# define SILENT
/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991, 1992 by Xerox Corporation. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to copy this garbage collector for any purpose,
* provided the above notices are retained on all copies.
*/
/* Machine specific parts contributed by various people. See README file. */
# ifndef GC←PRIVATE←H
# define GC←PRIVATE←H
# ifndef GC←H
# include "gc.h"
# endif
# ifndef HEADERS←H
# include "gc←headers.h"
# endif
typedef int bool;
# define TRUE 1
# define FALSE 0
typedef char * ptr←t; /* A generic pointer to which we can add */
/* byte displacments. */
#ifdef ←←STDC←←
# include <stddef.h>
typedef void * extern←ptr←t;
#else
typedef char * extern←ptr←t;
#endif
/*********************************/
/* */
/* Definitions for conservative */
/* collector */
/* */
/*********************************/
/*********************************/
/* */
/* Easily changeable parameters */
/* */
/*********************************/
# if defined(sun) && defined(mc68000)
# define M68K←SUN
# define mach←type←known
# endif
# if defined(hp9000s300)
# define M68K←HP
# define mach←type←known
# endif
# if defined(vax)
# define VAX
# ifdef ultrix
# define ULTRIX
# else
# define BSD
# endif
# define mach←type←known
# endif
# if defined(mips)
# define MIPS
# ifdef ultrix
# define ULTRIX
# else
# define RISCOS
# endif
# define mach←type←known
# endif
# if defined(sequent) && defined(i386)
# define I386
# define mach←type←known
# endif
# if defined(ibm032)
# define RT
# define mach←type←known
# endif
# if defined(sun) && defined(sparc)
# define SPARC
# define mach←type←known
# endif
# if defined(←IBMR2)
# define IBMRS6000
# define mach←type←known
# endif
# if defined(SCO)
/* define SCO */
# define mach←type←known
/* --> incompletely implemented */
# endif
# if defined(←AUX←SOURCE)
# define M68K←SYSV
# define mach←type←known
# endif
# if defined(←PA←RISC1←0) || defined(←PA←RISC1←1)
# define HP←PA
# define mach←type←known
/* --> incompletely implemented */
# endif
/* Feel free to add more clauses here */
/* Or manually define the machine type here. A machine type is */
/* characterized by the architecture and assembler syntax. Some */
/* machine types are further subdivided by OS. In that case, we use */
/* the macros ULTRIX, RISCOS, and BSD to distinguish. */
/* Note that SGI IRIX is treated identically to RISCOS. */
/* The distinction in these cases is usually the stack starting address */
# ifndef mach←type←known
# define M68K←SUN /* Guess "Sun" */
/* Mapping is: M68K←SUN ==> Sun3 assembler, */
/* M68K←HP ==> HP9000/300, */
/* M68K←SYSV ==> A/UX, maybe others */
/* I386 ==> Sequent Symmetry, */
/* NS32K ==> Encore Multimax, */
/* MIPS ==> R2000 or R3000 */
/* (RISCOS, ULTRIX variants) */
/* VAX ==> DEC VAX */
/* (BSD, ULTRIX variants) */
/* SCO ==> SCO Unix 3.2 */
# endif
#define PRINTSTATS /* Print garbage collection statistics */
/* For less verbose output, undefine in reclaim.c */
#define PRINTTIMES /* Print the amount of time consumed by each garbage */
/* collection. */
#define PRINTBLOCKS /* Print object sizes associated with heap blocks, */
/* whether the objects are atomic or composite, and */
/* whether or not the block was found to be empty */
/* duing the reclaim phase. Typically generates */
/* about one screenful per garbage collection. */
#undef PRINTBLOCKS
#define PRINTBLACKLIST /* Print black listed blocks, i.e. values that */
/* cause the allocator to avoid allocating certain */
/* blocks in order to avoid introducing "false */
/* hits". */
#undef PRINTBLACKLIST
#ifdef SILENT
