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https://github.com/LadybirdBrowser/ladybird.git
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2b69af2dfe
JS::Value stores 48 bit pointers to separately allocated objects in its payload. On x86-64, canonical addresses have their top 16 bits set to the same value as bit 47, effectively meaning that the value has to be sign-extended to get the pointer. AArch64, however, expects the topmost bits to be all zeros. This commit gates sign extension behind `#if ARCH(X86_64)`, and adds an `#error` for unsupported architectures, so that we do not forget to think about pointer handling when porting to a new architecture. Fixes #15290 Fixes SerenityOS/ladybird#56
115 lines
4.2 KiB
C++
115 lines
4.2 KiB
C++
/*
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* Copyright (c) 2022, David Tuin <davidot@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibJS/Runtime/Value.h>
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#include <LibTest/TestCase.h>
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using namespace JS;
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template<typename Type>
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static void test_nullptr_input()
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{
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Type* ptr = nullptr;
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JS::Value val { ptr };
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EXPECT(val.is_null());
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EXPECT(!val.is_object());
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EXPECT(!val.is_string());
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EXPECT(!val.is_bigint());
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EXPECT(!val.is_symbol());
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EXPECT(!val.is_accessor());
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EXPECT(!val.is_cell());
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EXPECT(!val.is_number());
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EXPECT(!val.is_undefined());
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}
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#define TEST_NULLPTR_INPUT(type) \
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TEST_CASE(value_nullptr_input_##type) \
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{ \
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test_nullptr_input<type>(); \
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}
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TEST_NULLPTR_INPUT(Object);
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TEST_NULLPTR_INPUT(PrimitiveString);
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TEST_NULLPTR_INPUT(Symbol);
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TEST_NULLPTR_INPUT(BigInt);
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TEST_NULLPTR_INPUT(Accessor);
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#undef TEST_NULLPTR_INPUT
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TEST_CASE(valid_pointer_in_gives_same_pointer_out)
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{
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if (sizeof(void*) < sizeof(double))
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return;
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#define EXPECT_POINTER_TO_SURVIVE(input) \
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{ \
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JS::Value value(reinterpret_cast<Object*>(static_cast<u64>(input))); \
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EXPECT(value.is_object()); \
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EXPECT(!value.is_null()); \
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auto extracted_pointer = JS::Value::extract_pointer_bits(value.encoded()); \
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EXPECT_EQ(static_cast<u64>(input), extracted_pointer); \
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}
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EXPECT_POINTER_TO_SURVIVE(0x1);
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EXPECT_POINTER_TO_SURVIVE(0x10);
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EXPECT_POINTER_TO_SURVIVE(0x100);
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EXPECT_POINTER_TO_SURVIVE(0x00007fffffffffff);
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EXPECT_POINTER_TO_SURVIVE(0x0000700000000000);
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EXPECT_POINTER_TO_SURVIVE(0x0000100000000000);
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#if ARCH(X86_64)
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// On x86-64, the top 16 bits of pointers are equal to bit 47.
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EXPECT_POINTER_TO_SURVIVE(0xffff800000000000);
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EXPECT_POINTER_TO_SURVIVE(0xffff800000000001);
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EXPECT_POINTER_TO_SURVIVE(0xffff800000000010);
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#elif ARCH(AARCH64)
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// ... but they should contain zeroes on AArch64.
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EXPECT_POINTER_TO_SURVIVE(0x0000800000000000);
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EXPECT_POINTER_TO_SURVIVE(0x0000800000000001);
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EXPECT_POINTER_TO_SURVIVE(0x0000800000000010);
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#endif
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#undef EXPECT_POINTER_TO_SURVIVE
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}
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TEST_CASE(non_canon_nans)
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{
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#define EXPECT_TO_BE_NAN(input) \
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{ \
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Value val { bit_cast<double>(input) }; \
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EXPECT(val.is_nan()); \
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EXPECT(val.is_number()); \
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EXPECT(!val.is_integral_number()); \
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EXPECT(!val.is_finite_number()); \
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EXPECT(!val.is_infinity()); \
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EXPECT(!val.is_empty()); \
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EXPECT(!val.is_nullish()); \
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}
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | 0x1);
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | 0x10);
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | (NULL_TAG << TAG_SHIFT));
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | (UNDEFINED_TAG << TAG_SHIFT));
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | (INT32_TAG << TAG_SHIFT) | 0x88);
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | (OBJECT_TAG << TAG_SHIFT));
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | (OBJECT_TAG << TAG_SHIFT) | 0x1230);
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | (STRING_TAG << TAG_SHIFT));
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | (STRING_TAG << TAG_SHIFT) | 0x1230);
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u64 sign_bit = 1ULL << 63;
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | 0x1);
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | 0x10);
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | (NULL_TAG << TAG_SHIFT));
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | (UNDEFINED_TAG << TAG_SHIFT));
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | (INT32_TAG << TAG_SHIFT) | 0x88);
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | (OBJECT_TAG << TAG_SHIFT));
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | (OBJECT_TAG << TAG_SHIFT) | 0x1230);
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | (STRING_TAG << TAG_SHIFT));
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EXPECT_TO_BE_NAN(CANON_NAN_BITS | sign_bit | (STRING_TAG << TAG_SHIFT) | 0x1230);
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#undef EXPECT_TO_BE_NAN
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}
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