm-interpreter.cc
index 17ca6111e3a5e947570491f32a4102a5d7383440..94b385033d5110f94692c7fde2978eb63ed93f43 100644
--- a/src/wasm/wasm-interpreter.cc
+++ b/src/wasm/wasm-interpreter.cc
@@ -654,6 +654,45 @@ static inline int64_t ExecuteI64ReinterpretF64(double a, TrapReason* trap) {
   return bit_cast<int64_t>(a);
 }
 
+static inline int32_t ExecuteGrowMemory(uint32_t delta_pages,
+                                        WasmModuleInstance* instance) {
+  // TODO(ahaas): Move memory allocation to wasm-module.cc for better
+  // encapsulation.
+  uint32_t old_size = instance->mem_size;
+  uint32_t new_size;
+  byte* new_mem_start;
+  if (instance->mem_size == 0) {
+    if (delta_pages > wasm::WasmModule::kMaxMemPages) {
+      return -1;
+    }
+    // TODO(gdeepti): Fix bounds check to take into account size of memtype.
+    new_size = delta_pages * wasm::WasmModule::kPageSize;
+    new_mem_start = static_cast<byte*>(calloc(new_size, sizeof(byte)));
+    if (!new_mem_start) {
+      return -1;
+    }
+  } else {
+    DCHECK_NOT_NULL(instance->mem_start);
+    new_size = old_size + delta_pages * wasm::WasmModule::kPageSize;
+    if (new_size >
+        wasm::WasmModule::kMaxMemPages * wasm::WasmModule::kPageSize) {
+      return -1;
+    }
+    new_mem_start = static_cast<byte*>(realloc(instance->mem_start, new_size));
+    if (!new_mem_start) {
+      return -1;
+    }
+    // Zero initializing uninitialized memory from realloc
+    memset(new_mem_start + old_size, 0, new_size - old_size);
+  }
+  instance->mem_start = new_mem_start;
+  instance->mem_size = new_size;
+  // realloc
+  // update mem_start
+  // update mem_size
+  return static_cast<int32_t>(old_size / WasmModule::kPageSize);
+}
+
 enum InternalOpcode {
 #define DECL_INTERNAL_ENUM(name, value) kInternal##name = value,
   FOREACH_INTERNAL_OPCODE(DECL_INTERNAL_ENUM)
@@ -1546,7 +1585,11 @@ class ThreadImpl : public WasmInterpreter::Thread {
           ASMJS_STORE_CASE(F32AsmjsStoreMem, float, float);
           ASMJS_STORE_CASE(F64AsmjsStoreMem, double, double);
 #undef ASMJS_STORE_CASE
-
+        case kExprGrowMemory: {
+          uint32_t delta_pages = Pop().to<uint32_t>();
+          Push(pc, WasmVal(ExecuteGrowMemory(delta_pages, instance())));
+          break;
+        }
         case kExprMemorySize: {
           Push(pc, WasmVal(static_cast<uint32_t>(instance()->mem_size)));
           break;