# ifdef PRINTSTATS
# undef PRINTSTATS
# endif
# ifdef PRINTTIMES
# undef PRINTTIMES
# endif
# ifdef PRINTNBLOCKS
# undef PRINTNBLOCKS
# endif
#endif
#if defined(PRINTSTATS) && !defined(GATHERSTATS)
# define GATHERSTATS
#endif
#ifdef SPARC
# define ALIGN←DOUBLE /* Align objects of size > 1 word on 2 word */
/* boundaries. Wasteful of memory, but */
/* apparently required by SPARC architecture. */
#endif
#define MERGE←SIZES /* Round up some object sizes, so that fewer distinct */
/* free lists are actually maintained. This applies */
/* only to the top level routines in misc.c, not to */
/* user generated code that calls GC←allocobj and */
/* GC←allocaobj directly. */
/* Slows down average programs slightly. May however */
/* substantially reduce fragmentation if allocation */
/* request sizes are widely scattered. */
/* May save significant amounts of space for obj←map */
/* entries. */
/* ALIGN←DOUBLE requires MERGE←SIZES at present. */
# if defined(ALIGN←DOUBLE) && !defined(MERGE←SIZES)
# define MERGE←SIZES
# endif
/* For PRINTTIMES to tell the truth, we need to know the value of HZ for
this system. */
#include <time.h>
#if !defined(CLOCKS←PER←SEC) && !defined(PCR)
/* This is technically a bug in the implementation. ANSI requires that
* CLOCKS←PER←SEC be defined. But at least under SunOS4.1.2, it isn't. */
# if defined(M68K←HP)||defined(M68K←SUN)||defined M68K←SYSV||defined(SPARC)
# include <sys/param.h>
# define FLOAT←HZ (double)HZ
# else
# define FLOAT←HZ 60.0
# endif
#else
# ifdef CLOCKS←PER←SEC
# define FLOAT←HZ (double)CLOCKS←PER←SEC
# else
# define FLOAT←HZ 60.0
# endif
#endif
#if defined(M68K←SUN) || defined(M68K←SYSV)
# define ALIGNMENT 2 /* Pointers are aligned on 2 byte boundaries */
/* by the Sun C compiler. */
#else
# ifdef VAX
# define ALIGNMENT 4 /* Pointers are longword aligned by 4.2 C compiler */
# else
# ifdef RT
# define ALIGNMENT 4
# else
# ifdef SPARC
# define ALIGNMENT 4
# else
# ifdef I386
# define ALIGNMENT 4 /* Sequent compiler aligns pointers */
# else
# ifdef NS32K
# define ALIGNMENT 4 /* Pointers are aligned on NS32K */
# else
# ifdef MIPS
# define ALIGNMENT 4 /* MIPS hardware requires pointer */
/* alignment */
# else
# ifdef M68K←HP
# define ALIGNMENT 2 /* 2 byte alignment inside struct/union, */
/* 4 bytes elsewhere */
# else
# ifdef IBMRS6000
# define ALIGNMENT 4
# else
# ifdef HP←PA
# define ALIGNMENT 4
# else
--> specify alignment <--
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
/* STACKBOTTOM is the cool end of the stack, which is usually the */
/* highest address in the stack. */
/* Under PCR, we have other ways of finding thread stacks. */
#ifndef PCR
# ifdef RT
# define STACKBOTTOM ((ptr←t) 0x1fffd800)
# else
# ifdef I386
# define STACKBOTTOM ((ptr←t) 0x3ffff000) /* For Sequent */
# else
# ifdef NS32K
# define STACKBOTTOM ((ptr←t) 0xfffff000) /* for Encore */
# else
# ifdef MIPS
# ifdef ULTRIX
# define STACKBOTTOM ((ptr←t) 0x7fffc000)
# else
# ifdef RISCOS
# define STACKBOTTOM ((ptr←t) 0x7ffff000)
/* Could probably be slightly lower since */
/* startup code allocates lots of junk */
# else
--> fix it
# endif
# endif
# else
# ifdef M68K←HP
# define STACKBOTTOM ((ptr←t) 0xffeffffc)
/* empirically determined. seems to work. */
# else
# ifdef IBMRS6000
# define STACKBOTTOM ((ptr←t) 0x2ff80000)
# else
# if defined(VAX) && defined(ULTRIX)
# define STACKBOTTOM ((ptr←t) 0x7fffc800)
# else
# ifdef SCO
# define STACKBOTTOM ((ptr←t) 0x7ffffffc)
# else
# ifdef M68K←SYSV
# define STACKBOTTOM ((ptr←t)0xFFFFFFFC)
/* The stack starts at the top of memory, */
/* near as I can figure. --Parag */
