1/*
2 * Copyright (C) 2013, 2014 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef StackAllocator_h
27#define StackAllocator_h
28
29#if ENABLE(CSS_SELECTOR_JIT)
30
31#include "RegisterAllocator.h"
32#include <JavaScriptCore/MacroAssembler.h>
33
34namespace WebCore {
35
36class StackAllocator {
37public:
38    class StackReference {
39    public:
40        StackReference()
41            : m_offsetFromTop(-1)
42        { }
43        explicit StackReference(unsigned offset)
44            : m_offsetFromTop(offset)
45        { }
46        operator unsigned() const { return m_offsetFromTop; }
47    private:
48        unsigned m_offsetFromTop;
49    };
50
51    typedef Vector<StackReference, maximumRegisterCount> StackReferenceVector;
52
53    StackAllocator(JSC::MacroAssembler& assembler)
54        : m_assembler(assembler)
55        , m_offsetFromTop(0)
56        , m_hasFunctionCallPadding(false)
57    {
58    }
59
60    ~StackAllocator()
61    {
62        RELEASE_ASSERT(!m_offsetFromTop);
63        RELEASE_ASSERT(!m_hasFunctionCallPadding);
64    }
65
66    StackReference allocateUninitialized()
67    {
68        RELEASE_ASSERT(!m_hasFunctionCallPadding);
69        m_assembler.addPtrNoFlags(JSC::MacroAssembler::TrustedImm32(-stackUnitInBytes()), JSC::MacroAssembler::stackPointerRegister);
70        m_offsetFromTop += stackUnitInBytes();
71        return StackReference(m_offsetFromTop);
72    }
73
74    StackReferenceVector push(const Vector<JSC::MacroAssembler::RegisterID>& registerIDs)
75    {
76        RELEASE_ASSERT(!m_hasFunctionCallPadding);
77        StackReferenceVector stackReferences;
78#if CPU(ARM64)
79        unsigned pushRegisterCount = registerIDs.size();
80        for (unsigned i = 0; i < pushRegisterCount - 1; i += 2) {
81            m_assembler.pushPair(registerIDs[i + 1], registerIDs[i]);
82            m_offsetFromTop += stackUnitInBytes();
83            stackReferences.append(StackReference(m_offsetFromTop - stackUnitInBytes() / 2));
84            stackReferences.append(StackReference(m_offsetFromTop));
85        }
86        if (pushRegisterCount % 2)
87            stackReferences.append(push(registerIDs[pushRegisterCount - 1]));
88#else
89        for (auto registerID : registerIDs)
90            stackReferences.append(push(registerID));
91#endif
92        return stackReferences;
93    }
94
95    StackReference push(JSC::MacroAssembler::RegisterID registerID)
96    {
97        RELEASE_ASSERT(!m_hasFunctionCallPadding);
98        m_assembler.pushToSave(registerID);
99        m_offsetFromTop += stackUnitInBytes();
100        return StackReference(m_offsetFromTop);
101    }
102
103    void pop(const StackReferenceVector& stackReferences, const Vector<JSC::MacroAssembler::RegisterID>& registerIDs)
104    {
105        RELEASE_ASSERT(!m_hasFunctionCallPadding);
106
107        unsigned popRegisterCount = registerIDs.size();
108        RELEASE_ASSERT(stackReferences.size() == popRegisterCount);
109#if CPU(ARM64)
110        ASSERT(m_offsetFromTop >= stackUnitInBytes() * ((popRegisterCount + 1) / 2));
111        unsigned popRegisterCountOdd = popRegisterCount % 2;
112        if (popRegisterCountOdd)
113            pop(stackReferences[popRegisterCount - 1], registerIDs[popRegisterCount - 1]);
114        for (unsigned i = popRegisterCount - popRegisterCountOdd; i > 0; i -= 2) {
115            RELEASE_ASSERT(stackReferences[i - 1] == m_offsetFromTop);
116            RELEASE_ASSERT(stackReferences[i - 2] == m_offsetFromTop - stackUnitInBytes() / 2);
117            RELEASE_ASSERT(m_offsetFromTop >= stackUnitInBytes());
118            m_offsetFromTop -= stackUnitInBytes();
119            m_assembler.popPair(registerIDs[i - 1], registerIDs[i - 2]);
120        }
121#else
122        ASSERT(m_offsetFromTop >= stackUnitInBytes() * popRegisterCount);
123        for (unsigned i = popRegisterCount; i > 0; --i)
124            pop(stackReferences[i - 1], registerIDs[i - 1]);
125#endif
126    }
127
128    void pop(StackReference stackReference, JSC::MacroAssembler::RegisterID registerID)
