smith
22058efe41
Fixing various bugs all over the VM that make assumptions about RefData and TypedValue layout. Here are the assumptions fixed by this diff: offsetof(RefData, m_tv) == 0. Both JIT's assumed this in many subtle ways, by punning RefData* as TypedValue* without adding an offset. This assumption also causes RefData._count to overlap TypedValue.m_aux, which constraints TypedValue layout. offsetof(TypedValue, m_data) == 0. gen_ext_hhvm.php assumes you can cast TypedValue* to Value*; the JITs often weren't using offsetof(TypedValue, m_data) in their addressing calculations. HHIR assumed return-by-value TV's have m_data/m_type in rax/rdx, which can change when TV layout changes. offsetof(TypedValue, m_type) > 8 is an assumption baked into the pass-by-value register assignment logic in HHIR's codegen.cpp; if the type is in the low word, register assignment is swapped. sizeof(TypedValue::m_type) == 4. We used dword-sized operations in both JIT's when accessing m_type. Now, we use helper functions that are sensitive to sizeof(DataType) Configuration: DEBUG=: (opt) same layouts as trunk for RefData & TypedValue DEBUG=1: (dbg) new RefData layout (m_tv doesn't overlap RefData::_count) PACKED_TV=1, DEBUG=*: new RefData and TypedValue layout.
129 linhas
3.8 KiB
C++
129 linhas
3.8 KiB
C++
/*
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+----------------------------------------------------------------------+
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| HipHop for PHP |
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+----------------------------------------------------------------------+
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| Copyright (c) 2010- Facebook, Inc. (http://www.facebook.com) |
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+----------------------------------------------------------------------+
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| This source file is subject to version 3.01 of the PHP license, |
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| that is bundled with this package in the file LICENSE, and is |
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| available through the world-wide-web at the following url: |
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| http://www.php.net/license/3_01.txt |
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| If you did not receive a copy of the PHP license and are unable to |
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| obtain it through the world-wide-web, please send a note to |
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| license@php.net so we can mail you a copy immediately. |
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+----------------------------------------------------------------------+
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*/
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#ifndef __INSIDE_HPHP_COMPLEX_TYPES_H__
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#error Directly including 'ref_data.h' is prohibited. \
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Include 'complex_types.h' instead.
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#endif
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#ifndef __HPHP_REF_DATA_H
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#define __HPHP_REF_DATA_H
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namespace HPHP {
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/**
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* We heap allocate a RefData when we make a reference to something.
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* A Variant or TypedValue can be KindOfRef and point to a RefData,
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* but the value held here must not be KindOfRef.
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*/
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class RefData {
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enum Magic : uint64_t { kMagic = 0xfacefaceb00cb00c };
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public:
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enum NullInit { nullinit };
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RefData() { assert(m_magic = kMagic); }
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RefData(NullInit) {
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assert(m_magic = kMagic);
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_count = 1;
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m_tv.m_type = KindOfNull;
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}
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RefData(DataType t, int64_t datum) {
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assert(m_magic = kMagic);
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init(t, datum);
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}
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~RefData();
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// Don't extend Countable but use these methods to directly
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// update _count, declared below.
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IMPLEMENT_COUNTABLE_METHODS_NO_STATIC
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// Memory allocator methods
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DECLARE_SMART_ALLOCATION(RefData);
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void dump() const;
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const TypedValue* tv() const {
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assert(m_magic == kMagic);
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return &m_tv;
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}
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TypedValue* tv() {
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assert(m_magic == kMagic);
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return &m_tv;
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}
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const Variant* var() const { return (const Variant*)tv(); }
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Variant* var() { return reinterpret_cast<Variant*>(tv()); }
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static constexpr size_t tvOffset() { return offsetof(RefData, m_tv); }
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void assertValid() const {
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assert(m_magic == kMagic);
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}
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// TODO: t2221110: get rid of this hack.
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static RefData* refDataFromVariantIfYouDare(const Variant* var) {
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RefData* ref = reinterpret_cast<RefData*>(uintptr_t(var) - tvOffset());
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ref->assertValid();
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return ref;
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}
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private:
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// initialize this value by laundering uninitNull -> Null
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void init(DataType t, int64_t datum) {
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_count = 1;
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if (!IS_NULL_TYPE(t)) {
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m_tv.m_type = t;
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m_tv.m_data.num = datum;
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} else {
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m_tv.m_type = KindOfNull;
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}
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}
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static void compileTimeAsserts() {
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static_assert(offsetof(RefData, _count) == FAST_REFCOUNT_OFFSET, "");
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}
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#if defined(DEBUG) || defined(PACKED_TV)
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// don't overlap TypedValue with _count. sizeof(*this) = 32.
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private: Magic m_magic;
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public: mutable int32_t _count;
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private: TypedValue m_tv;
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static void layoutAsserts() {
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static_assert(offsetof(RefData, m_tv) >
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offsetof(RefData, _count) + sizeof(int32_t), "");
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};
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#else
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// overlap TypedValue with count
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private:
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union {
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struct {
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void* _ptr;
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mutable int32_t _count;
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};
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TypedValue m_tv;
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};
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static void layoutAsserts() {
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static_assert(offsetof(RefData, _count) == TypedValueAux::auxOffset, "");
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static_assert(sizeof(RefData::_count) == TypedValueAux::auxSize, "");
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}
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#endif
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};
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ALWAYS_INLINE inline void decRefRef(RefData* ref) {
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if (ref->decRefCount() == 0) ref->release();
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}
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} // namespace HPHP
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#endif //__HPHP_REF_DATA_H
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