# else
# ifdef HP←PA
# include <sys/param.h>
# include <sys/user.h>
# define STACKBOTTOM ((ptr←t) (USRSTACK))
# define STACK←GROWS←UP
# else
/* other VAXes, SPARC, and various flavors of Sun 2s and Sun 3s use */
/* the default heuristic, which is to take the address of a local */
/* variable in gc←init, and round it up to the next multiple */
/* of 16 Meg. This is crucial on Suns, since various models */
/* that are supposed to be able to share executables, do not */
/* use the same stack base. In particular, Sun 3/80s are */
/* different from other Sun 3s. */
/* This probably works on some more of the above machines. */
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
#endif /* PCR */
# ifndef STACK←GROWS←UP
# define STACK←GROWS←DOWN
# endif
/* Start of data segment for each of the above systems. Note that the */
/* default case works only for contiguous text and data, such as on a */
/* Vax. */
# ifdef M68K←SUN
extern char etext;
# define DATASTART ((ptr←t)((((word) (&etext)) + 0x1ffff) & ~0x1ffff))
# else
# ifdef RT
# define DATASTART ((ptr←t) 0x10000000)
# else
# if defined(I386) || defined(SPARC)
extern int etext;
# define DATASTART ((ptr←t)((((word) (&etext)) + 0xfff) & ~0xfff))
/* On very old SPARCs this is too conservative. */
# else
# ifdef NS32K
extern char **environ;
# define DATASTART ((ptr←t)(&environ))
/* hideous kludge: environ is the first */
/* word in crt0.o, and delimits the start */
/* of the data segment, no matter which */
/* ld options were passed through. */
# else
# ifdef MIPS
# define DATASTART 0x10000000
/* Could probably be slightly higher since */
/* startup code allocates lots of junk */
# else
# ifdef M68K←HP
extern char etext;
# define DATASTART ((ptr←t)((((word) (&etext)) + 0xfff) & ~0xfff))
# else
# ifdef IBMRS6000
# define DATASTART ((ptr←t)0x20000000)
# else
# ifdef SCO
# define DATASTART ((ptr←t)(0x00400000
+((long)&etext & 0xFFC00000)
+((long)&etext & 0xFFC00FFF)))
# else
# ifdef M68K←SYSV
/* This only works for shared-text binaries with magic number 0413.
The other sorts of SysV binaries put the data at the end of the text,
in which case the default of &etext would work. Unfortunately,
handling both would require having the magic-number available.
-- Parag
*/
# define DATASTART ((ptr←t)(0x4000000))
# else
# ifdef HP←PA
extern int ←←data←start;
# define DATASTART ((ptr←t)(&←←data←start))
# else
extern char etext;
# define DATASTART ((ptr←t)(&etext))
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# endif
# define HINCR 16 /* Initial heap increment, in blocks of 4K */
# define MAXHINCR 512 /* Maximum heap increment, in blocks */
# define HINCR←MULT 3 /* After each new allocation, GC←hincr is multiplied */
# define HINCR←DIV 2 /* by HINCR←MULT/HINCR←DIV */
# define GC←MULT 3 /* Don't collect if the fraction of */
/* non-collectable memory in the heap */
/* exceeds GC←MUL/GC←DIV */
# define GC←DIV 4
# define NON←GC←HINCR ((word)8)
/* Heap increment if most of heap if collection */
/* was suppressed because most of heap is not */
/* collectable */
/*********************************/
/* */
/* OS interface routines */
/* */
/*********************************/
/* HBLKSIZE aligned allocation. 0 is taken to mean failure */
/* space is assumed to be cleared. */
# ifdef PCR
# ifdef ←←STDC←←
void * real←malloc(size←t size);
# else
char * real←malloc();
# endif
# define GET←MEM(bytes) HBLKPTR(real←malloc((size←t)bytes + HBLKSIZE) \
+ HBLKSIZE-1);
# define THREADS
# else
caddr←t sbrk();
# ifdef ←←STDC←←
# define GET←MEM(bytes) HBLKPTR(sbrk((size←t)(bytes + HBLKSIZE)) \
+ HBLKSIZE-1);
# else
# define GET←MEM(bytes) HBLKPTR(sbrk((int)(bytes + HBLKSIZE)) + HBLKSIZE-1);
# endif
# endif
/*
* Mutual exclusion between allocator/collector routines.