129    {
130        RELEASE_ASSERT(stackReference == m_offsetFromTop);
131        RELEASE_ASSERT(!m_hasFunctionCallPadding);
132        RELEASE_ASSERT(m_offsetFromTop >= stackUnitInBytes());
133        m_offsetFromTop -= stackUnitInBytes();
134        m_assembler.popToRestore(registerID);
135    }
136
137    void popAndDiscard(StackReference stackReference)
138    {
139        RELEASE_ASSERT(stackReference == m_offsetFromTop);
140        m_assembler.addPtr(JSC::MacroAssembler::TrustedImm32(stackUnitInBytes()), JSC::MacroAssembler::stackPointerRegister);
141        m_offsetFromTop -= stackUnitInBytes();
142    }
143
144    void popAndDiscardUpTo(StackReference stackReference)
145    {
146        unsigned positionBeforeStackReference = stackReference - stackUnitInBytes();
147        RELEASE_ASSERT(positionBeforeStackReference < m_offsetFromTop);
148
149        unsigned stackDelta = m_offsetFromTop - positionBeforeStackReference;
150        m_assembler.addPtr(JSC::MacroAssembler::TrustedImm32(stackDelta), JSC::MacroAssembler::stackPointerRegister);
151        m_offsetFromTop -= stackDelta;
152    }
153
154    void alignStackPreFunctionCall()
155    {
156#if CPU(X86_64)
157        RELEASE_ASSERT(!m_hasFunctionCallPadding);
158        unsigned topAlignment = stackUnitInBytes();
159        if ((topAlignment + m_offsetFromTop) % 16) {
160            m_hasFunctionCallPadding = true;
161            m_assembler.addPtrNoFlags(JSC::MacroAssembler::TrustedImm32(-stackUnitInBytes()), JSC::MacroAssembler::stackPointerRegister);
162        }
163#endif
164    }
165
166    void unalignStackPostFunctionCall()
167    {
168#if CPU(X86_64)
169        if (m_hasFunctionCallPadding) {
170            m_assembler.addPtrNoFlags(JSC::MacroAssembler::TrustedImm32(stackUnitInBytes()), JSC::MacroAssembler::stackPointerRegister);
171            m_hasFunctionCallPadding = false;
172        }
173#endif
174    }
175
176    void merge(StackAllocator&& stackA, StackAllocator&& stackB)
177    {
178        RELEASE_ASSERT(stackA.m_offsetFromTop == stackB.m_offsetFromTop);
179        RELEASE_ASSERT(stackA.m_hasFunctionCallPadding == stackB.m_hasFunctionCallPadding);
180        ASSERT(&stackA.m_assembler == &stackB.m_assembler);
181        ASSERT(&m_assembler == &stackB.m_assembler);
182
183        m_offsetFromTop = stackA.m_offsetFromTop;
184        m_hasFunctionCallPadding = stackA.m_hasFunctionCallPadding;
185
186        stackA.reset();
187        stackB.reset();
188    }
189
190    void merge(StackAllocator&& stackA, StackAllocator&& stackB, StackAllocator&& stackC)
191    {
192        RELEASE_ASSERT(stackA.m_offsetFromTop == stackB.m_offsetFromTop);
193        RELEASE_ASSERT(stackA.m_offsetFromTop == stackC.m_offsetFromTop);
194        RELEASE_ASSERT(stackA.m_hasFunctionCallPadding == stackB.m_hasFunctionCallPadding);
195        RELEASE_ASSERT(stackA.m_hasFunctionCallPadding == stackC.m_hasFunctionCallPadding);
196        ASSERT(&stackA.m_assembler == &stackB.m_assembler);
197        ASSERT(&stackA.m_assembler == &stackC.m_assembler);
198        ASSERT(&m_assembler == &stackB.m_assembler);
199
200        m_offsetFromTop = stackA.m_offsetFromTop;
201        m_hasFunctionCallPadding = stackA.m_hasFunctionCallPadding;
202
203        stackA.reset();
204        stackB.reset();
205        stackC.reset();
206    }
207
208    unsigned offsetToStackReference(StackReference stackReference)
209    {
210        RELEASE_ASSERT(m_offsetFromTop >= stackReference);
211        return m_offsetFromTop - stackReference;
212    }
213
214private:
215    static unsigned stackUnitInBytes()
216    {
217        return JSC::MacroAssembler::pushToSaveByteOffset();
218    }
219
220    void reset()
221    {
222        m_offsetFromTop = 0;
223        m_hasFunctionCallPadding = false;
224    }
225
226    JSC::MacroAssembler& m_assembler;
227    unsigned m_offsetFromTop;
228    bool m_hasFunctionCallPadding;
229};
230
231} // namespace WebCore
232
233#endif // ENABLE(CSS_SELECTOR_JIT)
234
235#endif // StackAllocator_h
236