/js/src/nanojit/RegAlloc.h
http://github.com/zpao/v8monkey · C Header · 205 lines · 86 code · 23 blank · 96 comment · 7 complexity · 597112439028fe52b88dd2890359ffe4 MD5 · raw file
- /* -*- Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 4 -*- */
- /* vi: set ts=4 sw=4 expandtab: (add to ~/.vimrc: set modeline modelines=5) */
- /* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is [Open Source Virtual Machine].
- *
- * The Initial Developer of the Original Code is
- * Adobe System Incorporated.
- * Portions created by the Initial Developer are Copyright (C) 2004-2007
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- * Adobe AS3 Team
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
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- * decision by deleting the provisions above and replace them with the notice
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- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
- #ifndef __nanojit_RegAlloc__
- #define __nanojit_RegAlloc__
- namespace nanojit
- {
- class RegAlloc
- {
- public:
- RegAlloc()
- {
- clear();
- }
- void clear()
- {
- VMPI_memset(this, 0, sizeof(*this));
- }
- bool isFree(Register r) const
- {
- return (free & rmask(r)) != 0;
- }
- void addFree(Register r)
- {
- NanoAssert(!isFree(r));
- free |= rmask(r);
- }
- void removeFree(Register r)
- {
- NanoAssert(isFree(r));
- free &= ~rmask(r);
- }
- void addActive(Register r, LIns* v)
- {
- // Count++;
- NanoAssert(v);
- NanoAssert(active[REGNUM(r)] == NULL);
- active[REGNUM(r)] = v;
- useActive(r);
- }
- void useActive(Register r)
- {
- NanoAssert(active[REGNUM(r)] != NULL);
- usepri[REGNUM(r)] = priority++;
- }
- void removeActive(Register r)
- {
- //registerReleaseCount++;
- NanoAssert(active[REGNUM(r)] != NULL);
- // remove the given register from the active list
- active[REGNUM(r)] = NULL;
- }
- void retire(Register r)
- {
- NanoAssert(active[REGNUM(r)] != NULL);
- active[REGNUM(r)] = NULL;
- free |= rmask(r);
- }
- int32_t getPriority(Register r) {
- NanoAssert(active[REGNUM(r)]);
- return usepri[REGNUM(r)];
- }
- LIns* getActive(Register r) const {
- return active[REGNUM(r)];
- }
- // Return a mask containing the active registers. For each register
- // in this set, getActive(register) will be a nonzero LIns pointer.
- RegisterMask activeMask() const {
- return ~free & managed;
- }
- debug_only( bool isConsistent(Register r, LIns* v) const; )
- // Some basics:
- //
- // - 'active' indicates which registers are active at a particular
- // point, and for each active register, which instruction
- // defines the value it holds. At the start of register
- // allocation no registers are active.
- //
- // - 'free' indicates which registers are free at a particular point
- // and thus available for use. At the start of register
- // allocation most registers are free; those that are not
- // aren't available for general use, e.g. the stack pointer and
- // frame pointer registers.
- //
- // - 'managed' is exactly this list of initially free registers,
- // ie. the registers managed by the register allocator.
- //
- // - Each LIns has a "reservation" which includes a register value,
- // 'reg'. Combined with 'active', this provides a two-way
- // mapping between registers and LIR instructions.
- //
- // - Invariant 1: each register must be in exactly one of the
- // following states at all times: unmanaged, free, or active.
- // In terms of the relevant fields:
- //
- // * A register in 'managed' must be in 'active' or 'free' but
- // not both.
- //
- // * A register not in 'managed' must be in neither 'active' nor
- // 'free'.
- //
- // - Invariant 2: the two-way mapping between active registers and
- // their defining instructions must always hold in both
- // directions and be unambiguous. More specifically:
- //
- // * An LIns can appear at most once in 'active'.
- //
- // * An LIns named by 'active[R]' must have an in-use
- // reservation that names R.
- //
- // * And vice versa: an LIns with an in-use reservation that
- // names R must be named by 'active[R]'.
- //
- // * If an LIns's reservation names 'deprecated_UnknownReg' then LIns
- // should not be in 'active'.
- //
- LIns* active[LastRegNum + 1]; // active[REGNUM(r)] = LIns that defines r
- int32_t usepri[LastRegNum + 1]; // used priority. lower = more likely to spill.
- RegisterMask free; // Registers currently free.
- RegisterMask managed; // Registers under management (invariant).
- int32_t priority;
- DECLARE_PLATFORM_REGALLOC()
- };
- // Return the lowest numbered Register in mask.
- inline Register lsReg(RegisterMask mask) {
- // This is faster than it looks; we rely on the C++ optimizer
- // to strip the dead branch and inline just one alternative.
- Register r = { (sizeof(RegisterMask) == 4) ? lsbSet32(mask) : lsbSet64(mask) };
- return r;
- }
- // Return the highest numbered Register in mask.
- inline Register msReg(RegisterMask mask) {
- // This is faster than it looks; we rely on the C++ optimizer
- // to strip the dead branch and inline just one alternative.
- Register r = { (sizeof(RegisterMask) == 4) ? msbSet32(mask) : msbSet64(mask) };
- return r;
- }
- // Clear bit r in mask, then return lsReg(mask).
- inline Register nextLsReg(RegisterMask& mask, Register r) {
- return lsReg(mask &= ~rmask(r));
- }
- // Clear bit r in mask, then return msReg(mask).
- inline Register nextMsReg(RegisterMask& mask, Register r) {
- return msReg(mask &= ~rmask(r));
- }
- }
- #endif // __nanojit_RegAlloc__