* Needed if there is more than one allocator thread.
* FASTLOCK() is assumed to try to acquire the lock in a cheap and
* dirty way that is acceptable for a few instructions, e.g. by
* inhibiting preemption. This is assumed to have succeeded only
* if a subsequent call to FASTLOCK←SUCCEEDED() returns TRUE.
* If signals cannot be tolerated with the FASTLOCK held, then
* FASTLOCK should disable signals. The code executed under
* FASTLOCK is otherwise immune to interruption, provided it is
* not restarted.
* DCL←LOCK←STATE declares any local variables needed by LOCK and UNLOCK
* and/or DISABLE←SIGNALS and ENABLE←SIGNALS and/or FASTLOCK.
* (There is currently no equivalent for FASTLOCK.)
*/
# ifdef PCR
# include "pcr/th/PCR←Th.h"
# include "pcr/th/PCR←ThCrSec.h"
extern struct PCR←Th←MLRep GC←allocate←ml;
# define DCL←LOCK←STATE PCR←sigset←t GC←old←sig←mask
# define LOCK() PCR←Th←ML←Acquire(&GC←allocate←ml)
# define UNLOCK() PCR←Th←ML←Release(&GC←allocate←ml)
# define FASTLOCK() PCR←ThCrSec←EnterSys()
/* Here we cheat (a lot): */
# define FASTLOCK←SUCCEEDED() (*(int *)(&GC←allocate←ml) == 0)
/* TRUE if nobody currently holds the lock */
# define FASTUNLOCK() PCR←ThCrSec←ExitSys()
# else
# define DCL←LOCK←STATE
# define LOCK()
# define UNLOCK()
# define FASTLOCK() LOCK()
# define FASTLOCK←SUCCEEDED() TRUE
# define FASTUNLOCK() UNLOCK()
# endif
/* Delay any interrupts or signals that may abort this thread. Data */
/* structures are in a consistent state outside this pair of calls. */
/* ANSI C allows both to be empty (though the standard isn't very */
/* clear on that point). Standard malloc implementations are usually */
/* neither interruptable nor thread-safe, and thus correspond to */
/* empty definitions. */
# ifdef PCR
# define DISABLE←SIGNALS() \
PCR←Th←SetSigMask(PCR←allSigsBlocked,&GC←old←sig←mask)
# define ENABLE←SIGNALS() \
PCR←Th←SetSigMask(&GC←old←sig←mask, NIL)
# else
# if 0 /* debugging */
# define DISABLE←SIGNALS()
# define ENABLE←SIGNALS()
# else
# define DISABLE←SIGNALS() GC←disable←signals()
void GC←disable←signals();
# define ENABLE←SIGNALS() GC←enable←signals()
void GC←enable←signals();
# endif
# endif
/*
* Stop and restart mutator threads.
