[Interpreter] Minimal bytecode generator.

test/cctest/interpreter/test-bytecode-generator.cc

+// Copyright 2015 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/v8.h"
+
+#include "src/compiler.h"
+#include "src/interpreter/bytecode-generator.h"
+#include "src/interpreter/interpreter.h"
+#include "test/cctest/cctest.h"
+
+namespace v8 {
+namespace internal {
+namespace interpreter {
+
+class BytecodeGeneratorHelper {
+ public:
+  const char* kFunctionName = "my_function";
+
+  BytecodeGeneratorHelper() {
+    i::FLAG_ignition = true;
+    i::FLAG_ignition_filter = kFunctionName;
+    CcTest::i_isolate()->interpreter()->Initialize();
+  }
+
+
+  Handle<BytecodeArray> MakeBytecode(const char* script,
+                                     const char* function_name) {
+    CompileRun(script);
+    Local<Function> function =
+        Local<Function>::Cast(CcTest::global()->Get(v8_str(function_name)));
+    i::Handle<i::JSFunction> js_function = v8::Utils::OpenHandle(*function);
+    return handle(js_function->shared()->bytecode_array(), CcTest::i_isolate());
+  }
+
+
+  Handle<BytecodeArray> MakeBytecodeForFunctionBody(const char* body) {
+    ScopedVector<char> program(1024);
+    SNPrintF(program, "function %s() { %s }\n%s();", kFunctionName, body,
+             kFunctionName);
+    return MakeBytecode(program.start(), kFunctionName);
+  }
+};
+
+
+// Structure for containing expected bytecode snippets.
+struct ExpectedSnippet {
+  const char* body;
+  int frame_size;
+  int bytecode_length;
+  const uint8_t bytecode[16];
+};
+
+
+// Helper macros for handcrafting bytecode sequences.
+#define B(x) static_cast<uint8_t>(Bytecode::k##x)
+#define U8(x) static_cast<uint8_t>(x & 0xff)
+#define R(x) static_cast<uint8_t>(-x & 0xff)
+
+
+TEST(PrimitiveReturnStatements) {
+  InitializedHandleScope handle_scope;
+  BytecodeGeneratorHelper helper;
+
+  ExpectedSnippet snippets[] = {
+      {"return;", 0, 2, {B(LdaUndefined), B(Return)}},
+      {"return null;", 0, 2, {B(LdaNull), B(Return)}},
+      {"return true;", 0, 2, {B(LdaTrue), B(Return)}},
+      {"return false;", 0, 2, {B(LdaFalse), B(Return)}},
+      {"return 0;", 0, 2, {B(LdaZero), B(Return)}},
+      {"return +1;", 0, 3, {B(LdaSmi8), U8(1), B(Return)}},
+      {"return -1;", 0, 3, {B(LdaSmi8), U8(-1), B(Return)}},
+      {"return +127;", 0, 3, {B(LdaSmi8), U8(127), B(Return)}},
+      {"return -128;", 0, 3, {B(LdaSmi8), U8(-128), B(Return)}},
+  };
+
+  size_t num_snippets = sizeof(snippets) / sizeof(snippets[0]);
+  for (size_t i = 0; i < num_snippets; i++) {
+    Handle<BytecodeArray> ba =
+        helper.MakeBytecodeForFunctionBody(snippets[i].body);
+    CHECK_EQ(ba->frame_size(), snippets[i].frame_size);
+    CHECK_EQ(ba->length(), snippets[i].bytecode_length);
+    CHECK(!memcmp(ba->GetFirstBytecodeAddress(), snippets[i].bytecode,
+                  ba->length()));
+  }
+}
+
+
+TEST(PrimitiveExpressions) {
+  InitializedHandleScope handle_scope;
+  BytecodeGeneratorHelper helper;
+
+  ExpectedSnippet snippets[] = {
+      {"var x = 0; return x;",
+       kPointerSize,
+       6,
+       {
+           B(LdaZero),     //
+           B(Star), R(0),  //
+           B(Ldar), R(0),  //
+           B(Return)       //
+       }},
+      {"var x = 0; return x + 3;",
+       2 * kPointerSize,
+       12,
+       {
+           B(LdaZero),         //
+           B(Star), R(0),      //
+           B(Ldar), R(0),      // Easy to spot r1 not really needed here.
+           B(Star), R(1),      // Dead store.
+           B(LdaSmi8), U8(3),  //
+           B(Add), R(1),       //
+           B(Return)           //
+       }}};
+
+  size_t num_snippets = sizeof(snippets) / sizeof(snippets[0]);
+  for (size_t i = 0; i < num_snippets; i++) {
+    Handle<BytecodeArray> ba =
+        helper.MakeBytecodeForFunctionBody(snippets[i].body);
+    CHECK_EQ(ba->frame_size(), snippets[i].frame_size);
+    CHECK_EQ(ba->length(), snippets[i].bytecode_length);
+    CHECK(!memcmp(ba->GetFirstBytecodeAddress(), snippets[i].bytecode,
+                  ba->length()));
+  }
+}
+
+}  // namespace interpreter
+}  // namespace internal
+}  // namespance v8