[wasm] Implement GrowMemory in the wasm interpreter

src/wasm/wasm-interpreter.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/wasm/wasm-interpreter.h"
 
 #include "src/utils.h"
 #include "src/wasm/ast-decoder.h"
 #include "src/wasm/decoder.h"
 #include "src/wasm/wasm-external-refs.h"
@@ skipping 636 matching lines @@
 }
 
 static inline int32_t ExecuteI32ReinterpretF32(float a, TrapReason* trap) {
   return bit_cast<int32_t>(a);
 }
 
 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) {
+  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));

[titzer, 2016/09/14 07:57:08]

Can you put a TODO here to call back into something in wasm-module.cc for the
actual allocation of memory? For example, it might be in the future that the
memory actually really is a JS array buffer and the instance needs to be fixed
(e.g. when debugging).

[ahaas, 2016/09/14 08:47:18]

Done.

+    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)
 #undef DECL_INTERNAL_ENUM
 };
 
 static const char* OpcodeName(uint32_t val) {
   switch (val) {
 #define DECL_INTERNAL_CASE(name, value) \
   case kInternal##name:                 \
@@ skipping 872 matching lines @@
     Push(pc, val);                                                             \
     break;                                                                     \
   }
 
           ASMJS_STORE_CASE(I32AsmjsStoreMem8, int32_t, int8_t);
           ASMJS_STORE_CASE(I32AsmjsStoreMem16, int32_t, int16_t);
           ASMJS_STORE_CASE(I32AsmjsStoreMem, int32_t, int32_t);
           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;
         }
 #define EXECUTE_SIMPLE_BINOP(name, ctype, op)             \
   case kExpr##name: {                                     \
     WasmVal rval = Pop();                                 \
     WasmVal lval = Pop();                                 \
     WasmVal result(lval.to<ctype>() op rval.to<ctype>()); \
     Push(pc, result);                                     \
@@ skipping 244 matching lines @@
 
 ControlTransferMap WasmInterpreter::ComputeControlTransfersForTesting(
     Zone* zone, const byte* start, const byte* end) {
   ControlTransfers targets(zone, 0, start, end);
   return targets.map_;
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8