*/
# ifdef PCR
# include "pcr/th/PCR←ThCtl.h"
# define STOP←WORLD() \
PCR←ThCtl←SetExclusiveMode(PCR←ThCtl←ExclusiveMode←stopNormal, \
PCR←allSigsBlocked, \
PCR←waitForever)
# define START←WORLD() \
PCR←ThCtl←SetExclusiveMode(PCR←ThCtl←ExclusiveMode←null, \
PCR←allSigsBlocked, \
PCR←waitForever);
# else
# define STOP←WORLD()
# define START←WORLD()
# endif
/* Abandon ship */
# ifdef PCR
void PCR←Base←Panic(const char *fmt, ...);
# define ABORT(s) PCR←Base←Panic(s)
# else
# define ABORT(s) abort(s)
# endif
/* Exit abnormally, but without making a mess (e.g. out of memory) */
# ifdef PCR
void PCR←Base←Exit(int status);
# define EXIT() PCR←Base←Exit(1)
# else
# ifndef ←←STDC←←
void exit();
# endif
# define EXIT() exit(1)
# endif
/*********************************/
/* */
/* Word-size-dependent defines */
/* */
/*********************************/
#define WORDS←TO←BYTES(x) ((x)<<2)
#define BYTES←TO←WORDS(x) ((x)>>2)
#define CPP←WORDSZ 32
#define WORDSZ ((word)CPP←WORDSZ)
#define LOGWL ((word)5) /* log[2] of above */
#define BYTES←PER←WORD ((word)(sizeof (word)))
#define ONES 0xffffffff
#define MSBYTE 0xff000000
#define SIGNB 0x80000000
#define MAXSHORT 0x7fff
#define modHALFWORDSZ(n) ((n) & 0xf) /* mod n by size of half word */
#define divHALFWORDSZ(n) ((n) >> 4) /* divide n by size of half word */
#define modWORDSZ(n) ((n) & 0x1f) /* mod n by size of word */
#define divWORDSZ(n) ((n) >> 5) /* divide n by size of word */
#define twice(n) ((n) << 1) /* double n */
/*********************/
/* */
/* Size Parameters */
/* */
/*********************/
/* heap block size, bytes. Should be power of 2 */
#define CPP←LOG←HBLKSIZE 12
#define LOG←HBLKSIZE ((word)CPP←LOG←HBLKSIZE)
#define CPP←HBLKSIZE (1 << CPP←LOG←HBLKSIZE)
#define HBLKSIZE ((word)CPP←HBLKSIZE)
/* max size objects supported by freelist (larger objects may be */
/* allocated, but less efficiently) */
#define CPP←MAXOBJSZ BYTES←TO←WORDS(CPP←HBLKSIZE/2)
#define MAXOBJSZ ((word)CPP←MAXOBJSZ)
# define divHBLKSZ(n) ((n) >> LOG←HBLKSIZE)
# define modHBLKSZ(n) ((n) & (HBLKSIZE-1))
# define HBLKPTR(objptr) ((struct hblk *)(((word) (objptr)) & ~(HBLKSIZE-1)))
# define HBLKDISPL(objptr) (((word) (objptr)) & (HBLKSIZE-1))
/********************************************/
/* */
/* H e a p B l o c k s */
/* */
/********************************************/
/* heap block header */
#define HBLKMASK (HBLKSIZE-1)
#define BITS←PER←HBLK (HBLKSIZE * 8)
#define MARK←BITS←PER←HBLK (BITS←PER←HBLK/CPP←WORDSZ)
/* upper bound */
/* We allocate 1 bit/word. Only the first word */
/* in each object is actually marked. */
# ifdef ALIGN←DOUBLE
# define MARK←BITS←SZ (((MARK←BITS←PER←HBLK + 2*CPP←WORDSZ - 1) \
/ (2*CPP←WORDSZ))*2)
# else
# define MARK←BITS←SZ ((MARK←BITS←PER←HBLK + CPP←WORDSZ - 1)/CPP←WORDSZ)
# endif
/* Upper bound on number of mark words per heap block */
/* Mark stack entries. */
typedef struct ms←entry {
word * mse←start; /* inclusive */
word * mse←end; /* exclusive */
} mse;
typedef mse * (*mark←proc)(/* word * addr, hdr * hhdr, mse * msp, mse * msl */);
/* Procedure to arrange for the descendents of the object at */
/* addr to be marked. Msp points at the top entry on the */
