--- /dev/null
+/*
+ * Copyright (C) 2008 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ * its contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef RegisterFile_h
+#define RegisterFile_h
+
+#include "Register.h"
+#include "Collector.h"
+#include <wtf/Noncopyable.h>
+
+#if HAVE(MMAP)
+#include <errno.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#endif
+
+namespace JSC {
+
+/*
+ A register file is a stack of register frames. We represent a register
+ frame by its offset from "base", the logical first entry in the register
+ file. The bottom-most register frame's offset from base is 0.
+
+ In a program where function "a" calls function "b" (global code -> a -> b),
+ the register file might look like this:
+
+ | global frame | call frame | call frame | spare capacity |
+ -----------------------------------------------------------------------------------------------------
+ | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | | | | | | <-- index in buffer
+ -----------------------------------------------------------------------------------------------------
+ | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | | | | | | <-- index relative to base
+ -----------------------------------------------------------------------------------------------------
+ | <-globals | temps-> | <-vars | temps-> | <-vars |
+ ^ ^ ^ ^
+ | | | |
+ buffer base (frame 0) frame 1 frame 2
+
+ Since all variables, including globals, are accessed by negative offsets
+ from their register frame pointers, to keep old global offsets correct, new
+ globals must appear at the beginning of the register file, shifting base
+ to the right.
+
+ If we added one global variable to the register file depicted above, it
+ would look like this:
+
+ | global frame |< >
+ -------------------------------> <
+ | 0 | 1 | 2 | 3 | 4 | 5 |< >snip< > <-- index in buffer
+ -------------------------------> <
+ | -4 | -3 | -2 | -1 | 0 | 1 |< > <-- index relative to base
+ -------------------------------> <
+ | <-globals | temps-> |
+ ^ ^
+ | |
+ buffer base (frame 0)
+
+ As you can see, global offsets relative to base have stayed constant,
+ but base itself has moved. To keep up with possible changes to base,
+ clients keep an indirect pointer, so their calculations update
+ automatically when base changes.
+
+ For client simplicity, the RegisterFile measures size and capacity from
+ "base", not "buffer".
+*/
+
+ class JSGlobalObject;
+
+ class RegisterFile : Noncopyable {
+ friend class JIT;
+ public:
+ enum CallFrameHeaderEntry {
+ CallFrameHeaderSize = 8,
+
+ CodeBlock = -8,
+ ScopeChain = -7,
+ CallerFrame = -6,
+ ReturnPC = -5, // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
+ ReturnValueRegister = -4,
+ ArgumentCount = -3,
+ Callee = -2,
+ OptionalCalleeArguments = -1,
+ };
+
+ enum { ProgramCodeThisRegister = -CallFrameHeaderSize - 1 };
+ enum { ArgumentsRegister = 0 };
+
+ static const size_t defaultCapacity = 524288;
+ static const size_t defaultMaxGlobals = 8192;
+ static const size_t allocationSize = 1 << 14;
+ static const size_t allocationSizeMask = allocationSize - 1;
+
+ RegisterFile(size_t capacity = defaultCapacity, size_t maxGlobals = defaultMaxGlobals)
+ : m_numGlobals(0)
+ , m_maxGlobals(maxGlobals)
+ , m_start(0)
+ , m_end(0)
+ , m_max(0)
+ , m_buffer(0)
+ , m_globalObject(0)
+ {
+ size_t bufferLength = (capacity + maxGlobals) * sizeof(Register);
+#if HAVE(MMAP)
+ m_buffer = static_cast<Register*>(mmap(0, bufferLength, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0));
+ if (m_buffer == MAP_FAILED) {
+ fprintf(stderr, "Could not allocate register file: %d\n", errno);
+ CRASH();
+ }
+#elif HAVE(VIRTUALALLOC)
+ // Ensure bufferLength is a multiple of allocation size
+ bufferLength = (bufferLength + allocationSizeMask) & ~allocationSizeMask;
+ m_buffer = static_cast<Register*>(VirtualAlloc(0, bufferLength, MEM_RESERVE, PAGE_READWRITE));
+ if (!m_buffer) {
+ fprintf(stderr, "Could not allocate register file: %d\n", errno);
+ CRASH();
+ }
+ int initialAllocation = (maxGlobals * sizeof(Register) + allocationSizeMask) & ~allocationSizeMask;
+ void* commitCheck = VirtualAlloc(m_buffer, initialAllocation, MEM_COMMIT, PAGE_READWRITE);
+ if (commitCheck != m_buffer) {
+ fprintf(stderr, "Could not allocate register file: %d\n", errno);
+ CRASH();
+ }
+ m_maxCommitted = reinterpret_cast<Register*>(reinterpret_cast<char*>(m_buffer) + initialAllocation);
+#else
+ #error "Don't know how to reserve virtual memory on this platform."
+#endif
+ m_start = m_buffer + maxGlobals;
+ m_end = m_start;
+ m_max = m_start + capacity;
+ }
+
+ ~RegisterFile();
+
+ Register* start() const { return m_start; }
+ Register* end() const { return m_end; }
+ size_t size() const { return m_end - m_start; }
+
+ void setGlobalObject(JSGlobalObject* globalObject) { m_globalObject = globalObject; }
+ JSGlobalObject* globalObject() { return m_globalObject; }
+
+ void shrink(Register* newEnd)
+ {
+ if (newEnd < m_end)
+ m_end = newEnd;
+ }
+
+ bool grow(Register* newEnd)
+ {
+ if (newEnd > m_end) {
+ if (newEnd > m_max)
+ return false;
+#if !HAVE(MMAP) && HAVE(VIRTUALALLOC)
+ if (newEnd > m_maxCommitted) {
+ ptrdiff_t additionalAllocation = ((reinterpret_cast<char*>(newEnd) - reinterpret_cast<char*>(m_maxCommitted)) + allocationSizeMask) & ~allocationSizeMask;
+ if (!VirtualAlloc(m_maxCommitted, additionalAllocation, MEM_COMMIT, PAGE_READWRITE)) {
+ fprintf(stderr, "Could not allocate register file: %d\n", errno);
+ CRASH();
+ }
+ m_maxCommitted = reinterpret_cast<Register*>(reinterpret_cast<char*>(m_maxCommitted) + additionalAllocation);
+ }
+#endif
+ m_end = newEnd;
+ }
+ return true;
+ }
+
+ void setNumGlobals(size_t numGlobals) { m_numGlobals = numGlobals; }
+ int numGlobals() const { return m_numGlobals; }
+ size_t maxGlobals() const { return m_maxGlobals; }
+
+ Register* lastGlobal() const { return m_start - m_numGlobals; }
+
+ void markGlobals(Heap* heap) { heap->markConservatively(lastGlobal(), m_start); }
+ void markCallFrames(Heap* heap) { heap->markConservatively(m_start, m_end); }
+
+ private:
+ size_t m_numGlobals;
+ const size_t m_maxGlobals;
+ Register* m_start;
+ Register* m_end;
+ Register* m_max;
+ Register* m_buffer;
+#if HAVE(VIRTUALALLOC)
+ Register* m_maxCommitted;
+#endif
+
+ JSGlobalObject* m_globalObject; // The global object whose vars are currently stored in the register file.
+ };
+
+} // namespace JSC
+
+#endif // RegisterFile_h
projects / apple / javascriptcore.git / blobdiff