/usr/include/js/RegAlloc.h is in libmozjs185-dev 1.8.5-1.0.0+dfsg-4ubuntu1.
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/* ***** 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
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* and other provisions required by the GPL or the LGPL. If you do not delete
* 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
{
NanoAssert(r != deprecated_UnknownReg);
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(r != deprecated_UnknownReg);
NanoAssert(active[REGNUM(r)] == NULL);
active[REGNUM(r)] = v;
useActive(r);
}
void useActive(Register r)
{
NanoAssert(r != deprecated_UnknownReg);
NanoAssert(active[REGNUM(r)] != NULL);
usepri[REGNUM(r)] = priority++;
}
void removeActive(Register r)
{
//registerReleaseCount++;
NanoAssert(r != deprecated_UnknownReg);
NanoAssert(active[REGNUM(r)] != NULL);
// remove the given register from the active list
active[REGNUM(r)] = NULL;
}
void retire(Register r)
{
NanoAssert(r != deprecated_UnknownReg);
NanoAssert(active[REGNUM(r)] != NULL);
active[REGNUM(r)] = NULL;
free |= rmask(r);
}
int32_t getPriority(Register r) {
NanoAssert(r != deprecated_UnknownReg && active[REGNUM(r)]);
return usepri[REGNUM(r)];
}
LIns* getActive(Register r) const {
NanoAssert(r != deprecated_UnknownReg);
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__
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