/* mark stack. Msl delimits the hot end of the mark stack. */
/* hhdr is the hdr structure corresponding to addr. */
/* Returns the new mark stack pointer. */
struct hblkhdr {
signed←word hb←sz; /* If in use, size in words, of objects in the block. */
/* if free, the size in bytes of the whole block */
struct hblk * hb←next; /* Link field for hblk free list */
/* and for lists of chunks waiting to be */
/* reclaimed. */
mark←proc hb←mark←proc; /* Procedure to mark objects. Can */
/* also be retrived through obj←kind. */
/* But one level of indirection matters */
/* here. */
char* hb←map; /* A pointer to a pointer validity map of the block. */
/* See GC←obj←map. */
/* Valid for all blocks with headers. */
int hb←obj←kind; /* Kind of objects in the block. Each kind */
/* identifies a mark procedure and a set of */
/* list headers. sometimes called regions. */
word hb←marks[MARK←BITS←SZ];
/* Bit i in the array refers to the */
/* object starting at the ith word (header */
/* INCLUDED) in the heap block. */
};
/* heap block body */
# define DISCARD←WORDS 0
/* Number of words to be dropped at the beginning of each block */
/* Must be a multiple of 32. May reasonably be nonzero */
/* on mcachines that don't guarantee longword alignment of */
/* pointers, so that the number of false hits is minimized. */
/* 0 and 32 are probably the only reasonable values. */
# define BODY←SZ ((HBLKSIZE-WORDS←TO←BYTES(DISCARD←WORDS))/sizeof(word))
struct hblk {
# if (DISCARD←WORDS != 0)
word garbage[DISCARD←WORDS];
# endif
word hb←body[BODY←SZ];
};
# define HDR←WORDS ((word)DISCARD←WORDS)
# define HDR←BYTES ((word)WORDS←TO←BYTES(DISCARD←WORDS))
/* Object free list link */
# define obj←link(p) (*(ptr←t *)(p))
/* lists of all heap blocks and free lists */
/* These are grouped together in a struct */
/* so that they can be easily skipped by the */
/* GC←mark routine. */
/* The ordering is weird to make GC←malloc */
/* faster by keeping the important fields */
/* sufficiently close together that a */
/* single load of a base register will do. */
struct ←GC←arrays {
word ←heapsize;
ptr←t ←last←heap←addr;
ptr←t ←prev←heap←addr;
word ←words←allocd;
/* Number of words allocated during this collection cycle */
ptr←t ←objfreelist[MAXOBJSZ+1];
/* free list for objects */
# ifdef MERGE←SIZES
unsigned ←size←map[WORDS←TO←BYTES(MAXOBJSZ+1)];
/* Number of words to allocate for a given allocation request in */
/* bytes. */
# endif
ptr←t ←aobjfreelist[MAXOBJSZ+1];
/* free list for atomic objs*/
ptr←t ←obj←map[MAXOBJSZ+1];
/* If not NIL, then a pointer to a map of valid */
/* object addresses. hbh←map[sz][i] is j if the */
/* address block←start+i is a valid pointer */
/* to an object at block←start+i&~3 - 4*j. It */
/* is OBJ←INVALID if block←start+4*i is not */
/* valid as a pointer to an object. */
/* We assume that all values of j <= OBJ←INVALID */
/* The zeroth entry corresponds to large objects.*/
# define OBJ←INVALID 0x7f
# define CPP←MAX←OFFSET (WORDS←TO←BYTES(OBJ←INVALID) - 1)
# define MAX←OFFSET ((word)CPP←MAX←OFFSET)
struct hblk * ←reclaim←list[MAXOBJSZ+1];
struct hblk * ←areclaim←list[MAXOBJSZ+1];
};
# define VALID←OFFSET←SZ \
(CPP←MAX←OFFSET > WORDS←TO←BYTES(CPP←MAXOBJSZ)? \
