CSSValue Immediates: Make CSSPrimitiveValue store a tagged pointer

Source/core/css/CSSPrimitiveValueTest.cpp

+// Copyright 2015 The Chromium 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 "config.h"
+
+#include "core/css/CSSPrimitiveValue.h"
+
+#include "core/css/CSSValueTestHelper.h"
+#include <gtest/gtest.h>
+#include <strings.h>
+
+using namespace blink;
+
+namespace {
+
+void clearTaggedPtr(CSSPrimitiveValue::CSSTaggedPtrValue& taggedPtr)
+{
+    taggedPtr.flag = 0;
+    taggedPtr.type = static_cast<CSSPrimitiveValue::UnitType>(0);
+    taggedPtr.setValue(0.0);
+}
+
+TEST(CSSPrimitiveValueTest, CSSPrimitiveValueTest)
+{
+    // 1.0 can be stored in a tagged ptr.
+    CSSPrimitiveValue value = CSSPrimitiveValue::create(1.0, CSSPrimitiveValue::CSS_INTEGER);
+    EXPECT_EQ(1.0, value.getDoubleValue());
+    EXPECT_EQ("1", value.customCSSText());
+    EXPECT_TRUE(value.isNumber());
+    EXPECT_FALSE(value.isAttr());
+
+    CSSValue cssValue(value);
+    EXPECT_TRUE(cssValue.isPrimitiveValue());
+    EXPECT_FALSE(cssValue.isImageValue());
+    EXPECT_EQ("1", cssValue.cssText());
+
+    // 3.3 cannot be stored in a tagged ptr.
+    CSSPrimitiveValue valueInTaggedPtr = CSSPrimitiveValue::create(3.3, CSSPrimitiveValue::CSS_NUMBER);
+    EXPECT_EQ(3.3, valueInTaggedPtr.getDoubleValue());
+    EXPECT_EQ("3.3", valueInTaggedPtr.customCSSText());
+    EXPECT_TRUE(valueInTaggedPtr.isNumber());
+    EXPECT_FALSE(value.isAttr());
+
+    CSSValue cssValueWithTaggedPtr(valueInTaggedPtr);
+    EXPECT_TRUE(cssValueWithTaggedPtr.isPrimitiveValue());
+    EXPECT_FALSE(cssValueWithTaggedPtr.isImageValue());
+    EXPECT_EQ("3.3", cssValueWithTaggedPtr.cssText());
+
+    EXPECT_FALSE(cssValue.equals(cssValueWithTaggedPtr));
+    EXPECT_FALSE(cssValueWithTaggedPtr.equals(cssValue));
+
+    CSSValue cssValueCopy(cssValue);
+    EXPECT_TRUE(cssValue.equals(cssValueCopy));
+    EXPECT_TRUE(cssValueCopy.equals(cssValue));
+
+    CSSValue cssValueWithTaggedPtrCopy(cssValueWithTaggedPtr);
+    EXPECT_TRUE(cssValueWithTaggedPtr.equals(cssValueWithTaggedPtrCopy));
+    EXPECT_TRUE(cssValueWithTaggedPtrCopy.equals(cssValueWithTaggedPtr));
+}
+
+TEST(CSSPrimitiveValueTest, CSSTaggedPtrValueTest)
+{
+    CSSPrimitiveValue::CSSTaggedPtrValue taggedPtr;
+    clearTaggedPtr(taggedPtr);
+
+    // Check that all fields can be get/set correctly.
+    EXPECT_EQ(0UL, taggedPtr.flag);
+    taggedPtr.flag = 1;
+    EXPECT_EQ(1UL, taggedPtr.flag);
+
+    EXPECT_EQ(0UL, taggedPtr.type);
+    taggedPtr.type = CSSPrimitiveValue::CSS_INTEGER;
+    EXPECT_EQ(CSSPrimitiveValue::CSS_INTEGER, taggedPtr.type);
+
+    EXPECT_EQ(0UL, taggedPtr.getValue());
+    taggedPtr.setValue(1.0);
+    EXPECT_EQ(1.0, taggedPtr.getValue());
+
+    taggedPtr.flag = 1;
+    taggedPtr.type = CSSPrimitiveValue::CSS_INTEGER;
+    taggedPtr.setValue(1.0);
+    EXPECT_EQ(1UL, taggedPtr.flag);
+    EXPECT_EQ(CSSPrimitiveValue::CSS_INTEGER, taggedPtr.type);
+    EXPECT_EQ(1.0, taggedPtr.getValue());
+
+    clearTaggedPtr(taggedPtr);
+    EXPECT_EQ(0UL, taggedPtr.flag);
+    EXPECT_EQ(0UL, taggedPtr.type);
+    EXPECT_EQ(0UL, taggedPtr.getValue());
+    EXPECT_EQ(0UL, *reinterpret_cast<uintptr_t*>(&taggedPtr));
+}
+
+TEST(CSSPrimitiveValueTest, FitsWithoutDataLossTest)
+{
+    // Consistent on 32-bit/64-bit
+    EXPECT_EQ(true, CSSPrimitiveValue::CSSTaggedPtrValue::fitsWithoutDataLoss(1.0));
+    EXPECT_EQ(false, CSSPrimitiveValue::CSSTaggedPtrValue::fitsWithoutDataLoss(3.3));
+
+    uint64_t trailing1sOnAllPlatforms = 0xf;
+    EXPECT_EQ(false, CSSPrimitiveValue::CSSTaggedPtrValue::fitsWithoutDataLoss(*reinterpret_cast<double*>(&trailing1sOnAllPlatforms)));
+
+    // Fits on 64-bit, but not on 32-bit
+    uint64_t trailing1sOn32BitOnly = 0xf00;
+    bool expectToFit;
+#if CPU(32BIT)
+    expectToFit = false;
+#elif CPU(64BIT)
+    expectToFit = true;
+#endif
+    EXPECT_EQ(expectToFit, CSSPrimitiveValue::CSSTaggedPtrValue::fitsWithoutDataLoss(*reinterpret_cast<double*>(&trailing1sOn32BitOnly)));
+}
+
+// Tests that the flag bit is in the least-significant bit. This test is important
+// since we implement CSSTaggedPtrValue using bitfields, and the C++ standard specifies
+// that bitfield packing behavior is implementation-specific.
+TEST(CSSPrimitiveValueTest, FlagBitInLSBTest)
+{
+    CSSPrimitiveValue::CSSTaggedPtrValue taggedPtr;
+    clearTaggedPtr(taggedPtr);
+
+    taggedPtr.flag = 1;
+    EXPECT_EQ(1UL, *reinterpret_cast<uintptr_t*>(&taggedPtr));
+
+    taggedPtr.flag = 0;
+    EXPECT_EQ(0UL, *reinterpret_cast<uintptr_t*>(&taggedPtr));
+}
+
+// Test that all valid values for UnitType fit in the UnitType bit field in the
+// tagged pointer.
+TEST(CSSPrimitiveValueTest, UnitTypeSizeTest)
+{
+    CSSPrimitiveValue::CSSTaggedPtrValue taggedPtr;
+    clearTaggedPtr(taggedPtr);
+
+    // We can't take the sizeof() of a bitfield. Instead, try set the largest primitive
+    // value type we have, and see if we can read it out again.
+    taggedPtr.type = CSSPrimitiveValue::CSS_QEM;
+    ASSERT_EQ(CSSPrimitiveValue::CSS_QEM, taggedPtr.type);
+}
+
+
+} // namespace