CPP←MAX←OFFSET+1 \
: WORDS←TO←BYTES(CPP←MAXOBJSZ)+1)
extern char GC←valid←offsets[VALID←OFFSET←SZ];
/* GC←valid←offsets[i] == TRUE ==> i */
/* is registered as a displacement. */
extern char GC←modws←valid←offsets[sizeof(word)];
/* GC←valid←offsets[i] ==> */
/* GC←modws←valid←offsets[i%sizeof(word)] */
extern struct ←GC←arrays GC←arrays;
# define GC←objfreelist GC←arrays.←objfreelist
# define GC←aobjfreelist GC←arrays.←aobjfreelist
# define GC←reclaim←list GC←arrays.←reclaim←list
# define GC←areclaim←list GC←arrays.←areclaim←list
# define GC←obj←map GC←arrays.←obj←map
# define GC←last←heap←addr GC←arrays.←last←heap←addr
# define GC←prev←heap←addr GC←arrays.←prev←heap←addr
# define GC←words←allocd GC←arrays.←words←allocd
# define GC←heapsize GC←arrays.←heapsize
# ifdef MERGE←SIZES
# define GC←size←map GC←arrays.←size←map
# endif
# define beginGC←arrays ((ptr←t)(&GC←arrays))
# define endGC←arrays (((ptr←t)(&GC←arrays)) + (sizeof GC←arrays))
# define MAXOBJKINDS 16
/* Object kinds: */
extern struct obj←kind {
ptr←t *ok←freelist; /* Array of free listheaders for this kind of object */
/* Point either to GC←arrays or to storage allocated */
/* with GC←scratch←alloc. */
struct hblk **ok←reclaim←list;
/* List headers for lists of blocks waiting to be */
/* swept. */
mark←proc ok←mark←proc; /* Procedure to either mark referenced objects, */
/* or push them on the mark stack. */
bool ok←init; /* Clear objects before putting them on the free list. */
} GC←obj←kinds[MAXOBJKINDS];
/* Predefined kinds: */
# define PTRFREE 0
# define NORMAL 1
extern int GC←n←kinds;
extern char * GC←invalid←map;
/* Pointer to the nowhere valid hblk map */
/* Blocks pointing to this map are free. */
extern struct hblk * GC←hblkfreelist;
/* List of completely empty heap blocks */
/* Linked through hb←next field of */
/* header structure associated with */
/* block. */
extern bool GC←is←initialized; /* GC←init() has been run. */
extern word GC←words←allocd←before←gc;
/* Number of words allocated before this */
/* collection cycle. */
# ifdef GATHERSTATS
extern word GC←composite←in←use;
/* Number of words in accessible composite */
/* objects. */
extern word GC←atomic←in←use;
/* Number of words in accessible atomic */
/* objects. */
# endif
# ifndef PCR
extern ptr←t GC←stackbottom; /* Cool end of user stack */
# endif
extern word GC←hincr; /* current heap increment, in blocks */
extern ptr←t GC←least←plausible←heap←addr;
extern ptr←t GC←greatest←plausible←heap←addr;
/* Bounds on the heap. Guaranteed valid */
/* Likely to include future heap expansion. */
/* Operations */
# define update←GC←hincr GC←hincr = (GC←hincr * HINCR←MULT)/HINCR←DIV; \
if (GC←hincr > MAXHINCR) {GC←hincr = MAXHINCR;}
# define abs(x) ((x) < 0? (-(x)) : (x))
/****************************/
/* */
/* Objects */
/* */
/****************************/
/* Marks are in a reserved area in */
/* each heap block. Each word has one mark bit associated */
/* with it. Only those corresponding to the beginning of an */
/* object are used. */
/* Operations */
/*
* Retrieve, set, clear the mark bit corresponding
* to the nth word in a given heap block.
*
* (Recall that bit n corresponds to object beginning at word n
* relative to the beginning of the block, including unused words)
*/
# define mark←bit←from←hdr(hhdr,n) (((hhdr)->hb←marks[divWORDSZ(n)] \
>> (modWORDSZ(n))) & 1)
# define set←mark←bit←from←hdr(hhdr,n) (hhdr)->hb←marks[divWORDSZ(n)] \
|= 1 << modWORDSZ(n)
# define clear←mark←bit←from←hdr(hhdr,n) (hhdr)->hb←marks[divWORDSZ(n)] \
&= ~(1 << modWORDSZ(n))
/* Important internal collector routines */
void GC←apply←to←all←blocks(/*fn, client←data*/);
/* Invoke fn(hbp, client←data) for each */
/* allocated heap block. */
mse * GC←no←mark←proc(/*addr,hhdr,msp,msl*/);
/* Mark procedure for PTRFREE objects. */
mse * GC←normal←mark←proc(/*addr,hhdr,msp,msl*/);
/* Mark procedure for NORMAL objects. */
void GC←mark←init();
void GC←mark(); /* Mark from everything on the mark stack. */
void GC←mark←reliable(); /* as above, but fix things up after */
/* a mark stack overflow. */
void GC←mark←all(/*b,t*/); /* Mark from everything in a range. */
void GC←mark←all←stack(/*b,t*/); /* Mark from everything in a range, */
/* consider interior pointers as valid */
void GC←remark(); /* Mark from all marked objects. Used */
/* only if we had to drop something. */
void GC←tl←mark(/*p*/); /* Mark from a single root. */
void GC←add←to←black←list←normal(/* bits */);
/* Register bits as a possible future false */
/* reference from the heap or static data */
void GC←add←to←black←list←stack(/* bits */);
struct hblk * GC←is←black←listed(/* h, len */);
/* If there are likely to be false references */
/* to a block starting at h of the indicated */
/* length, then return the next plausible */
/* starting location for h that might avoid */
/* these false references. */
void GC←promote←black←lists();
/* Declare an end to a black listing phase. */
ptr←t GC←scratch←alloc(/*bytes*/);
/* GC internal memory allocation for */
/* small objects. Deallocation is not */
/* possible. */
void GC←invalidate←map(/* hdr */);
/* Remove the object map associated */
/* with the block. This identifies */
/* the block as invalid to the mark */
/* routines. */
void GC←add←map←entry(/*sz*/);
/* Add a heap block map for objects of */
/* size sz to obj←map. */
void GC←register←displacement←inner(/*offset*/);
/* Version of GC←register←displacement */
/* that assumes lock is already held */
/* and signals are already disabled. */
void GC←init←inner();
void GC←new←hblk(/*size←in←words, kind*/);
/* Allocate a new heap block, and build */
/* a free list in it. */
struct hblk * GC←allochblk(/*size←in←words, kind*/);
/* Allocate a heap block, clear it if */
/* for composite objects, inform */
/* the marker that block is valid */
/* for objects of indicated size. */
/* sz < 0 ==> atomic. */
void GC←freehblk(); /* Deallocate a heap block and mark it */
/* as invalid. */
void GC←start←reclaim(/*abort←if←found*/);
/* Restore unmarked objects to free */
/* lists, or (if abort←if←found is */
/* TRUE) report them. */
/* Sweeping of small object pages is */
/* largely deferred. */
void GC←continue←reclaim(/*size, kind*/);
/* Sweep pages of the given size and */
/* kind, as long as possible, and */
/* as long as the corr. free list is */
/* empty. */
void GC←gcollect←inner(); /* Collect; caller must have acquired */
/* lock and disabled signals. */
void GC←init(); /* Initialize collector. */
ptr←t GC←generic←malloc(/* bytes, kind */);
/* Allocate an object of the given */
/* kind. By default, there are only */
/* two kinds: composite, and atomic. */
/* We claim it's possible for clever */
/* client code that understands GC */
/* internals to add more, e.g. to */
/* communicate object layout info */
/* to the collector. */
ptr←t GC←generic←malloc←words←small(/*words, kind*/);
/* As above, but size in units of words */
/* Bypasses MERGE←SIZES. Assumes */
/* words <= MAXOBJSZ. */
ptr←t GC←allocobj(/* sz←inn←words, kind */);
/* Make the indicated */
/* free list nonempty, and return its */
/* head. */
void GC←install←header(/*h*/);
/* Install a header for block h. */
void GC←install←counts(/*h, sz*/);
/* Set up forwarding counts for block */
/* h of size sz. */
void GC←remove←header(/*h*/);
/* Remove the header for block h. */
void GC←remove←counts(/*h, sz*/);
/* Remove forwarding counts for h. */
hdr * GC←find←header(/*p*/); /* Debugging only. */
void GC←finalize(); /* Perform all indicated finalization actions */
/* on unmarked objects. */
void GC←add←to←heap(/*p, bytes*/);
/* Add a HBLKSIZE aligned chunk to the heap. */
# endif /* GC←PRIVATE←H */